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Document And Entity Information - USD ($)	12 Months Ended
Document And Entity Information - USD ($)	Dec. 31, 2018	Feb. 28, 2019	Jun. 30, 2018
Document Information [Line Items]
Entity Registrant Name	KEMPHARM, INC
Entity Central Index Key	0001434647
Trading Symbol	kmph
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	No
Entity Emerging Growth Company	true
Entity Small Business	true
Entity Common Stock, Shares Outstanding (in shares)		26,455,352
Entity Public Float			$ 71,917,131
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Shell Company	false
Entity Ex Transition Period	true

Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Assets
Cash and cash equivalents	$ 18,409	$ 10,871
Marketable securities	3,260	31,358
Trade date receivables		2,005
Prepaid expenses and other current assets	2,052	1,662
Total current assets	23,721	45,896
Property and equipment, net	1,753	2,004
Long-term investments		3,250
Restricted cash	710	1,100
Other long-term assets	562	206
Total assets	26,746	52,456
Liabilities and stockholders’ deficit
Accounts payable and accrued expenses	8,342	7,875
Current portion of convertible notes	3,333	3,333
Current portion of capital lease obligation	214	189
Other current liabilities	115	112
Total current liabilities	12,004	11,509
Convertible notes, less current portion, net	78,105	89,398
Derivative and warrant liability	2,118	7,709
Capital lease obligation, less current portion	396	562
Other long-term liabilities	689	794
Total liabilities	93,312	109,972
Commitments and contingencies (Note G)
Stockholders' deficit:
Common stock, $0.0001 par value, 250,000,000 shares authorized, 26,455,352 shares issued and outstanding as of December 31, 2018; 14,657,430 shares issued and outstanding as of December 31, 2017	3	1
Additional paid-in capital	154,623	107,209
Accumulated deficit	(221,192)	(164,726)
Total stockholders' deficit	(66,566)	(57,516)
Total liabilities and stockholders' deficit	26,746	52,456
Series A Convertible Preferred Stock [Member]
Stockholders' deficit:
Preferred stock
Undesignated Preferred Stock [Member]
Stockholders' deficit:
Preferred stock

Balance Sheets (Parentheticals) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	9,577
Preferred stock, shares outstanding (in shares)	3,337
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	250,000,000	250,000,000
Common stock, shares issued (in shares)	26,455,352	14,657,430
Common stock, shares outstanding (in shares)	26,455,352	14,657,430
Series A Convertible Preferred Stock [Member]
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (in shares)	9,578	0
Preferred stock, shares issued (in shares)	9,577	0
Preferred stock, shares outstanding (in shares)	3,337	0
Undesignated Preferred Stock [Member]
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (in shares)	9,990,422	10,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0

Statements of Operations - USD ($) $ in Thousands	12 Months Ended
Statements of Operations - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Revenue
Operating expenses:
Research and development	41,759	20,593
General and administrative	12,508	12,773
Severance expense	1,636
Total operating expenses	55,903	33,366
Loss from operations	(55,903)	(33,366)
Other (expense) income:
Gain on extinguishment of debt	2
Interest expense related to amortization of debt issuance costs and discount	(1,618)	(1,561)
Interest expense on principal	(5,469)	(5,776)
Fair value adjustment related to derivative and warrant liability	5,976	(3,091)
Interest and other income, net	420	365
Total other (expense) income	(689)	(10,063)
Loss before income taxes	(56,592)	(43,429)
Income tax benefit	126	43
Net loss	$ (56,466)	$ (43,386)
Net loss per share:
Basic and diluted (in dollars per share)	$ (3.15)	$ (2.96)
Weighted average number of shares of common stock outstanding:
Basic and diluted (in shares)	17,930,023	14,652,898

Statements of Changes in Stockholders' Deficit - USD ($)	ATM Agreement Sales [Member] Common Stock [Member]	ATM Agreement Sales [Member] Additional Paid-in Capital [Member]	ATM Agreement Sales [Member]	Deerfield Convertible Notes [Member] Additional Paid-in Capital [Member]	Deerfield Convertible Notes [Member]	Underwriting Public Offering [Member] Common Stock [Member]	Underwriting Public Offering [Member] Additional Paid-in Capital [Member]	Underwriting Public Offering [Member]	Convertible Notes 2021 [Member] Additional Paid-in Capital [Member]	Convertible Notes 2021 [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Total
Balance at Dec. 31, 2016											$ 1,000	$ 102,643,000	$ (121,340,000)	$ (18,696,000)
Net loss													(43,386,000)	(43,386,000)
Stock-based compensation expense												4,562,000		4,562,000
Exercise of stock options and warrants												4,000		4,000
Exercise of stock options														7,000
Balance at Dec. 31, 2017											1,000	107,209,000	(164,726,000)	(57,516,000)
Net loss													(56,466,000)	(56,466,000)
Stock-based compensation expense												6,495,000		6,495,000
Issuance of common stock in connection with ATM, net of commissions	$ 1,000	$ 4,827,000	$ 4,828,000			$ 1,000	$ 23,499,000	$ 23,500,000
Offering expenses charged to equity												(554,000)		(554,000)
Conversion of principal and interest on Deerfield Convertible Note				$ 3,502,000	$ 3,502,000				$ 9,577,000	$ 9,577,000
Exercise of stock options												68,000		68,000
Balance at Dec. 31, 2018											$ 3,000	$ 154,623,000	$ (221,192,000)	$ (66,566,000)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Statements of Cash Flows - USD ($)	12 Months Ended
Statements of Cash Flows - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net loss	$ (56,466,000)	$ (43,386,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Gain on extinguishment of debt	(2,000)
Write-off of deferred offering costs		60,000
Stock-based compensation expense	6,495,000	4,562,000
Non-cash interest expense	2,089,000	2,222,000
Amortization of debt issuance costs and debt discount	1,618,000	1,561,000
Depreciation and amortization expense	324,000	336,000
Fair value adjustment related to derivative and warrant liability	(5,976,000)	3,091,000
Loss on sublease and disposal of fixed assets		104,000
Change in assets and liabilities:
Prepaid expenses and other assets	(548,000)	(926,000)
Accounts payable and accrued expenses	(1,635,000)	(801,000)
Other liabilities	(102,000)	77,000
Net cash used in operating activities	(54,203,000)	(33,100,000)
Cash flows from investing activities:
Purchases of property and equipment	(21,000)	(181,000)
Purchases of marketable securities and long-term investments		(27,378,000)
Maturities and sales of marketable securities	33,353,000	54,971,000
Net cash provided by investing activities	33,332,000	27,412,000
Cash flows from financing activities:
Proceeds from underwritten public offering, net of commissions	23,500,000
Proceeds from at-the-market offering, net of commissions	4,828,000
Repayment of obligations under capital lease	(193,000)	(157,000)
Payment of deferred offering costs	(184,000)	(50,000)
Proceeds from exercise of common stock options and warrants	68,000	4,000
Net cash provided by (used in) financing activities	28,019,000	(203,000)
Net increase (decrease) in cash, cash equivalents and restricted cash	7,148,000	(5,891,000)
Cash, cash equivalents and restricted cash, beginning of year	11,971,000	17,862,000
Cash, cash equivalents and restricted cash, end of year	19,119,000	11,971,000
Supplemental cash flow information:
Cash paid for interest	5,593,000	5,717,000
Trade date receivables		2,005,000
Deerfield Convertible Note principal and interest converted to common stock	3,502,000
Property and equipment financed under a lease agreement	52,000	284,000
Property and equipment included in accounts payable and accrued expenses		3,000
Deferred offering costs included in accounts payable and accrued expenses	181,000
Exchanged 2021 Notes for Series A Preferred Stock [Member]
Supplemental cash flow information:
2021 Notes principal converted to preferred stock	$ 9,577,000

Note A - Description of Business and Basis of Presentation

12 Months Ended

Dec. 31, 2018

Notes to Financial Statements

Business Description and Basis of Presentation [Text Block]

A.	Description of Business and Basis of Presentation

Organization

KemPharm, Inc. (the “Company”) is a specialty pharmaceutical company focused on the discovery and development of proprietary prodrugs to treat serious medical conditions through its proprietary Ligand Activated Therapy ("LAT") technology. The Company utilizes its proprietary LAT technology to generate improved prodrug versions of U.S. Food and Drug Administration (the "FDA") approved drugs as well as to generate prodrug versions of existing compounds that

may

have applications for new disease indications. The Company's product candidate pipeline is focused on the high need areas of attention deficit hyperactivity disorder ("ADHD") and stimulant use disorder ("SUD"). The Company was formed and incorporated in Iowa on

October

30,

2006

and reorganized in Delaware on

May 30, 2014.

Going Concern

The financial statements have been prepared on a going concern basis which assumes that the Company will be able to realize its assets and discharge its liabilities in the normal course of business for the foreseeable future. The Company has experienced recurring losses from operations, negative operating cash flows and has a stockholders' deficit and its existing cash and cash equivalents, restricted cash and marketable securities are

not

sufficient to fund the Company’s operating expenses and capital expenditure requirements for at least

one

year from date these financial statements are issued. The Company also has an accumulated deficit as of

December 31, 2018.

Various internal and external factors will affect whether and when product candidates become approved drugs and how significant the market share of those approved products will be. The length of time and cost of developing and commercializing these product and product candidates and/or failure of them at any stage of the drug approval or commercialization process will materially affect the Company’s financial condition and future operations. The Company's ability to continue as a going concern

may

require additional financing to fund operations. The perception of the Company's inability to continue as a going concern

may

make it more difficult to obtain financing for the continuation of operations and could result in the loss of confidence by investors, suppliers and employees. Adequate additional financing

may

not

be available to the Company on acceptable terms, or at all.

Management believes these conditions raise substantial doubt about the Company’s ability to continue as a going concern within the

twelve

months after the date these financial statements are issued. The ability to continue as a going concern is dependent upon profitable future operations, positive cash flows and additional financing.

Management intends to finance operating costs over the next

twelve

months with existing cash and cash equivalents and marketable securities, as well as, financing through the Company's active registration statement on Form S-

covering the sale of up to

$150.0

million of the Company's common stock, preferred stock, and debt and/or warrants. As of December

31,

2018,

the Company had approximately

$120.1

million available under its Form S-

registration statement, of which,

$50.0

million was covered under a prospectus supplement related to Second ATM Agreement (as defined below). After the Company files its Annual Report on Form

-K for the fiscal year ended December

31,

2018

(the “Annual Report”), in order to issue securities under registration statement, it must rely on Instruction

I.B.6.

of Form S-

which imposes a limitation on the maximum amount of securities that it may sell pursuant to the registration statement during any

twelve

-month period. At the time it sells securities pursuant to the registration statement, the amount of securities to be sold plus the amount of any securities it has sold during the prior

twelve

months in reliance on Instruction

I.B.6.

may

not

exceed

one

third

of the aggregate market value of its outstanding common stock held by non-affiliates as of a day during the

days immediately preceding such sale, as computed in accordance with Instruction

I.B.6.

This calculation will be updated immediately after the Company’s files the Annual Report and the Company expects that the amount of securities it will be able to sell under the registration statement on Form S-

thereafter will be approximately

$18.5

million, of which it anticipates filing prospectus supplements to register (i) approximately

$15.3

million for sales under the Purchase Agreement (as defined below); and (ii) approximately

$3.2

million for sales under our Second ATM Agreement (as defined below). Based on this calculation, the Company expects it will be unable to sell additional securities pursuant to its effective registration statement on Form S-

for a period of

twelve

months, unless and until the market value of its outstanding common stock held by non-affiliates increases significantly.

As discussed below, the Company sold shares of its common stock through an at-the-market offering and an underwritten public offering which resulted in gross proceeds of

$4.9

million and

$25.0

million, respectively.

Entry into First ATM Agreement

October 3, 2016,

the Company entered into a Common Stock Sales Agreement (the “First ATM Agreement”) with Cowen and Company, LLC (“Cowen”). The First ATM Agreement was terminated on

September 14, 2018.

Prior to termination of the First ATM Agreement, the Company sold an aggregate of

762,338

shares of common stock under the First ATM Agreement resulting in gross proceeds to the Company of

$4.9

million. The Company paid Cowen a commission of up to

three

percent (

3.0%

) of the gross sales proceeds for such sales of common stock. Pursuant to the terms of the First ATM Agreement, specified obligations of the parties, including the Company’s indemnification obligations to Cowen, survive the termination of the First ATM Agreement.

Entry into Second ATM Agreement

September 4, 2018,

the Company entered into a Common Stock Sales Agreement (the “Second ATM Agreement”) with RBC Capital Markets, LLC (“RBCCM”) under which the Company

may

offer and sell, from time to time, in its sole discretion, shares of common stock having an aggregate offering price of up to

$50,000,000

through RBCCM as its sales agent. The Company’s registration statement on Form S-

contemplated under the Second ATM Agreement was declared effective by the SEC on

October 17, 2016.

The registration statement on Form S-

includes a prospectus supplement covering the offering of up to

$50,000,000

of shares of common stock in accordance with the Second ATM Agreement, but as noted above the Company anticipates that due to the limitations of Instruction

I.B.6

of Form S-

it will file a prospectus supplement reducing this offering to approximately

$3.2

million.

RBCCM

may

sell common stock under the Second ATM Agreement by any method permitted by law deemed to be an “at the market offering” as defined in Rule

415

of the Securities Act of

1933,

as amended (the "Securities Act"), including without limitation sales made by means of ordinary brokers’ transactions on the Nasdaq Global Market or otherwise at market prices prevailing at the time of sale, in block transactions, or as otherwise directed by the Company. RBCCM will use commercially reasonable efforts to sell the common stock from time to time, based upon instructions from the Company (including any price, time or size limits or other customary parameters or conditions the Company

may

impose). The Company will pay RBCCM a commission of up to

three

percent (

3.0%

) of the gross sales proceeds of any common stock sold through RBCCM under the Second ATM Agreement, and also has provided RBCCM with customary indemnification rights.

The Company is

not

obligated to make any sales of common stock under the Second ATM Agreement. The offering of shares of common stock pursuant to the Second ATM Agreement will terminate upon the earlier of (i) the sale of all common stock subject to the Second ATM Agreement, or (ii) termination of the Second ATM Agreement in accordance with its terms. As of

December 31, 2018,

the Company has

not

sold any shares of common stock under the Second ATM Agreement.

Underwritten Public Offering

October 5, 2018,

the Company entered into an underwriting agreement (the “Underwriting Agreement”) with RBCCM, pursuant to which, on

October 10, 2018,

the Company sold

8,333,334

shares of common stock of the Company in an underwritten public offering pursuant to the Company's registration statement on Form S-

filed with the SEC on

October 17, 2016,

and a related prospectus and prospectus supplement, filed with the SEC on

October 17, 2016

and

October 5, 2018,

respectively. The offering price to the public was

$3.00

per share. The Company’s net proceeds from the offering were approximately

$23.1

million, after deducting underwriting discounts and commissions and estimated offering expenses.

Entry into Purchase Agreement

February 28, 2019,

the Company entered into a purchase agreement (the “Purchase Agreement”) with Lincoln Park Capital Fund, LLC (“Lincoln Park”) which provides that, upon the terms and subject to the conditions and limitations set forth therein, the Company

may

sell to Lincoln Park up to

$15.0

million of shares of common stock from time to time over the

-month term of the Purchase Agreement, and the Company shall issue an additional

120,200

shares of common stock to Lincoln Park as commitment shares under the Purchase Agreement. Concurrently with entering into the Purchase Agreement, the Company also entered into a registration rights agreement with Lincoln Park (the “Registration Rights Agreement”) pursuant to which the Company agreed to register the sale of the shares of our common stock that have been and

may

be issued to Lincoln Park under the Purchase Agreement pursuant to the Company’s existing shelf registration statement on Form S-

or a new registration statement.

The Company is

not

obligated to make any future sales of common stock under the Purchase Agreement, and while it has yet to make any sales under the Purchase Agreement, it is obligated to issue

120,200

commitment shares to Lincoln Park upon satisfaction of the closing conditions contained in the Purchase Agreement.

Note B - Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2018

Notes to Financial Statements

Significant Accounting Policies [Text Block]

B.	Summary of Significant Accounting Policies

Use of Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America ("GAAP")

requires the Company to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates.

On an ongoing basis, the Company evaluates its estimates, includ

ing those related to the useful lives of property and equipment, and assumptions used for purposes of determining stock-based compensation, income taxes, and the fair value of the derivative and warrant liability, among others. The Company bases its estimates on historical experience and on various other assumptions that it believes to be reasonable, the results of which form the basis for making judgments about the carrying value of assets and liabilities.

Concentration of Credit Risk

Financial instruments that potentially expose

the Company to concentrations of credit risk consist principally of cash on deposit with multiple financial institutions, the balances of which frequently exceed insured limits.

Cash and Cash Equivalents

The Company considers any highly liquid investm

ents with an original maturity of

three

months or less to be cash equivalents.

Marketable Securities and Long-term Investments

The Company maintains investment securities that are classified as trading securities. These securities are carried at fair value with unreali

zed gains and losses included in other (expense) income on the statements of operations. The securities primarily consist of certificates of deposit, U.S. Treasury securities and U.S. government-sponsored agency securities.

