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<p style="font: 8pt Times New Roman, Times, Serif; margin: 0"><b><i>Description of Business</i></b></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.5in">We are a biopharmaceutical company dedicated
to developing and delivering medicines for patients with B-cell mediated diseases, including Chronic Lymphocytic Leukemia (CLL),
non-Hodgkin Lymphoma (NHL) and Multiple Sclerosis (MS). We have developed a robust B-cell directed research and development (R&D)
platform for identification of key B-cell pathways of interest and rapid clinical testing. Currently, we have five B-cell targeted
drug candidates in clinical development, with the lead two therapies, ublituximab (TG-1101) and umbralisib (TGR-1202), in pivotal
trials for CLL and NHL, with ublituximab also in pivotal trials for MS. Ublituximab is a novel anti-CD20 monoclonal antibody (mAb)
that has been glycoengineered for enhanced potency over first generation antibodies. Umbralisib is an oral, once daily inhibitor
of PI3K delta. Umbralisib also uniquely inhibits CK1-epsilon, which may allow it to overcome certain tolerability issues associated
with first generation PI3K delta inhibitors. When used together in combination therapy, ublituximab and umbralisib are referred
to as "U2". Additionally, we have recently brought into Phase 1 clinical development TG-1501, an anti-PD-L1 monoclonal
antibody, TG-1701, a covalently-bound Bruton’s Tyrosine Kinase (BTK) inhibitor, and TG-1801, an anti-CD47/CD19 bispecific
antibody.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">We also actively evaluate
complementary products, technologies and companies for in-licensing, partnership, acquisition and/or investment opportunities.
To date, we have not received approval for the sale of any of our drug candidates in any market and, therefore, have not generated
any product sales from our drug candidates.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">The accompanying unaudited
condensed consolidated financial statements were prepared in accordance with U.S. generally accepted accounting principles, or
GAAP, for interim financial information and with the instructions to Quarterly Report on Form 10-Q and Article 10 of Regulation
S-X of the Exchange Act. Accordingly, they may not include all of the information and footnotes required by GAAP for complete financial
statements. All adjustments that are, in the opinion of management, of a normal recurring nature and are necessary for a fair presentation
of the condensed consolidated financial statements have been included. Nevertheless, these condensed consolidated financial statements
should be read in conjunction with the audited consolidated financial statements contained in our Annual Report on Form 10-K for
the year ended December 31, 2018. The accompanying condensed December 31, 2018 balance sheet has been derived from these statements.
The results of operations for the three months ended March 31, 2019 are not necessarily indicative of the results that may be expected
for the entire fiscal year or any other interim period.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0"><b><i>Liquidity and Capital Resources</i></b></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">We have incurred operating
losses since our inception, expect to continue to incur operating losses for the foreseeable future, and may never become profitable.
As of March 31, 2019, we have an accumulated deficit of approximately $563.5 million.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Our major sources of cash
have been proceeds from the private placement and public offering of equity securities, as well as debt financings. We have not
yet commercialized any of our drug candidates and cannot be sure if we will ever be able to do so. Even if we commercialize one
or more of our drug candidates, we may not become profitable. Our ability to achieve profitability depends on many factors, including
our ability to obtain regulatory approval for our drug candidates; successfully complete any post-approval regulatory obligations;
and successfully commercialize our drug candidates alone or in partnership. We may continue to incur substantial operating losses
even if we begin to generate revenues from our drug candidates.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">As of March 31, 2019, we
had $92.5 million in cash and cash equivalents, and investment securities. The Company believes its cash, cash equivalents, and
investment securities on hand as of March 31, 2019 along with the additional capital raised in the second quarter of 2019 (see
Note 5) will be sufficient to fund the Company’s planned operations through mid-2020. The actual amount of cash that we will
need to operate is subject to many factors, including, but not limited to, the timing, design and conduct of clinical trials for
our drug candidates. We are dependent upon significant future financing to provide the cash necessary to execute our current operations,
including the commercialization of any of our drug candidates.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Our common stock is listed
on the Nasdaq Capital Market and trades under the symbol “TGTX.”</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0"><b><i>Recently Issued Accounting Standards</i></b></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">In July 2018, the Financial
Accounting Standards Board ("FASB") issued Accounting Standards Update (“ASU”) No. 2018-11, “Leases -
Targeted Improvements” (“ASU 2018-11”) as an update to ASU 2016-02, Leases (“ASU 2016-02” or “Topic
842”) issued on February 25, 2016. ASU 2016-02 is effective for public business entities for fiscal years beginning January
1, 2019. ASU 2016-02 required companies to adopt the new leases standard at the beginning of the earliest period presented in the
financial statements, which is January 1, 2017, using a modified retrospective transition method where lessees must recognize lease
assets and liabilities for all leases even though those leases may have expired before the effective date of January 1, 2017. Lessees
must also provide the new and enhanced disclosures for each period presented, including the comparative periods.</p>
<p style="font: 12pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">ASU 2018-11 provides an
entity with an additional (and optional) transition method to adopt the new leases standard. Under this new transition method,
an entity initially applies the new lease standard at the adoption date and recognizes a cumulative-effect adjustment to the opening
balance of retained earnings in the period of adoption. Consequently, an entity’s reporting for the comparative periods presented
in the financial statements in which it adopts the new lease standard will continue to be in accordance with ASC 840, Leases. An
entity that elects this additional (and optional) transition method must provide the required ASC 840 disclosures for all periods
that continue to be in accordance with ASC 840. The amendments do not change the existing disclosure requirements in ASC 840.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">ASU 2018-11 is effective
for public business entities for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years,
with earlier adoption permitted. The Company adopted ASU 2018-11 on January 1, 2019 using a modified retrospective method and will
not restate comparative periods. We elected the package of practical expedients permitted under the transition guidance, which
allows us to carryforward our historical lease classification and our assessment on whether a contract is or contains a lease.
The adoption of this guidance resulted in the addition of material balances of right of use assets and lease liability to our consolidated
balance sheets at January 1, 2019, primarily relating to our lease of office space (see Note 8). The impact to our consolidated
statements of operations was not material as a result of this standard.</p>
<p style="font: 12pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">In June 2018, the FASB issued
ASU No. 2018-07, “Improvements to Nonemployee Share-Based Payment Accounting” (“ASU 2018-07”). ASU 2018-07
expands the scope of FASB Topic 718, Compensation – Stock Compensation (“Topic 718”) to include share-based payment
transactions for acquiring goods and services from nonemployees. An entity should only remeasure equity-classified awards for which
a measurement date has not been established through a cumulative-effect adjustment to retained earnings as of the beginning of
the fiscal year of adoption. Upon transition, the entity is required to measure these nonemployee awards at fair value as of the
adoption date. The entity must not remeasure assets that are completed. Disclosures required at transition include the nature of
and reason for the change in accounting principle and, if applicable, quantitative information about the cumulative effect of the
change on retained earnings or other components of equity.</p>
<p style="font: 12pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">ASU 2018-07 is effective
for public business entities for fiscal years beginning after December 15, 2018, including interim periods within that fiscal year.
The Company adopted ASU 2018-07 on January 1, 2019. The adoption of ASU 2018-07 did not have a material effect on our consolidated
financial statements as of January 1, 2019. The adoption of ASU 2018-07 had no impact on nonemployee performance awards as they
are measured based on the outcome that is probable.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Other pronouncements issued
by the FASB or other authoritative accounting standards group with future effective dates are either not applicable or not significant
to our consolidated financial statements.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0"><b><i>Use of Estimates</i></b></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.5in">The preparation of financial statements in conformity
with U.S. generally accepted accounting principles (“GAAP”) requires management to make estimates and judgments that
affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the
financial statements and the reported amounts of revenues and expenses during the applicable reporting period. On an ongoing basis,
we evaluate our estimates and judgments, including those related to accrued expenses and stock-based compensation. Actual results
could differ from those estimates. Such differences could be material to the financial statements.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0"><b><i>Cash and Cash Equivalents</i></b></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">We treat liquid investments
with original maturities of less than three months when purchased as cash and cash equivalents.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"><b><i>Restricted Cash</i></b></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">We record cash pledged or
held in trust as restricted cash. As of March 31, 2019 and December 31, 2018, we have approximately $1.2 million of restricted
cash pledged to secure a line of credit as a security deposit for an <font style="background-color: white">Office Agreement</font>
(see Note 10).</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"><b><i>Investment Securities</i></b></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Investment securities at
March 31, 2019 and December 31, 2018 consist of short-term government securities. We classify these securities as held-to-maturity.
Held-to-maturity securities are those securities in which we have the ability and intent to hold the security until maturity. Held-to-maturity
securities are recorded at amortized cost, adjusted for the amortization or accretion of premiums or discounts. Premiums and discounts
are amortized or accreted over the life of the related held-to-maturity security as an adjustment to yield using the effective
interest method.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">A decline in the market
value of any investment security below cost, that is deemed to be other than temporary, results in a reduction in the carrying
amount to fair value. The impairment is charged to operations and a new cost basis for the security is established. Other-than-temporary
impairment charges are included in interest and other income (expense), net. Unrealized gains, if determined to be temporary, are
included in accumulated other comprehensive income in equity. Dividend and interest income are recognized when earned.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"><b><i>Credit Risk</i></b></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Financial instruments that
potentially subject the Company to concentrations of credit risk consist primarily of cash and cash equivalents and short-term
investments. The Company maintains its cash and cash equivalents and short-term investments with high-credit quality financial
institutions. At times, such amounts may exceed federally-insured limits.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0"><b><i>Revenue Recognition</i></b></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Effective January 1, 2018,
the Company began recognizing revenue under ASC Topic 606, <i>Revenue from Contracts with Customers</i> (“ASC 606”),
using the modified retrospective transition method. The impact of adopting the new revenue standard was not material to our
consolidated financial statements and there was no adjustment to beginning retained earnings on January 1, 2018. The core
principle of this new revenue standard is that a company should recognize revenue to depict the transfer of promised goods or services
to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods
or services. The following five steps are applied to achieve that core principle:</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0 0 0 0.75in; text-indent: -0.25in"> </p>
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<td style="font: 12pt Times New Roman, Times, Serif; text-align: justify"><font style="font-size: 8pt">Step 1: Identify the contract with the customer</font></td></tr>
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<p style="font: 12pt Times New Roman, Times, Serif; margin: 0"> </p>
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<tr>
<td style="vertical-align: top; width: 52px; padding-left: 0.5in; font: 12pt Times New Roman, Times, Serif; text-align: right"><font style="font-size: 8pt">●</font></td>
<td style="font: 12pt Times New Roman, Times, Serif; text-align: justify"><font style="font-size: 8pt">Step 2: Identify the performance obligations in the contract</font></td></tr>
</table>
<p style="font: 12pt Times New Roman, Times, Serif; margin: 0"> </p>
<table cellpadding="0" style="width: 100%">
<tr>
<td style="vertical-align: top; width: 52px; padding-left: 0.5in; font: 12pt Times New Roman, Times, Serif; text-align: right"><font style="font-size: 8pt">●</font></td>
<td style="font: 12pt Times New Roman, Times, Serif; text-align: justify"><font style="font-size: 8pt">Step 3: Determine the transaction price</font></td></tr>
</table>
<p style="font: 12pt Times New Roman, Times, Serif; margin: 0"> </p>
<table cellpadding="0" style="width: 100%">
<tr>
<td style="vertical-align: top; width: 52px; padding-left: 0.5in; font: 12pt Times New Roman, Times, Serif; text-align: right"><font style="font-size: 8pt">●</font></td>
<td style="font: 12pt Times New Roman, Times, Serif; text-align: justify"><font style="font-size: 8pt">Step 4: Allocate the transaction price to the performance obligations in the contract</font></td></tr>
</table>
<p style="font: 12pt Times New Roman, Times, Serif; margin: 0"> </p>
<table cellpadding="0" style="width: 100%">
<tr>
<td style="vertical-align: top; width: 52px; padding-left: 0.5in; font: 12pt Times New Roman, Times, Serif; text-align: right"><font style="font-size: 8pt">●</font></td>
<td style="font: 12pt Times New Roman, Times, Serif; text-align: justify"><font style="font-size: 8pt">Step 5: Recognize revenue when the company satisfies a performance obligation</font></td></tr>
</table>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0 0 0 0.75in; text-indent: -0.25in"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">In order to identify the
performance obligations in a contract with a customer, a company must assess the promised goods or services in the contract and
identify each promised good or service that is distinct. A performance obligation meets ASC 606’s definition of a “distinct”
good or service (or bundle of goods or services) if both of the following criteria are met:</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0 0 0 0.75in; text-align: justify; text-indent: -0.25in"> </p>
<table cellpadding="0" style="width: 100%">
<tr>
<td style="vertical-align: top; width: 52px; padding-left: 0.5in; font: 12pt Times New Roman, Times, Serif; text-align: right"><font style="font-size: 8pt">●</font></td>
<td style="font: 12pt Times New Roman, Times, Serif; text-align: justify"><font style="font-size: 8pt">The customer can benefit from the good or service either on its own or together with other resources that are readily available to the customer (i.e., the good or service is capable of being distinct).</font></td></tr>
</table>
<p style="font: 12pt Times New Roman, Times, Serif; margin: 0"> </p>
<table cellpadding="0" style="width: 100%">
<tr>
<td style="vertical-align: top; width: 52px; padding-left: 0.5in; font: 12pt Times New Roman, Times, Serif; text-align: right"><font style="font-size: 8pt">●</font></td>
<td style="font: 12pt Times New Roman, Times, Serif; text-align: justify"><font style="font-size: 8pt">The entity’s promise to transfer the good or service to the customer is separately identifiable from other promises in the contract (i.e., the promise to transfer the good or service is distinct within the context of the contract).</font></td></tr>
</table>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">If a good or service is
not distinct, the good or service is combined with other promised goods or services until a bundle of goods or services is identified
that is distinct.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">The transaction price is
the amount of consideration to which an entity expects to be entitled in exchange for transferring promised goods or services to
a customer, excluding amounts collected on behalf of third parties (for example, some sales taxes). The consideration promised
in a contract with a customer may include fixed amounts, variable amounts, or both. Variable consideration is included in the transaction
price only to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will not
occur when the uncertainty associated with the variable consideration is subsequently resolved.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.25in"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">The transaction price is
allocated to each performance obligation on a relative standalone selling price basis. The transaction price allocated to each
performance obligation is recognized when that performance obligation is satisfied, at a point in time or over time as appropriate.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: right"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"><b><i>Research and Development Costs</i></b></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Generally, research and
development costs are expensed as incurred. Nonrefundable advance payments for goods or services that will be used or rendered
for future research and development activities are deferred and amortized over the period that the goods are delivered or the related
services are performed, subject to an assessment of recoverability. We make estimates of costs incurred in relation to external
clinical research organizations, or CROs, and clinical site costs. We analyze the progress of clinical trials, including levels
of patient enrollment, invoices received and contracted costs when evaluating the adequacy of the amount expensed and the related
prepaid asset and accrued liability. Significant judgments and estimates must be made and used in determining the accrued balance
and expense in any accounting period. We review and accrue CRO expenses and clinical trial study expenses based on work performed
and rely upon estimates of those costs applicable to the stage of completion of a study. Accrued CRO costs are subject to revisions
as such trials progress to completion. Revisions are charged to expense in the period in which the facts that give rise to the
revision become known. With respect to clinical site costs, the financial terms of these agreements are subject to negotiation
and vary from contract to contract. Payments under these contracts may be uneven, and depend on factors such as the achievement
of certain events, the successful recruitment of patients, the completion of portions of the clinical trial or similar conditions.
