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Document And Entity Information - USD ($)	12 Months Ended
Document And Entity Information - USD ($)	Dec. 31, 2017	Mar. 28, 2018	Jun. 30, 2017
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	Smaller Reporting Company
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	No
Entity Common Stock, Shares Outstanding (in shares)		15,104,848
Entity Public Float			$ 46,538,484
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY
Amendment Flag	false

Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Assets
Cash and cash equivalents	$ 10,871	$ 16,762
Restricted cash	1,100	1,100
Marketable securities	31,358	51,003
Trade date receivables	2,005	5,003
Prepaid expenses and other current assets	1,662	489
Total current assets	46,996	74,357
Property and equipment, net	2,004	1,970
Long-term investments	3,250	8,200
Other long-term assets	206	360
Total assets	52,456	84,887
Liabilities and stockholders’ deficit
Accounts payable and accrued expenses	7,875	6,444
Current portion of convertible notes	3,333
Current portion of capital lease obligation	189	157
Other current liabilities	112	41
Total current liabilities	11,509	6,642
Convertible notes, less current portion, net	89,398	91,170
Derivative and warrant liability	7,709	4,618
Capital lease obligation, less current portion	562	657
Other long-term liabilities	794	496
Total liabilities	109,972	103,583
Commitments and contingencies (Note G)
Stockholders' deficit:
Common stock, $0.0001 par value, 250,000,000 shares authorized, 14,657,430 shares issued and outstanding as of December 31, 2017; 14,646,982 shares issued and outstanding as of December 31, 2016	1	1
Additional paid-in capital	107,209	102,643
Preferred stock, $0.0001 par value, 10,000,000 shares authorized, no shares issued or outstanding as of December 31, 2017 or December 31, 2016	0	0
Accumulated deficit	(164,726)	(121,340)
Total stockholders' deficit	(57,516)	(18,696)
Total liabilities and stockholders' deficit	$ 52,456	$ 84,887

Balance Sheets (Parentheticals) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
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)	14,657,430	14,646,982
Common stock, shares outstanding (in shares)	14,657,430	14,646,982
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (in shares)	10,000,000	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	3 Months Ended								12 Months Ended
Statements of Operations - USD ($) $ in Thousands	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue
Operating expenses:
Research and development	5,536	6,293	4,650	4,114	7,963	4,287	4,988	3,234	20,593	20,472	13,931
General and administrative	2,614	3,319	3,574	3,266	2,873	3,104	4,287	3,736	12,773	14,000	8,883
Severance expense						3,010				3,010
Total operating expenses	8,150	9,612	8,224	7,380	10,836	10,401	9,275	6,970	33,366	37,482	22,814
Loss from operations	(8,150)	(9,612)	(8,224)	(7,380)	(10,836)	(10,401)	(9,275)	(6,970)	(33,366)	(37,482)	(22,814)
Other (expense) income:
Loss on extinguishment of debt								(4,740)		(4,740)
Interest expense related to amortization of debt issuance costs and discount	(390)	(391)	(390)	(390)	(391)	(390)	(393)	(442)	(1,561)	(1,616)	(1,909)
Interest expense on principal	(1,444)	(1,448)	(1,443)	(1,441)	(1,445)	(1,441)	(1,475)	(1,150)	(5,776)	(5,511)	(2,671)
Fair value adjustment related to derivative and warrant liability	(710)	1,312	3,523	(7,216)	2,723	(1,299)	20,763	10,278	(3,091)	32,465	(27,276)
Interest and other income, net	97	154	13	101	9	98	144	102	365	353	32
Total other (expense) income	(2,447)	(373)	1,703	(8,946)	896	(3,032)	19,039	4,048	(10,063)	20,951	(31,824)
Loss before income taxes	(10,597)	(9,985)	(6,521)	(16,326)	(9,940)	(13,433)	9,764	(2,922)	(43,429)	(16,531)	(54,638)
Income tax benefit (expense)	31	4	4	4	4	19	4	(12)	43	15	(26)
Net loss	$ (10,566)	$ (9,981)	$ (6,517)	$ (16,322)	$ (9,936)	$ (13,414)	$ 9,768	$ (2,934)	$ (43,386)	$ (16,516)	$ (54,664)
Net loss per share:
Basic and diluted (in dollars per share)									$ (2.96)	$ (1.13)	$ (7.42)
Weighted average number of shares of common stock outstanding:
Basic and diluted (in shares)									14,652,898	14,597,053	7,368,681