Property and Equipment

The Company records property and equipment at cost less accumulated

depreciation and amortization. Costs of renewals and improvements that extend the useful lives of the assets are capitalized. Maintenance and repairs are expensed as incurred. Depreciation is determined on a straight-line basis over the estimated useful lives of the assets, which generally range from

three

ten

years. Leasehold improvements are amortized over the shorter of the useful life of the asset or the term of the related lease. Upon retirement or disposition of assets, the costs and related accumulated depreciation and amortization are removed from the accounts with the resulting gains or losses, if any, reflected in the statements of operations.

Debt Issuance Costs

Debt issuance costs incurred in connection with financing arrangements are amortiz

ed over the life of the respective financing arrangement using the effective interest method.

Supply Arrangements

The Company enters into supply arrangements for the supply of components of its product and product candidates. These arrangements also

may

include a

share of future revenue if related product or product candidates reach commercialization. Costs under these supply arrangements, if any, are expensed as incurred (Note H).

Impairment of Long-Lived Assets

Long-lived assets to be held and used are reviewed for

impairment whenever events or changes in circumstances indicate that the carrying amounts of the assets

may

not

be recoverable. When such events occur, the Company compares the carrying amounts of the assets to their undiscounted expected future cash flows. If the undiscounted cash flows are insufficient to recover the carrying values, an impairment loss is recorded for the difference between the carrying values and fair values of the asset.

such impairment occurred for the years ended

December 31, 2018

2017.

Fair Value of Financial Instruments

The accounting standard for fair value measurements provides a framework for measuring fair value and requires disclosures regarding fair value measurements. Fair value is defined as the price that would be

received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date, based on the Company’s principal or, in absence of a principal, most advantageous market for the specific asset or liability.

The Company uses a

three

-tier fair value hierarchy to classify and disclose all assets and liabilities measured at fair value on a recurring basis, as well as assets and liabilities measured at fair value on a non-recurring basis, in periods subs

equent to their initial measurement. The hierarchy requires the Company to use observable inputs when available, and to minimize the use of unobservable inputs, when determining fair value. The

three

tiers are defined as follows:

●

Level

—Observable inputs that reflect quoted market prices (unadjusted) for identical assets or liabilities in active markets;

●

Level

—Observable inputs other than quoted prices in active markets that are observable either directly or indirectly in the marketplace for identical or similar assets and liabilities; and

●

Level

—Unobservable inputs that are supported by little or

market data, which require the Company to develop its own assumptions.

Research and Development

Major components of research and development costs include cash compensation, stock-based compensation, depreciation and amortization expense on research and development property and equipment, costs of preclinical studies, clin

ical trials and related clinical manufacturing, costs of drug development, costs of materials and supplies, facilities cost, overhead costs, regulatory and compliance costs, and fees paid to consultants and other entities that conduct certain research and development activities on the Company’s behalf. Costs incurred in research and development are expensed as incurred.

The Company records nonrefundable advance payments it makes for future research and development activities as prepaid expenses. Prepaid

expenses are recognized as expense in the statements of operations as the Company receives the related goods or services.

The Company enters into contractual agreements with

third

-party vendors who provide research and development, manufacturing, and other services in the ordinary course of business. Some of these contracts are subject to milestone-based invoicing and services are com

pleted over an extended period of time. The Company records liabilities under these contractual commitments when an obligation has been incurred. This accrual process involves reviewing open contracts and purchase orders, communicating with the applicable personnel to identify services that have been performed and estimating the level of service performed and the associated cost when the Company has

not

yet been invoiced or otherwise notified of actual cost. The majority of the service providers invoice the Company monthly in arrears for services performed. The Company makes estimates of the accrued expenses as of each balance sheet date based on the facts and circumstances known. The Company periodically confirms the accuracy of the estimates with the service providers and make adjustments, if necessary.

Patent Costs

Patent costs, including related legal costs, are expensed as incurred and recorded within general and administrative

expenses on the statements of operations.

Income Taxes

The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the financial reporting and tax basis of assets and liabilities,

as well as for operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using the tax rates that are expected to apply to taxable income for the years in which those tax assets and liabilities are expected to be realized or settled. Valuation allowances are recorded to reduce deferred tax assets to the amount the Company believes is more likely than

not

to be realized.

Uncertain tax positions are recognized only when the Company believes it is more likely than

not

tha

t the tax position will be upheld on examination by the taxing authorities based on the merits of the position. The Company recognizes interest and penalties, if any, related to unrecognized income tax uncertainties in income tax expense. The Company did

not

have any accrued interest or penalties associated with uncertain tax positions as of

December 31, 2018

and

2017.

The Company files income tax returns in the United States for federal and various state jurisdictions. With few exceptions,

the Company is

longer subject to U.S. federal and state and local income tax examinations for years prior to

2014,

although carryforward attributes that were generated prior to

2014

may

still be adjusted upon examination by the Internal Revenue Service if used in a future period.

income tax returns are currently under examination by taxing authorities.

Stock-Based Compensation

The Company measures and recognizes compensation expense for all stock-based payment awards made to employees, officers an

d directors based on the estimated fair values of the awards as of the grant date. The Company records the value of the portion of the award that is ultimately expected to vest as expense over the requisite service period. The Company also accounts for equity instruments issued to non-employees using a fair value approach under Accounting Standards Codification ("ASC") subtopic

505

50.

The Company values equity instruments and stock options granted using the Black-Scholes option pricing model. The value of non-employee stock-based compensation is subject to periodic adjustments as the underlying equity instruments vest and is recognized as an expense over the term of the related financing or the period over which services are received.

Basic and Diluted Net

Loss per Share of Common Stock

The Company uses the

two

-class method to compute net loss per common share because the Company has issued securities, other than common stock, that contractually

entitle the holders to participate in dividends and earnings of the Company. The

two

-class method requires earnings for the period to be allocated between common stock and participating securities based upon their respective rights to receive distributed and undistributed earnings. Holders of each series of the Company’s convertible preferred stock are entitled to participate in distributions, when and if declared by the board of directors, that are made to common stockholders and, as a result, are considered participating securities.

Segment and Geographic Information

Operating segments are defined as components of an enterprise (business activity from which it earns revenue and incurs expenses) for which discrete financial information is ava

ilable and regularly reviewed by the chief operating decision maker ("CODM") in deciding how to allocate resources and in assessing performance. The Company’s CODM is its Chief Executive Officer. The Company views its operations and manages its business as a single operating and reporting segment. All assets of the Company were held in the United States as of

December 31, 2018

and

2017.

Application of New or Revised Accounting Standards

—Adopted

From time to time, the Financial Accounting Standards Board (the “FASB”) or other standard-setting bodies issue accounting standards that are adopted by the Company as of the specified effective date

April 5, 2012,

President Obama signed the Jump-Start Our Business Startups Act (the “

JOBS Act”) into law. The JOBS Act contains provisions that, among other things, reduce certain reporting requirements for an emerging growth company. As an emerging growth company, the Company

may

elect to adopt new or revised accounting standards when they become effective for non-public companies, which typically is later than public companies must adopt the standards. The Company has elected

not

to take advantage of the extended transition period afforded by the JOBS Act and, as a result, will comply with new or revised accounting standards on the relevant dates on which adoption of such standards is required for non-emerging growth companies.

May 2014,

the FASB issued guidance codified in ASC Topic

606,

Revenue Recognition—Revenue from Contracts with Customers

("ASC

606"

), which amended the guidance in former ASC

605,

Revenue Recognition

, and became effective

January 1, 2018.

This guidance did

not

have a material impact on the Company's financial statements and disclosures upon adoption since the Company is

not

generating revenue at this time.

January 2016,

the FASB issued ASU

2016

01,

Financial Instruments Overall – Recognition and Measurement of Financial Assets and Liabilities (Topic

825

)

(“ASU

2016

01”

), which provides several updates related to Topic

825

10.

This update applies to all entities that hold financial assets or owe financial liabilities. This guidance is effective for financial statements issued for fiscal years beginning after

December 15, 2017,

and interim periods within those fiscal years. The adoption of ASU

2016

did

not

have a material impact on the Company's financial statements and disclosures.

August 2016,

the FASB issued ASU

2016

15,

Statement of Cash Flows – Classification of Certain Cash Receipts and Cash Payments (Topic

230

)

(“ASU

2016

15”

), which addresses

eight

specific cash flow issues with the objective of reducing the existing diversity in practice. This update applies to all entities that are required to present a statement of cash flows under Topic

230.

This guidance is effective for financial statements issued for fiscal years beginning after

December 15, 2017,

and interim periods within those fiscal years. The adoption of ASU

2016

did

not

have a material impact on the Company's financial statements and disclosures.

May 2017,

the FASB issued ASU

2017

09,

Compensation – Stock Compensation (Topic

718

) – Scope of Modification Accounting

("ASU

2017

09"

), which provides guidance about which changes to the terms or conditions of a stock-based payment award require an entity to apply modification accounting in Topic

718.

This update applies to any entity that changes the terms or conditions of a stock-based payment award. This guidance is effective for financial statements issued for fiscal years beginning after

December 15, 2017,

and interim periods within those fiscal years. The adoption of ASU

2017

did

not

have a material impact on the Company's financial statements and disclosures.

Application of New or Revised Accounting Standards

—Not

Yet Adopted

February 2016,

the FASB issued ASU

2016

02,

Leases (Topic

842

)

(“ASU

2016

02”

), which requires lessees to recognize operating and finance lease liabilities and corresponding right-of-use assets on the balance sheet and to provide enhanced disclosures surrounding the amount, timing and uncertainty of cash flows arising from leases. The Company leases office space and laboratory facilities under non-cancelable operating leases. In addition, the Company leases various laboratory equipment, furniture and office equipment and leasehold improvements that are accounted for as capital leases. The Company will adopt the new standard effective

January 1, 2019

on a modified retrospective basis and will

not

restate comparative periods. The Company will elect the package of practical expedients permitted under the transition guidance, which allows the Company to carryforward its historical lease classification and its assessment on whether a contract is or contains a lease for any leases that exist prior to adoption of the new standard. The Company will also elect to combine lease and non-lease components and to keep leases with an initial term of

months or less off the balance sheet and recognize the associated lease payments in the statements of operations on a straight-line basis over the lease term. The Company estimates the adoption of this new standard to result in the recognition of total right-of-use assets and total lease liabilities of approximately

$3.0

million on the balance sheet as of

January 1, 2019.

July 2017,

the FASB issued ASU

2017

11,

Earnings Per Share (Topic

260

), Distinguishing Liabilities from Equity (Topic

480

), Derivatives and Hedging (Topic

815

) – I. Accounting for Certain Financial Instruments with Down Round Features and II. Replacement of the Indefinite Deferral for Mandatorily Redeemable Financial Instruments of Certain Nonpublic Entities and Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception

("ASU

2017

11"

), which addresses the complexity of accounting for certain financial instruments with down round features and addresses the difficulty of navigating Topic

480

because of the existence of extensive pending content in the ASC as a result of the indefinite deferral of accounting requirements about mandatorily redeemable financial instruments of certain nonpublic entities and certain mandatorily redeemable noncontrolling interests. This update applies to all entities that issue financial instruments that include down round features and entities that present earnings per share in accordance with Topic

260.

This guidance is effective for financial statements issued for fiscal years beginning after

December 15, 2018,

and interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period. If early adopted in an interim period, any adjustments should be reflected as of the beginning of the fiscal year that includes that interim period.

The Company does

not

expect the adoption of ASU

2017

to have a material impact on the Company's financial statements and disclosures.

June 2018,

the FASB issued ASU

2018

07,

Compensation –

Stock Compensation (Topic

820

) – Improvements to Nonemployee Share-Based Payment Accounting

("ASU

2018

07"

), which simplifies several aspects of the accounting for nonemployee share-based payment transactions resulting from expanding the scope of Topic

718,

Compensation—Stock Compensation, to include share-based payment transactions for acquiring goods and services from nonemployees. This update applies to all entities that enter into share-based payment transactions for acquiring goods and services from nonemployees. This guidance is effective for financial statements issued for fiscal years beginning after

December 15, 2018,

and interim periods within those fiscal years. The amendments in this ASU expand the scope of Topic

718

to include share-based payment transactions for acquiring goods and services from nonemployees. An entity should apply the requirements of Topic

718

to nonemployee awards except for specific guidance on inputs to an option pricing model and the attribution of cost (that is, the period of time over which share-based payment awards vest and the pattern of cost recognition over that period). The amendments specify that Topic

718

applies to all share-based payment transactions in which a grantor acquires goods or services to be used or consumed in a grantor’s own operations by issuing share-based payment awards. Early adoption is permitted, but

earlier than an entity’s adoption date of Topic

606.

The Company does

not

expect the adoption of ASU

2018

to have a material impact on the Company's financial statements and disclosures.

August 2018,

the FASB issued ASU

2018

13,

Fair Value Measurement (Topic

820

) – Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement

("ASU

2018

13"

), which modifies the disclosure requirements on fair value measurements in Topic

820,

Fair Value Measurement, based on the concepts in the FASB Concepts Statement,

Conceptual Framework for Financial Reporting—Chapter

Notes to Financial Statements,

which the FASB finalized on

August 28, 2018,

including the consideration of costs and benefits. This update applies to all entities that are required, under existing GAAP, to make disclosures about recurring or nonrecurring fair value measurements. This guidance is effective for financial statements issued for fiscal years beginning after

December 15, 2019,

and interim periods within those fiscal years. The amendments on changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level

fair value measurements, and the narrative description of measurement uncertainty should be applied prospectively for only the most recent interim or annual period presented in the initial fiscal year of adoption. All other amendments should be applied retrospectively to all periods presented upon their effective date. Early adoption is permitted. An entity is permitted to early adopt any removed or modified disclosures and delay adoption of the additional disclosures until their effective date. The Company is currently evaluating the impact of the adoption of ASU

2018

on the Company's financial statements and disclosures.

Note C - Prepaid Expenses and Other Current Assets

12 Months Ended

Dec. 31, 2018

Notes to Financial Statements

Other Current Assets [Text Block]

C.	Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets consist of the following (in thousands):

	December 31,
	2018		2017
Prepaid insurance	$	224	$	202
Other receivables		140		76
Other prepaid expenses and current assets		1,688		1,384
Total prepaid expenses and other current assets	$	2,052	$	1,662

Note D - Property and Equipment

12 Months Ended

Dec. 31, 2018

Notes to Financial Statements

Property, Plant and Equipment Disclosure [Text Block]

D.	Property and Equipment

Property and equipment consists of the following (in thousands):

	December 31,
	2018			2017
Laboratory equipment	$	1,035		$	983
Furniture and office equipment		655			655
Computers and hardware		299			292
Leasehold improvements		1,017			1,003
Total property and equipment		3,006			2,933
Less: accumulated depreciation and amortization		(1,253	)		(929	)
Property and equipment, net	$	1,753		$	2,004

The Company leases various equipment and leasehold improvements under capital lease agreements. The assets under capital leases are included in property and equipment as follows (in thousands):

	December 31,
	2018			2017
Laboratory equipment	$	418		$	366
Furniture and office equipment		541			541
Leasehold improvements		59			59
Total property and equipment financed under a capital lease agreement		1,018			966
Less: accumulated depreciation and amortization		(272	)		(150	)
Property and equipment financed under a capital lease agreement, net	$	746		$	816

The estimated useful lives of property and equipment are as follows:

	Useful Life
Asset Category	(in years)
Laboratory equipment		10
Furniture and office equipment		5 - 10
Computers and hardware		3 - 7
Leasehold improvements		9

Depreciation and amortization expense, including amounts

pertaining to assets held under capital leases, was approximately

$324,000

and

$336,000

for the years ended

December 31, 2018

and

2017,

respectively.

Note E - Accounts Payable and Accrued Expenses

12 Months Ended

Dec. 31, 2018

Notes to Financial Statements

Accounts Payable, Accrued Liabilities, and Other Liabilities Disclosure, Current [Text Block]

E.	Accounts Payable and Accrued Expenses

Accounts payable and accrued expenses consist

of the following (in thousands):

	December 31,
	2018		2017
Accrued interest	$	1,921	$	2,222
Accrued banking fees		700		700
Accrued severance		193		—
Accrued payroll		731		1,118
Accounts payable		3,715		2,177
Other accrued expenses		1,082		1,658
Total accounts payable and accrued expenses	$	8,342	$	7,875

Note F - Debt Obligations

12 Months Ended

Dec. 31, 2018

Notes to Financial Statements

Debt Disclosure [Text Block]

F.	Debt Obligations

Deerfield Facility Agreement

June

2014,

the Company entered into a

$60

million facility agreement (the “Deerfield Facility Agreement”) with Deerfield Private Design Fund III, LP (“Deerfield”). The

first

payment to the Company under the terms of the Deerfield Facility Agreement consisted of a term loan of

$15

million (the “Term Notes”) and a senior secured loan of

$10

million (the “Deerfield Convertible Note”). As of

June 30, 2016,

Deerfield is

longer obligated to provide the Company any additional disbursements under the Deerfield Facility Agreement. All loans issued under the Deerfield Facility Agreement bear interest at

9.75%

per annum. Deerfield

may

convert any portion of the outstanding principal and any accrued but unpaid interest on the Deerfield Convertible Note into shares of the Company’s common stock at an initial conversion price of

$5.85

per share (the "Deerfield Note Conversion Feature").