The objective of our policy is to match the recording of expenses in our financial statements to the actual services received and
efforts expended. As such, expense accruals related to clinical site costs are recognized based on our estimate of the degree of
completion of the event or events specified in the specific clinical study or trial contract.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Prepaid research and development
in our consolidated balance sheets includes, among other things, certain costs to third party service providers related to development
and manufacturing services as well as clinical development. These agreements often require payments in advance of services performed
or goods received. Accordingly, as of March 31, 2019 and December 31, 2018, we recorded approximately $11.1 million and $9.7 million,
respectively, in prepaid research and development related to such advance agreements.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"><b><i>Income Taxes</i></b></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Income taxes are accounted
for under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable
to temporary differences between the financial statement carrying amounts of existing assets and liabilities and their respective
tax bases, operating losses and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates
expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled.
The effect on deferred tax assets and liabilities of a change in tax rates is recognized in operations in the period that includes
the enactment date. If the likelihood of realizing the deferred tax assets or liability is less than “more likely than not,”
a valuation allowance is then created.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">We, and our subsidiaries,
file income tax returns in the U.S. Federal jurisdiction and in various states. We have tax net operating loss carryforwards that
are subject to examination for a number of years beyond the year in which they were generated for tax purposes. Since a portion
of these net operating loss carryforwards may be utilized in the future, many of these net operating loss carryforwards will remain
subject to examination. We recognize interest and penalties related to uncertain income tax positions in income tax expense.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0"><b><i>Stock-Based Compensation</i></b></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">We recognize all stock-based
payments to employees and non-employee directors (as compensation for service) as noncash compensation expense in the condensed
consolidated financial statements based on the fair values of such payments. Stock-based compensation expense recognized each period
is based on the value of the portion of stock-based payment awards that is ultimately expected to vest during the period. Forfeitures
are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">In addition, because some
of the options, restricted stock and warrants issued to employees, consultants and other third-parties vest upon achievement of
certain milestones, the total expense is uncertain. Compensation expense for such awards that vest upon the achievement of milestones
is recognized when the achievement of such milestones becomes probable.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0"><b><i>Basic and Diluted Net Loss Per Common Share</i></b></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Basic net loss per share
of our common stock is calculated by dividing net loss applicable to the common stock by the weighted average number of our common
stock outstanding for the period. Diluted net loss per share of common stock is the same as basic net loss per share of common
stock since potentially dilutive securities from stock options, stock warrants and convertible preferred stock would have an antidilutive
effect either because we incurred a net loss during the periods presented or because such potentially dilutive securities were
out of the money and the Company realized net income during the periods presented. The amounts of potentially dilutive securities
excluded from the calculation were 6,768,530 and 4,660,180 for the three months ended March 31, 2019 and 2018, respectively. The
following outstanding shares of potentially dilutive securities were excluded from the computation of net loss per share attributable
to common stockholders for the periods presented because including them would have been antidilutive:</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="6" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Three Months Ended March 31,</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>2019</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>2018</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td style="width: 64%"><font style="font-size: 8pt">Unvested restricted stock</font></td>
<td style="width: 1%"> </td>
<td style="width: 1%"> </td>
<td style="width: 14%; text-align: right"><font style="font-size: 8pt">4,039,620</font></td>
<td style="width: 1%"> </td>
<td style="width: 1%"> </td>
<td style="width: 1%"> </td>
<td style="width: 14%; text-align: right"><font style="font-size: 8pt">4,159,428</font></td>
<td style="width: 3%"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Stock options</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">2,565,310</font></td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">485,000</font></td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Warrants</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">147,058</font></td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">--</font></td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Shares issuable upon note conversion</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"> </td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">16,542</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"> </td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">15,752</font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Total</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"> </td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">6,768,530</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"> </td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">4,660,180</font></td>
<td style="padding-bottom: 3pt"> </td></tr>
</table>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0"><b><i>Long-Lived Assets and Goodwill</i></b></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Long-lived assets are reviewed
for potential impairment when circumstances indicate that the carrying value of long-lived tangible and intangible assets with
finite lives may not be recoverable. Management’s policy in determining whether an impairment indicator exists, a triggering
event, comprises measurable operating performance criteria as well as qualitative measures. If an analysis is necessitated by the
occurrence of a triggering event, we make certain assumptions in determining the impairment amount. If the carrying amount of an
asset exceeds its estimated future cash flows, an impairment charge is recognized.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Goodwill is reviewed for
impairment annually, or earlier when events arise that could indicate that an impairment exists. We test for goodwill impairment
using a two-step process. The first step compares the fair value of the reporting unit with the unit's carrying value, including
goodwill. When the carrying value of the reporting unit is greater than fair value, the unit’s goodwill may be impaired,
and the second step must be completed to measure the amount of the goodwill impairment charge, if any. In the second step, the
implied fair value of the reporting unit’s goodwill is compared with the carrying amount of the unit’s goodwill. If
the carrying amount is greater than the implied fair value, the carrying value of the goodwill must be written down to its implied
fair value. We will continue to perform impairment tests annually, at December 31, and whenever events or changes in circumstances
suggest that the carrying value of an asset may not be recoverable.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.5in">The following tables summarize our cash and cash
equivalents at March 31, 2019 and December 31, 2018:</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">(in thousands)</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>March 31, 2019</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>December 31, 2018</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td style="width: 64%"><font style="font-size: 8pt">Checking and bank deposits</font></td>
<td style="width: 1%"> </td>
<td style="width: 1%"><font style="font-size: 8pt">$</font></td>
<td style="width: 15%; text-align: right"><font style="font-size: 8pt">62,671</font></td>
<td style="width: 1%"> </td>
<td style="width: 1%"> </td>
<td style="width: 1%"><font style="font-size: 8pt">$</font></td>
<td style="width: 15%; text-align: right"><font style="font-size: 8pt">39,268</font></td>
<td style="width: 1%"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Money market funds</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"> </td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">1,678</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"> </td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">2,690</font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Total</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">64,349</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">41,958</font></td>
<td style="padding-bottom: 3pt"> </td></tr>
</table>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.5in">Our investments as of March 31, 2019 and December
31, 2018 are classified as held-to-maturity. Held-to-maturity investments are recorded at amortized cost.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.5in">The following tables summarize our investment
securities at March 31, 2019 and December 31, 2018:</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">(in thousands)</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="14" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>March 31, 2019</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Amortized cost, as adjusted</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Gross unrealized holding gains</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Gross unrealized holding losses</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Estimated fair value</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Short-term investments:</font></td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td style="width: 49%"><font style="font-size: 8pt">Obligations of domestic governmental agencies (maturing between April 2019 to March 2020) (held-to-maturity)</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">28,113</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">15</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">3</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">28,125</font></td>
<td style="width: 4%; padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Total short-term investment securities</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">28,113</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">15</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">3</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">28,125</font></td>
<td style="padding-bottom: 3pt"> </td></tr>
</table>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="14" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>December 31, 2018</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Amortized cost, as adjusted</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Gross unrealized holding gains</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Gross unrealized holding losses</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Estimated fair value</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Short-term investments:</font></td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td style="width: 49%"><font style="font-size: 8pt">Obligations of domestic governmental agencies (maturing between January 2019 and November 2019) (held-to-maturity)</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">26,951</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">2</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">10</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">26,943</font></td>
<td style="width: 4%; padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Total short-term investment securities</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">26,951</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">2</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">10</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">26,943</font></td>
<td style="padding-bottom: 3pt"> </td></tr>
</table>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.5in">We measure certain financial assets and liabilities
at fair value on a recurring basis in the condensed consolidated financial statements. The fair value hierarchy ranks the quality
and reliability of inputs, or assumptions, used in the determination of fair value and requires financial assets and liabilities
carried at fair value to be classified and disclosed in one of the following three categories:</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0 0 0 27pt">● Level 1 – quoted prices in active markets
for identical assets and liabilities;</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0 0 0 27pt; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0 0 0 27pt">● Level 2 – inputs other than Level 1 quoted
prices that are directly or indirectly observable; and</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0 0 0 27pt; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0 0 0 27pt">● Level 3 – unobservable inputs that are not
corroborated by market data.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.5in">           
   As of March 31, 2019 and December 31, 2018, the fair values of cash and cash equivalents, restricted cash, and notes
and interest payable approximate their carrying value.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"><font style="background-color: white">At
the time of our merger (we were then known as Manhattan Pharmaceuticals, Inc.) with Ariston Pharmaceuticals, Inc. (“Ariston”)
in March 2010, Ariston issued $15.5 million of five-year 5% notes payable (the “5% Notes”) in satisfaction of several
note payable issuances. The 5% Notes and accrued and unpaid interest thereon are convertible at the option of the holder into common
stock at the conversion price of $1,125 per share. Ariston agreed to make quarterly payments on the 5% Notes equal to 50% of the
net product cash flow received from the exploitation or commercialization of Ariston’s product candidates, AST-726 and AST-915.
We have no obligations under the 5% Notes aside from (a) 50% of the net product cash flows from Ariston’s product candidates,
if any, payable to noteholders; and (b) the conversion feature, discussed above.</font></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"><font style="background-color: white">The
cumulative liability to the Ariston subsidiary including accrued and unpaid interest of the 5% Notes was approximately $18.6 million
at March 31, 2019 and $18.4 million at December 31, 2018.</font> No payments have been made on the 5% Notes since the merger and
through March 31, 2019.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">In December 2011, we elected
the fair value option for valuing the 5% Notes. The fair value option was elected in order to reflect in our financial statements
the assumptions that market participants use in evaluating these financial instruments.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">As of December 31, 2013,
as a result of expiring intellectual property rights and other factors, it was determined that net product cash flows from AST-726
were unlikely. As we have no other obligations under the 5% Notes aside from the net product cash flows and the conversion feature,
the conversion feature was used to estimate the 5% Notes’ fair value as of March 31, 2019 and December 31, 2018. The assumptions,
assessments and projections of future revenues are subject to uncertainties, difficult to predict, and require significant judgment.