Statements of Changes in Redeemable Convertible Preferred Stock and Stockholders' Deficit - USD ($) $ in Thousands	Preferred Stock [Member] Series A Redeemable Convertible Preferred Stock [Member]	Preferred Stock [Member] Series B Redeemable Convertible Preferred Stock [Member]	Preferred Stock [Member] Series C Redeemable Convertible Preferred Stock [Member]	Preferred Stock [Member] Series D Redeemable Convertible Preferred Stock [Member]	Preferred Stock [Member] Series D-1 Redeemable Convertible Preferred Stock [Member]	Preferred Stock [Member] Redeemable Convertible Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Total
Balance at Dec. 31, 2014	$ 3,343	$ 3,313	$ 11,892	$ 5,659		$ 24,207
Balance at Dec. 31, 2014								$ 1,652	$ (50,160)	$ (48,508)
Net loss									(54,664)	(54,664)
Stock-based compensation expense								2,369		2,369
Exercise of stock options and warrants								4,749		4,749
Issuance of Series D-1 preferred stock					$ 4,000	4,000
Issuance of common stock in connection with IPO, net of discounts and commissions							1	59,891		59,892
Conversion of 2013 warrants to equity classification								1,110		1,110
Conversion of preferred stock into common stock upon IPO	$ (3,343)	$ (3,313)	$ (11,892)	$ (5,659)	$ (4,000)	$ (28,207)		28,207		28,207
Offering expenses charged to equity								(3,276)		(3,276)
Balance at Dec. 31, 2015							1	94,702	(104,824)	(10,121)
Net loss									(16,516)	(16,516)
Stock-based compensation expense								6,600		6,600
Exercise of stock options and warrants								896		896
Balance at Dec. 31, 2016							1	102,643	(121,340)	(18,696)
Write-off of deferred offering costs								445		445
Net loss									(43,386)	(43,386)
Stock-based compensation expense								4,562		4,562
Exercise of stock options and warrants								4		4
Balance at Dec. 31, 2017							$ 1	$ 107,209	$ (164,726)	$ (57,516)

Statements of Cash Flows - USD ($)	12 Months Ended
Statements of Cash Flows - USD ($)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net loss	$ (43,386,000)	$ (16,516,000)	$ (54,664,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Loss on extinguishment of debt		4,740,000
Write-off of deferred offering costs	60,000	445,000
Stock-based compensation expense	4,562,000	6,600,000	2,369,000
Non-cash interest expense	2,222,000	2,222,000	2,671,000
Amortization of debt issuance costs and debt discount	1,561,000	1,616,000	1,909,000
Depreciation and amortization expense	336,000	175,000	84,000
Fair value adjustment	3,091,000	(32,465,000)	27,276,000
Loss on sublease and disposal of fixed assets	104,000	91,000
Change in assets and liabilities:
Prepaid expenses and other assets	(926,000)	2,018,000	(1,228,000)
Accounts payable and accrued expenses	(801,000)	1,118,000	1,315,000
Other liabilities	77,000	184,000
Net cash used in operating activities	(33,100,000)	(29,772,000)	(20,268,000)
Cash flows from investing activities:
Purchases of property and equipment	(181,000)	(643,000)	(135,000)
Purchases of marketable securities and long-term investments	(27,378,000)	(89,849,000)	(19,002,000)
Maturities of marketable securities	54,971,000	44,645,000
Net cash provided by (used in) investing activities	27,412,000	(45,847,000)	(19,137,000)
Cash flows from financing activities:
Proceeds from issuance of debt, net of discounts and commissions		82,800,000
Repayment of term notes and related accrued interest		(18,621,000)
Payment of principal on convertible notes arising from capitalized interest		(1,931,000)
Payment of deferred offering costs	(50,000)	(164,000)	(315,000)
Payment of debt and stock issuance costs		(983,000)	(2,533,000)
Repayment of obligations under capital lease	(157,000)	(79,000)	(32,000)
Proceeds from exercise of common stock options and warrants	4,000	141,000	413,000
Proceeds from initial public offering, net of discounts and commissions			59,892,000
Net cash (used in) provided by financing activities	(203,000)	61,163,000	61,468,000
Net (decrease) increase in cash, cash equivalents and restricted cash	(5,891,000)	(14,456,000)	22,063,000
Cash, cash equivalents and restricted cash, beginning of year	17,862,000	32,318,000	10,255,000
Cash, cash equivalents and restricted cash, end of year	11,971,000	17,862,000	32,318,000
Supplemental cash flow information:
Cash paid for interest	5,717,000	3,289,000
Trade date receivables	2,005,000	5,003,000
Property and equipment financed under a lease agreement	284,000	867,000
Transfer of warrants to equity upon exercise		755,000	4,293,000
Property and equipment included in accounts payable and accrued expenses	3,000	281,000
Deferred offering costs included in accounts payable and accrued expenses		85,000	428,000
Conversion of preferred stock into common stock upon initial public offering			28,207,000
Unpaid offering costs charged to equity			3,276,000
Reclassification of 2013 warrants to equity			1,110,000
Series D-1 Redeemable Convertible Preferred Stock [Member]
Cash flows from financing activities:
Proceeds from issuance of Series D-1 redeemable convertible preferred stock			4,000,000
Series D Redeemable Convertible Preferred Stock [Member]
Cash flows from financing activities:
Proceeds from exercise of common stock options and warrants			$ 43,000