The Company also issued to Deerfield a warrant to purchase

14,423,076

shares of Series D redeemable convertible preferred stock (“

Series D Preferred”) at an exercise price of

$0.78

per share, which is exercisable until

June

2024

(the “Deerfield Warrant”). Upon completion of the IPO, the Deerfield Warrant automatically converted into a warrant to purchase

1,923,077

shares of the Company’s common stock at an exercise price of

$5.85

per share. This warrant qualifies as a participating security under ASC Topic

260,

Earnings per Share,

and is treated as such in the net loss per share calculation (Note N). If a Major Transaction occurs, as defined below, Deerfield

may

require the Company to redeem the Deerfield Warrant for a cash amount equal to the Black-Scholes value of the portion of the Deerfield Warrant to be redeemed (the “Warrant Put Option”). A Major Transaction is (i) a consolidation, merger, exchange of shares, recapitalization, reorganization, business combination or other similar event; (ii) the sale or transfer in

one

transaction or a series of related transactions of all or substantially all of the assets of the Company; (iii) a

third

-party purchase, tender or exchange offer made to the holders of outstanding shares, such that following such purchase, tender or exchange offer a change of control has occurred; (iv) the liquidation, bankruptcy, insolvency, dissolution or winding-up affecting the Company; (v) the shares of the Company’s common stock cease to be listed on any eligible market; and (vi) at any time, the shares of the Company’s common stock cease to be registered under Section

of the Securities Exchange Act of

1934,

as amended (the “Exchange Act”).

In addition, the Company issued to Deerfield

1,923,077

shares of Series D Preferred as consideration for the loans provided to the Company under the Deerfield Facility Agreement. Upon completion of the IPO, these shares automatically reclassified into

256,

410

shares of the Company’s common stock. The Company recorded the fair value of the shares of Series D Preferred of

$1.5

million, to debt issuance costs on the date of issuance. The Company recorded the fair value of the Deerfield Warrant and the embedded Warrant Put Option to debt discount on the date of issuance. The debt issuance costs and debt discount are amortized over the term of the related debt and the expense is recorded as interest expense

related to amortization of debt issuance costs and discount

in the statements of operations.

Pursuant to the Deerfield Fac

ility Agreement, the Company

may

not

enter into specified transactions, including a debt financing in the aggregate value of

$750,000

or more, a merger, an asset sale or any other change of control transaction or any joint venture, partnership or other profit sharing arrangement, without the prior approval of Deerfield. Additionally, if the Company were to enter into a major transaction, including a merger, consolidation, sale of substantially all of its assets or other change of control transaction, Deerfield would have the ability to demand that prior to consummation of such transaction the Company repay all outstanding principal and accrued interest of any notes issued under the Deerfield Facility Agreement.

Under each warrant issued pursuant to the Deerfield Facility Agreement, Deerfield has the right to demand that the Company redeem the warrant for a cash amount equal to the Black-Scholes value of a portion of the warrant upon the occurrence of specified events, including a merger, an asset sale or any other change of control transaction.

The Company

must repay

one

third

of the outstanding principal amount of all debt issued under the Deerfield Facility Agreement on the

fourth

and

fifth

anniversaries of the Deerfield Facility Agreement. The Company is then also obligated to repay the balance of the outstanding principal amount on

February

14,

2020.

The Company prepaid all outstanding interest and principal on the Term Notes in

February 2016.

The outstanding principal amount due on the

fourth

anniversary of the Deerfield Facility Agreement and the related accrued but unpaid interest as of such date was converted in common stock of the Company in accordance with the provisions of the Deerfield Convertible Note, as amended. Refer to the section entitled

"Facility Agreement Waiver and Fifth Amendment to Senior Secured Convertible Note"

below.

Interest accrued on outstanding debt under the Deerfield Fa

cility Agreement is due quarterly in arrears. Upon notice to Deerfield, the Company had the option to have

one

or more of the

first

eight

of such scheduled interest payments added to the outstanding principal amount of the debt issued under the Deerfield Facility Agreement, provided that all such interest was due on

July

2016.

The Company elected this option on all

eight

of the scheduled interest payments through

June 30, 2016.

The accrued interest added to outstanding principal was paid to Deerfield on

July 1, 2016.

First Amendment to Facility Agreement, Senior Secured Convertible Note and Warrant

In connection with the IPO, on

March 6, 2015,

the Company entered into a First Amendment (the “First Amendment) to the Deerfield Facility Agreement, the Deerfield Convertible Note and Deerfield Warrant, by and between the Company and Deerfield. The First Amendment, among other things, clarified that all references to the conversion of shares of Series D Preferred into the Company’s common stock in the Deerfield Facility Agreement, the Deerfield Convertible Note and Deerfield Warrant shall include any reclassification of the outstanding shares of Series D Preferred into shares of the Company’s common stock.

Second Amendment to Senior Secured Convertible Note and Warrant

January 6, 2016,

the Company entered into a Second Amendment (the “Second Amendment”) to the Deerfield Convertible Note and Deerfield Warrant, by and between the Company and Deerfield. The Second Amendment, among other things, clarified the calculation of an anti-dilution adjustment of the conversion price and exercise price of the Deerfield Convertible Note and Deerfield Warrant, respectively, in the event that the Company effects a firm commitment underwritten public offering of its securities.

Issuance of

5.50%

Senior Convertible

Notes and Third Amendment to Senior Secured Convertible Note and Warrant

February 9, 2016,

the Company issued

$86.3

million aggregate principal amount of its

5.50%

Senior Convertible Notes due

2021

(the “

2021

Notes”) to Cowen and RBC Capital Markets, LLC., as representatives of the several initial purchasers (the “Initial Purchasers”), who subsequently resold the

2021

Notes to qualified institutional buyers (the “Note Offering”) in reliance on the exemption from registration provided by Rule

144A

under the Securities Act.

The net proceeds from the Note Offering were approximately

$82.8

million, after deducting the Initial Purchasers

’ discount and estimated offering expenses. Concurrent with the Note Offering, the Company used approximately

$18.6

million of the net proceeds from the Note Offering to repay in full the Term Notes, plus all accrued but unpaid interest, a make-whole interest payment and a prepayment premium on the Term Notes.

The

2021

Notes were issued pursuant to an Indenture, dated as of

February

2016

(the “Indenture”), between the Company and U.S. Bank National Association, as trustee (the "Trustee"). Interest on the

2021

Notes is payable semi-annually in cash in arrears on

February

and

August

of each year, beginning on

August

2016,

at a rate of

5.50%

per year. The

2021

Notes mature on

February

2021

unless earlier converted or repurchased. The

2021

Notes are

not

redeemable prior to the maturity date, and

sinking fund is provided for the

2021

Notes.

The

2021

Notes are convertible at an initial conversion rate of

58.4454

shares of the Company

’s common stock per

$1,000

principal amount of the

2021

Notes, subject to adjustment under the Indenture, which is equal to an initial conversion price of approximately

$17.11

per share of common stock. Upon conversion, the

2021

Notes will be settled in shares of the Company’s common stock, together with a cash payment in lieu of delivering any fractional share. The conversion rate will be subject to adjustment in some events but will

not

be adjusted for any accrued and unpaid interest. In addition, following certain corporate events that occur prior to the maturity date, the Company will increase the conversion rate for a holder who elects to convert its

2021

Notes in connection with such a corporate event in certain circumstances.

If the Company undergoes a “

fundamental change” (as defined in the Indenture), holders

may

require that the Company repurchase for cash all or any portion of their

2021

Notes at a fundamental change repurchase price equal to

100%

of the principal amount of the

2021

Notes to be repurchased, plus accrued and unpaid interest to, but excluding, the fundamental change repurchase date. In addition, holders who convert their

2021

Notes on or after the date that is

one

year after the last date of original issuance of the

2021

Notes

may

also be entitled to receive, under certain circumstances, an interest make-whole payment payable in shares of the Company’s common stock. The Company is bifurcating the fundamental change and make-whole interest payment provisions as embedded derivatives and marking them to fair value each reporting period (Note L).

The Indenture includes customary terms and covenants, including certain events of default after which the

2021

Notes

may

be due and payable immediately.

In connection with the Note Offering, on

February

2016,

the Company entered into a Third Amendment (the “Third Amendment”) to the Deerfield Facility Agreement, Deerfield Convertible Note and Deerfield Warrant with Deerfield. The Third Amendment, among other things, eliminated the Company’s ability to require Deerfield to convert the Deerfield Convertible Note into Company common stock. In addition, pursuant to the Third Amendment, Deerfield consented to the prepayment of the Term Notes and the issuance of the

2021

Notes.

Refer to the section entitled Exchange Agreement below for a further discussion of an exchange of a certain portion of the

2021

Notes for shares of the Company's Series A Convertible Preferred Stock, par value

$0.0001

per share (the "Series A Preferred Stock").

Fourth Amendment to Senior Secured Convertible Note and Warrant

In connection with entering into the

ATM Agreement, on

October 3, 2016,

the Company entered into a Fourth Amendment (the “Fourth Amendment”) to the Deerfield Convertible Note and the Deerfield Warrant with Deerfield. The Fourth Amendment, among other things, clarifies the calculation of an anti-dilution adjustment of the conversion price and exercise price of the Deerfield Convertible Note and Deerfield Warrant, respectively, in the event that the Company effects an “at the market offering” as defined in Rule

415

of the Securities Act of its common stock.

Facility Agreement Waiver and Fifth Amendment to Senior Secured Convertible Note

June 11, 2018,

the Company entered into the Facility Agreement Waiver and Fifth Amendment (the "Fifth Amendment") to the Deerfield Convertible Note with Deerfield. The Fifth Amendment, among other things, provided that (i)

$3,333,333

of the principal amount, plus

$168,288

of accrued interest, of the Deerfield Convertible Note was converted into

598,568

shares of the Company’s common stock, with such principal conversion amount being applied against and in full satisfaction of the amortization payment due

June 2, 2018; (

ii) Deerfield waived specified rights under the Deerfield Facility Agreement with regards to such principal and interest amount; and (iii) specified provisions of the Deerfield Convertible Note were amended as they relate to the delivery of shares of the Company’s common stock in connection with any conversion of the Deerfield Convertible Note.

Exchange Agreement

October 5, 2018,

the Company entered into an Exchange Agreement (the “Exchange Agreement”) with Deerfield and Deerfield Special Situations Fund, L.P. (the “Holders”). Under the Exchange Agreement, the Holders exchanged an aggregate of

$9,577,000

principal amount of the

2021

Notes for an aggregate of

9,577

shares of Series A Preferred Stock. The Company also agreed to pay the Holders an amount of

$95,105

in cash, which represented the amount of accrued and unpaid interest on the exchanged notes. The Exchange Agreement contains customary representations, warranties and covenants made by the Company and the Holders. The Exchange Agreement required the Company to reimburse the Holders for up to

$25,000

of expenses relating to the exchange.

As a condition to closing of the Exchange Agreement, the Company filed a Certificate of Designation of Preferences, Rights and Limitations of Series A Convertible Preferred Stock (the “Certificate of Designation”) with the Secretary of State of the State Delaware, setting forth the preferences, rights and limitations of the Series A Preferred Stock.

Each share of Series A Preferred Stock has an aggregate stated value of

$1,000

and is convertible into shares of common stock at a price equal to

$3.00

per share (subject to adjustment to reflect stock splits and similar events). Immediately following the exchange, there were an aggregate of

3,192,334

shares of common stock issuable upon conversion of the Series A Preferred Stock (without giving effect to the limitation on conversion described below). The Series A Preferred Stock is convertible at any time at the option of the Holders, provided that the Holders are prohibited from converting shares of Series A Preferred Stock into shares of common stock if, as a result of such conversion, such Holders (together with certain affiliates and “group” members) would beneficially own more than

4.985%

of the total number of shares of the Company’s common stock then issued and outstanding. The Series A Preferred Stock is

not

redeemable. In the event of the Company’s liquidation, dissolution or winding up, the Holders will receive an amount equal to

$0.0001

per share of Series A Preferred Stock, plus any declared but unpaid dividends, and thereafter will share ratably in any distribution of the Company’s assets with holders of common stock on an as-converted basis. With respect to rights upon liquidation, the Series A Preferred Stock ranks senior to the common stock and junior to existing and future indebtedness. Except as otherwise required by law (or with respect to approval of certain actions involving the Company’s organizational documents that materially and adversely affect the holders of Series A Preferred Stock), the Series A Preferred Stock does

not

have voting rights. The Series A Preferred Stock is

not

subject to any price-based anti-dilution protections and does

not

provide for any accruing dividends, but provides that holders of Series A Preferred Stock will participate in any dividends on the common stock on an as-converted basis (without giving effect to the limitation on conversion described above). The Certificate of Designation also provides for partial liquidated damages in the event that the Company fails to timely convert shares of Series A Preferred Stock into common stock in accordance with the Certificate of Designation.

First Supplemental Indenture, Sixth Amendment to Deerfield Convertible Note and Fifth Amendment to Deerfield Warrant

November 20, 2018,

the Company entered into a First Supplemental Indenture (the “Supplemental Indenture”) with the Trustee, to the Indenture, relating to the

2021

Notes. Pursuant to the Supplemental Indenture, the Indenture was amended to allow each Holder (as defined in the Indenture) or any beneficial holder of any

2021

Notes to, at its option, elect a limit on beneficial ownership as to such Holder or beneficial owner (but

not

as to any other Holder or beneficial owner) that is less than or equal to the

9.985%

Cap (as defined in the Indenture) or any other limit previously elected and then applicable to such Holder or beneficial owner upon written notice delivered to the Company at least

three

(

) business days prior to the date of effectiveness of such beneficial ownership limit (or such shorter period as

may

be agreed upon by the Company), specifying the percentage of shares of the Company’s common stock outstanding for the beneficial ownership limit that shall apply to such Holder or beneficial owner.

Also on

November 20, 2018,

in connection with entering into the Supplemental Indenture, the Company entered into an amendment (the “Sixth Amendment”) with Deerfield to the Deerfield Convertible Note and Deerfield Warrant. The Sixth Amendment, among other things, lowers the beneficial ownership limit under both the Deerfield Convertible Note and Deerfield Warrant to

4.985%

of the Company’s outstanding common stock. The Sixth Amendment also includes a notice from Deerfield that it has elected to lower the beneficial ownership limit under the

2021

Notes, as to Deerfield and its affiliates, to

4.985%.

Seventh Amendment to Deerfield Convertible Note and Sixth Amendment to Deerfield Warrant

February 28, 2019,

in connection with entering into the Purchase Agreement, the Company entered into an amendment (the “Seventh Amendment”), with Deerfield to the Deerfield Convertible Note and Deerfield Warrant. The Seventh Amendment, among other things, clarified that the anti-dilution protections contained in the Deerfield Convertible Note and Deerfield Warrant would

not

apply to sales made under the Purchase Agreement or Second ATM Agreement. The Seventh Amendment also includes a waiver from Deerfield regarding any rights it

may

have under the Company’s amended and restated investor rights agreement in connection with the Registration Rights Agreement.

Except as modified by the First Amendment, Second Amendment, Third Amendment, Fourth Amendment, Fifth Amendment, Sixth Amendment and Seventh Amendment, all terms and conditions of the Deerfield Facility Agreement, Deerfield Warrant and Deerfield Convertible Note remained in full force and effect.

Convertible Notes

Future minimum principal payments under convertible notes as of

December 31, 2018,

were as follows (in thousands):

	Convertible
Year Ending December 31,	Notes
2019		3,333
2020		3,334
2021		76,673
Total minimum principal payments		83,340
Less: debt issuance costs and discount		(1,902	)
Convertible notes, net	$	81,438

Line of Credit

During the

second

quarter of

2016,

the Company opened a

line of credit with a total borrowing capacity of

$1.1

million with City National Bank of Florida (the "Line of Credit Agreement") to support several irrevocable letters of credit issued by the bank on behalf of the Company. As of

December 31, 2018 and 2017,

the Company had unused letters of credit in the amount of

$0.4

million. The line of credit had a maturity date of

January 31, 2018.

January 31, 2018,

the line of credit was renewed for an additional

two

year term and will now mature on

January 31, 2020.

As of

December 31, 2018 and 2017,

the Company had

outstanding balances under the line of credit. The Line of Credit Agreement is collateralized by a restricted money market account, equal to the total amount of the letters of credit outstanding which are supported by the line of credit. The money market account is reported as restricted cash on the balance sheets. The line of credit contains

financial covenants. Borrowings under the Line of Credit Agreement carry interest at a rate equal to the

-month London Interbank Offered Rate plus

2.00%

per annum. The interest rate under the Line of Credit Agreement was

4.35

%, as of

December 31, 2018.

Note G - Commitments and Contingencies

12 Months Ended

Dec. 31, 2018

Notes to Financial Statements

Commitments and Contingencies Disclosure [Text Block]

G.	Commitments and Contingencies

Legal Matters

From time to time, the Company is involved in various legal proceedings arising in the normal course of business. For some matters, a liability is

not

probable, or the amount cannot be reasonably estimated and, therefore, an accrual has

not

been made. However, for such matters when it is probable that the Company has incurred a liability and can reasonably estimate the amount, the Company accrues and discloses such estimates. As of

December 31, 2018

and

2017,

accruals have been made related to commitments and contingencies

Lease Agreements

Florida

The Company leases office space in Florida, comprised of

two

contiguous office suites, under

non-cancelable operating leases, which

expire in

August 2025

and

February 2026,

as to each space respectively, and include the right to extend the term of the leases for

two

successive

five

-year terms upon expiration.

Iowa

The Company leases office and laboratory facilities in Iowa under a non-cancelable operating lease. The Company’s lease for its Iowa facilities expires in

September 2019

and includes a renewal option that could extend the lease for successive

one

-year terms upon expiration.