The use of different assumptions, applying different judgment to inherently subjective matters and changes in future market conditions
could result in significantly different estimates of fair value and the differences could be material to our condensed consolidated
financial statements.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.5in">The following tables provide the fair value measurements
of applicable financial liabilities as of March 31, 2019 and December 31, 2018:</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="14" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Financial liabilities at fair value as of March 31, 2019</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">(in thousands)</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Level 1</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Level 2</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Level 3</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Total</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td style="width: 49%"><font style="font-size: 8pt">5% Notes</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">133</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">133</font></td>
<td style="width: 4%; padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Total</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">133</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">133</font></td>
<td style="padding-bottom: 3pt"> </td></tr>
</table>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="14" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Financial liabilities at fair value as of December 31, 2018</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Level 1</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Level 2</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Level 3</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Total</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td style="width: 49%"><font style="font-size: 8pt">5% Notes</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">67</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">67</font></td>
<td style="width: 4%; padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Total</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">67</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">67</font></td>
<td style="padding-bottom: 3pt"> </td></tr>
</table>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.5in">The Level 3 amounts above represent the fair
value of the 5% Notes and related accrued interest.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.5in">The Company’s financial instruments include
cash, cash equivalents consisting of money market funds, accounts payable and debt. Cash, cash equivalents, accounts payable and
debt are stated at their respective historical carrying amounts, which approximate fair value due to their short-term nature.</p>
<p style="font: 12pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.5in">The following table summarizes the changes in
Level 3 instruments during the three months ended March 31, 2019:</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">(in thousands)</font></td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td style="width: 88%"><font style="font-size: 8pt">Fair value at December 31, 2018</font></td>
<td style="width: 1%"> </td>
<td style="width: 1%"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; text-align: right"><font style="font-size: 8pt">67</font></td>
<td style="width: 1%"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Interest accrued on face value of 5% Notes</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">224</font></td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Change in fair value of Level 3 liabilities</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"> </td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">(158</font></td>
<td style="padding-bottom: 1.5pt"><font style="font-size: 8pt">)</font></td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Fair value at March 31, 2019</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">133</font></td>
<td style="padding-bottom: 3pt"> </td></tr>
</table>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.5in">The change in the fair value of the Level 3 liabilities
is reported in other (income) expense in the accompanying condensed consolidated statements of operations.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="margin: 0pt"></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0"></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0"><b><i>Preferred Stock</i></b></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 9pt"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Our amended and restated
certificate of incorporation authorizes the issuance of up to 10,000,000 shares of preferred stock, $0.001 par value, with rights
senior to those of our common stock, <font style="background-color: white">issuable in one or more series. Upon issuance, we can
determine the rights, preferences, privileges and restrictions thereof. These rights, preferences and privileges could include
dividend rights, conversion rights, voting rights, terms of redemption, liquidation preferences, sinking fund terms and the number
of shares constituting any series or the designation of such series, any or all of which may be greater than the rights of common
stock.</font></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 9pt"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"><b><i>Common Stock</i></b></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Our amended and restated
certificate of incorporation authorizes the issuance of up to 150,000,000 shares of $0.001 par value common stock.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">In May 2017, we filed a
shelf registration statement on Form S-3 (the "2017 S-3"), which was declared effective in June 2017, replacing the 2015
S-3. Under the 2017 S-3, the Company may sell up to a total of $300 million of its securities. In connection with the 2017 S-3,
we entered into an At-the-Market Issuance Sales Agreement (the "2017 ATM") with Jefferies LLC, Cantor Fitzgerald &
Co., FBR Capital Markets & Co., SunTrust Robinson Humphrey, Inc., Raymond James & Associates, Inc., Ladenburg Thalmann
& Co. Inc. and H.C. Wainwright & Co., LLC (each a "2017 Agent" and collectively, the "2017 Agents"), relating
to the sale of shares of our common stock. Under the 2017 ATM we pay the 2017 Agents a commission rate of up to 3.0% of the gross
proceeds from the sale of any shares of common stock.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">In March 2019, we completed
an underwritten public offering of 4,100,000 shares of our common stock (plus a 30-day underwriter overallotment option to purchase
up to an additional 615,000 shares of common stock, which was exercised), at a price of $5.87 per share. Proceeds from this offering,
including the overallotment, after underwriting discounts and offering expenses were approximately $27.7 million.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Subsequent to the first
quarter, through May 10, 2019, we sold an aggregate of 3,030,611 shares of common stock pursuant to the 2017 ATM for total gross
proceeds of approximately $24.6 million at an average selling price of $8.11 per share, resulting in net proceeds of approximately
$24.2 million after deducting commissions and other transactions costs.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">The 2017 S-3 is currently
our only active shelf registration statement. After deducting shares already sold there is approximately $84.2 million of common
stock that remains available for sale under the 2017 S-3. We may offer the securities under the 2017 S-3 from time to time in response
to market conditions or other circumstances if we believe such a plan of financing is in the best interests of our stockholders.
We believe that the 2017 S-3 provides us with the flexibility to raise additional capital to finance our operations as needed.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 9pt"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"><b><i>Equity Incentive Plans</i></b></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">The TG Therapeutics, Inc.
Amended and Restated 2012 Incentive Plan (“2012 Incentive Plan”) was approved by stockholders in June 2018. As of March
31, 2019, 5,539,620 shares of restricted stock and 2,565,310 options were outstanding and up to an additional 2,612,431 shares
may be issued under the 2012 Incentive Plan.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Effective as of January
1, 2017, we entered into an amendment (the “Amendment”) to the employment agreement entered into as of December 15,
2011 (together with the Amendment, the “Employment Agreement”) with Michael S. Weiss, our Executive Chairman and Chief
Executive Officer and President. Under the Amendment, Mr. Weiss will remain as Chief Executive Officer and President, removing
the interim status. Simultaneously, we entered into a Strategic Advisory Agreement (the “Advisory Agreement”) with
Caribe BioAdvisors, LLC (the “Advisor”) owned by Mr. Weiss to provide the services of Mr. Weiss as Chairman of the
Board and as Executive Chairman. As part of the Amendment, Mr. Weiss also agreed to forfeit 3,381,866 restricted shares previously
granted under the Employment Agreement that were predominantly subject to time-based vesting over the next three years. Simultaneously,
(i) Mr. Weiss was issued 418,371 restricted shares under the Employment Agreement that vest in 2018 and 2019 and (ii) the Advisor
was issued 2,960,000 restricted shares under the Advisory Agreement that vested on market capitalization thresholds ranging from
$375 million to $750 million. In accordance with GAAP, there was no incremental stock compensation expense recognition as a result
of the modification.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0"></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0"><u>Stock Options</u></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.5in">The following table summarizes stock option activity
for the three months ended March 31, 2019:</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Number of shares</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Weighted-average exercise price</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Weighted-average Contractual Term</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Aggregate Intrinsic Value</b> </font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"><font style="font-size: 8pt"><b>(in years)</b></font></td>
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td style="width: 48%"><font style="font-size: 8pt">Outstanding at December 31, 2018</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 10%; padding-bottom: 1.5pt; text-align: right"><font style="font-size: 8pt">1,916,900</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"><font style="font-size: 8pt">$</font></td>
<td style="width: 10%; padding-bottom: 1.5pt; text-align: right"><font style="font-size: 8pt">6.50</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 10%; padding-bottom: 1.5pt; text-align: right"><font style="font-size: 8pt">9.75</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 10%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td style="padding-left: 0.25in"><font style="font-size: 8pt">Granted</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">715,000</font></td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">6.90</font></td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"> </td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"> </td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td style="padding-left: 0.25in"><font style="font-size: 8pt">Exercised</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">--</font></td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">--</font></td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"> </td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"> </td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td style="padding-left: 0.25in"><font style="font-size: 8pt">Forfeited</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">(66,590</font></td>
<td><font style="font-size: 8pt">)</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">6.80</font></td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"> </td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"> </td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td style="padding-left: 0.25in"><font style="font-size: 8pt">Expired</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"> </td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt; text-align: right"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt; text-align: right"> </td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Outstanding at March 31, 2019</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"> </td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">2,565,310</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">6.61</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"> </td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">9.63</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">5,800,421</font></td>
<td style="padding-bottom: 3pt"> </td></tr>
<tr style="vertical-align: bottom">
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"> </td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"> </td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"> </td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"> </td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Expected to vest at March 31, 2019</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"> </td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">2,565,310</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">6.61</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"> </td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">9.63</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">5,800,421</font></td>
<td style="padding-bottom: 3pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Exercisable at March 31, 2019</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"> </td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"> </td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="padding-bottom: 3pt"> </td></tr>
</table>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Total expense associated
with the stock options was approximately $0.7 million and zero during the three months ended March 31, 2019 and 2018, respectively.
As of March 31, 2019, the stock options outstanding include options granted to both employees and non-employees which are both
time-based and milestone-based. Stock-based compensation for milestone-based options will be recorded if and when a milestone occurs.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.5in">The fair value of the Company's option awards
were estimated using the assumptions below:</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Three months ended March 31, 2019</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td style="width: 82%"><font style="font-size: 8pt">Volatility</font></td>
<td style="width: 1%"> </td>
<td style="width: 1%"> </td>
<td style="width: 15%; text-align: right"><font style="font-size: 8pt">204.59-291.61</font></td>
<td style="width: 1%"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Expected term (in years)</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">5.0-6.25</font></td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Risk-free rate</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">2.40-2.49</font></td>
<td><font style="font-size: 8pt">%</font></td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Expected dividend yield</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">--</font></td>
<td><font style="font-size: 8pt">%</font></td></tr>
</table>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"><u>Restricted Stock</u></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Certain employees, directors
and consultants have been awarded restricted stock. The restricted stock vesting consists of milestone and time-based vesting.
The following table summarizes restricted share activity for the three months ended March 31, 2019:</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Number of Shares</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Weighted Average Grant Date Fair Value</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td style="width: 64%"><font style="font-size: 8pt">Outstanding at December 31, 2018</font></td>
<td style="width: 1%"> </td>
<td style="width: 1%"> </td>
<td style="width: 15%; text-align: right"><font style="font-size: 8pt">6,095,692</font></td>
<td style="width: 1%"> </td>
<td style="width: 1%"> </td>
<td style="width: 1%"><font style="font-size: 8pt">$</font></td>
<td style="width: 15%; text-align: right"><font style="font-size: 8pt">8.07</font></td>
<td style="width: 1%"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Granted</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">23,000</font></td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">12.95</font></td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Vested</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">(511,444</font></td>
<td><font style="font-size: 8pt">)</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">8.64</font></td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Forfeited</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"> </td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">(67,628</font></td>
<td style="padding-bottom: 1.5pt"><font style="font-size: 8pt">)</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt; text-align: right"><font style="font-size: 8pt">7.54</font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Outstanding at March 31, 2019</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"> </td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">5,539,620</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">7.95</font></td>
<td style="padding-bottom: 3pt"> </td></tr>
</table>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Total expense associated
with restricted stock grants was approximately $1.2 million and $7.3 million during the three months ended March 31, 2019 and 2018,
respectively. As of March 31, 2019, there was approximately $5.6 million of total unrecognized compensation cost related to unvested
time-based restricted stock, which is expected to be recognized over a weighted average period of 1.43 years. This amount does
not include, as of March 31, 2019, 3,003,011 shares of restricted stock outstanding which are milestone-based and vest upon certain
corporate milestones. Until the measurement date is reached for milestone awards, the total amount of compensation expense remains
uncertain. We record compensation expense based on the fair value of the award at the grant date.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0"><u>Warrants</u></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.5in">The following table summarizes warrant activity
for the three months ended March 31, 2019:</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid">
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: center"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: center"><b>Warrants</b></p></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid">
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: center"><b>Weighted-</b></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: center"><b>average</b></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: center"><b>exercise price</b></p></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Aggregate Intrinsic Value</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td style="width: 62%"><font style="font-size: 8pt">Outstanding at December 31, 2018</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 9%; padding-bottom: 1.5pt; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"><font style="font-size: 8pt">$</font></td>
<td style="width: 10%; padding-bottom: 1.5pt; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 10%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td style="padding-left: 0.25in"><font style="font-size: 8pt">Issued</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">147,058</font></td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">4.08</font></td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"> </td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td style="padding-left: 0.25in"><font style="font-size: 8pt">Exercised</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">--</font></td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">--</font></td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"> </td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td style="padding-left: 0.25in"><font style="font-size: 8pt">Expired</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"> </td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt; text-align: right"> </td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Outstanding at March 31, 2019</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"> </td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">147,058</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">4.08</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">582,350</font></td>
<td style="padding-bottom: 3pt"> </td></tr>
</table>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0"><b><i>Stock-Based Compensation</i></b></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.5in">The following table summarizes stock-based compensation
expense information about restricted stock and stock options for the three months ended March 31, 2019 and 2018:</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="6" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Three months ended March 31,</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">(in thousands)</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>2019</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>2018</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td style="width: 64%"><font style="font-size: 8pt">Stock-based compensation expense associated with restricted stock</font></td>