Note A - Description of Business and Basis of Presentation

12 Months Ended

Dec. 31, 2017

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 Ligand Activated Therapy ("LAT") platform technology. The Company utilizes its proprietary LAT platform technology to generate improved prodrug versions of U.S. Food and Drug Administration (the "FDA") approved drugs in the high need areas of attention deficit hyperactivity disorder ("ADHD"), pain and other central nervous system ("CNS") disorders. 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, stockholders' deficit and negative operating cash flows due to its ongoing research and development of its product and product candidates. The Company also has an accumulated deficit as of

December 31, 2017.

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.

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, marketable securities and trade date receivables, 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. The registration statement on Form S-

included a prospectus covering the offering up to

$20,000,000

of shares of common stock through an "at-the-market offering."

Initial Public Offering and Reverse Stock Split

April 2015,

the Company completed an initial public offering ("IPO") of its common stock. Prior to the commencement of the IPO, the Company effected a

-for-

7.5

reverse stock split of its issued common stock. All applicable share data, per share amounts and related information in the financial statements and notes thereto have been retroactively adjusted to give effect to this reverse stock split. Upon completion of the IPO, all outstanding shares of the Company’s redeemable convertible preferred stock were converted or reclassified into shares of common stock and all outstanding warrants to acquire shares of the Company’s redeemable convertible preferred stock became warrants to acquire the Company’s common stock. In connection with the IPO, the Company amended and restated its Amended and Restated Certificate of Incorporation to change the authorized capital stock to

250,000,000

shares, designated as common stock, and

10,000,000

shares, designated as preferred stock, each with a par value of

$0.0001

per share.

Reclassifications

Certain prior year amounts have been reclassified to conform with current year presentation.

During the

second

quarter of

2017,

the Company early adopted Accounting Standards Update ("ASU")

2016

18,

Statement of Cash Flows (Topic

230

): Restricted Cash

(“ASU

2016

18”

), which addresses the treatment of restricted cash and restricted cash equivalents in the statement of cash flows. The adoption of ASU

2016

reduced the Company’s net cash used in investing activities and net decrease in cash and cash equivalents on the statements of cash flows by

$1.1

million for the year ended

December 31, 2016,

as compared to the net cash used in investing activities and net decrease in cash and cash equivalents on the statements of cash flows if the Company had

not

early adopted ASU

2016

18.

This reclassification had

effect on the balance sheets, statements of operations or statements of changes in redeemable convertible preferred stock and stockholders' deficit. The Company did

not

have restricted cash for the year ended

December 31, 2015.

Entry into ATM Agreement

October 3, 2016,

the Company entered into a Common Stock Sales Agreement (the “ATM Agreement”) with Cowen and Company, LLC (“Cowen”) 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 Cowen as the Company's sales agent. The Company’s registration statement on Form S-

contemplated under the ATM Agreement was declared effective by the U.S. Securities and Exchange Commission ("SEC") on

October 17, 2016.

The registration statement on Form S-

included a prospectus covering the offering up to

$20,000,000

of shares of common stock in accordance with the ATM Agreement.