Virginia

The Company leases office and

laboratory facilities in Virginia under a non-cancelable operating lease.

The Company’s lease for its Virginia facilities expires in

August 2019.

North Carolina

The Company leases office space in North Carolina under a non-cancelable operating lease. The expiration date of the Company

’s lease is

May 2020,

and includes renewal options that could extend the lease for an additional

three

years.

During the

second

quarter of

2017,

the Company subleased its office space in North Carolina under a non-cancelable operating lease to a

third

-party tenant. The sublease term with the

third

-party runs concurrent with the lease term the Company has with the landlord.

Capital Lease

The Company leases various laboratory equipment, furniture and office equipment and leasehold improvements that are accounted for as capital leases and that require ongoing payments, including interest expense. The capital leases

are financed through various financial institutions and are collateralized by the underlying assets. As of

December 31, 2018 and 2017,

the interest rates for assets under remaining capital leases range from

7.19%

9.57

Rent expense for non-cancelable operating leases was

$0.7

million and

$0.6

million for the years ended

December 31, 2018

and

2017,

respectively.

Future minimum lease payments under capital leases and non-cancelable operating leases as of

December 31, 2018,

were as follows (in thousands):

	Capital			Operating
Year Ending December 31,	Leases			Leases
2019	$	254		$	714
2020		251			499
2021		163			449
2022		11			461
2023		—			472
Thereafter		—			903
Total minimum lease payments		679		$	3,498
Less: amounts representing interest		(69	)
Total minimum capital lease principal payments	$	610

Note H - Supply Arrangement

12 Months Ended

Dec. 31, 2018

Notes to Financial Statements

Collaborative Arrangement Disclosure [Text Block]

H.	Supply Arrangement

As of

December 31, 2018 and 2017,

the Company has

one

manufacturing arrangement that involves

potential future expenditures related to research and development.

November 2009,

the Company entered into a supply agreement (the “

Supply Agreement”) with Johnson Matthey Inc. (“JMI”) whereby JMI has agreed to supply the Company with all of the benzhydrocodone necessary for clinical trials and commercial sale for a price equal to JMI’s manufacturing cost and to provide process optimization and development services for benzhydrocodone. The Company’s FDA-approved drug, APADAZ, contains benzhydrocodone. Expense of

$3.6

million was recorded under this agreement for the year ended December

31,

2018.

expense was recorded under this agreement for the year ended

December 31, 2017

. The Company must purchase all of its U.S. benzhydrocodone needs from JMI and JMI cannot supply benzhydrocodone to other companies. The term of the Supply Agreement extends as long as the Company holds a valid and enforceable patent for benzhydrocodone or until the

tenth

anniversary of a commercial launch of a FDA-approved drug incorporating benzhydrocodone, whichever date is later. Upon the expiration of such term, the agreement will automatically renew for a period of

two

years unless either party provides

months prior notice of its intent

not

to renew. Under the agreement, JMI will receive a tiered-based royalty share on the net sales on the commercial sale of a FDA-approved drug incorporating benzhydrocodone.

reliable estimate of the future payments can be made at this time.

Note I - Preferred Stock and Warrants

12 Months Ended

Dec. 31, 2018

Notes to Financial Statements

Preferred Stock [Text Block]

I.	Preferred Stock and Warrants

Authorized, Issued, and Outstanding Preferred Stock

As of

December 31, 2018,

the Company had

10,000,000

shares of authorized preferred stock, of which

9,578

shares were designated as Series A Preferred Stock,

9,577

shares of which were issued in the fiscal year ended December

31,

2018

and

3,337

shares of which were outstanding at year-end. As of December

31,

2017,

the Company had

10,000,000

shares of authorized and undesignated preferred stock.

October 5, 2018,

the Company entered into the Exchange Agreement. Under the Exchange Agreement the Company issued to the Holders

9,577

shares of Series A Preferred Stock. Each share of Series A Preferred Stock has an aggregate stated value of

$1,000

and is convertible into shares of common stock at a price equal to

$3.00

per share (subject to adjustment to reflect stock splits and similar events). Immediately following the exchange, there were an aggregate of

3,192,334

4.985%

of the total number of shares of the Company's common stock then issued and outstanding. The Series A Preferred Stock is

not

redeemable. In the event of the Company’s liquidation, dissolution or winding up, the Holders will receive an amount equal to

$0.0001

not

have voting rights. The Series A Preferred Stock is

not

subject to any price-based anti-dilution protections and does

not

provide for any accruing dividends, but provides that the holders of Series A Preferred Stock will participate in any dividends on the common stock on an as-converted basis (without giving effect to the limitation on conversion described above). The Certificate of Designation also provides for partial liquidated damages in the event that the Company fails to timely convert shares of Series A Preferred Stock into common stock in accordance with the Certificate of Designation. As of

February 28, 2019,

6,240

shares of Series A Preferred Stock have been converted into

2,080,000

shares of common stock.

As of

February 28, 2019,

the Company has

3,337

shares of Series A Preferred Stock outstanding, which are convertible into

1,112,334

shares of common stock. Refer to Note F for a further discussion over the Exchange Agreement.

Warrants

During

2013,

the Company issued

$3.8

million of convertible notes and the warrants (the

“2013

Warrants”) to purchase

1,079,453

shares of equity securities in a future financing meeting specified requirements (a “Qualified Financing”). The

2013

Warrants allow the holders to purchase shares of the same class and series of equity securities issued in the Qualified Financing for an exercise price equal to the per share price paid by the purchasers of such equity securities in the Qualified Financing. When the Company entered into the Deerfield Facility Agreement, the

2013

Warrants became warrants to purchase

1,079,453

shares of Series D preferred stock. Upon completion of the IPO, the

2013

Warrants automatically converted into warrants to purchase

143,466

shares of the Company’s common stock at an exercise price of

$5.85

per share. The

2013

Warrants, if unexercised, expire on the earlier of

June 2, 2019,

or upon a liquidation event.

June 2, 2014,

pursuant to the terms of the Deerfiel

d Facility Agreement, the Company issued the Deerfield Warrant to purchase

14,423,076

shares of Series D preferred stock (Note F). The Company recorded the fair value of the Deerfield Warrant as a debt discount and a warrant liability. The Deerfield Warrant, if unexercised, expires on the earlier of

June 2, 2024,

or upon a liquidation event. Upon completion of the IPO, the Deerfield Warrant automatically converted into a warrant to purchase

1,923,077

shares of the Company’s common stock at an exercise price of

$5.85

per share.

The Company is amortizing the debt discount over the term of the Deerfield Convertible Note and the expense is recorded as interest expense related to amortization of debt issuance costs and discount in the statements of operations

The Company determined that the

2013

Warrants and Deerfield Warrant should be recorded as a liabili

ty and stated at fair value at each reporting period upon inception. As stated above, upon completion of the IPO, the

2013

Warrants and the Deerfield Warrant automatically converted into warrants to purchase the Company’s common stock. The Company marked the

2013

Warrants to fair value and reclassified them to equity upon closing of the IPO. The Deerfield Warrant remains classified as a liability and is recorded at fair value at each reporting period since it can be settled in cash. Changes to the fair value of the warrant liability are recorded through the statements of operations as a fair value adjustment (Note L).

Note J - Common Stock and Warrants

12 Months Ended

Dec. 31, 2018

Notes to Financial Statements

Stockholders' Equity Note Disclosure [Text Block]

J.	Common Stock and Warrants

Authorized, Issued, and Outstanding Common Shares

As of

December 31, 2018

and

2017,

the Company had

authorized shares of common stock of

250,000,000

shares. Of the authorized shares,

26,455,352

and

14,657,430

shares of common stock were issued and outstanding as of

December 31, 2018

and

2017,

respectively.

As of

Dec

ember

31,

2018

and

2017,

the Company had reserved authorized shares of common stock for future issuance as follows:

	December 31,
	2018		2017
Conversion of Deerfield Convertible Note		1,167,607		1,751,410
Conversion of 2021 Notes		4,481,182		5,040,914
Outstanding awards under equity incentive plans		3,704,755		2,853,924
Outstanding common stock warrants		2,527,763		2,027,763
Conversion of Series A Convertible Preferred Stock		1,112,334		—
Possible future issuances under equity incentive plans		648,272		944,700
Total common shares reserved for future issuance		13,641,913		12,618,711

Common Stock Activity

The following table summarizes common stock activity for the years ended

December 31, 2018 and

2017

	Shares of
	Common Stock
Balance as of January 1, 2017		14,646,982
Common stock warrants exercised		698
Common stock options exercised		9,750
Balance as of December 31, 2017		14,657,430
Common stock sold under First ATM Agreement		762,338
Common stock issued as a result of Deerfield Convertible Note principal and interest conversion		598,568
Common stock options exercised		23,682
Common stock sold under underwritten public offering		8,333,334
Common stock issued as a result of Series A Convertible Preferred Stock conversion		2,080,000
Balance as of December 31, 2018		26,455,352

September 4, 2018,

the Company terminated the First ATM Agreement with Cowen. Prior to termination of the First ATM Agreement, the Company sold an aggregate of

762,338

shares of common stock under the First ATM Agreement resulting in gross proceeds to the Company of

$4.9

million. As of

February 28, 2019,

the Company has

not

sold any shares of common stock under the Second ATM Agreement. Refer to Note A for a further discussion of the First and Second ATM Agreements.

October 5, 2018,

the Company entered into an underwriting agreement with RBCCM pursuant to which the Company issued and sold

8,333,334

shares of common stock of the Company in an underwritten public offering pursuant to the Company's registration statement on Form S-

Refer to Note A for a further discussion of the underwritten public offering.

Also on

October 5, 2018,

the Company entered into the Exchange Agreement pursuant to which the Company issued to the Holders

9,577

shares of Series A Preferred Stock. As of

February 28, 2019,

6,240

shares of Series A Preferred Stock have been converted into

2,080,000

shares of common stock. Refer to Note F for a further discussion of the Exchange Agreement.

Warrants

The Company calculates the fair value of common stock warrants (other than the KVK Warrant, as defined below) using a Monte Carlo simulation. There were warrants exercised for an aggregate of

698

shares of common stock during the year ended

December 31, 2017.

warrants were exercised during the year ended

December 31, 2018.

From

2008

through

2012,

the Company issued warrants to purchase

595,920

shares of common stock in its private placement offerings of Series A redeemable convertible preferred stock, Series B redeemable convertible preferred stock and Series C redeemable convertible preferred stock (the “Underwriter Warrants”) and for leasing laboratory space. The Company accounted for the Underwriter Warrants as a derivative liability, which is adjusted to fair value at each reporting period, with the change in fair value recorded as fair value adjustment in the statements of operations. The last of the Underwriter Warrants expired on the

second

anniversary of the Company's IPO in the

second

quarter of

2017.

In connection with a Collaboration and License Agreement (the “License Agreement”) with KVK Tech, Inc. (“KVK”), on

October 25, 2018,

the Company issued to KVK a warrant to purchase up to

500,000

shares of common stock of the Company at an exercise price of

$2.30

per share, which reflects the closing price of the Company’s common stock on the Nasdaq Global Market on

October 25, 2018 (

the “KVK Warrant”). The KVK Warrant is initially

not

exercisable for any shares of common stock. Upon the achievement of each of

four

specified milestones under the KVK Warrant, the KVK Warrant will become exercisable for an additional

125,000

shares for each of the

four

specified milestones, up to an aggregate of

500,000

shares of the Company’s common stock. The exercise price and the number and type of shares underlying the KVK Warrant are subject to adjustment in the event of specified events, including a reclassification of the Company’s common stock, a subdivision or combination of the Company’s common stock, or in the event of specified dividend payments. The KVK Warrant is exercisable until

October 24, 2023.

Upon exercise, the aggregate exercise price

may

be paid, at KVK’s election, in cash or on a net issuance basis, based upon the fair market value of the Company’s common stock at the time of exercise.

The Company determined that, since KVK qualifies as a customer under ASC

606,

the KVK Warrant should be recorded as a contract asset and recognized as contra-revenue as the Company recognizes revenue from the License Agreement. In addition, the Company determined that the KVK Warrant qualifies as a derivative under ASC

815

and should be recorded as a liability and stated at fair value each reporting period. The Company calculates the fair value of KVK Warrant using a probability-weighted Black-Scholes option pricing model. Changes in fair value resulting from changes in the inputs to the Black Scholes model are accounted for as changes in the fair value of the derivative under ASC

815

and are recorded as fair value adjustment related to derivative and warrant liability in the statement of operations. Changes in the number of shares that are expected to be issued are treated as changes in variable consideration under ASC

606

and are recorded as a reduction in contract asset in the balance sheet.

Note K - Stock-based Compensation

12 Months Ended

Dec. 31, 2018

Notes to Financial Statements

Disclosure of Compensation Related Costs, Share-based Payments [Text Block]

K.	Stock-Based Compensation

The Company maintains a stock-based compensation plan (the “

Incentive Stock Plan”) that governs stock awards made to employees and directors prior to completion of the IPO.

November 2014,

the Board of Directors of the Company ("the Board"), and in

April 2015,

the Company

’s stockholders, approved the Company’s

2014

Equity Incentive Plan (the

“2014

Plan”), which became effective in

April 2015.

The

2014

Plan provides for the grant of stock options, other forms of equity compensation, and performance cash awards. The maximum number of shares of common stock that

may

be issued under the

2014

Plan is

4,018,480

as of

December 31, 2018.

The number of shares of common stock reserved for issuance under the

2014

Plan will automatically increase on

January 1

of each year, beginning on

January 1, 2016,

and ending on and including

January 1, 2024,

of the total number of shares of the Company’s capital stock outstanding on

December 31

of the preceding calendar year, or a lesser number of shares determined by the Board. Pursuant to the terms of the

2014

Plan, on

January 1, 2019,

the common stock reserved for issuance under the

2014

Plan automatically increased by

1,058,214

shares.

During the years ended

December 31, 2018

and

2017,

stock options to acquire

23,682

and

9,750

shares of common stock were exercised for approximately

$68,000

and

$7,000

with an intrinsic value of approximately

$69,000

and

$32,000,

respectively.

Stock-based compensation expense recorded unde

r the Incentive Stock Plan and the

2014

Plan is included in the following line items in the accompanying statements of operations (in thousands):

	Year Ended December 31,
	2018		2017
Research and development	$	1,608	$	1,304
General and administrative		3,651		3,258
Severance expense		1,236		—
Total stock-based compensation expense	$	6,495	$	4,562

Stock Option Awards

The Company estimates the fair value of stock options using the Black-Scholes option-pricing model, which requires the use of subjective assumptions, including the expected term of the option, the expected stock price volatility, expe

cted dividend yield and the risk-free interest rate for the expected term of the option. The expected term represents the period of time the stock options are expected to be outstanding. Due to the lack of sufficient historical exercise data to provide a reasonable basis upon which to otherwise estimate the expected term of the stock options, the Company uses the simplified method to estimate the expected term for its “plain vanilla” stock options. Under the simplified method, the expected term of an option is presumed to be the mid-point between the vesting date and the end of the contractual term. Some options, for example those that have exercise prices in excess of the fair value of the underlying stock, are

not

considered “plain vanilla” stock options. For these options, the Company uses an expected term equal to the contractual term of the option. Expected volatility for options granted prior to the

second

anniversary of the IPO is based on a blend of historical volatilities for publicly traded stock of comparable

compan

ies and the Company over the estimated expected term of the stock options.

For options granted after the

second

anniversary of the IPO, expected volatility is based on the Company's historical volatility over the estimated expected term of the stock options.

The Company assumes

dividend yield because dividends are

not

expected to be paid in the near future, which is consistent with the Company’s history of

not

paying dividends.

The Company recogni

zes compensation expense related to stock-based payment transactions upon satisfaction of the requisite service or vesting requirements. Forfeitures are estimated at the time of grant and revised based on actual forfeitures, if necessary, in subsequent periods if actual forfeitures differ from those estimates.

Using the Black-Scholes option-pricing model, the weighted-average fair value of awards granted during the years ended

December 31, 2018

and

2017,

fair value was

$4.05

and

$2.77

per sha

re, respectively. The assumptions used to estimate fair value are as follows:

	December 31,
	2018		2017
Risk-free interest rate		2.43% - 2.91%		1.88% - 2.26%
Expected term (in years)		5.50 - 6.79		5.12 - 7.00
Expected volatility		83.10% - 85.05%		85.35% - 95.08%
Expected dividend yield		0%		0%

The activity under the Incentive Stock Plan and the

2014

Plan

for the year ended

December 31, 2018,

is summarized as follows:

						Weighted Average
	Number of			Weighted Average		Remaining Contractual		Aggregate Intrinsic
	Options			Exercise Price		Term (in years)		Value
Outstanding balance as of January 1, 2018		2,853,924		$	10.50		7.90	$	471,539
Granted		898,000		$	5.54
Exercised		(23,682	)	$	3.15
Canceled or forfeited		(20,821	)	$	10.63
Expired		(2,666	)	$	3.00
Outsta nding balance as of December 31, 2018		3,704,755		$	9.35		7.48	$	—
Exercisable as of December 31, 2018		1,837,582		$	11.56		6.67	$	—
Vested and expected to vest as of December 31, 2018		3,656,474		$	9.40		7.47	$	—

Information regarding currently outstanding and exercisable options as of

December 31, 2018,

is as follows:

	Options Outstanding		Options Exercisable
		Weighted Average		Weighted Average
	Number of	Remaining Contractual	Number of	Remaining Contractual
Exercise Price	Shares	Term (in years)	Shares	Term (in years)
$2.75 to $5.00	1,024,995	7.89	390,244	7.59
$5.01 to $10.00	1,256,427	7.85	437,527	5.50
$10.01 to $15.00	471,833	6.94	285,249	6.85
$15.01 to $20.00	603,700	6.89	463,712	6.88
$20.01 to $22.12	347,800	6.68	260,850	6.68
	3,704,755	7.48	1,837,582	6.67

The total fair value of stock options vested during the years ended

December 31, 2018

and

2017,

was

$5.9

million and

$4.1

million, respectively.