<td style="width: 1%"> </td>
<td style="width: 1%"><font style="font-size: 8pt">$</font></td>
<td style="width: 14%; text-align: right"><font style="font-size: 8pt">1,177</font></td>
<td style="width: 1%"> </td>
<td style="width: 1%"> </td>
<td style="width: 1%"><font style="font-size: 8pt">$</font></td>
<td style="width: 14%; text-align: right"><font style="font-size: 8pt">7,337</font></td>
<td style="width: 3%"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Stock-based compensation expense associated with option grants</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"> </td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">705</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"> </td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Total</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">1,882</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">7,337</font></td>
<td style="padding-bottom: 3pt"> </td></tr>
</table>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="margin: 0pt"></p>
<p style="margin: 0pt; font: 8pt Times New Roman, Times, Serif"></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.5in"><font style="font: 8pt Times New Roman, Times, Serif">The
following is a summary of Notes Payable included in other current liabilities on the Company’s condensed consolidated balance
sheet:</font></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"><font style="font: 8pt Times New Roman, Times, Serif"> </font></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"><font style="font: 8pt Times New Roman, Times, Serif"> </font></p>
<table cellspacing="0" cellpadding="0" style="font: 8pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom; font: 8pt Times New Roman, Times, Serif">
<td style="font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td style="padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td colspan="10" style="border-bottom: black 1pt solid; font: 8pt Times New Roman, Times, Serif; text-align: center"><font style="font: 8pt Times New Roman, Times, Serif"><b>March
31, 2019</b></font></td>
<td style="padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td style="padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td colspan="10" style="border-bottom: black 1pt solid; font: 8pt Times New Roman, Times, Serif; text-align: center"><font style="font: 8pt Times New Roman, Times, Serif"><b>December
31, 2018</b></font></td>
<td style="padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td></tr>
<tr style="vertical-align: bottom; font: 8pt Times New Roman, Times, Serif">
<td style="font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif">(in
thousands)</font></td>
<td style="padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td colspan="2" style="border-bottom: black 1pt solid; font: 8pt Times New Roman, Times, Serif; text-align: center"><font style="font: 8pt Times New Roman, Times, Serif"><b>Current
portion, net</b></font></td>
<td style="padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td style="padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td colspan="2" style="border-bottom: black 1pt solid; font: 8pt Times New Roman, Times, Serif; text-align: center"><font style="font: 8pt Times New Roman, Times, Serif"><b>Non-current
portion, net</b></font></td>
<td style="padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td style="padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td colspan="2" style="border-bottom: black 1pt solid; font: 8pt Times New Roman, Times, Serif; text-align: center"><font style="font: 8pt Times New Roman, Times, Serif"><b>Total</b></font></td>
<td style="padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td style="padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td colspan="2" style="border-bottom: black 1pt solid; font: 8pt Times New Roman, Times, Serif; text-align: center"><font style="font: 8pt Times New Roman, Times, Serif"><b>Current
portion, net</b></font></td>
<td style="padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td style="padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td colspan="2" style="border-bottom: black 1pt solid; font: 8pt Times New Roman, Times, Serif; text-align: center"><font style="font: 8pt Times New Roman, Times, Serif"><b>Non-current
portion, net</b></font></td>
<td style="padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td style="padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td colspan="2" style="border-bottom: black 1pt solid; font: 8pt Times New Roman, Times, Serif; text-align: center"><font style="font: 8pt Times New Roman, Times, Serif"><b>Total</b></font></td>
<td style="padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td></tr>
<tr style="vertical-align: bottom; font: 8pt Times New Roman, Times, Serif">
<td style="width: 36%; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif">Convertible
5% Notes Payable</font></td>
<td style="width: 1%; padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td style="width: 1%; border-bottom: black 1pt solid; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif">$</font></td>
<td style="width: 7%; border-bottom: black 1pt solid; font: 8pt Times New Roman, Times, Serif; text-align: right"><font style="font: 8pt Times New Roman, Times, Serif">133</font></td>
<td style="width: 1%; padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td style="width: 1%; padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td style="width: 1%; border-bottom: black 1pt solid; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif">$</font></td>
<td style="width: 7%; border-bottom: black 1pt solid; font: 8pt Times New Roman, Times, Serif; text-align: right"><font style="font: 8pt Times New Roman, Times, Serif">--</font></td>
<td style="width: 1%; padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td style="width: 1%; padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td style="width: 1%; border-bottom: black 1pt solid; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif">$</font></td>
<td style="width: 7%; border-bottom: black 1pt solid; font: 8pt Times New Roman, Times, Serif; text-align: right"><font style="font: 8pt Times New Roman, Times, Serif">133</font></td>
<td style="width: 3%; padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td style="width: 1%; padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td style="width: 1%; border-bottom: black 1pt solid; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif">$</font></td>
<td style="width: 7%; border-bottom: black 1pt solid; font: 8pt Times New Roman, Times, Serif; text-align: right"><font style="font: 8pt Times New Roman, Times, Serif">67</font></td>
<td style="width: 1%; padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td style="width: 1%; padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td style="width: 1%; border-bottom: black 1pt solid; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif">$</font></td>
<td style="width: 7%; border-bottom: black 1pt solid; font: 8pt Times New Roman, Times, Serif; text-align: right"><font style="font: 8pt Times New Roman, Times, Serif">--</font></td>
<td style="width: 1%; padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td style="width: 1%; padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td style="width: 1%; border-bottom: black 1pt solid; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif">$</font></td>
<td style="width: 7%; border-bottom: black 1pt solid; font: 8pt Times New Roman, Times, Serif; text-align: right"><font style="font: 8pt Times New Roman, Times, Serif">67</font></td>
<td style="width: 3%; padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td></tr>
<tr style="vertical-align: bottom; font: 8pt Times New Roman, Times, Serif">
<td style="font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif">Total</font></td>
<td style="padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td style="border-bottom: black 1pt solid; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif">$</font></td>
<td style="border-bottom: black 1pt solid; font: 8pt Times New Roman, Times, Serif; text-align: right"><font style="font: 8pt Times New Roman, Times, Serif">133</font></td>
<td style="padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td style="padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td style="border-bottom: black 1pt solid; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif">$</font></td>
<td style="border-bottom: black 1pt solid; font: 8pt Times New Roman, Times, Serif; text-align: right"><font style="font: 8pt Times New Roman, Times, Serif">--</font></td>
<td style="padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td style="padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td style="border-bottom: black 1pt solid; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif">$</font></td>
<td style="border-bottom: black 1pt solid; font: 8pt Times New Roman, Times, Serif; text-align: right"><font style="font: 8pt Times New Roman, Times, Serif">133</font></td>
<td style="padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td style="padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td style="border-bottom: black 1pt solid; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif">$</font></td>
<td style="border-bottom: black 1pt solid; font: 8pt Times New Roman, Times, Serif; text-align: right"><font style="font: 8pt Times New Roman, Times, Serif">67</font></td>
<td style="padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td style="padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td style="border-bottom: black 1pt solid; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif">$</font></td>
<td style="border-bottom: black 1pt solid; font: 8pt Times New Roman, Times, Serif; text-align: right"><font style="font: 8pt Times New Roman, Times, Serif">--</font></td>
<td style="padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td style="padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td>
<td style="border-bottom: black 1pt solid; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif">$</font></td>
<td style="border-bottom: black 1pt solid; font: 8pt Times New Roman, Times, Serif; text-align: right"><font style="font: 8pt Times New Roman, Times, Serif">67</font></td>
<td style="padding-bottom: 1.5pt; font: 8pt Times New Roman, Times, Serif"><font style="font: 8pt Times New Roman, Times, Serif"> </font></td></tr>
</table>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"><font style="font: 8pt Times New Roman, Times, Serif"> </font></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0"><font style="font: 8pt Times New Roman, Times, Serif"><b><i>Convertible
5% Notes Payable</i></b></font></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"><font style="font: 8pt Times New Roman, Times, Serif"> </font></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"><font style="font: 8pt Times New Roman, Times, Serif">The
5% Notes and accrued and unpaid interest thereon are convertible at the option of the holder into common stock at the conversion
price of $1,125 per share. <font style="background-color: white">We have no obligation under the 5% Notes aside from (a) 50% of
the net product cash flows from Ariston’s product candidates, if any, payable to noteholders; and (b) the conversion feature,
discussed above.</font> Interest accrues monthly, is added to principal on an annual basis, every March 8, and is payable at maturity,
which was March 8, 2015 (see Note 4 for further details).</font></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"><font style="font: 8pt Times New Roman, Times, Serif"> </font></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"><font style="font: 8pt Times New Roman, Times, Serif; background-color: white">The
cumulative liability including accrued and unpaid interest of these notes was approximately $18.6 million at March 31, 2019 and
$18.4 million at December 31, 2018.</font> <font style="font: 8pt Times New Roman, Times, Serif">No payments
have been made on the 5% Notes as of March 31, 2019.</font></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"><font style="font: 8pt Times New Roman, Times, Serif"> </font></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"><font style="font: 8pt Times New Roman, Times, Serif">In
December 2011, we elected the fair value option for valuing the 5% Notes. The fair value option was elected in order to reflect
in our financial statements the assumptions that market participants use in evaluating these financial instruments (see Note 4
for further details).</font></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"><font style="font: 8pt Times New Roman, Times, Serif"> </font></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0"><font style="font: 8pt Times New Roman, Times, Serif"><b><i>Current
Liabilities</i></b></font></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"><font style="font: 8pt Times New Roman, Times, Serif"> </font></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"></p>
<p style="font: 8pt Times New Roman, Times, Serif; text-align: justify; text-indent: 0.5in; margin-right: 0; margin-left: 0"><font style="font: 8pt Times New Roman, Times, Serif; background-color: white">In
2018, we entered into an agreement with a contract manufacturer for the clinical and potential commercial supply of one of our
product candidates. As part of this agreement, the contract manufacturer has agreed to defer payment of certain costs and expenses
under the agreement in exchange for the payment of an administrative fee. To date we have incurred expenses related to this agreement
of approximately $18.6 million as of March 31, 2019 which includes both service fees and raw material costs. No payments have
been made to the contract manufacturer as of March 31, 2019. Accordingly, as of March 31, 2019, $17.8 million is included in current
liabilities and $0.8 million is included in accounts payable in the Company’s unaudited condensed consolidated balance sheet.
As of December 31, 2018, $18.4 million is included in long term liabilities in the Company’s audited consolidated balance
sheet. All costs incurred to date are due in the first quarter of 2020. We will incur an administrative fee of six percent (6%)
per year starting from the date of invoice issuance. As of March 31, 2019 we have accrued $0.3 million in administrative fees
in connection with these costs, which has been included in interest expense in the Company’s unaudited condensed consolidated
statements of operations.</font></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">       
      On February 28, 2019 (the “Closing Date”), the Company (“Borrower”) entered
into a term loan facility of up to $60.0 million (“Term Loan”) with Hercules Capital, Inc., (“Hercules”),
the proceeds of which will be used for its ongoing research and development programs and for general corporate purposes. The Term
Loan is governed by a loan and security agreement, dated February 28, 2019 (the “Loan Agreement”), which provides for
up to four separate advances. The first advance of $30.0 million was drawn on the Closing Date. Two additional advances of $10.0
million may be drawn at the Borrower’s option but subject to the clinical trial milestones, and the fourth advance of $10.0
million, available in minimum increments of $5.0 million, is available through December 15, 2020 subject to the approval of Hercules’
investment committee.  </p>
<table cellspacing="0" cellpadding="0" style="width: 100%">
<tr>
<td style="width: 100%"> </td></tr>
</table>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.5in">The Term Loan will mature on March 1, 2022 (the
“Loan Maturity Date”). Each advance accrues interest at a per annum rate of interest equal to the greater of either
(i) the “prime rate” as reported in The Wall Street Journal plus 4.75%, and (ii) 10.25%. The Term Loan provides for
interest-only payments until October 1, 2020. The interest-only period may be extended to April 1, 2021 if the Borrower, on or
before September 30, 2020, achieves either the third milestone or the Company has raised at least an amount equal to $150.0 million
in unrestricted net cash proceeds from one or more equity financings, subordinated indebtedness and/or upfront proceeds from business
development transactions permitted under the Loan Agreement, in each case after February 7, 2019, and prior to September 30, 2020.
Thereafter, amortization payments will be payable monthly in eighteen installments (or, if the period requiring interest-only payments
has been extended to April 1, 2021, in twelve installments) of principal and interest (subject to recalculation upon a change in
prime rates). At its option upon seven business days’ prior written notice to Hercules, the Company may prepay all or any
portion greater than or equal to $5.0 million of the outstanding advances by paying the entire principal balance (or portion thereof),
all accrued and unpaid interest, subject to a prepayment charge of 3.0%, if such advance is prepaid in any of the first twelve
months following the Closing Date, 1.5%, if such advance is prepaid after twelve months following the Closing Date but on or prior
to twenty-four months following the Closing Date, and 0% thereafter. In addition, an end of term charge equal to 3.25% of the aggregate
principal amount of the loan extended by Hercules is due on the maturity date. Amounts outstanding during an event of default shall
be payable on demand and shall accrue interest at an additional rate of 4.0% per annum of the past due amount outstanding.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">The Term Loan is secured
by a lien on substantially all of the assets of the Borrower, other than intellectual property and contains customary covenants
and representations, including a liquidity covenant, financial reporting covenant and limitations on dividends, indebtedness, collateral,
investments, distributions, transfers, mergers or acquisitions, taxes, corporate changes, deposit accounts, and subsidiaries.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">The events of default under
the Loan Agreement include, without limitation, and subject to customary grace periods, (1) the Borrower’s failure to make
any payments of principal or interest under the Loan Agreement, promissory notes or other loan documents, (2) the Borrower’s
breach or default in the performance of any covenant under the Loan Agreement, (3) the occurrence of a material adverse effect,
(4) the Borrower making a false or misleading representation or warranty in any material respect, (5) the Borrower’s insolvency
or bankruptcy, (6) certain attachments or judgments on the Borrower’s assets, or (7) the occurrence of any material default
under certain agreements or obligations of the Borrower involving indebtedness in excess of $750,000. If an event of default occurs,
Hercules is entitled to take enforcement action, including acceleration of amounts due under the Loan Agreement.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">The Loan Agreement also
contains warrant coverage of 2% of the total amount funded. A warrant (the “Warrant”) was issued by Borrower to Hercules
to purchase 147,058 shares of common stock with an exercise price of $4.08. The Warrant shall be exercisable for seven years from
the date of issuance. Hercules may exercise the Warrant either by (a) cash or check or (b) through a net issuance conversion. The
shares will be registered and freely tradeable within six months of issuance. The Company accounted for the Warrant as an equity
instrument since it was indexed to the Company’s common shares and met the criteria for classification in shareholders’
equity. The relative fair value of the Warrant on the date of issuance was approximately $1.0 million and was treated as an offset
to the Term Loan. This amount will be amortized to interest expense using the effective interest method over the life of the Term
Loan. The Company estimated the fair value of the Warrant using the Black-Scholes model based on the following key assumptions:</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td style="width: 88%"><font style="font-size: 8pt">Exercise Price</font></td>
<td style="width: 1%"> </td>
<td style="width: 1%"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; text-align: right"><font style="font-size: 8pt">4.08</font></td>
<td style="width: 1%"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Common share price on date of issuance</font></td>
<td> </td>
<td><font style="font-size: 8pt">$</font></td>
<td style="text-align: right"><font style="font-size: 8pt">6.80</font></td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Volatility</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">195.9</font></td>
<td><font style="font-size: 8pt">%</font></td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Risk-free interest rate</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">2.63</font></td>
<td><font style="font-size: 8pt">%</font></td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Expected dividend yield</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">--</font></td>
<td><font style="font-size: 8pt">%</font></td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Contractual term (in years)</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">7.00 years</font></td>
<td> </td></tr>
</table>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">The Company incurred financing
expenses of $2.8 million related to the Hercules Loan Agreement which are recorded as an offset to long-term debt on the Company's
condensed consolidated balance sheet. The debt issuance costs are being amortized over the term of the debt using the effective
interest method and are included in interest expense in the Company’s unaudited condensed consolidated statements of operations.