Cowen

may

sell common stock under the 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 or

1933,

as amended ("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. Cowen 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 Cowen a commission of up to

three

percent (

3.0%

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

The Company is

not

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

December 31, 2017,

the Company had deferred offering costs recorded within other long-term assets in the amount of

$0.2

million.

As of

March 28, 2018,

the Company has sold

446,111

shares of common stock under the ATM Agreement, resulting in gross proceeds of

$2.9

million.

Note B - Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2017

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, 2017,

2016

2015.

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, 2017

and

2016.

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

2013,

although carryforward attributes that were generated prior to

2013

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 redeemable 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, 2017

and

2016.

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.

November 2015,

the FASB issued ASU

2015

17,

Income Taxes: Balance Sheet Classification of Deferred Taxes (Topic

740

)

(“ASU

2015

17”

), which requires that deferred tax liabilities and assets be classified as noncurrent in a classified statement of financial position. This update applies to all entities that present a classified statement of financial position. This guidance is effective for financial statements issued for fiscal years beginning after

December 15, 2016,

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

2015

did

not

have a material impact on the Company's financial statements and disclosures as the Company maintains a full valuation allowance over its deferred tax liabilities and assets.

March 2016,

the FASB issued ASU

2016

06,

Derivatives and Hedging (Topic

815

), Contingent Put and Call Options in Debt Instruments

(“ASU

2016

06”

), which clarifies the requirements for assessing whether contingent call and put options that can accelerate the payment of principal on debt instruments are clearly and closely related to their debt hosts. ASU

2016

is effective for fiscal years beginning after

December 15, 2016,

including interim periods within those fiscal years, with early adoption permitted. The adoption of ASU

2016

did

not

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

March 2016,

the FASB issued ASU

2016

09,

Compensation–Stock Compensation (Topic

718

), Improvements to Employee Share-Based Payment Accounting

(“ASU

2016

09”

), which simplifies several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. ASU

2016

is effective for fiscal years beginning after

December 15, 2016,

including interim periods within those fiscal years, with early adoption permitted. The adoption of ASU

2016

did

not

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

November 2016,

the FASB issued ASU

2016

18,

which

applies to all entities that have restricted cash or restricted cash equivalents and are required to present a statement of cash flows. This guidance is effective for financial statements issued for fiscal years beginning after

December 15, 2017,

and interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period.

The Company early adopted ASU

2016

in the

second

quarter of

2017.

Refer to Note A for discussion regarding the impact the adoption of ASU

2016

had on the Company's financial statements and disclosures.

Application of New or Revised Accounting Standards

—Not

Yet Adopted

May 2014,

the FASB issued guidance codified in ASC Topic

606,

Revenue Recognition—Revenue from Contracts with Customers

("ASC

606"

), which amends the guidance in former ASC

605,

Revenue Recognition

, and becomes effective beginning

January 1, 2018.

The Company does

not

currently expect this standard to have a material effect on its financial statements 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 Company does

not

currently expect ASU

2016

to have a material effect on its financial statements and disclosures upon adoption.

February 2016,

the FASB issued ASU

2016

02,

Leases (Topic

842

)

(“ASU

2016

02”

), which requires lessees to recognize assets and liabilities for operating leases with lease terms greater than

twelve

months in the balance sheet. The update also requires improved disclosures to help users of financial statements better understand the amount, timing and uncertainty of cash flows arising from leases. ASU

2016

is effective for fiscal years beginning after

December 15, 2018,

including interim periods within those fiscal years, with early adoption permitted.

The Company is currently evaluating the impact of the adoption of ASU

2016

on its 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 Company does

not

currently expect ASU

2016

to have a material effect on its financial statements and disclosures upon adoption.

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 Company does

not

currently expect ASU

2017

to have a material effect on its financial statements and disclosures upon adoption.

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 is currently evaluating the impact of the adoption of ASU

2017

on its financial statements and disclosures.