Unvested stock options as of

December 31, 2018

and

2017,

were as follows:

	Number of Unvested Shares
	December 31,
Exercise Price	2018		2017
$2.75 to $5.00		634,751		979,000
$5.01 to $10.00		818,900		21,301
$10.01 to $15.00		186,584		282,542
$15.01 to $20.00		139,988		352,789
$20.01 to $22.12		86,950		173,900
Total number of unvested shares		1,867,173		1,809,532

As of

December 31, 2018,

there was

$6.0

million of total unrecognized compensation cost related to unvested share-based compensation arrangements granted under the I

ncentive Stock Plan and

2014

Plan. That compensation cost is expected to be recognized over a weighted-average period of

1.84

years.

There was

stock-based compensation expense related to performance-based awards recognized during the years ended

December 31, 2018 or 2017.

Note L - Fair Value of Financial Instruments

12 Months Ended

Dec. 31, 2018

Notes to Financial Statements

Fair Value Disclosures [Text Block]

L.	Fair Value of Financial Instruments

The

carrying amounts of certain financial instruments, including cash and cash equivalents, restricted cash and accounts payable and accrued expenses, approximate their respective fair values due to the short-term nature of such instruments.

The fair value of the Deerfield Convertible Note

was

$6.2

million and

$11.0

million, respectively, as of

December 31, 2018

and

2017.

The fair value of the

2021

Notes was

$51.2

million and

$51.9

million, respectively, as of

December 31, 2018

and

2017.

Both the Deerfield Convertible Note and

2021

Notes fall within Level

of the fair value hierarchy as their value is based on the credit worthiness of the Company, which is an unobservable input.

The Company used a Tsiveriotis-Fernandes model to value the Deerfield Convertible Note and

2021

Notes

as of

December 31, 2018

and

2017.

Assets and Liabilities Measured at Fair Value on a Recurring Basis

The Company evaluates its financial assets and liabilities subject to fair value measurements on a recurring basis to determine the appropriate level in whi

ch to classify them for each reporting period. This determination requires significant judgments to be made. The following table summarizes the conclusions reached regarding fair value measurements as of

December 31, 2018

and

2017

(in thousands):

			Quoted Prices in				Significant
	Balance as of		Active Markets		Significant Other		Unobservable
	December 31,		for Identical Assets		Observable Inputs		Inputs
	2018		(Level 1)		(Level 2)		(Level 3)
Deerfield Warrant liability	$	1,557	$	—	$	—	$	1,557
Embedded Warrant Put Option		154		—		—		154
Fundamental change and make-whole interest provisions embedded in 2021 Notes		—		—		—		—
Deerfield Note Conversion Feature		134		—		—		134
KVK Warrant liability		273		—		273		—
Total liabilities	$	2,118	$	—	$	273	$	1,845
Trading securities:
Certificates of deposit		246		246		—		—
U.S. Treasury securities		3,014		3,014		—		—
Total assets	$	3,260	$	3,260	$	—	$	—

			Quoted Prices in				Significant
	Balance as of		Active Markets		Significant Other		Unobservable
	December 31,		for Identical Assets		Observable Inputs		Inputs
	2017		(Level 1)		(Level 2)		(Level 3)
Deerfield Warrant liability	$	5,115	$	—	$	—	$	5,115
Embedded Warrant Put Option		365		—		—		365
Fundamental change and make-whole interest provisions embedded in 2021 Notes		14		—		—		14
Deerfield Note Conversion Feature		2,215						2,215
Total liabilities	$	7,709	$	—	$	—	$	7,709
Trading securities:
Certificates of deposit		5,616		5,616		—		—
U.S. Treasury securities		25,988		25,988		—		—
U.S. government-sponsored agency securities		3,004		—		3,004		—
Total assets	$	34,608	$	31,604	$	3,004	$	—

The Company

’s Deerfield Warrant liability, embedded Warrant Put Option, the fundamental change and the make-whole interest provisions embedded in the

2021

Notes and the Deerfield Note Conversion Feature, as well as the trading securities are measured at fair value on a recurring basis. As of

December 31, 2018

and

2017,

the Deerfield Warrant liability, embedded Warrant Put Option the fundamental change and make-whole interest provisions embedded in the

2021

Notes and the Deerfield Note Conversion Feature are reported on the balance sheets in derivative and warrant liability, while the trading securities are reported on the balance sheets in marketable securities and long-term investments. The Company used a Monte Carlo simulation to value the Deerfield Warrant liability, embedded Warrant Put Option, the fundamental change and make-whole interest provisions embedded in the

2021

Notes and the Deerfield Note Conversion Feature as of

December 31, 2018

and

2017.

Significant unobservable inputs used in measuring the fair value of these financial instruments included the Company’s estimated enterprise value, an estimate of the timing of a liquidity or fundamental change event, a present value discount rate and an estimate of the Company’s stock volatility using the volatilities of guideline peer companies. Changes in the fair value of the Deerfield

Warrant liability, embedded Warrant Put Option, the fundamental change and make-whole interest provisions embedded in the

2021

Notes and the Deerfield Note Conversion Feature are reflected in the statements of operations for the years ended December

31,

2018

and

2017

as a

fair value adjustment related to derivative and warrant liability.

The Company’s KVK Warrant liability is measured at fair value on a recurring basis. As of

December 31, 2018,

the KVK Warrant liability is reported on the balance sheets in derivative and warrant liability. The Company estimates the fair value of KVK Warrant using a probability-weighted Black-Scholes option-pricing model, which requires the use of subjective assumptions, including the expected term of the warrant, the expected stock price volatility, expected dividend yield and the risk-free interest rate for the expected term of the warrant. The expected term represents the period of time the warrant is expected to be outstanding. For the warrant, the Company used an expected term equal to the contractual term of the warrant. Expected volatility is based on the Company's historical volatility since IPO. The Company assumes

dividend yield because dividends are

not

expected to be paid in the near future, which is consistent with the Company’s history of

not

paying dividends. Changes in the fair value of the KVK Warrant liability are reflected in the statements of operations for the years ended

December 31, 2018

as a fair value adjustment related to derivative and warrant liability. The KVK Warrant liability had

value as of

December 31, 2017

since it was issued in

October 2018.

A reconciliation of the beginning and ending balances for the derivative and warrant liability measured at fair value on a recurring basis using signific

ant unobservable inputs (Level

) is as follows (in thousands):

	2018			2017
Balance as of beginning of period	$	7,709		$	4,618
Gain on extinguishment of debt		(2	)		—
Adjustment to fair value		(5,862	)		3,091
Balance as of end of period	$	1,845		$	7,709

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Note M - Income Taxes

12 Months Ended

Dec. 31, 2018

Notes to Financial Statements

Income Tax Disclosure [Text Block]

M.	Income Taxes

The Company

’s financial statements include a total state tax benefit related to research and development credits of

$126,000

and

$43,000

on a loss before income taxes of

$56.6

million and

$43.4

million for the years ended

December 31, 2018

and

2017,

respectively. A reconciliation of the difference between the benefit for income taxes and income taxes at the statutory U.S. federal income tax rate is as follows (in thousands):

	Year ended December 31,
	2018			2017
Federal statutory rate		21.00	%		34.00	%
Effect of:
Change in valuation allowance		(30.44	)		13.38
Return to provision and deferred true-up		0.38			2.18
Change in rate		0.03			(49.06	)
State tax benefit (net of federal)		4.35			2.71
Warrant liability		2.02			(2.42	)
State research and development credit		0.22			0.10
Federal research and development credit		3.30			1.50
Amortization		—			(1.22	)
Stock-based compensation		(0.63	)		(1.03	)
Other		(0.01	)		(0.04	)
Federal income tax benefit effective rate		0.22	%		0.10	%

The components of deferred tax assets and liabilities are as follows (in thousands):

	December 31,
	2018			2017
Deferred tax assets relating to:
Net operating loss carryforwards	$	51,269		$	37,028
Research and development tax carryforward		5,657			3,788
Other deferred tax assets		3,437			2,409
Total gross deferred tax assets		60,363			43,225
Deferred tax liabilities relating to:
Property and equipment		161			260
Other deferred tax liabilities		10			—
Total gross deferred tax liabilities		171			260
Deferred tax assets less liabilities		60,192			42,965
Valuation allowance		(60,192	)		(42,965	)
Net deferred tax asset (liability)	$	—		$	—

H.R.

“An Act to provide for reconciliation pursuant to titles II and V of the concurrent resolution on the budget for fiscal year

2018”

(the

"2017

Tax Act") was signed into law on

December 22, 2017.

The

2017

Tax Act significantly revises the U.S. corporate income tax by, among other things, lowering the statutory corporate tax rate from

35%

21%,

eliminating certain deductions, imposing a mandatory

one

-time tax on accumulated earnings of foreign subsidiaries, introducing new tax regimes, and changing how foreign earnings are subject to U.S. tax. The

2017

Tax Act also enhanced and extended through

2026

the option to claim accelerated depreciation deductions on qualified property.

In assessing the realizability of deferred tax assets, management considers whether it is more likely than

not

that some portion or all of the deferred tax assets will

not

be realized. The ultimate realization of deferred tax

assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. Management considers the scheduled reversal of deferred tax liabilities, projected future taxable income and tax planning strategies in making this assessment. Based upon the level of historical taxable income and projections for future taxable income over the periods in which the deferred tax assets are deductible, management believes it is more likely than

not

that the Company will

not

realize the benefits of these deductible differences in the future.

The Company had the following federal net operating loss carryforward and research activities credits as of

December 31, 2018 (

in thousands):

	Net		Research
	Operating Loss		Activities
Year Incurred	Carryforwards		Credit		Expiration
2007	$	454	$	30		2027
2008		1,178		65		2028
2009		3,060		176		2029
2010		3,423		149		2030
2011		9,929		176		2031
2012		—		170		2032
2013		4,353		133		2033
2014		15,897		894		2034
2015		23,496		598		2035
2016		41,580		745		2036
2017		34,776		652		2037
2018		56,105		1,869		Indefinite
	$	194,251	$	5,657

The Company also has certain state net operating loss carryforwards totaling

$136.0

million that expire between

2027

and

2037.

Due to potential ownership changes that

may

have occurred or would occur in the future, Internal Revenue Code Section

382

may

place additional l

imitations on the Company’s ability to utilize the net operating loss carryforward.

ASC

740

10,

Accounting for Uncertainty in Income Taxes

, uses the term “more likely than

not”

to evaluate whether or

not

a tax position will be sustained upon examination. The Company has

not

identified any tax positions that do

not

meet the more likely than

not

threshold.

Note N - Net Loss Per Share

12 Months Ended

Dec. 31, 2018

Notes to Financial Statements

Earnings Per Share [Text Block]

N.	Net Loss Per Share

Under the

two

-class method, for periods with net income, basic net income per common share

is computed by dividing the net income attributable to common stockholders by the weighted average number of shares of common stock outstanding during the period. Net income attributable to common stockholders is computed by subtracting from net income the portion of current year earnings that participating securities would have been entitled to receive pursuant to their dividend rights had all of the year’s earnings been distributed.

such adjustment to earnings is made during periods with a net loss as the holders of the participating securities have

obligation to fund losses. Diluted net earnings per common share is computed under the

two

-class method by using the weighted average number of shares of common stock outstanding plus, for periods with net income attributable to common stockholders, the potential dilutive effects of stock options and warrants. In addition, the Company analyzes the potential dilutive effect of the outstanding participating securities under the if-converted method when calculating diluted earnings per share in which it is assumed that the outstanding participating securities convert into common stock at the beginning of the period. The Company reports the more dilutive of the approaches (

two

-class or if-converted) as its diluted net earnings per share during the period.

The following table summarizes the computation of basic and diluted net loss and net loss per share of the Company (in thousands, except share and pe

r share amounts):

	Year ended December 31,
	2018			2017
Net loss - basic and diluted	$	(56,466	)	$	(43,386	)
Weighted average number of shares of common stock - basic and diluted		17,930,023			14,652,898
Net loss per share - basic and diluted	$	(3.15	)	$	(2.96	)

Diluted net loss per share is the same as basic net loss per share for all periods presented because the effects of potentially dilutive items were anti-dilutive given the Company

’s net loss. The following securities, presented on a common stock equivalent basis, have been excluded from the calculation of weighted average number of shares of common stock outstanding because their effect is anti-dilutive:

	December 31,
	2018		2017
Deerfield Convertible Note		1,167,607		1,751,410
2021 Notes		4,481,182		5,040,914
Awards under equity incentive plans		3,704,755		2,853,924
Warrants to purchase common stock		2,527,763		2,027,763
Series A Convertible Preferred Stock		1,112,334		—
Total securities excluded from the calculation of weighted average number of shares of common stock outstanding		12,993,641		11,674,011

Note O - Severance Expense

12 Months Ended

Dec. 31, 2018

Notes to Financial Statements

Restructuring and Related Activities Disclosure [Text Block]

O.	Severance Expense

August 31, 2018,

Daniel L. Cohen resigned from his position as the executive vice president, government and public relations of the Company, effective immediately. In connection with his resignation, Mr. Cohen and the Company entered into a separation and release agreement which included among other items, severance benefits. The severance benefits consisted of personnel and other related charges of approximately

$0.4

million and stock compensation expense of approximately

$1.2

million related to the acceleration of vesting on unvested shares subject to certain stock options and the extension of the exercise period for certain stock options. These severance benefits are presented as severance expense in the statements of operations for the fiscal year ended

December 31, 2018.

As of

December 31, 2018,

the Company had accrued severance expense recorded within accounts payable and accrued expenses in the amount of

$0.2

million.

Note P - Employee Benefit Plan

12 Months Ended

Dec. 31, 2018

Notes to Financial Statements

Compensation and Employee Benefit Plans [Text Block]

P.	Employee Benefit Plan

The Company has a

401

(k) retirement plan (the “

401

(k) Plan”) that covers substantially all employees. The Company

may

provide a discretionary match with a maximum amount of

of the participant’s compensation, which vests immediately. The Company made matching contributions under the

401

(k) Plan of

$212,000

and

$207,000

for the years ended

December 31, 2018

and

2017,

respectively.

The Company has a discretionary profit sharing plan (the “

Profit Sharing Plan”) that covers all employees. Employees become eligible participants in the Profit Sharing Plan once they have provided

three

years of service to the Company. The Company made

contributions to the Profit Sharing Plan in

2018

2017.

Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Use of Estimates, Policy [Policy Text Block]

Use of Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America ("GAAP")

requires the Company to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates.

On an ongoing basis, the Company evaluates its estimates, includ

Concentration Risk, Credit Risk, Policy [Policy Text Block]

Concentration of Credit Risk

Financial instruments that potentially expose

the Company to concentrations of credit risk consist principally of cash on deposit with multiple financial institutions, the balances of which frequently exceed insured limits.

Cash and Cash Equivalents, Policy [Policy Text Block]

Cash and Cash Equivalents

The Company considers any highly liquid investm

ents with an original maturity of

three

months or less to be cash equivalents.

Marketable Securities, Policy [Policy Text Block]

Marketable Securities and Long-term Investments

The Company maintains investment securities that are classified as trading securities. These securities are carried at fair value with unreali

Property, Plant and Equipment, Policy [Policy Text Block]

Property and Equipment

The Company records property and equipment at cost less accumulated

three

ten

Debt, Policy [Policy Text Block]

Debt Issuance Costs

Debt issuance costs incurred in connection with financing arrangements are amortiz

ed over the life of the respective financing arrangement using the effective interest method.

Collaborative Arrangement, Accounting Policy [Policy Text Block]

Supply Arrangements

The Company enters into supply arrangements for the supply of components of its product and product candidates. These arrangements also

may

include a

share of future revenue if related product or product candidates reach commercialization. Costs under these supply arrangements, if any, are expensed as incurred (Note H).

Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block]

Impairment of Long-Lived Assets

Long-lived assets to be held and used are reviewed for

impairment whenever events or changes in circumstances indicate that the carrying amounts of the assets

may

not

such impairment occurred for the years ended

December 31, 2018

2017.

Fair Value of Financial Instruments, Policy [Policy Text Block]

Fair Value of Financial Instruments

The Company uses a

three

equent to their initial measurement. The hierarchy requires the Company to use observable inputs when available, and to minimize the use of unobservable inputs, when determining fair value. The

three

tiers are defined as follows:

●

Level

—Observable inputs that reflect quoted market prices (unadjusted) for identical assets or liabilities in active markets;

●

Level

—Observable inputs other than quoted prices in active markets that are observable either directly or indirectly in the marketplace for identical or similar assets and liabilities; and

●

Level

—Unobservable inputs that are supported by little or

market data, which require the Company to develop its own assumptions.