Amortization of debt issuance costs was $0.1 million and zero for the three months ended March 31, 2019. At March 31, 2019, the
remaining unamortized balance of debt issuance costs were $2.7 million.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.5in"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.5in">Long-term debt as of as of March 31, 2019, is
as follows (in thousands):</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>March 31, 2019</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td style="width: 71%"><font style="font-size: 8pt">Long-term debt</font></td>
<td style="width: 3%"> </td>
<td style="width: 1%"><font style="font-size: 8pt">$</font></td>
<td style="width: 22%; text-align: right"><font style="font-size: 8pt">30,000</font></td>
<td style="width: 3%"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">End of term fee</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"> </td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">975</font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">30,975</font></td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Less: unamortized debt issuance costs</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"> </td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">(2,689</font></td>
<td style="padding-bottom: 1.5pt"><font style="font-size: 8pt">)</font></td></tr>
<tr style="vertical-align: bottom">
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">28,286</font></td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Less: Current portion</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"> </td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="padding-bottom: 3pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Long-term debt– non-current</font></td>
<td> </td>
<td><font style="font-size: 8pt">$</font></td>
<td style="text-align: right"><font style="font-size: 8pt">28,286</font></td>
<td> </td></tr>
</table>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.5in">In October 2014, we entered into an agreement
(the “Office Agreement”) with Fortress Biotech, Inc. (“FBIO”) to occupy approximately 45% of the 24,000
square feet of New York City office space leased by FBIO, which is now our corporate headquarters. The Office Agreement requires
us to pay our respective share of the average annual rent and other costs of the 15-year lease. We approximate an average annual
rental obligation of $1.1 million under the Office Agreement. We began to occupy this new space in April 2016, with rental payments
beginning in the third quarter of 2016. During the three months ended March 31, 2019, we recognized a lease liability of $9.4 million,
with a corresponding Right of Use (ROU) asset of $7.9 million based on the present value of the remaining lease payments for all
of our leased office spaces, the majority of which is comprised of our New York City office space. Our leases have remaining lease
terms of 1 year to 12 years. One lease has a renewal option to extend the lease for an additional term of 2 years.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.5in">After an initial commitment period of the 45%
rate for a period of three (3) years, we and FBIO will determine actual office space utilization annually and if our utilization
differs from the amount we have been billed, we will either receive credits or be assessed incremental utilization charges. Also
in connection with this lease, in October 2014 we pledged $0.6 million to secure a line of credit as a security deposit for the
Office Agreement, which has been recorded as restricted cash in the accompanying consolidated balance sheets. Additional collateral
of $0.6 million was pledged in April 2018 to increase the letter of credit for the office space.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.5in">The following components of lease expense are
included in the Company's consolidated statements of operations for the three months ended March 31, 2019:</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.5in"> </p>
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt"> (in thousands)</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b> March 31, 2019</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td style="width: 82%"><font style="font-size: 8pt"> Operating lease cost</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 15%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">418</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt"> Net lease cost</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">418</font></td>
<td style="padding-bottom: 3pt"> </td></tr>
</table>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">As of March 31, 2019, the
weighted-average remaining operating lease term was 9.75 years and the weighted-average discount rate for operating leases
was 10.25%. Cash paid for amounts included in the measurement of operating lease liabilities in the first quarter
of fiscal 2019 was $0.3 million.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.5in">The balance sheet classification of lease liabilities
was as follows:</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">(in thousands)</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>March 31, 2019</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt"><b>Liabilities</b></font></td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td style="width: 82%"><font style="font-size: 8pt">Lease liability – current portion</font></td>
<td style="width: 1%"> </td>
<td style="width: 1%"><font style="font-size: 8pt">$</font></td>
<td style="width: 15%; text-align: right"><font style="font-size: 8pt">1,261</font></td>
<td style="width: 1%"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Lease liability – non-current</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"> </td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">8,182</font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td style="padding-left: 0.5in"><font style="font-size: 8pt">Total lease liability</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">9,443</font></td>
<td style="padding-bottom: 3pt"> </td></tr>
</table>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.5in">As of March 31, 2019, the maturities
of lease liabilities were as follows:</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">(in thousands)</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Operating leases</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td style="width: 82%"><font style="font-size: 8pt">Remainder of 2019</font></td>
<td style="width: 1%"> </td>
<td style="width: 1%"><font style="font-size: 8pt">$</font></td>
<td style="width: 15%; text-align: right"><font style="font-size: 8pt">1,023</font></td>
<td style="width: 1%"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">2020</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">1,348</font></td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">2021</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">1,353</font></td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">2022</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">1,376</font></td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">2023</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">1,367</font></td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">After 2023</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"> </td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">10,281</font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Total lease payments</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">16,748</font></td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Less: Interest</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"> </td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">(7,305</font></td>
<td style="padding-bottom: 1.5pt"><font style="font-size: 8pt">)</font></td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Present value of lease liabilities(*)</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">9,443</font></td>
<td style="padding-bottom: 3pt"> </td></tr>
<tr style="vertical-align: bottom">
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"> </td>
<td> </td></tr>
</table>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0">(*) As our leases do not provide an implicit rate, we use our incremental
borrowing rate based on the information available at commencement date and considering the term of the lease to determine the present
value of lease payments. We used the incremental borrowing rate of 10.25% on February 28, 2019, for operating leases that commenced
prior to that date.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="margin: 0pt"></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"><b><i>TG-1101 (Ublituximab)</i></b></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">In November 2012, we entered
into an exclusive (within the territory) sublicense agreement with Ildong Pharmaceutical Co. Ltd. (“Ildong”) relating
to the development and commercialization of ublituximab in South Korea and Southeast Asia. Under the terms of the sublicense agreement,
Ildong has been granted a royalty bearing, exclusive right, including the right to grant sublicenses, to develop and commercialize
ublituximab in South Korea, Taiwan, Singapore, Indonesia, Malaysia, Thailand, Philippines, Vietnam, and Myanmar.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">An upfront payment of $2.0
million, which was received in December 2012, net of $0.3 million of income tax withholdings, is being recognized as license
revenue on a straight-line basis over the life of the agreement, which is through the expiration of the last licensed patent right
or 15 years after the first commercial sale of a product in such country, unless the agreement is earlier terminated, and represents
the estimated period over which we will have certain ongoing responsibilities under the sublicense agreement. We recorded license
revenue of approximately $38,000 for each of the three months ended March 31, 2019 and 2018, and, at March 31, 2019 and December
31, 2018, have deferred revenue of approximately $1.0 million, and $1.1 million, respectively, associated with this $2 million
payment (approximately $152,000 of which has been classified in current liabilities at March 31, 2019 and December 31, 2018).</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">We may receive up to an
additional $5.0 million in payments upon the achievement of pre-specified milestones. In addition, upon commercialization, Ildong
will make royalty payments to us on net sales of ublituximab in the sublicense territory.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"><b><i>TG-1701: BTK</i></b></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">       
    In January 2018, we entered into a global exclusive license agreement with Jiangsu Hengrui Medicine Co. (“Hengrui”),
to acquire worldwide intellectual property rights, excluding Asia but including Japan, and for the research, development, manufacturing,
and commercialization of products containing or comprising of any of Hengrui’s Bruton’s Tyrosine Kinase inhibitors
containing the compounds of either TG-1701 (SHR1459 or EBI1459) or TG1702 (SHR1266 or EBI1266). Pursuant to the agreement, in April
2018, we paid Jiangsu an upfront fee of $1.0 million in our common stock recorded to non-cash stock expense associated with in-licensing
agreements in our consolidated statement of operations. Jiangsu is eligible to receive milestone payments totaling approximately
$350 million upon and subject to the achievement of certain milestones. Various provisions allow for payments in conjunction with
the agreement to be made in cash or our common stock, while others limit the form of payment. Royalty payments in the low double
digits are due on net sales of licensed products and revenue from sublicenses</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"><b><i>TG-1801: anti-CD47/anti-CD19</i></b></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">       
    In June 2018, we entered into a Joint Venture and License Option Agreement with Novimmune SA (“Novimmune”)
to collaborate on the development and commercialization of Novimmune’s novel first-in-class anti-CD47/anti-CD19 bispecific
antibody known as TG-1801 (previously NI-1701). The companies will jointly develop the product on a worldwide basis, focusing on
indications in the area of hematologic B-cell malignancies. We serve as the primary responsible party for the development, manufacturing
and commercialization of the product. Pursuant to the agreement, in June 2018 we paid Novimmune an upfront payment of $3.0 million
in our common stock recorded to non-cash stock expense associated with in-licensing agreements in our consolidated statement of
operations. Further milestone payments will be paid based on early clinical development, and the Company will be responsible for
the costs of clinical development of the product through the end of the Phase 2 clinical trials, after which the Company and Novimmune
will be jointly responsible for all development and commercialization costs. The Company and Novimmune will each maintain an exclusive
option, exercisable at specific times during development, for the Company to license the rights to TG-1801, in which case Novimmune
is eligible to receive additional milestone payments totaling approximately $185 million as well as tiered royalties on net sales
in the high single to low double digits upon and subject to the achievement of certain milestones.</p>
<p style="margin: 0pt"></p>
<p style="margin: 0pt"></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">In October 2014, we entered
into an agreement (the “Office Agreement”) with Fortress Biotech, Inc. (“FBIO”) to occupy approximately
45% of the 24,000 square feet of New York City office space leased by FBIO, which is now our corporate headquarters. The Office
Agreement requires us to pay our respective share of the average annual rent and other costs of the 15-year lease. We approximate
an average annual rental obligation of $1.1 million under the Office Agreement. We began to occupy this new space in April 2016,
with rental payments beginning in the third quarter of 2016. During the three months ended March 31, 2019, we recognized a lease
liability of $9.4 million, with a corresponding Right of Use (ROU) asset of $7.9 million based on the present value of the remaining
lease payments for all of our leased office spaces, the majority of which is comprised of our New York City office space. Mr. Weiss,
our Executive Chairman and CEO, is also Executive Vice Chairman of FBIO.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Under the Office Agreement,
we agreed to pay FBIO our portion of the build out costs, which have been allocated to us at the 45% rate mentioned above. The
allocated build-out costs have been recorded in Leasehold Interest, net on the Company’s consolidated balance sheets and
will be amortized over the 15-year term of the Office Agreement. After an initial commitment period of the 45% rate for a period
of three (3) years, we and FBIO will determine actual office space utilization annually and if our utilization differs from the
amount we have been billed, we will either receive credits or be assessed incremental utilization charges. Also in connection with
this lease, in October 2014 we pledged $0.6 million to secure a line of credit as a security deposit for the Office Agreement,
which has been recorded as restricted cash in the accompanying consolidated balance sheets. Additional collateral of $0.6 million
was pledged in April 2018 to increase the letter of credit for the office space.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">In July 2015, we entered
into a Shared Services Agreement (the “Shared Services Agreement”) with FBIO to share the cost of certain services
such as facilities use, personnel costs and other overhead and administrative costs. This Shared Services Agreement requires us
to pay our respective share of services utilized. In connection with the Shared Services Agreement, we incurred expenses of approximately
$0.2 million and $0.4 million for shared services for the three months ended March 31, 2019 and 2018, respectively, primarily related
to shared personnel.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">In March 2015, we entered
into a Global Collaboration Agreement (“Collaboration Agreement”) with Checkpoint for the development and commercialization
of anti-PD-L1 and anti-GITR antibody research programs in the field of hematological malignancies. We incurred expenses of approximately
$0.3 million and zero for the three months ended March 31, 2019 and 2018, related mainly to manufacturing costs of PD-L1. The relevant
expenses are recorded in other research and development in the accompanying condensed consolidated statement of operations.</p>
<p style="margin: 0pt"></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">In October 2018, a purported
securities class action complaint was filed in the U.S. District Court for the Southern District of New York (the “Southern
District”) against the Company and one of its officers on behalf of all shareholders who purchased or otherwise acquired
TG Therapeutics common stock between June 4, 2018 and September 25, 2018 (the “Class Period”). The case was captioned
Randall Reinmann v. TG Therapeutics Inc., and Michael S. Weiss, Case No. 1:18-cv-09104-KPF. The complaint alleged that, throughout
the Class Period, the Company made false and/or misleading statements and/or failed to disclose various facts and circumstances
regarding its UNITY-CLL study allegedly in violation of the Securities Exchange Act of 1934 and Rule 10b-5 promulgated thereunder.