Note C - Prepaid Expenses and Other Current Assets

12 Months Ended

Dec. 31, 2017

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,
	2017		2016
Prepaid insurance	$	202	$	333
Other receivables		76		58
Other prepaid expenses and current assets		1,384		98
Total prepaid expenses and other current assets	$	1,662	$	489

Note D - Property and Equipment

12 Months Ended

Dec. 31, 2017

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,
	2017			2016
Laboratory equipment	$	983		$	842
Furniture and office equipment		655			733
Computers and hardware		292			231
Leasehold improvements		1,003			769
Total property and equipment		2,933			2,575
Less: accumulated depreciation and amortization		(929	)		(605	)
Property and equipment, net	$	2,004		$	1,970

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,
	2017			2016
Laboratory equipment	$	366		$	271
Furniture and office equipment		541			537
Leasehold improvements		59			59
Total property and equipment financed under a capital lease agreement		966			867
Less: accumulated depreciation and amortization		(150	)		(31	)
Property and equipment financed under a capital lease agreement, net	$	816		$	836

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

$336,000,

$175,000

and

$84,000

for the years ended

December 31, 2017,

2016

and

2015,

respectively.

Note E - Accounts Payable and Accrued Expenses

12 Months Ended

Dec. 31, 2017

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,
	2017		2016
Accrued interest	$	2,222	$	2,222
Accrued banking fees		700		700
Accrued severance		—		646
Accrued payroll		1,118		1,024
Accounts payable		2,177		469
Other accrued expenses		1,658		1,383
Total accounts payable and accrued expenses	$	7,875	$	6,444

Note F - Debt Obligations

12 Months Ended

Dec. 31, 2017

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 Notes”). 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 Notes into shares of the Company’s common stock at an initial conversion price of

$5.85

per share (the "Deerfield Note Put Option").

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 I). 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.

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.

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 Notes 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 Notes and Deerfield Warrant, respectively, in the event that the Company effects a firm commitment underwritten public offering of its securities. Except as modified by the Second Amendment, the Third Amendment (as described below) and the Fourth Amendment (as described below), all terms and conditions of the Deerfield Convertible Notes and Deerfield Warrant remain in full force and effect

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. This principal, accrued but unpaid interest, make-whole interest payment and prepayment premium on the Term Notes is reflected as a cash outflow from financing activity in the statements of cash flows.

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. 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 Notes and Deerfield Warrant with Deerfield. The Third Amendment, among other things, eliminated the Company’s ability to require Deerfield to convert the Deerfield Convertible Notes 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. Except as modified by the Third Amendment and the Fourth Amendment (as described below), all terms and conditions of the Deerfield Facility Agreement remain in full force and effect.

Fourth Amendment to Deerfield Convertible Notes and Deerfield 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.

Convertible Notes

Future minimum principal payments under convertible notes as of

December 31, 2017,

were as follows (in thousands):

	Convertible
Year Ending December 31,	Notes
2018	$	3,333
2019		3,333
2020		3,334
2021		86,250
Total minimum principal payments		96,250
Less: debt issuance costs and discount		(3,519	)
Convertible notes, net	$	92,731

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, 2017 and 2016,

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, 2017 and 2016,

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 borrowing capacity under the line of credit, held by the same bank institution. 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

3.36%,

as of

December 31, 2017.

Note G - Commitments and Contingencies

12 Months Ended

Dec. 31, 2017

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, 2017

and

2016,

accruals have been made related to commitments and contingencies

2014,

a former financial advisor of the Company filed a request with the Iowa District Court to declare valid a purported right of

first

refusal to serve as the Company

’s exclusive financial advisor for specified strategic transactions and to receive fees for the specified strategic transactions irrespective of whether any such specified transaction occurred during or after the term of the financial advisor’s service agreement. This filing by the former financial advisor was made in response to an action initiated by the Company in

2013

seeking a declaratory judgement finding that such purported right was invalid and unenforceable. Two former members of the Company’s board of directors (the “Board”) joined the lawsuit as intervenors based on the former financial advisor’s purported assignment of its rights, or a portion thereof, under the agreement to the intervenors. In

September 2015,

the court granted summary judgement in favor of the Company with respect to the Company’s declaratory judgement action and the former financial advisor’s counterclaims and the Company separately entered into settlement agreements with each of the intervenors. The settlements reached with the intervenors did

not

differ from the accrual previously recorded by the Company by a material amount. The former financial advisor subsequently filed a notice of appeal of the court’s ruling with the Supreme Court of Iowa. On

January 6, 2016,

the Company entered into a Settlement Agreement and Mutual Release (the “Settlement Agreement”) with the former financial advisor and Donald DeWaay, Jr. pursuant to which, among other things, the former financial advisor agreed, in exchange for the consideration described therein, to dismiss with prejudice its pending appeal. The former financial advisor's appeal was subsequently dismissed by the Supreme Court of Iowa on

January 7, 2016.