Research and Development Expense, Policy [Policy Text Block]

Research and Development

The Company records nonrefundable advance payments it makes for future research and development activities as prepaid expenses. Prepaid

expenses are recognized as expense in the statements of operations as the Company receives the related goods or services.

The Company enters into contractual agreements with

third

not

Intangible Assets, Finite-Lived, Policy [Policy Text Block]

Patent Costs

Patent costs, including related legal costs, are expensed as incurred and recorded within general and administrative

expenses on the statements of operations.

Income Tax, Policy [Policy Text Block]

Income Taxes

The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of temporary differences between the financial reporting and tax basis of assets and liabilities,

not

to be realized.

Uncertain tax positions are recognized only when the Company believes it is more likely than

not

tha

not

have any accrued interest or penalties associated with uncertain tax positions as of

December 31, 2018

and

2017.

The Company files income tax returns in the United States for federal and various state jurisdictions. With few exceptions,

the Company is

longer subject to U.S. federal and state and local income tax examinations for years prior to

2014,

although carryforward attributes that were generated prior to

2014

may

still be adjusted upon examination by the Internal Revenue Service if used in a future period.

income tax returns are currently under examination by taxing authorities.

Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block]

Stock-Based Compensation

The Company measures and recognizes compensation expense for all stock-based payment awards made to employees, officers an

505

50.

Earnings Per Share, Policy [Policy Text Block]

Basic and Diluted Net

Loss per Share of Common Stock

The Company uses the

two

-class method to compute net loss per common share because the Company has issued securities, other than common stock, that contractually

entitle the holders to participate in dividends and earnings of the Company. The

two

Segment Reporting, Policy [Policy Text Block]

Segment and Geographic Information

Operating segments are defined as components of an enterprise (business activity from which it earns revenue and incurs expenses) for which discrete financial information is ava

December 31, 2018

and

2017.

New Accounting Pronouncements, Not Yet Adopted, Policy [Policy Text Block]

Application of New or Revised Accounting Standards

—Adopted

April 5, 2012,

President Obama signed the Jump-Start Our Business Startups Act (the “

JOBS Act”) into law. The JOBS Act contains provisions that, among other things, reduce certain reporting requirements for an emerging growth company. As an emerging growth company, the Company

may

not

May 2014,

the FASB issued guidance codified in ASC Topic

606,

Revenue Recognition—Revenue from Contracts with Customers

("ASC

606"

), which amended the guidance in former ASC

605,

Revenue Recognition

, and became effective

January 1, 2018.

This guidance did

not

have a material impact on the Company's financial statements and disclosures upon adoption since the Company is

not

generating revenue at this time.

January 2016,

the FASB issued ASU

2016

01,

Financial Instruments Overall – Recognition and Measurement of Financial Assets and Liabilities (Topic

825

)

(“ASU

2016

01”

), which provides several updates related to Topic

825

10.

This update applies to all entities that hold financial assets or owe financial liabilities. This guidance is effective for financial statements issued for fiscal years beginning after

December 15, 2017,

and interim periods within those fiscal years. The adoption of ASU

2016

did

not

have a material impact on the Company's financial statements and disclosures.

August 2016,

the FASB issued ASU

2016

15,

Statement of Cash Flows – Classification of Certain Cash Receipts and Cash Payments (Topic

230

)

(“ASU

2016

15”

), which addresses

eight

specific cash flow issues with the objective of reducing the existing diversity in practice. This update applies to all entities that are required to present a statement of cash flows under Topic

230.

This guidance is effective for financial statements issued for fiscal years beginning after

December 15, 2017,

and interim periods within those fiscal years. The adoption of ASU

2016

did

not

have a material impact on the Company's financial statements and disclosures.

May 2017,

the FASB issued ASU

2017

09,

Compensation – Stock Compensation (Topic

718

) – Scope of Modification Accounting

("ASU

2017

09"

), which provides guidance about which changes to the terms or conditions of a stock-based payment award require an entity to apply modification accounting in Topic

718.

This update applies to any entity that changes the terms or conditions of a stock-based payment award. This guidance is effective for financial statements issued for fiscal years beginning after

December 15, 2017,

and interim periods within those fiscal years. The adoption of ASU

2017

did

not

have a material impact on the Company's financial statements and disclosures.

Application of New or Revised Accounting Standards

—Not

Yet Adopted

February 2016,

the FASB issued ASU

2016

02,

Leases (Topic

842

)

(“ASU

2016

02”

January 1, 2019

on a modified retrospective basis and will

not

$3.0

million on the balance sheet as of

January 1, 2019.

July 2017,

the FASB issued ASU

2017

11,

Earnings Per Share (Topic

260

), Distinguishing Liabilities from Equity (Topic

480

), Derivatives and Hedging (Topic

815

("ASU

2017

11"

), which addresses the complexity of accounting for certain financial instruments with down round features and addresses the difficulty of navigating Topic

480

260.

This guidance is effective for financial statements issued for fiscal years beginning after

December 15, 2018,

The Company does

not

expect the adoption of ASU

2017

to have a material impact on the Company's financial statements and disclosures.

June 2018,

the FASB issued ASU

2018

07,

Compensation –

Stock Compensation (Topic

820

) – Improvements to Nonemployee Share-Based Payment Accounting

("ASU

2018

07"

), which simplifies several aspects of the accounting for nonemployee share-based payment transactions resulting from expanding the scope of Topic

718,

December 15, 2018,

and interim periods within those fiscal years. The amendments in this ASU expand the scope of Topic

718

to include share-based payment transactions for acquiring goods and services from nonemployees. An entity should apply the requirements of Topic

718

earlier than an entity’s adoption date of Topic

606.

The Company does

not

expect the adoption of ASU

2018

to have a material impact on the Company's financial statements and disclosures.

August 2018,

the FASB issued ASU

2018

13,

Fair Value Measurement (Topic

820

) – Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement

("ASU

2018

13"

), which modifies the disclosure requirements on fair value measurements in Topic

820,

Fair Value Measurement, based on the concepts in the FASB Concepts Statement,

Conceptual Framework for Financial Reporting—Chapter

Notes to Financial Statements,

which the FASB finalized on

August 28, 2018,

December 15, 2019,

and interim periods within those fiscal years. The amendments on changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level

2018

on the Company's financial statements and disclosures.

Note C - Prepaid Expenses and Other Current Assets (Tables)

12 Months Ended

Dec. 31, 2018

Notes Tables

Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Table Text Block]

	December 31,
	2018		2017
Prepaid insurance	$	224	$	202
Other receivables		140		76
Other prepaid expenses and current assets		1,688		1,384
Total prepaid expenses and other current assets	$	2,052	$	1,662

Note D - Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2018

Notes Tables

Property, Plant and Equipment [Table Text Block]

	December 31,
	2018			2017
Laboratory equipment	$	1,035		$	983
Furniture and office equipment		655			655
Computers and hardware		299			292
Leasehold improvements		1,017			1,003
Total property and equipment		3,006			2,933
Less: accumulated depreciation and amortization		(1,253	)		(929	)
Property and equipment, net	$	1,753		$	2,004

Schedule of Capital Leased Assets [Table Text Block]

	December 31,
	2018			2017
Laboratory equipment	$	418		$	366
Furniture and office equipment		541			541
Leasehold improvements		59			59
Total property and equipment financed under a capital lease agreement		1,018			966
Less: accumulated depreciation and amortization		(272	)		(150	)
Property and equipment financed under a capital lease agreement, net	$	746		$	816

Property, Plant and Equipment, Useful Life [Table Text Block]

	Useful Life
Asset Category	(in years)
Laboratory equipment		10
Furniture and office equipment		5 - 10
Computers and hardware		3 - 7
Leasehold improvements		9

Note E - Accounts Payable and Accrued Expenses (Tables)

12 Months Ended

Dec. 31, 2018

Notes Tables

Schedule of Accounts Payable and Accrued Liabilities [Table Text Block]

	December 31,
	2018		2017
Accrued interest	$	1,921	$	2,222
Accrued banking fees		700		700
Accrued severance		193		—
Accrued payroll		731		1,118
Accounts payable		3,715		2,177
Other accrued expenses		1,082		1,658
Total accounts payable and accrued expenses	$	8,342	$	7,875

Note F - Debt Obligations (Tables)

12 Months Ended

Dec. 31, 2018

Notes Tables

Schedule of Maturities of Long-term Debt [Table Text Block]

	Convertible
Year Ending December 31,	Notes
2019		3,333
2020		3,334
2021		76,673
Total minimum principal payments		83,340
Less: debt issuance costs and discount		(1,902	)
Convertible notes, net	$	81,438

Note G - Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2018

Notes Tables

Contractual Obligation, Fiscal Year Maturity Schedule [Table Text Block]

	Capital			Operating
Year Ending December 31,	Leases			Leases
2019	$	254		$	714
2020		251			499
2021		163			449
2022		11			461
2023		—			472
Thereafter		—			903
Total minimum lease payments		679		$	3,498
Less: amounts representing interest		(69	)
Total minimum capital lease principal payments	$	610

Note J - Common Stock and Warrants (Tables)

12 Months Ended

Dec. 31, 2018

Notes Tables

Schedule of Authorized Shares of Common Stock Reserved for Future Issuance [Table Text Block]

	December 31,
	2018		2017
Conversion of Deerfield Convertible Note		1,167,607		1,751,410
Conversion of 2021 Notes		4,481,182		5,040,914
Outstanding awards under equity incentive plans		3,704,755		2,853,924
Outstanding common stock warrants		2,527,763		2,027,763
Conversion of Series A Convertible Preferred Stock		1,112,334		—
Possible future issuances under equity incentive plans		648,272		944,700
Total common shares reserved for future issuance		13,641,913		12,618,711

Schedule of Common Stock Outstanding Roll Forward [Table Text Block]

	Shares of
	Common Stock
Balance as of January 1, 2017		14,646,982
Common stock warrants exercised		698
Common stock options exercised		9,750
Balance as of December 31, 2017		14,657,430
Common stock sold under First ATM Agreement		762,338
Common stock issued as a result of Deerfield Convertible Note principal and interest conversion		598,568
Common stock options exercised		23,682
Common stock sold under underwritten public offering		8,333,334
Common stock issued as a result of Series A Convertible Preferred Stock conversion		2,080,000
Balance as of December 31, 2018		26,455,352

Note K - Stock-based Compensation (Tables)

12 Months Ended

Dec. 31, 2018

Notes Tables

Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]

	Year Ended December 31,
	2018		2017
Research and development	$	1,608	$	1,304
General and administrative		3,651		3,258
Severance expense		1,236		—
Total stock-based compensation expense	$	6,495	$	4,562

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	December 31,
	2018		2017
Risk-free interest rate		2.43% - 2.91%		1.88% - 2.26%
Expected term (in years)		5.50 - 6.79		5.12 - 7.00
Expected volatility		83.10% - 85.05%		85.35% - 95.08%
Expected dividend yield		0%		0%

Share-based Compensation, Stock Options, Activity [Table Text Block]

						Weighted Average
	Number of			Weighted Average		Remaining Contractual		Aggregate Intrinsic
	Options			Exercise Price		Term (in years)		Value
Outstanding balance as of January 1, 2018		2,853,924		$	10.50		7.90	$	471,539
Granted		898,000		$	5.54
Exercised		(23,682	)	$	3.15
Canceled or forfeited		(20,821	)	$	10.63
Expired		(2,666	)	$	3.00
Outsta nding balance as of December 31, 2018		3,704,755		$	9.35		7.48	$	—
Exercisable as of December 31, 2018		1,837,582		$	11.56		6.67	$	—
Vested and expected to vest as of December 31, 2018		3,656,474		$	9.40		7.47	$	—

Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table Text Block]

	Options Outstanding		Options Exercisable
		Weighted Average		Weighted Average
	Number of	Remaining Contractual	Number of	Remaining Contractual
Exercise Price	Shares	Term (in years)	Shares	Term (in years)
$2.75 to $5.00	1,024,995	7.89	390,244	7.59
$5.01 to $10.00	1,256,427	7.85	437,527	5.50
$10.01 to $15.00	471,833	6.94	285,249	6.85
$15.01 to $20.00	603,700	6.89	463,712	6.88
$20.01 to $22.12	347,800	6.68	260,850	6.68
	3,704,755	7.48	1,837,582	6.67

Schedule of Nonvested Restricted Stock Units Activity [Table Text Block]

	Number of Unvested Shares
	December 31,
Exercise Price	2018		2017
$2.75 to $5.00		634,751		979,000
$5.01 to $10.00		818,900		21,301
$10.01 to $15.00		186,584		282,542
$15.01 to $20.00		139,988		352,789
$20.01 to $22.12		86,950		173,900
Total number of unvested shares		1,867,173		1,809,532

Note L - Fair Value of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2018

Notes Tables

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

			Quoted Prices in				Significant
	Balance as of		Active Markets		Significant Other		Unobservable
	December 31,		for Identical Assets		Observable Inputs		Inputs
	2018		(Level 1)		(Level 2)		(Level 3)
Deerfield Warrant liability	$	1,557	$	—	$	—	$	1,557
Embedded Warrant Put Option		154		—		—		154
Fundamental change and make-whole interest provisions embedded in 2021 Notes		—		—		—		—
Deerfield Note Conversion Feature		134		—		—		134
KVK Warrant liability		273		—		273		—
Total liabilities	$	2,118	$	—	$	273	$	1,845
Trading securities:
Certificates of deposit		246		246		—		—
U.S. Treasury securities		3,014		3,014		—		—
Total assets	$	3,260	$	3,260	$	—	$	—

			Quoted Prices in				Significant
	Balance as of		Active Markets		Significant Other		Unobservable
	December 31,		for Identical Assets		Observable Inputs		Inputs
	2017		(Level 1)		(Level 2)		(Level 3)
Deerfield Warrant liability	$	5,115	$	—	$	—	$	5,115
Embedded Warrant Put Option		365		—		—		365
Fundamental change and make-whole interest provisions embedded in 2021 Notes		14		—		—		14
Deerfield Note Conversion Feature		2,215						2,215
Total liabilities	$	7,709	$	—	$	—	$	7,709
Trading securities:
Certificates of deposit		5,616		5,616		—		—
U.S. Treasury securities		25,988		25,988		—		—
U.S. government-sponsored agency securities		3,004		—		3,004		—
Total assets	$	34,608	$	31,604	$	3,004	$	—

Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]

	2018			2017
Balance as of beginning of period	$	7,709		$	4,618
Gain on extinguishment of debt		(2	)		—
Adjustment to fair value		(5,862	)		3,091
Balance as of end of period	$	1,845		$	7,709

Note M - Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

Notes Tables

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

	Year ended December 31,
	2018			2017
Federal statutory rate		21.00	%		34.00	%
Effect of:
Change in valuation allowance		(30.44	)		13.38
Return to provision and deferred true-up		0.38			2.18
Change in rate		0.03			(49.06	)
State tax benefit (net of federal)		4.35			2.71
Warrant liability		2.02			(2.42	)
State research and development credit		0.22			0.10
Federal research and development credit		3.30			1.50
Amortization		—			(1.22	)
Stock-based compensation		(0.63	)		(1.03	)
Other		(0.01	)		(0.04	)
Federal income tax benefit effective rate		0.22	%		0.10	%

Schedule of Deferred Tax Assets and Liabilities [Table Text Block]

	December 31,
	2018			2017
Deferred tax assets relating to:
Net operating loss carryforwards	$	51,269		$	37,028
Research and development tax carryforward		5,657			3,788
Other deferred tax assets		3,437			2,409
Total gross deferred tax assets		60,363			43,225
Deferred tax liabilities relating to:
Property and equipment		161			260
Other deferred tax liabilities		10			—
Total gross deferred tax liabilities		171			260
Deferred tax assets less liabilities		60,192			42,965
Valuation allowance		(60,192	)		(42,965	)
Net deferred tax asset (liability)	$	—		$	—

Summary of Operating Loss Carryforwards [Table Text Block]

	Net		Research
	Operating Loss		Activities
Year Incurred	Carryforwards		Credit		Expiration
2007	$	454	$	30		2027
2008		1,178		65		2028
2009		3,060		176		2029
2010		3,423		149		2030
2011		9,929		176		2031
2012		—		170		2032
2013		4,353		133		2033
2014		15,897		894		2034
2015		23,496		598		2035
2016		41,580		745		2036
2017		34,776		652		2037
2018		56,105		1,869		Indefinite
	$	194,251	$	5,657

Note N - Net Loss Per Share (Tables)

12 Months Ended

Dec. 31, 2018

Notes Tables

Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]

	Year ended December 31,
	2018			2017
Net loss - basic and diluted	$	(56,466	)	$	(43,386	)
Weighted average number of shares of common stock - basic and diluted		17,930,023			14,652,898
Net loss per share - basic and diluted	$	(3.15	)	$	(2.96	)

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]

	December 31,
	2018		2017
Deerfield Convertible Note		1,167,607		1,751,410
2021 Notes		4,481,182		5,040,914
Awards under equity incentive plans		3,704,755		2,853,924
Warrants to purchase common stock		2,527,763		2,027,763
Series A Convertible Preferred Stock		1,112,334		—
Total securities excluded from the calculation of weighted average number of shares of common stock outstanding		12,993,641		11,674,011