In December 2018, the Southern District appointed Co-Lead Plaintiffs to represent the putative class, and approved their selection
of Lead Counsel. On March 1, 2019, Co-Lead Plaintiffs filed a notice with the Southern District seeking to voluntarily dismiss
the action in its entirety without prejudice, which was so-ordered by the Southern District the same day.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">In addition, on December
18, 2018, a related shareholder derivative litigation was filed in the Southern District against the Company’s directors
and one of its officers in litigation captioned Thessalus Capital v. Weiss, et al., 1:18-cv-11918-KPF. The Company was named only
as a nominal defendant. The suit alleged that the officer and directors breached their fiduciary duties to the Company, wasted
corporate assets, and violated the Securities Exchange Act of 1934 and Rule 10b-5 promulgated thereunder in connection with the
Company’s alleged failure to disclose various facts and circumstances regarding its UNITY-CLL study. The plaintiff asserted
that the alleged disclosure violations concerning the Company’s UNITY-CLL study caused the Company to incur losses, including
defense costs, and further alleged that the named officer and directors received excessive compensation. On April 17, 2019, the
plaintiff filed a notice with the Southern District seeking to voluntarily dismiss the action in its entirety without prejudice,
which was so-ordered by the Southern District on April 18, 2019.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.5in">We are a biopharmaceutical company dedicated
to developing and delivering medicines for patients with B-cell mediated diseases, including Chronic Lymphocytic Leukemia (CLL),
non-Hodgkin Lymphoma (NHL) and Multiple Sclerosis (MS). We have developed a robust B-cell directed research and development (R&D)
platform for identification of key B-cell pathways of interest and rapid clinical testing. Currently, we have five B-cell targeted
drug candidates in clinical development, with the lead two therapies, ublituximab (TG-1101) and umbralisib (TGR-1202), in pivotal
trials for CLL and NHL, with ublituximab also in pivotal trials for MS. Ublituximab is a novel anti-CD20 monoclonal antibody (mAb)
that has been glycoengineered for enhanced potency over first generation antibodies. Umbralisib is an oral, once daily inhibitor
of PI3K delta. Umbralisib also uniquely inhibits CK1-epsilon, which may allow it to overcome certain tolerability issues associated
with first generation PI3K delta inhibitors. When used together in combination therapy, ublituximab and umbralisib are referred
to as "U2". Additionally, we have recently brought into Phase 1 clinical development TG-1501, an anti-PD-L1 monoclonal
antibody, TG-1701, a covalently-bound Bruton’s Tyrosine Kinase (BTK) inhibitor, and TG-1801, an anti-CD47/CD19 bispecific
antibody.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">We also actively evaluate
complementary products, technologies and companies for in-licensing, partnership, acquisition and/or investment opportunities.
To date, we have not received approval for the sale of any of our drug candidates in any market and, therefore, have not generated
any product sales from our drug candidates.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">The accompanying unaudited
condensed consolidated financial statements were prepared in accordance with U.S. generally accepted accounting principles, or
GAAP, for interim financial information and with the instructions to Quarterly Report on Form 10-Q and Article 10 of Regulation
S-X of the Exchange Act. Accordingly, they may not include all of the information and footnotes required by GAAP for complete financial
statements. All adjustments that are, in the opinion of management, of a normal recurring nature and are necessary for a fair presentation
of the condensed consolidated financial statements have been included. Nevertheless, these condensed consolidated financial statements
should be read in conjunction with the audited consolidated financial statements contained in our Annual Report on Form 10-K for
the year ended December 31, 2018. The accompanying condensed December 31, 2018 balance sheet has been derived from these statements.
The results of operations for the three months ended March 31, 2019 are not necessarily indicative of the results that may be expected
for the entire fiscal year or any other interim period.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="margin: 0pt"></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">We have incurred operating
losses since our inception, expect to continue to incur operating losses for the foreseeable future, and may never become profitable.
As of March 31, 2019, we have an accumulated deficit of approximately $563.5 million.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Our major sources of cash
have been proceeds from the private placement and public offering of equity securities, as well as debt financings. We have not
yet commercialized any of our drug candidates and cannot be sure if we will ever be able to do so. Even if we commercialize one
or more of our drug candidates, we may not become profitable. Our ability to achieve profitability depends on many factors, including
our ability to obtain regulatory approval for our drug candidates; successfully complete any post-approval regulatory obligations;
and successfully commercialize our drug candidates alone or in partnership. We may continue to incur substantial operating losses
even if we begin to generate revenues from our drug candidates.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">As of March 31, 2019, we
had $92.5 million in cash and cash equivalents, and investment securities. The Company believes its cash, cash equivalents, and
investment securities on hand as of March 31, 2019 along with the additional capital raised in the second quarter of 2019 (see
Note 5) will be sufficient to fund the Company’s planned operations through mid-2020. The actual amount of cash that we will
need to operate is subject to many factors, including, but not limited to, the timing, design and conduct of clinical trials for
our drug candidates. We are dependent upon significant future financing to provide the cash necessary to execute our current operations,
including the commercialization of any of our drug candidates.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Our common stock is listed
on the Nasdaq Capital Market and trades under the symbol “TGTX.”</p>
<p style="margin: 0pt"></p>
<p style="margin: 0pt"></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">In July 2018, the Financial
Accounting Standards Board ("FASB") issued Accounting Standards Update (“ASU”) No. 2018-11, “Leases -
Targeted Improvements” (“ASU 2018-11”) as an update to ASU 2016-02, Leases (“ASU 2016-02” or “Topic
842”) issued on February 25, 2016. ASU 2016-02 is effective for public business entities for fiscal years beginning January
1, 2019. ASU 2016-02 required companies to adopt the new leases standard at the beginning of the earliest period presented in the
financial statements, which is January 1, 2017, using a modified retrospective transition method where lessees must recognize lease
assets and liabilities for all leases even though those leases may have expired before the effective date of January 1, 2017. Lessees
must also provide the new and enhanced disclosures for each period presented, including the comparative periods.</p>
<p style="font: 12pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">ASU 2018-11 provides an
entity with an additional (and optional) transition method to adopt the new leases standard. Under this new transition method,
an entity initially applies the new lease standard at the adoption date and recognizes a cumulative-effect adjustment to the opening
balance of retained earnings in the period of adoption. Consequently, an entity’s reporting for the comparative periods presented
in the financial statements in which it adopts the new lease standard will continue to be in accordance with ASC 840, Leases. An
entity that elects this additional (and optional) transition method must provide the required ASC 840 disclosures for all periods
that continue to be in accordance with ASC 840. The amendments do not change the existing disclosure requirements in ASC 840.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">ASU 2018-11 is effective
for public business entities for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years,
with earlier adoption permitted. The Company adopted ASU 2018-11 on January 1, 2019 using a modified retrospective method and will
not restate comparative periods. We elected the package of practical expedients permitted under the transition guidance, which
allows us to carryforward our historical lease classification and our assessment on whether a contract is or contains a lease.
The adoption of this guidance resulted in the addition of material balances of right of use assets and lease liability to our consolidated
balance sheets at January 1, 2019, primarily relating to our lease of office space (see Note 8). The impact to our consolidated
statements of operations was not material as a result of this standard.</p>
<p style="font: 12pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">In June 2018, the FASB issued
ASU No. 2018-07, “Improvements to Nonemployee Share-Based Payment Accounting” (“ASU 2018-07”). ASU 2018-07
expands the scope of FASB Topic 718, Compensation – Stock Compensation (“Topic 718”) to include share-based payment
transactions for acquiring goods and services from nonemployees. An entity should only remeasure equity-classified awards for which
a measurement date has not been established through a cumulative-effect adjustment to retained earnings as of the beginning of
the fiscal year of adoption. Upon transition, the entity is required to measure these nonemployee awards at fair value as of the
adoption date. The entity must not remeasure assets that are completed. Disclosures required at transition include the nature of
and reason for the change in accounting principle and, if applicable, quantitative information about the cumulative effect of the
change on retained earnings or other components of equity.</p>
<p style="font: 12pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">ASU 2018-07 is effective
for public business entities for fiscal years beginning after December 15, 2018, including interim periods within that fiscal year.
The Company adopted ASU 2018-07 on January 1, 2019. The adoption of ASU 2018-07 did not have a material effect on our consolidated
financial statements as of January 1, 2019. The adoption of ASU 2018-07 had no impact on nonemployee performance awards as they
are measured based on the outcome that is probable.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Other pronouncements issued
by the FASB or other authoritative accounting standards group with future effective dates are either not applicable or not significant
to our consolidated financial statements.</p>
<p style="margin: 0pt"></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.5in">The preparation of financial statements in conformity
with U.S. generally accepted accounting principles (“GAAP”) requires management to make estimates and judgments that
affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the
financial statements and the reported amounts of revenues and expenses during the applicable reporting period. On an ongoing basis,
we evaluate our estimates and judgments, including those related to accrued expenses and stock-based compensation. Actual results
could differ from those estimates. Such differences could be material to the financial statements.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">We treat liquid investments
with original maturities of less than three months when purchased as cash and cash equivalents.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">We record cash pledged or
held in trust as restricted cash. As of March 31, 2019 and December 31, 2018, we have approximately $1.2 million of restricted
cash pledged to secure a line of credit as a security deposit for an <font style="background-color: white">Office Agreement</font>
(see Note 10).</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Investment securities at
March 31, 2019 and December 31, 2018 consist of short-term government securities. We classify these securities as held-to-maturity.