Note A - Description of Business and Basis of Presentation (Details Textual) - USD ($)						9 Months Ended	12 Months Ended	23 Months Ended
	Feb. 28, 2019	Oct. 10, 2018	Oct. 10, 2018	Oct. 05, 2018	Sep. 04, 2018	Sep. 30, 2018	Dec. 31, 2018	Sep. 04, 2018
Sale of Securities, Value, Available to Issue							$ 150,000,000
Sale of Securities, Value, Remaining Available to Issue							120,100,000
Sale of Securities Covered Under Prospectus Supplement, Value, Available to Issue							50,000,000
Sale of Securities Covered Under Prospectus Supplement, Value, Anticipated Amount to Be Sold Under Registration Statement							18,500,000
Sale of Securities Covered Under Prospectus Supplement, Value, Anticipated Sales Under Purchase Agreement							15,300,000
Sale of Securities Covered Under Prospectus Supplement, Value, Anticipated Sales Under ATM Agreement							$ 3,200,000
Second ATM Agreement [Member]
Stock Issued During Period, Shares, New Issues						0
Underwriting Agreement [Member]
Stock Issued During Period, Shares, New Issues							8,333,334
Cowen and Company, LLC [Member]
Proceeds from Issuance of Common Stock			$ 25,000,000		$ 4,900,000			$ 4,900,000
Stock Issued During Period, Shares, New Issues								762,338
Sale of Stock, Commission Fee					3.00%			3.00%
RBC Capital Markets, LLC [Member]
Sale of Stock, Authorized Offering Price					$ 50,000,000			$ 50,000,000
RBC Capital Markets, LLC [Member] \| Second ATM Agreement [Member]
Sale of Stock, Commission Fee					3.00%			3.00%
RBC Capital Markets, LLC [Member] \| Underwriting Agreement [Member]
Stock Issued During Period, Shares, New Issues		8,333,334		8,333,334
Shares Issued, Price Per Share		$ 3	$ 3
Proceeds from Issuance of Common Stock, Net		$ 23,100,000
RBC Capital Markets, LLC [Member] \| Maximum [Member] \| Second ATM Agreement [Member]
Sale of Stock, Authorized Offering Price					$ 50,000,000			$ 50,000,000
Lincoln Park [Member] \| Subsequent Event [Member]
Sale of Securities, Value, Available to Issue	$ 15,000,000
Purchase Agreement, Term	3 years
Purchase Agreement, Additional Shares to Be Issued as Commitment Shares	120,200

Note B - Summary of Significant Accounting Policies (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019
Asset Impairment Charges, Total	$ 0	$ 0
Accounting Standards Update 2016-02 [Member] \| Subsequent Event [Member]
Operating Lease, Right-of-Use Asset			$ 3,000
Operating Lease, Liability, Total			$ 3,000
Earliest Tax Year [Member]
Open Tax Year	2014
Minimum [Member]
Property, Plant and Equipment, Useful Life	3 years
Maximum [Member]
Property, Plant and Equipment, Useful Life	10 years

Note C - Prepaid Expenses and Other Current Assets - Components of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Prepaid insurance	$ 224	$ 202
Other receivables	140	76
Other prepaid expenses and current assets	1,688	1,384
Total prepaid expenses and other current assets	$ 2,052	$ 1,662

Note D - Property and Equipment (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Depreciation, Depletion and Amortization, Total	$ 324,000	$ 336,000

Note D - Property and Equipment - Components of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property and equipment, gross	$ 3,006	$ 2,933
Less: accumulated depreciation and amortization	(1,253)	(929)
Property and equipment, net	1,753	2,004
Laboratory Equipment [Member]
Property and equipment, gross	1,035	983
Furniture and Fixtures [Member]
Property and equipment, gross	655	655
Computer and Hardware [Member]
Property and equipment, gross	299	292
Leasehold Improvements [Member]
Property and equipment, gross	$ 1,017	$ 1,003

Note D - Property and Equipment - Assets Under Capital Leases Included in Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Capital leased assets, gross	$ 1,018	$ 966
Less: accumulated depreciation and amortization	(272)	(150)
Property and equipment financed under a capital lease agreement, net	746	816
Laboratory Equipment [Member]
Capital leased assets, gross	418	366
Furniture and Fixtures [Member]
Capital leased assets, gross	541	541
Leasehold Improvements [Member]
Capital leased assets, gross	$ 59	$ 59

Note D - Property and Equipment - Estimated Useful Lives of Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2018
Minimum [Member]
Property and equipment, useful lives (Year)	3 years
Maximum [Member]
Property and equipment, useful lives (Year)	10 years
Laboratory Equipment [Member]
Property and equipment, useful lives (Year)	10 years
Furniture and Fixtures [Member] \| Minimum [Member]
Property and equipment, useful lives (Year)	5 years
Furniture and Fixtures [Member] \| Maximum [Member]
Property and equipment, useful lives (Year)	10 years
Computer and Hardware [Member] \| Minimum [Member]
Property and equipment, useful lives (Year)	3 years
Computer and Hardware [Member] \| Maximum [Member]
Property and equipment, useful lives (Year)	7 years
Leasehold Improvements [Member]
Property and equipment, useful lives (Year)	9 years

Note E - Accounts Payable and Accrued Expenses - Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accrued interest	$ 1,921	$ 2,222
Accrued banking fees	700	700
Accrued severance	193
Accrued payroll	731	1,118
Accounts payable	3,715	2,177
Other accrued expenses	1,082	1,658
Total accounts payable and accrued expenses	$ 8,342	$ 7,875

Note F - Debt Obligations (Details Textual) - USD ($)					12 Months Ended
Note F - Debt Obligations (Details Textual) - USD ($)	Oct. 05, 2018	Jun. 11, 2018	Feb. 09, 2016	Jun. 02, 2014	Dec. 31, 2018	Dec. 31, 2017	Nov. 20, 2018	Jun. 30, 2016	Dec. 31, 2013
Interest Paid, Excluding Capitalized Interest, Operating Activities					$ 5,593,000	$ 5,717,000
Deerfield Warrant [Member]
Beneficial Ownership, Cap Limit, Percentage							4.985%
Conversion from Deerfield Convertible Note to Common Stock [Member]
Debt Conversion, Converted Instrument, Shares Issued		598,568
Debt Conversion, Original Debt, Amount		$ 3,333,333
Debt Conversion, Accrued Interest		$ 168,288
Exchanged 2021 Notes for Series A Preferred Stock [Member]
Debt Conversion, Converted Instrument, Shares Issued	9,577
Debt Conversion, Original Debt, Amount	$ 9,577,000				9,577,000
Interest Paid, Excluding Capitalized Interest, Operating Activities	95,105
Debt Conversion, Expenses, Reimbursement	$ 25,000
Preferred Stock, Aggregate Stated Value Per Share	$ 1,000
Convertible Notes 2021 [Member]
Beneficial Ownership, Cap Limit, Percentage							9.985%
Deerfield Convertible Notes [Member]
Beneficial Ownership, Cap Limit, Percentage							4.985%
Series D Redeemable Convertible Preferred Stock [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights									1,079,453
Series A Preferred Stock [Member]
Preferred Stock, Par or Stated Value Per Share	0.0001		$ 0.0001
Preferred Stock, Aggregate Stated Value Per Share	1,000
Convertible Preferred Stock, Conversion Price	$ 3
Convertible Preferred Stock, Shares Issuable Upon Conversion	3,192,334
Convertible Preferred Stock, Conversion Restriction, Percentage of Common Stock	4.985%
2021 Notes [Member]
Debt Instrument, Convertible, Conversion Price			$ 17.11
Debt Instrument, Face Amount			$ 86,300,000
Debt Instrument, Interest Rate, Stated Percentage			5.50%
Proceeds from Debt, Net of Issuance Costs			$ 82,800,000
Repayments of Long-term Debt, Total			18,600,000
Debt Instrument, Sinking Fund Payment			$ 0
Debt Conversion, Converted Instrument, Shares Issued			58.4454
Debt Conversion, Original Debt, Amount			$ 1,000
Debt Instrument Repurchase Price Equal to Percentage of Principal Amount			100.00%
Deerfield Facility Agreement [Member]
Line of Credit Facility, Maximum Borrowing Capacity				$ 60,000,000
Line of Credit Facility, Interest Rate at Period End				9.75%
Debt Covenant, Debt Financing Restriction				$ 750,000
Deerfield Facility Agreement [Member] \| IPO [Member]
Reclassification of Common Stock Shares				256,410
Deerfield Facility Agreement [Member] \| Deerfield Warrant [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights				$ 0.78
Deerfield Facility Agreement [Member] \| Deerfield Warrant [Member] \| IPO [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights				1,923,077
Deerfield Facility Agreement [Member] \| Series D Redeemable Convertible Preferred Stock [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights				14,423,076
Own-share Lending Arrangement, Shares, Issued				1,923,077
Mandatorily Redeemable Preferred Stock, Fair Value Disclosure				$ 1,500,000
Deerfield Facility Agreement [Member] \| Term Notes [Member]
Proceeds from Secured Notes Payable				15,000,000
Deerfield Facility Agreement [Member] \| Deerfield Convertible Notes [Member]
Proceeds from Secured Notes Payable				$ 10,000,000
Debt Instrument, Convertible, Conversion Price				$ 5.85
Third Line of Credit Agreement [Member] \| City National Bank of Florida [Member]
Line of Credit Facility, Maximum Borrowing Capacity								$ 1,100,000
Line of Credit Facility, Remaining Borrowing Capacity					400,000	400,000
Long-term Line of Credit, Total					$ 0	$ 0
Third Line of Credit Agreement [Member] \| City National Bank of Florida [Member] \| Prime Rate [Member]
Debt Instrument, Interest Rate, Stated Percentage					4.35%
Debt Instrument, Basis Spread on Variable Rate					2.00%

Note F - Debt Obligations - Future Minimum Payments (Details) $ in Thousands	Dec. 31, 2018 USD ($)
2019	$ 3,333
2020	3,334
2021	76,673
Total minimum principal payments	83,340
Less: debt issuance costs and discount	(1,902)
Convertible notes, net	$ 81,438

Note G - Commitments and Contingencies (Details Textual) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Loss Contingency Accrual, Ending Balance	$ 0	$ 0
Operating and Capital Leases, Rent Expense, Net	$ 700	$ 600
Capital Lease One [Member]
Capital Lease, Interest Rate	7.19%
Capital Lease Two [Member]
Capital Lease, Interest Rate		9.57%
FLORIDA
Number of Units Leased	2
Lessee Leasing Arrangements, Operating Leases, Number of Lease Renewals	2
Lessee, Operating Lease, Renewal Term	5 years
IOWA
Lessee, Operating Lease, Renewal Term	1 year
North Carolina 1 [Member]
Lessee, Operating Lease, Renewal Term	3 years

Note G - Commitments and Contingencies - Future Minimum Lease Payments Under Capital Leases and Non-cancelable Operating Leases (Details) $ in Thousands	Dec. 31, 2018 USD ($)
2019	$ 254
2019	714
2020	251
2020	499
2021	163
2021	449
2022	11
2022	461
2023
2023	472
Thereafter
Thereafter	903
Total minimum lease payments	679
Total minimum lease payments	3,498
Less: amounts representing interest	(69)
Total minimum capital lease principal payments	$ 610

Note H - Supply Arrangement (Details Textual) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Number of Manufacturing Arrangements	1	1
Supply Arrangement Expense	$ 3,600	$ 0
Supply Arrangement, Automatic Renewal Period	2 years
Supply Arrangement, Period of Prior Notice	1 year

Note I - Preferred Stock and Warrants (Details Textual) - USD ($) $ / shares in Units, $ in Millions				12 Months Ended
	Feb. 28, 2019	Oct. 05, 2018	Jun. 02, 2014	Dec. 31, 2013	Dec. 31, 2018	Dec. 31, 2017	Feb. 09, 2016
Preferred Stock, Shares Authorized					10,000,000	10,000,000
Preferred Stock, Shares Issued, Total					9,577
Preferred Stock, Shares Outstanding, Ending Balance					3,337
Common Stock [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights				143,466
Class of Warrant or Right, Exercise Price of Warrants or Rights				$ 5.85
2013 Warrants [Member]
Class of Warrant or Right Issued				1,079,453
Deerfield Warrant [Member]
Class of Warrant or Right Issued			14,423,076
Deerfield Warrant [Member] \| Common Stock [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights			1,923,077
Class of Warrant or Right, Exercise Price of Warrants or Rights			$ 5.85
Convertible Notes Payable [Member]
Debt Instrument, Face Amount				$ 3.8
Exchanged 2021 Notes for Series A Preferred Stock [Member]
Debt Conversion, Converted Instrument, Shares Issued		9,577
Preferred Stock, Aggregate Stated Value Per Share		$ 1,000
Series A Preferred Stock [Member]
Preferred Stock, Shares Authorized					9,578
Preferred Stock, Aggregate Stated Value Per Share		1,000
Convertible Preferred Stock, Conversion Price		$ 3
Convertible Preferred Stock, Shares Issuable Upon Conversion		3,192,334
Convertible Preferred Stock, Conversion Restriction, Percentage of Common Stock		4.985%
Preferred Stock, Par or Stated Value Per Share		$ 0.0001					$ 0.0001
Series A Preferred Stock [Member] \| Subsequent Event [Member]
Preferred Stock, Shares Outstanding, Ending Balance	3,337
Convertible Preferred Stock, Shares Issuable Upon Conversion	1,112,334
Conversion of Stock, Shares Converted	6,240
Conversion of Stock, Shares Issued	2,080,000
Series D Redeemable Convertible Preferred Stock [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights				1,079,453

Note J - Common Stock and Warrants (Details Textual) - USD ($)							12 Months Ended		23 Months Ended
	Feb. 28, 2019	Oct. 25, 2018	Oct. 10, 2018	Oct. 10, 2018	Oct. 05, 2018	Sep. 04, 2018	Dec. 31, 2018	Dec. 31, 2017	Sep. 04, 2018	Dec. 31, 2016	Dec. 31, 2012
Common Stock, Shares Authorized							250,000,000	250,000,000
Common Stock, Shares, Issued, Total							26,455,352	14,657,430
Common Stock Issued During Period from Warrants Exercised								698
Class of Warrant or Right Exercised							0
Common Stock, Shares, Outstanding, Ending Balance							26,455,352	14,657,430		14,646,982
Warrant Issued to KVK [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		500,000
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 2.30
Class of Warrant or Right, Additional Shares Exercisable for Each Milestones		125,000
Series A Preferred Stock Converted Into Common Stock [Member]
Conversion of Stock, Shares Converted	6,240
Conversion of Stock, Shares Issued	2,080,000						2,080,000
Exchanged 2021 Notes for Series A Preferred Stock [Member]
Debt Conversion, Converted Instrument, Shares Issued					9,577
Underwriting Agreement [Member]
Stock Issued During Period, Shares, New Issues							8,333,334
Private Placement [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights											595,920
Cowen and Company, LLC [Member]
Stock Issued During Period, Shares, New Issues									762,338
Proceeds from Issuance of Common Stock				$ 25,000,000		$ 4,900,000			$ 4,900,000
RBC Capital Markets, LLC [Member] \| Underwriting Agreement [Member]
Stock Issued During Period, Shares, New Issues			8,333,334		8,333,334

Note J - Common Stock and Warrants - Reserved Authorized Shares of Common Stock for Future Issuance (Details) - shares	Dec. 31, 2018	Dec. 31, 2017
Common shares reserved for future issuance (in shares)	13,641,913	12,618,711
Series A Convertible Preferred Stock [Member]
Common shares reserved for future issuance (in shares)	1,112,334
Warrant [Member]
Common shares reserved for future issuance (in shares)	2,527,763	2,027,763
Stock Compensation Plan [Member]
Common shares reserved for future issuance (in shares)	3,704,755	2,853,924
Possible Future Issuances Under Equity Incentive Plans [Member]
Common shares reserved for future issuance (in shares)	648,272	944,700
2021 Notes [Member]
Common shares reserved for future issuance (in shares)	4,481,182	5,040,914
Convertible Notes Payable [Member]
Common shares reserved for future issuance (in shares)	1,167,607	1,751,410

Note J - Common Stock and Warrants - Common Stock Activity (Details) - shares		12 Months Ended
	Feb. 28, 2019	Dec. 31, 2018	Dec. 31, 2017
Balance (in shares)		14,657,430	14,646,982
Common stock warrants exercised (in shares)			698
Common stock options exercised (in shares)		23,682	9,750
Common stock issued as a result of Deerfield Convertible Note principal and interest conversion (in shares)		598,568
Balance (in shares)		26,455,352	14,657,430
Series A Preferred Stock Converted Into Common Stock [Member]
Common stock issued as a result of Series A Convertible Preferred Stock conversion (in shares)	2,080,000	2,080,000
First ATM Agreement [Member]
Common stock sold under First ATM Agreement (in shares)		762,338
Underwriting Agreement [Member]
Common stock sold under First ATM Agreement (in shares)		8,333,334

Note K - Stock-based Compensation (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Increase in Common Stock Reserved for Issuance	1,058,214
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	23,682	9,750
Stock Issued During Period, Value, Stock Options Exercised	$ 68,000	$ 7,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value	$ 69,000	$ 32,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Weighted Average Grant Date Fair Value	$ 4.05	$ 2.77
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value	$ 5,900,000	$ 4,100,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Total	$ 6,000,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	1 year 306 days
Allocated Share-based Compensation Expense, Total	$ 6,495,000	4,562,000
Performance Shares [Member]
Allocated Share-based Compensation Expense, Total	$ 0	$ 0
2014 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	4,018,480
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Reserved for Issuance, Incremental Percentage of Capital Stock Outstanding	4.00%