Held-to-maturity securities are those securities in which we have the ability and intent to hold the security until maturity. Held-to-maturity
securities are recorded at amortized cost, adjusted for the amortization or accretion of premiums or discounts. Premiums and discounts
are amortized or accreted over the life of the related held-to-maturity security as an adjustment to yield using the effective
interest method.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">A decline in the market
value of any investment security below cost, that is deemed to be other than temporary, results in a reduction in the carrying
amount to fair value. The impairment is charged to operations and a new cost basis for the security is established. Other-than-temporary
impairment charges are included in interest and other income (expense), net. Unrealized gains, if determined to be temporary, are
included in accumulated other comprehensive income in equity. Dividend and interest income are recognized when earned.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Financial instruments that
potentially subject the Company to concentrations of credit risk consist primarily of cash and cash equivalents and short-term
investments. The Company maintains its cash and cash equivalents and short-term investments with high-credit quality financial
institutions. At times, such amounts may exceed federally-insured limits.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Effective January 1, 2018,
the Company began recognizing revenue under ASC Topic 606, <i>Revenue from Contracts with Customers</i> (“ASC 606”),
using the modified retrospective transition method. The impact of adopting the new revenue standard was not material to our
consolidated financial statements and there was no adjustment to beginning retained earnings on January 1, 2018. The core
principle of this new revenue standard is that a company should recognize revenue to depict the transfer of promised goods or services
to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods
or services. The following five steps are applied to achieve that core principle:</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0 0 0 0.75in; text-indent: -0.25in"> </p>
<table cellpadding="0" style="width: 100%">
<tr>
<td style="vertical-align: top; width: 52px; padding-left: 0.5in; font: 12pt Times New Roman, Times, Serif; text-align: right"><font style="font-size: 8pt">●</font></td>
<td style="font: 12pt Times New Roman, Times, Serif; text-align: justify"><font style="font-size: 8pt">Step 1: Identify the contract with the customer</font></td></tr>
</table>
<p style="font: 12pt Times New Roman, Times, Serif; margin: 0"> </p>
<table cellpadding="0" style="width: 100%">
<tr>
<td style="vertical-align: top; width: 52px; padding-left: 0.5in; font: 12pt Times New Roman, Times, Serif; text-align: right"><font style="font-size: 8pt">●</font></td>
<td style="font: 12pt Times New Roman, Times, Serif; text-align: justify"><font style="font-size: 8pt">Step 2: Identify the performance obligations in the contract</font></td></tr>
</table>
<p style="font: 12pt Times New Roman, Times, Serif; margin: 0"> </p>
<table cellpadding="0" style="width: 100%">
<tr>
<td style="vertical-align: top; width: 52px; padding-left: 0.5in; font: 12pt Times New Roman, Times, Serif; text-align: right"><font style="font-size: 8pt">●</font></td>
<td style="font: 12pt Times New Roman, Times, Serif; text-align: justify"><font style="font-size: 8pt">Step 3: Determine the transaction price</font></td></tr>
</table>
<p style="font: 12pt Times New Roman, Times, Serif; margin: 0"> </p>
<table cellpadding="0" style="width: 100%">
<tr>
<td style="vertical-align: top; width: 52px; padding-left: 0.5in; font: 12pt Times New Roman, Times, Serif; text-align: right"><font style="font-size: 8pt">●</font></td>
<td style="font: 12pt Times New Roman, Times, Serif; text-align: justify"><font style="font-size: 8pt">Step 4: Allocate the transaction price to the performance obligations in the contract</font></td></tr>
</table>
<p style="font: 12pt Times New Roman, Times, Serif; margin: 0"> </p>
<table cellpadding="0" style="width: 100%">
<tr>
<td style="vertical-align: top; width: 52px; padding-left: 0.5in; font: 12pt Times New Roman, Times, Serif; text-align: right"><font style="font-size: 8pt">●</font></td>
<td style="font: 12pt Times New Roman, Times, Serif; text-align: justify"><font style="font-size: 8pt">Step 5: Recognize revenue when the company satisfies a performance obligation</font></td></tr>
</table>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0 0 0 0.75in; text-indent: -0.25in"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">In order to identify the
performance obligations in a contract with a customer, a company must assess the promised goods or services in the contract and
identify each promised good or service that is distinct. A performance obligation meets ASC 606’s definition of a “distinct”
good or service (or bundle of goods or services) if both of the following criteria are met:</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0 0 0 0.75in; text-align: justify; text-indent: -0.25in"> </p>
<table cellpadding="0" style="width: 100%">
<tr>
<td style="vertical-align: top; width: 52px; padding-left: 0.5in; font: 12pt Times New Roman, Times, Serif; text-align: right"><font style="font-size: 8pt">●</font></td>
<td style="font: 12pt Times New Roman, Times, Serif; text-align: justify"><font style="font-size: 8pt">The customer can benefit from the good or service either on its own or together with other resources that are readily available to the customer (i.e., the good or service is capable of being distinct).</font></td></tr>
</table>
<p style="font: 12pt Times New Roman, Times, Serif; margin: 0"> </p>
<table cellpadding="0" style="width: 100%">
<tr>
<td style="vertical-align: top; width: 52px; padding-left: 0.5in; font: 12pt Times New Roman, Times, Serif; text-align: right"><font style="font-size: 8pt">●</font></td>
<td style="font: 12pt Times New Roman, Times, Serif; text-align: justify"><font style="font-size: 8pt">The entity’s promise to transfer the good or service to the customer is separately identifiable from other promises in the contract (i.e., the promise to transfer the good or service is distinct within the context of the contract).</font></td></tr>
</table>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">If a good or service is
not distinct, the good or service is combined with other promised goods or services until a bundle of goods or services is identified
that is distinct.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">The transaction price is
the amount of consideration to which an entity expects to be entitled in exchange for transferring promised goods or services to
a customer, excluding amounts collected on behalf of third parties (for example, some sales taxes). The consideration promised
in a contract with a customer may include fixed amounts, variable amounts, or both. Variable consideration is included in the transaction
price only to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will not
occur when the uncertainty associated with the variable consideration is subsequently resolved.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.25in"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">The transaction price is
allocated to each performance obligation on a relative standalone selling price basis. The transaction price allocated to each
performance obligation is recognized when that performance obligation is satisfied, at a point in time or over time as appropriate.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Generally, research and
development costs are expensed as incurred. Nonrefundable advance payments for goods or services that will be used or rendered
for future research and development activities are deferred and amortized over the period that the goods are delivered or the related
services are performed, subject to an assessment of recoverability. We make estimates of costs incurred in relation to external
clinical research organizations, or CROs, and clinical site costs. We analyze the progress of clinical trials, including levels
of patient enrollment, invoices received and contracted costs when evaluating the adequacy of the amount expensed and the related
prepaid asset and accrued liability. Significant judgments and estimates must be made and used in determining the accrued balance
and expense in any accounting period. We review and accrue CRO expenses and clinical trial study expenses based on work performed
and rely upon estimates of those costs applicable to the stage of completion of a study. Accrued CRO costs are subject to revisions
as such trials progress to completion. Revisions are charged to expense in the period in which the facts that give rise to the
revision become known. With respect to clinical site costs, the financial terms of these agreements are subject to negotiation
and vary from contract to contract. Payments under these contracts may be uneven, and depend on factors such as the achievement
of certain events, the successful recruitment of patients, the completion of portions of the clinical trial or similar conditions.
The objective of our policy is to match the recording of expenses in our financial statements to the actual services received and
efforts expended. As such, expense accruals related to clinical site costs are recognized based on our estimate of the degree of
completion of the event or events specified in the specific clinical study or trial contract.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Prepaid research and development
in our consolidated balance sheets includes, among other things, certain costs to third party service providers related to development
and manufacturing services as well as clinical development. These agreements often require payments in advance of services performed
or goods received. Accordingly, as of March 31, 2019 and December 31, 2018, we recorded approximately $11.1 million and $9.7 million,
respectively, in prepaid research and development related to such advance agreements.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Income taxes are accounted
for under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable
to temporary differences between the financial statement carrying amounts of existing assets and liabilities and their respective
tax bases, operating losses and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates
expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled.
The effect on deferred tax assets and liabilities of a change in tax rates is recognized in operations in the period that includes
the enactment date. If the likelihood of realizing the deferred tax assets or liability is less than “more likely than not,”
a valuation allowance is then created.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">We, and our subsidiaries,
file income tax returns in the U.S. Federal jurisdiction and in various states. We have tax net operating loss carryforwards that
are subject to examination for a number of years beyond the year in which they were generated for tax purposes. Since a portion
of these net operating loss carryforwards may be utilized in the future, many of these net operating loss carryforwards will remain
subject to examination. We recognize interest and penalties related to uncertain income tax positions in income tax expense.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">We recognize all stock-based
payments to employees and non-employee directors (as compensation for service) as noncash compensation expense in the condensed
consolidated financial statements based on the fair values of such payments. Stock-based compensation expense recognized each period
is based on the value of the portion of stock-based payment awards that is ultimately expected to vest during the period. Forfeitures
are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">In addition, because some
of the options, restricted stock and warrants issued to employees, consultants and other third-parties vest upon achievement of
certain milestones, the total expense is uncertain. Compensation expense for such awards that vest upon the achievement of milestones
is recognized when the achievement of such milestones becomes probable.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Basic net loss per share
of our common stock is calculated by dividing net loss applicable to the common stock by the weighted average number of our common
stock outstanding for the period. Diluted net loss per share of common stock is the same as basic net loss per share of common
stock since potentially dilutive securities from stock options, stock warrants and convertible preferred stock would have an antidilutive
effect either because we incurred a net loss during the periods presented or because such potentially dilutive securities were
out of the money and the Company realized net income during the periods presented. The amounts of potentially dilutive securities
excluded from the calculation were 6,768,530 and 4,660,180 for the three months ended March 31, 2019 and 2018, respectively. The
following outstanding shares of potentially dilutive securities were excluded from the computation of net loss per share attributable
to common stockholders for the periods presented because including them would have been antidilutive:</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="6" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Three Months Ended March 31,</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>2019</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>2018</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td style="width: 64%"><font style="font-size: 8pt">Unvested restricted stock</font></td>
<td style="width: 1%"> </td>
<td style="width: 1%"> </td>
<td style="width: 14%; text-align: right"><font style="font-size: 8pt">4,039,620</font></td>
<td style="width: 1%"> </td>
<td style="width: 1%"> </td>
<td style="width: 1%"> </td>
<td style="width: 14%; text-align: right"><font style="font-size: 8pt">4,159,428</font></td>
<td style="width: 3%"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Stock options</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">2,565,310</font></td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">485,000</font></td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Warrants</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">147,058</font></td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">--</font></td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Shares issuable upon note conversion</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"> </td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">16,542</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"> </td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">15,752</font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Total</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"> </td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">6,768,530</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"> </td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">4,660,180</font></td>
<td style="padding-bottom: 3pt"> </td></tr>
</table>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Long-lived assets are reviewed
for potential impairment when circumstances indicate that the carrying value of long-lived tangible and intangible assets with
finite lives may not be recoverable. Management’s policy in determining whether an impairment indicator exists, a triggering
event, comprises measurable operating performance criteria as well as qualitative measures. If an analysis is necessitated by the
occurrence of a triggering event, we make certain assumptions in determining the impairment amount. If the carrying amount of an
asset exceeds its estimated future cash flows, an impairment charge is recognized.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify; text-indent: 0.5in">Goodwill is reviewed for
impairment annually, or earlier when events arise that could indicate that an impairment exists. We test for goodwill impairment
using a two-step process. The first step compares the fair value of the reporting unit with the unit's carrying value, including
goodwill. When the carrying value of the reporting unit is greater than fair value, the unit’s goodwill may be impaired,
and the second step must be completed to measure the amount of the goodwill impairment charge, if any. In the second step, the
implied fair value of the reporting unit’s goodwill is compared with the carrying amount of the unit’s goodwill. If
the carrying amount is greater than the implied fair value, the carrying value of the goodwill must be written down to its implied
fair value. We will continue to perform impairment tests annually, at December 31, and whenever events or changes in circumstances
suggest that the carrying value of an asset may not be recoverable.</p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="6" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Three Months Ended March 31,</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>2019</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>2018</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td style="width: 64%"><font style="font-size: 8pt">Unvested restricted stock</font></td>
<td style="width: 1%"> </td>
<td style="width: 1%"> </td>
<td style="width: 14%; text-align: right"><font style="font-size: 8pt">4,039,620</font></td>
<td style="width: 1%"> </td>
<td style="width: 1%"> </td>
<td style="width: 1%"> </td>
<td style="width: 14%; text-align: right"><font style="font-size: 8pt">4,159,428</font></td>
<td style="width: 3%"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Stock options</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">2,565,310</font></td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">485,000</font></td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Warrants</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">147,058</font></td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">--</font></td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Shares issuable upon note conversion</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"> </td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">16,542</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"> </td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">15,752</font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Total</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"> </td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">6,768,530</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"> </td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">4,660,180</font></td>
<td style="padding-bottom: 3pt"> </td></tr>
</table>
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">(in thousands)</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>March 31, 2019</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>December 31, 2018</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td style="width: 64%"><font style="font-size: 8pt">Checking and bank deposits</font></td>
<td style="width: 1%"> </td>
<td style="width: 1%"><font style="font-size: 8pt">$</font></td>
<td style="width: 15%; text-align: right"><font style="font-size: 8pt">62,671</font></td>
<td style="width: 1%"> </td>
<td style="width: 1%"> </td>
<td style="width: 1%"><font style="font-size: 8pt">$</font></td>
<td style="width: 15%; text-align: right"><font style="font-size: 8pt">39,268</font></td>
<td style="width: 1%"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Money market funds</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"> </td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">1,678</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"> </td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">2,690</font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Total</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">64,349</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">41,958</font></td>
<td style="padding-bottom: 3pt"> </td></tr>
</table>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.5in"></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">(in thousands)</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="14" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>March 31, 2019</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Amortized cost, as adjusted</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Gross unrealized holding gains</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Gross unrealized holding losses</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Estimated fair value</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Short-term investments:</font></td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td style="width: 49%"><font style="font-size: 8pt">Obligations of domestic governmental agencies (maturing between April 2019 to March 2020) (held-to-maturity)</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">28,113</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">15</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">3</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">28,125</font></td>
<td style="width: 4%; padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Total short-term investment securities</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">28,113</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">15</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">3</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">28,125</font></td>
<td style="padding-bottom: 3pt"> </td></tr>
</table>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="14" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>December 31, 2018</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Amortized cost, as adjusted</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Gross unrealized holding gains</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Gross unrealized holding losses</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Estimated fair value</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Short-term investments:</font></td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td style="width: 49%"><font style="font-size: 8pt">Obligations of domestic governmental agencies (maturing between January 2019 and November 2019) (held-to-maturity)</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">26,951</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">2</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">10</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">26,943</font></td>
<td style="width: 4%; padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Total short-term investment securities</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">26,951</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">2</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">10</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">26,943</font></td>
<td style="padding-bottom: 3pt"> </td></tr>
</table>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-indent: 0.5in"></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="14" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Financial liabilities at fair value as of March 31, 2019</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">(in thousands)</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Level 1</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Level 2</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Level 3</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Total</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td style="width: 49%"><font style="font-size: 8pt">5% Notes</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">133</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">133</font></td>
<td style="width: 4%; padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Total</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">133</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">133</font></td>
<td style="padding-bottom: 3pt"> </td></tr>
</table>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="14" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Financial liabilities at fair value as of December 31, 2018</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Level 1</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Level 2</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Level 3</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Total</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td style="width: 49%"><font style="font-size: 8pt">5% Notes</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">67</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">67</font></td>
<td style="width: 4%; padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Total</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">67</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">67</font></td>
<td style="padding-bottom: 3pt"> </td></tr>
</table>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: justify"> </p>
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">(in thousands)</font></td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td style="width: 88%"><font style="font-size: 8pt">Fair value at December 31, 2018</font></td>
<td style="width: 1%"> </td>
<td style="width: 1%"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; text-align: right"><font style="font-size: 8pt">67</font></td>
<td style="width: 1%"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Interest accrued on face value of 5% Notes</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">224</font></td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Change in fair value of Level 3 liabilities</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"> </td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">(158</font></td>
<td style="padding-bottom: 1.5pt"><font style="font-size: 8pt">)</font></td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Fair value at March 31, 2019</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">133</font></td>
<td style="padding-bottom: 3pt"> </td></tr>
</table>
<p style="margin: 0pt"></p>
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="10" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>March 31, 2019</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="10" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>December 31, 2018</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">(in thousands)</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Current portion, net</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Non-current portion, net</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Total</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Current portion, net</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Non-current portion, net</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Total</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td style="width: 36%"><font style="font-size: 8pt">Convertible 5% Notes Payable</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 7%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">133</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 7%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 7%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">133</font></td>
<td style="width: 3%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 7%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">67</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 7%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 7%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">67</font></td>
<td style="width: 3%; padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Total</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">133</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">133</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">67</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">67</font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
</table>
<p style="margin: 0pt"></p>
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>March 31, 2019</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td style="width: 71%"><font style="font-size: 8pt">Long-term debt</font></td>
<td style="width: 3%"> </td>
<td style="width: 1%"><font style="font-size: 8pt">$</font></td>
<td style="width: 22%; text-align: right"><font style="font-size: 8pt">30,000</font></td>
<td style="width: 3%"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">End of term fee</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"> </td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">975</font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">30,975</font></td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Less: unamortized debt issuance costs</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"> </td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">(2,689</font></td>
<td style="padding-bottom: 1.5pt"><font style="font-size: 8pt">)</font></td></tr>
<tr style="vertical-align: bottom">
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">28,286</font></td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Less: Current portion</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"> </td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="padding-bottom: 3pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Long-term debt– non-current</font></td>
<td> </td>
<td><font style="font-size: 8pt">$</font></td>
<td style="text-align: right"><font style="font-size: 8pt">28,286</font></td>
<td> </td></tr>
</table>
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td style="width: 88%"><font style="font-size: 8pt">Exercise Price</font></td>
<td style="width: 1%"> </td>
<td style="width: 1%"><font style="font-size: 8pt">$</font></td>
<td style="width: 9%; text-align: right"><font style="font-size: 8pt">4.08</font></td>
<td style="width: 1%"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Common share price on date of issuance</font></td>
<td> </td>
<td><font style="font-size: 8pt">$</font></td>
<td style="text-align: right"><font style="font-size: 8pt">6.80</font></td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Volatility</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">195.9</font></td>
<td><font style="font-size: 8pt">%</font></td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Risk-free interest rate</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">2.63</font></td>
<td><font style="font-size: 8pt">%</font></td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Expected dividend yield</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">--</font></td>
<td><font style="font-size: 8pt">%</font></td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Contractual term (in years)</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">7.00 years</font></td>
<td> </td></tr>
</table>
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt"> (in thousands)</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b> March 31, 2019</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td style="width: 82%"><font style="font-size: 8pt"> Operating lease cost</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 15%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">418</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt"> Net lease cost</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">418</font></td>
<td style="padding-bottom: 3pt"> </td></tr>
</table>
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">(in thousands)</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>March 31, 2019</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt"><b>Liabilities</b></font></td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td style="width: 82%"><font style="font-size: 8pt">Lease liability – current portion</font></td>
<td style="width: 1%"> </td>
<td style="width: 1%"><font style="font-size: 8pt">$</font></td>
<td style="width: 15%; text-align: right"><font style="font-size: 8pt">1,261</font></td>
<td style="width: 1%"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Lease liability – non-current</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"> </td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">8,182</font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td style="padding-left: 0.5in"><font style="font-size: 8pt">Total lease liability</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">9,443</font></td>
<td style="padding-bottom: 3pt"> </td></tr>
</table>
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">(in thousands)</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Operating leases</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td style="width: 82%"><font style="font-size: 8pt">Remainder of 2019</font></td>
<td style="width: 1%"> </td>
<td style="width: 1%"><font style="font-size: 8pt">$</font></td>
<td style="width: 15%; text-align: right"><font style="font-size: 8pt">1,023</font></td>
<td style="width: 1%"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">2020</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">1,348</font></td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">2021</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">1,353</font></td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">2022</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">1,376</font></td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">2023</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">1,367</font></td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">After 2023</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"> </td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">10,281</font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Total lease payments</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">16,748</font></td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Less: Interest</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"> </td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">(7,305</font></td>
<td style="padding-bottom: 1.5pt"><font style="font-size: 8pt">)</font></td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Present value of lease liabilities(*)</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">9,443</font></td>
<td style="padding-bottom: 3pt"> </td></tr>
<tr style="vertical-align: bottom">
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"> </td>
<td> </td></tr>
</table>
6768530
4660180
4039620
147058
16542
4159428
0
15752
2565310
485000
1200000
1200000
62671000
39268000
1678000
2690000
28125000
26943000
26943000
28125000
28113000
26951000
26951000
28113000
15000
2000
2000
15000
3000
10000
10000
3000
133000
67000
0
0
133000
0
0
67000
133000
67000
0
0
133000
0
0
67000
133000
67000
224000
-158000
18600000
18400000
2565310
1916900
0
66590
0
715000
2565310
0
6.61
6.50
0.00
6.80
0.00
6.90
6.61
0.00
P9Y7M17D
P9Y9M
P9Y7M17D
5800421000
5800421000
0.00
0.00
2.0459
2.9161
0.0240
0.0249
P5Y
P6Y3M
6095692
5539620
67628
511444
23000
8.07
7.95
7.54
8.64
12.95
1177000
7337000
705000
0
133000
67000
133000
67000
133000
67000
133000
67000
0
0
0
0
0
28286000
30975000
-2689000
30000000
975000
418000
418000
9443000
0
9400000
1023000
1348000
1353000
1376000
1367000
10281000
16748000
-7305000
1000000
1100000
152000
152000
300000
2000000
1000000
3000000
200000
400000
300000
0
0.45
4.08
6.80
1.959
0.0263
147058
0
147058
0
0
4.08
4.08
582350
538000
0
P7Y
3030611
24600000
8.11
24200000
17800000
0
0
18400000
800000
0
2800000
P15Y
600000
600000
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Number of shares</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Weighted-average exercise price</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Weighted-average Contractual Term</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Aggregate Intrinsic Value</b> </font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"><font style="font-size: 8pt"><b>(in years)</b></font></td>
<td> </td>
<td> </td>
<td colspan="2" style="text-align: center"> </td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td style="width: 48%"><font style="font-size: 8pt">Outstanding at December 31, 2018</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 10%; padding-bottom: 1.5pt; text-align: right"><font style="font-size: 8pt">1,916,900</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"><font style="font-size: 8pt">$</font></td>
<td style="width: 10%; padding-bottom: 1.5pt; text-align: right"><font style="font-size: 8pt">6.50</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 10%; padding-bottom: 1.5pt; text-align: right"><font style="font-size: 8pt">9.75</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 10%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td style="padding-left: 0.25in"><font style="font-size: 8pt">Granted</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">715,000</font></td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">6.90</font></td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"> </td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"> </td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td style="padding-left: 0.25in"><font style="font-size: 8pt">Exercised</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">--</font></td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">--</font></td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"> </td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"> </td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td style="padding-left: 0.25in"><font style="font-size: 8pt">Forfeited</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">(66,590</font></td>
<td><font style="font-size: 8pt">)</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">6.80</font></td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"> </td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"> </td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td style="padding-left: 0.25in"><font style="font-size: 8pt">Expired</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"> </td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt; text-align: right"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt; text-align: right"> </td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Outstanding at March 31, 2019</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"> </td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">2,565,310</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">6.61</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"> </td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">9.63</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">5,800,421</font></td>
<td style="padding-bottom: 3pt"> </td></tr>
<tr style="vertical-align: bottom">
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"> </td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"> </td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"> </td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"> </td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Expected to vest at March 31, 2019</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"> </td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">2,565,310</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">6.61</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"> </td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">9.63</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">5,800,421</font></td>
<td style="padding-bottom: 3pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Exercisable at March 31, 2019</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"> </td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"> </td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="padding-bottom: 3pt"> </td></tr>
</table>
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Three months ended March 31, 2019</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td style="width: 82%"><font style="font-size: 8pt">Volatility</font></td>
<td style="width: 1%"> </td>
<td style="width: 1%"> </td>
<td style="width: 15%; text-align: right"><font style="font-size: 8pt">204.59-291.61</font></td>
<td style="width: 1%"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Expected term (in years)</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">5.0-6.25</font></td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Risk-free rate</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">2.40-2.49</font></td>
<td><font style="font-size: 8pt">%</font></td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Expected dividend yield</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">--</font></td>
<td><font style="font-size: 8pt">%</font></td></tr>
</table>
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Number of Shares</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Weighted Average Grant Date Fair Value</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td style="width: 64%"><font style="font-size: 8pt">Outstanding at December 31, 2018</font></td>
<td style="width: 1%"> </td>
<td style="width: 1%"> </td>
<td style="width: 15%; text-align: right"><font style="font-size: 8pt">6,095,692</font></td>
<td style="width: 1%"> </td>
<td style="width: 1%"> </td>
<td style="width: 1%"><font style="font-size: 8pt">$</font></td>
<td style="width: 15%; text-align: right"><font style="font-size: 8pt">8.07</font></td>
<td style="width: 1%"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Granted</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">23,000</font></td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">12.95</font></td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Vested</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">(511,444</font></td>
<td><font style="font-size: 8pt">)</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">8.64</font></td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Forfeited</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"> </td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">(67,628</font></td>
<td style="padding-bottom: 1.5pt"><font style="font-size: 8pt">)</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt; text-align: right"><font style="font-size: 8pt">7.54</font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Outstanding at March 31, 2019</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"> </td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">5,539,620</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">7.95</font></td>
<td style="padding-bottom: 3pt"> </td></tr>
</table>
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid">
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: center"> </p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: center"><b>Warrants</b></p></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid">
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: center"><b>Weighted-</b></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: center"><b>average</b></p>
<p style="font: 8pt Times New Roman, Times, Serif; margin: 0; text-align: center"><b>exercise price</b></p></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Aggregate Intrinsic Value</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td style="width: 62%"><font style="font-size: 8pt">Outstanding at December 31, 2018</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 9%; padding-bottom: 1.5pt; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"><font style="font-size: 8pt">$</font></td>
<td style="width: 10%; padding-bottom: 1.5pt; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td>
<td style="width: 1%; border-bottom: black 1pt solid"><font style="font-size: 8pt">$</font></td>
<td style="width: 10%; border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="width: 1%; padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td style="padding-left: 0.25in"><font style="font-size: 8pt">Issued</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">147,058</font></td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">4.08</font></td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"> </td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td style="padding-left: 0.25in"><font style="font-size: 8pt">Exercised</font></td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">--</font></td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"><font style="font-size: 8pt">--</font></td>
<td> </td>
<td> </td>
<td> </td>
<td style="text-align: right"> </td>
<td> </td></tr>
<tr style="vertical-align: bottom">
<td style="padding-left: 0.25in"><font style="font-size: 8pt">Expired</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"> </td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt; text-align: right"> </td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Outstanding at March 31, 2019</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"> </td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">147,058</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">4.08</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">582,350</font></td>
<td style="padding-bottom: 3pt"> </td></tr>
</table>
<table cellspacing="0" cellpadding="0" style="font: 12pt Times New Roman, Times, Serif; width: 100%">
<tr style="vertical-align: bottom">
<td> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="6" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>Three months ended March 31,</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">(in thousands)</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>2019</b></font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td colspan="2" style="border-bottom: black 1pt solid; text-align: center"><font style="font-size: 8pt"><b>2018</b></font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td style="width: 64%"><font style="font-size: 8pt">Stock-based compensation expense associated with restricted stock</font></td>
<td style="width: 1%"> </td>
<td style="width: 1%"><font style="font-size: 8pt">$</font></td>
<td style="width: 14%; text-align: right"><font style="font-size: 8pt">1,177</font></td>
<td style="width: 1%"> </td>
<td style="width: 1%"> </td>
<td style="width: 1%"><font style="font-size: 8pt">$</font></td>
<td style="width: 14%; text-align: right"><font style="font-size: 8pt">7,337</font></td>
<td style="width: 3%"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Stock-based compensation expense associated with option grants</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"> </td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">705</font></td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="padding-bottom: 1.5pt"> </td>
<td style="border-bottom: black 1pt solid"> </td>
<td style="border-bottom: black 1pt solid; text-align: right"><font style="font-size: 8pt">--</font></td>
<td style="padding-bottom: 1.5pt"> </td></tr>
<tr style="vertical-align: bottom">
<td><font style="font-size: 8pt">Total</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">1,882</font></td>
<td style="padding-bottom: 3pt"> </td>
<td style="padding-bottom: 3pt"> </td>
<td style="border-bottom: black 1pt double"><font style="font-size: 8pt">$</font></td>
<td style="border-bottom: black 1pt double; text-align: right"><font style="font-size: 8pt">7,337</font></td>
<td style="padding-bottom: 3pt"> </td></tr>
</table>
84200000
5600000
300000
24000
1100000
P9Y9M
0.1025
4.08
1000000