Note K - Stock-based Compensation - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Stock based compensation expense	$ 6,495	$ 4,562
Research and Development Expense [Member]
Stock based compensation expense	1,608	1,304
General and Administrative Expense [Member]
Stock based compensation expense	3,651	3,258
Severance Expense [Member]
Stock based compensation expense	$ 1,236

Note K - Stock-based Compensation - Black-Scholes Option-pricing Model (Details)	12 Months Ended
	Dec. 31, 2017
Expected dividend yield	0.00%
Minimum [Member]
Expected dividend yield	0.00%

Note K - Stock-based Compensation - Schedule of Stock Option Activity (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Outstanding, number of options (in shares)	2,853,924
Outstanding, weighted average exercise price (in dollars per share)	$ 10.50
Outstanding, weighted average remaining contractual term (Year)	7 years 175 days	7 years 328 days
Outstanding, aggregate intrinsic value	$ 471,539
Granted, number of options (in shares)	898,000
Granted, weighted average exercise price (in dollars per share)	$ 5.54
Exercised, number of options (in shares)	(23,682)	(9,750)
Exercised, weighted average exercise price (in dollars per share)	$ 3.15
Canceled or forfeited, number of options (in shares)	(20,821)
Canceled or forfeited, weighted average exercise price (in dollars per share)	$ 10.63
Expired, number of options (in shares)	(2,666)
Expired, weighted average exercise price (in dollars per share)	$ 3
Outstanding, number of options (in shares)	3,704,755	2,853,924
Outstanding, weighted average exercise price (in dollars per share)	$ 9.35	$ 10.50
Exercisable, number of options (in shares)	1,837,582
Exercisable, weighted average exercise price (in dollars per share)	$ 11.56
Exercisable, weighted average remaining contractual term (Year)	6 years 244 days
Vested and expected to vest, number of options (in shares)	3,656,474
Vested and expected to vest, weighted average exercise price (in dollars per share)	$ 9.40
Vested and expected to vest, weighted average remaining contractual term (Year)	7 years 171 days

Note K - Stock-based Compensation - Information Regarding Currently Outstanding and Exercisable Options (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Options outstanding, number of shares (in shares)	3,704,755	2,853,924
Outstanding, weighted average remaining contractual term (Year)	7 years 175 days	7 years 328 days
Exercisable, number of options (in shares)	1,837,582
Exercisable, weighted average remaining contractual term (Year)	6 years 244 days
Exercise Price Range One [Member]
Lower range (in dollars per share)	$ 2.75
Upper range (in dollars per share)	$ 5
Options outstanding, number of shares (in shares)	1,024,995
Outstanding, weighted average remaining contractual term (Year)	7 years 324 days
Exercisable, number of options (in shares)	390,244
Exercisable, weighted average remaining contractual term (Year)	7 years 215 days
Exercise Price Range Two [Member]
Lower range (in dollars per share)	$ 5.01
Upper range (in dollars per share)	$ 10
Options outstanding, number of shares (in shares)	1,256,427
Outstanding, weighted average remaining contractual term (Year)	7 years 310 days
Exercisable, number of options (in shares)	437,527
Exercisable, weighted average remaining contractual term (Year)	5 years 182 days
Exercise Price Range Three [Member]
Lower range (in dollars per share)	$ 10.01
Upper range (in dollars per share)	$ 15
Options outstanding, number of shares (in shares)	471,833
Outstanding, weighted average remaining contractual term (Year)	6 years 343 days
Exercisable, number of options (in shares)	285,249
Exercisable, weighted average remaining contractual term (Year)	6 years 310 days
Exercise Price Range Four [Member]
Lower range (in dollars per share)	$ 15.01
Upper range (in dollars per share)	$ 20
Options outstanding, number of shares (in shares)	603,700
Outstanding, weighted average remaining contractual term (Year)	6 years 324 days
Exercisable, number of options (in shares)	463,712
Exercisable, weighted average remaining contractual term (Year)	6 years 321 days
Exercise Price Range Five [Member]
Lower range (in dollars per share)	$ 20.01
Upper range (in dollars per share)	$ 22.12
Options outstanding, number of shares (in shares)	347,800
Outstanding, weighted average remaining contractual term (Year)	6 years 248 days
Exercisable, number of options (in shares)	260,850
Exercisable, weighted average remaining contractual term (Year)	6 years 248 days

Note K - Stock-based Compensation - Nonvested Stock Option Awards (Details) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Number of unvested shares (in shares)	1,867,173	1,809,532
Exercise Price Range One [Member]
Number of unvested shares (in shares)	634,751	979,000
Exercise Price Range One [Member] \| Minimum [Member]
Exercise price (in dollars per share)	$ 2.75
Exercise Price Range One [Member] \| Maximum [Member]
Exercise price (in dollars per share)	$ 5
Exercise Price Range Two [Member]
Number of unvested shares (in shares)	818,900	21,301
Exercise Price Range Two [Member] \| Minimum [Member]
Exercise price (in dollars per share)	$ 5.01
Exercise Price Range Two [Member] \| Maximum [Member]
Exercise price (in dollars per share)	$ 10
Exercise Price Range Three [Member]
Number of unvested shares (in shares)	186,584	282,542
Exercise Price Range Three [Member] \| Minimum [Member]
Exercise price (in dollars per share)	$ 10.01
Exercise Price Range Three [Member] \| Maximum [Member]
Exercise price (in dollars per share)	$ 15
Exercise Price Range Four [Member]
Number of unvested shares (in shares)	139,988	352,789
Exercise Price Range Four [Member] \| Minimum [Member]
Exercise price (in dollars per share)	$ 15.01
Exercise Price Range Four [Member] \| Maximum [Member]
Exercise price (in dollars per share)	$ 20
Exercise Price Range Five [Member]
Number of unvested shares (in shares)	86,950	173,900
Exercise Price Range Five [Member] \| Minimum [Member]
Exercise price (in dollars per share)	$ 20.01
Exercise Price Range Five [Member] \| Maximum [Member]
Exercise price (in dollars per share)	$ 22.12

Note L - Fair Value of Financial Instruments (Details Textual) - Fair Value, Inputs, Level 3 [Member] - Deerfield Facility Agreement [Member] - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Deerfield Convertible Notes [Member]
Long-term Debt, Fair Value	$ 6.2	$ 11.0
Term Notes [Member]
Long-term Debt, Fair Value	$ 51.2	$ 51.9

Note L - Fair Value of Financial Instruments - Reconciliation of Beginning and Ending Balances for Derivative and Warrant Liability Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Balance as of beginning of period	$ 7,709	$ 4,618
Gain on extinguishment of debt	(2)
Adjustment to fair value	(5,862)	3,091
Balance as of end of period	$ 1,845	$ 7,709

Note M - Income Taxes (Details Textual) - USD ($)	12 Months Ended
Note M - Income Taxes (Details Textual) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
State and Local Income Tax Expense (Benefit), Continuing Operations, Total	$ (126,000)	$ (43,000)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest, Total	(56,592,000)	$ (43,429,000)
Operating Loss Carryforwards, Total	194,251,000
State and Local Jurisdiction [Member]
Operating Loss Carryforwards, Total	$ 136,000,000
Operating Loss Carryforwards, Expiration, Beginning Year	2027
Operating Loss Carryforwards, Expiration, Ending Year	2037

Note M - Income Taxes - Schedule of Reconciliation of Difference Between Benefit for Income Taxes and Income Taxes at Statutory U.S. Federal Income Tax Rate (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Federal statutory rate	21.00%	34.00%
Change in valuation allowance	(30.44%)	13.38%
Return to provision and deferred true-up	0.38%	2.18%
Change in rate	0.03%	(49.06%)
State tax benefit (net of federal)	4.35%	2.71%
Warrant liability	2.02%	(2.42%)
State research and development credit	0.22%	0.10%
Federal research and development credit	3.30%	1.50%
Amortization		(1.22%)
Stock-based compensation	(0.63%)	(1.03%)
Other	(0.01%)	(0.04%)
Federal income tax benefit effective rate	0.22%	0.10%

Note M - Income Taxes - Components of Net Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Net operating loss carryforwards	$ 51,269	$ 37,028
Research and development tax carryforward	5,657	3,788
Other deferred tax assets	3,437	2,409
Total gross deferred tax assets	60,363	43,225
Property and equipment	161	260
Other deferred tax liabilities	10
Total gross deferred tax liabilities	171	260
Deferred tax assets less liabilities	60,192	42,965
Valuation allowance	(60,192)	(42,965)
Net deferred tax asset (liability)

Note M - Income Taxes - Federal Net Operating Loss Carryforward and Research Activities Credit (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Net Operating Loss Carryforwards	$ 194,251
Research Activities Tax Credit	5,657	$ 3,788
Tax Year 2007 [Member]
Net Operating Loss Carryforwards	454
Research Activities Tax Credit	$ 30
Expiration	2027
Tax Year 2008 [Member]
Net Operating Loss Carryforwards	$ 1,178
Research Activities Tax Credit	$ 65
Expiration	2028
Tax Year 2009 [Member]
Net Operating Loss Carryforwards	$ 3,060
Research Activities Tax Credit	$ 176
Expiration	2029
Tax Year 2010 [Member]
Net Operating Loss Carryforwards	$ 3,423
Research Activities Tax Credit	$ 149
Expiration	2030
Tax Year 2011 [Member]
Net Operating Loss Carryforwards	$ 9,929
Research Activities Tax Credit	$ 176
Expiration	2031
Tax Year 2012 [Member]
Net Operating Loss Carryforwards
Research Activities Tax Credit	$ 170
Expiration	2032
Tax Year 2013 [Member]
Net Operating Loss Carryforwards	$ 4,353
Research Activities Tax Credit	$ 133
Expiration	2033
Tax Year 2014 [Member]
Net Operating Loss Carryforwards	$ 15,897
Research Activities Tax Credit	$ 894
Expiration	2034
Tax Year 2015 [Member]
Net Operating Loss Carryforwards	$ 23,496
Research Activities Tax Credit	$ 598
Expiration	2035
Tax Year 2016 [Member]
Net Operating Loss Carryforwards	$ 41,580
Research Activities Tax Credit	$ 745
Expiration	2036
Tax Year 2017 [Member]
Net Operating Loss Carryforwards	$ 34,776
Research Activities Tax Credit	$ 652
Expiration	2037
Tax Year 2018 [Member]
Net Operating Loss Carryforwards	$ 56,105
Research Activities Tax Credit	$ 1,869

Note N - Net Loss Per Share - Summary of Computation of Basic and Diluted Net Loss and Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Net loss - basic and diluted	$ (56,466)	$ (43,386)
Weighted average number of shares of common stock - basic and diluted (in shares)	17,930,023	14,652,898
Net loss per share - basic and diluted (in dollars per share)	$ (3.15)	$ (2.96)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Note N - Net Earnings Per Share - Anti-dilutive Securities (Details) - shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Antidilutive securities (in shares)	12,993,641	11,674,011
Convertible Debt Securities [Member]
Antidilutive securities (in shares)	1,167,607	1,751,410
2021 Notes [Member]
Antidilutive securities (in shares)	4,481,182	5,040,914
Stock Compensation Plan [Member]
Antidilutive securities (in shares)	3,704,755	2,853,924
Warrants to Purchase Common Stock [Member]
Antidilutive securities (in shares)	2,527,763	2,027,763
Series A Convertible Preferred Stock [Member]
Antidilutive securities (in shares)	1,112,334

Note O - Severance Expense (Details Textual) - USD ($) $ in Thousands		12 Months Ended
	Aug. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Allocated Share-based Compensation Expense, Total		$ 6,495	$ 4,562
Severance Expense [Member]
Allocated Share-based Compensation Expense, Total		1,236
Employee Severance [Member] \| Accounts Payable and Accrued Liabilities [Member]
Accrued Severance Expense		$ 200
Employee Severance [Member] \| Severance Expense [Member]
Severance Charges	$ 400
Allocated Share-based Compensation Expense, Total	$ 1,200

Note P - Employee Benefit Plan (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Retirement Plan [Member]
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	4.00%
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 212,000	$ 207,000
Profit Sharing Plan [Member]
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 0	$ 0
Defined Contribution Plan, Requisite Service Period	3 years

Note L - Fair Value of Financial Instruments - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financial liabilities measured at fair value on recurring basis	$ 2,118	$ 7,709
Financial assets measured at fair value on recurring basis	3,260	34,608
Certificates of Deposit [Member]
Financial assets measured at fair value on recurring basis	246	5,616
US Treasury Securities [Member]
Financial assets measured at fair value on recurring basis	3,014	25,988
US Government Corporations and Agencies Securities [Member]
Financial assets measured at fair value on recurring basis		3,004
Fair Value, Inputs, Level 1 [Member]
Financial liabilities measured at fair value on recurring basis
Financial assets measured at fair value on recurring basis	3,260	31,604
Fair Value, Inputs, Level 1 [Member] \| Certificates of Deposit [Member]
Financial assets measured at fair value on recurring basis	246	5,616
Fair Value, Inputs, Level 1 [Member] \| US Treasury Securities [Member]
Financial assets measured at fair value on recurring basis	3,014	25,988
Fair Value, Inputs, Level 1 [Member] \| US Government Corporations and Agencies Securities [Member]
Financial assets measured at fair value on recurring basis
Fair Value, Inputs, Level 2 [Member]
Financial liabilities measured at fair value on recurring basis	273
Financial assets measured at fair value on recurring basis		3,004
Fair Value, Inputs, Level 2 [Member] \| Certificates of Deposit [Member]
Financial assets measured at fair value on recurring basis
Fair Value, Inputs, Level 2 [Member] \| US Treasury Securities [Member]
Financial assets measured at fair value on recurring basis
Fair Value, Inputs, Level 2 [Member] \| US Government Corporations and Agencies Securities [Member]
Financial assets measured at fair value on recurring basis		3,004
Fair Value, Inputs, Level 3 [Member]
Financial liabilities measured at fair value on recurring basis	1,845	7,709
Financial assets measured at fair value on recurring basis
Fair Value, Inputs, Level 3 [Member] \| Certificates of Deposit [Member]
Financial assets measured at fair value on recurring basis
Fair Value, Inputs, Level 3 [Member] \| US Treasury Securities [Member]
Financial assets measured at fair value on recurring basis
Fair Value, Inputs, Level 3 [Member] \| US Government Corporations and Agencies Securities [Member]
Financial assets measured at fair value on recurring basis
Deerfield Warrant Liability [Member]
Financial liabilities measured at fair value on recurring basis	1,557	5,115
Deerfield Warrant Liability [Member] \| Fair Value, Inputs, Level 1 [Member]
Financial liabilities measured at fair value on recurring basis
Deerfield Warrant Liability [Member] \| Fair Value, Inputs, Level 2 [Member]
Financial liabilities measured at fair value on recurring basis
Deerfield Warrant Liability [Member] \| Fair Value, Inputs, Level 3 [Member]
Financial liabilities measured at fair value on recurring basis	1,557	5,115
Embedded Put Option [Member]
Financial liabilities measured at fair value on recurring basis	154	365
Embedded Put Option [Member] \| Fair Value, Inputs, Level 1 [Member]
Financial liabilities measured at fair value on recurring basis
Embedded Put Option [Member] \| Fair Value, Inputs, Level 2 [Member]
Financial liabilities measured at fair value on recurring basis
Embedded Put Option [Member] \| Fair Value, Inputs, Level 3 [Member]
Financial liabilities measured at fair value on recurring basis	154	365
Fundamental Change and Make-Whole Interest Provisions Embedded in 2021 Notes [Member]
Financial liabilities measured at fair value on recurring basis		14
Fundamental Change and Make-Whole Interest Provisions Embedded in 2021 Notes [Member] \| Fair Value, Inputs, Level 1 [Member]
Financial liabilities measured at fair value on recurring basis
Fundamental Change and Make-Whole Interest Provisions Embedded in 2021 Notes [Member] \| Fair Value, Inputs, Level 2 [Member]
Financial liabilities measured at fair value on recurring basis
Fundamental Change and Make-Whole Interest Provisions Embedded in 2021 Notes [Member] \| Fair Value, Inputs, Level 3 [Member]
Financial liabilities measured at fair value on recurring basis		14
Embedded Deerfield Note Put Option [Member]
Financial liabilities measured at fair value on recurring basis	134	2,215
Embedded Deerfield Note Put Option [Member] \| Fair Value, Inputs, Level 1 [Member]
Financial liabilities measured at fair value on recurring basis
Embedded Deerfield Note Put Option [Member] \| Fair Value, Inputs, Level 2 [Member]
Financial liabilities measured at fair value on recurring basis
Embedded Deerfield Note Put Option [Member] \| Fair Value, Inputs, Level 3 [Member]
Financial liabilities measured at fair value on recurring basis	134	$ 2,215
KVK Warrant Liability [Member]
Financial liabilities measured at fair value on recurring basis	273
KVK Warrant Liability [Member] \| Fair Value, Inputs, Level 1 [Member]
Financial liabilities measured at fair value on recurring basis
KVK Warrant Liability [Member] \| Fair Value, Inputs, Level 2 [Member]
Financial liabilities measured at fair value on recurring basis	273
KVK Warrant Liability [Member] \| Fair Value, Inputs, Level 3 [Member]
Financial liabilities measured at fair value on recurring basis