The settlement amount was commensurate with the contingency recorded in the books and records of the Company. The consideration in the Settlement Agreement did

not

differ from the accrual previously recorded by the Company by a material amount.

December 2016,

a class action suit was filed against the Company in the Iowa District Court in Johnson County by a stockholder alleging that the Company, certain of its senior executives and directors who signed the

registration statement in connection with its IPO, and each of the investment banks that acted as underwriters for the offering negligently issued untrue statements of material facts and omitted to state material facts required to be stated in the registration statement and incorporated offering materials that the Company filed with the SEC in support of the offering. The plaintiff does

not

quantify any alleged damages in his complaint but, in addition to attorneys' fees and costs, the plaintiff seeks to recover damages and obtain other relief on behalf of himself and all other persons who purchased the Company's common stock pursuant or traceable to the offering and the registration statement and who were allegedly damaged thereby.

January 2017,

the class action suit was removed to the U.S. District Court for the Southern District of Iowa. The plaintiff subsequently filed a motion to remand the case to the Iowa District Court, and that motion was granted. In

January 2018,

the Iowa District Court issued an order postponing all deadlines and the setting of any schedule in the case pending a decision by the United States Supreme Court in

Cyan, Inc. v. Beaver County Employees Retirement Fund.

March 20, 2018,

the Supreme Court issued its decision in

Cyan

and held that state courts have subject matter jurisdiction over putative class actions like the

one

filed against us, which assert claims arising under the Securities Act. Accordingly, the case will proceed in Iowa District Court.

The suit against the Company is still in a preliminary stage and has

not

yet been set for trial. Accordingly, the Company is unable to predict the timing or outcome of this litigation as of the date of this report.

Lease Agreements

Iowa

The Company leases office and laboratory facilities in Iowa under a non-can

celable operating lease. The Company’s lease for its Iowa facilities expires in

September 2018

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

one

-year terms upon expiration.

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.

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 2018.

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, 2017 and 2016,

the interest rates for assets under remaining capital leases range from

7.19%

8.05%.

Rent expense for non-cancelable operating and capital leases was

$0.6

million,

$0.6

million and

$0.3

million for the years ended

December 31, 2017,

2016

and

2015,

respectively.

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

December 31, 2017,

were as follows (in thousands):

	Capital			Operating
Year Ending December 31,	Leases			Leases
2018	$	242		$	688
2019		231			604
2020		231			499
2021		151			449
2022		11			461
Thereafter		—			1,376
Total minimum lease payments		866		$	4,077
Less: amounts representing interest		(115	)
Total minimum capital lease principal payments	$	751

Note H - Supply Arrangement

12 Months Ended

Dec. 31, 2017

Notes to Financial Statements

Collaborative Arrangement Disclosure [Text Block]

H.	Supply Arrangement

As of

December 31, 2017 and 2016,

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

KP201

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

KP201.

The Company’s FDA-approved drug, APADAZ, and product candidate,

KP201/IR,

contain

KP201.

expense was recorded under this agreement for the years ended

December 31, 2017,

2016

and

2015.

The Company must purchase all of its U.S.

KP201

needs from JMI and JMI cannot supply

KP201

to other companies. The term of the Supply Agreement extends as long as the Company holds a valid and enforceable patent for

KP201

or until the

tenth

anniversary of a commercial launch of a FDA-approved drug incorporating

KP201,

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

KP201.

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

Note I - Preferred Stock and Warrants

12 Months Ended

Dec. 31, 2017

Notes to Financial Statements

Preferred Stock [Text Block]

I.	Preferred Stock and Warrants

Authorized, Issued, and Outstanding Preferred Stock

April 2015,

the Company amended and restated its Certificate of Incorporation to decrease

the number of its authorized shares of preferred stock to

10,000,000

shares with a par value of

$0.0001

per share. As described in Note A, in

April 2015,

the Company completed an IPO of its common stock. Upon completion of the IPO, all outstanding shares of the Company’s redeemable convertible preferred stock were automatically converted or reclassified into an aggregate of

5,980,564

shares of the Company’s common stock. As of

December 31, 2017,

the Company had

10,000,000

shares of authorized and undesignated preferred stock and did

not

have any preferred stock outstanding.

Preferred Stock Activity

The following table summarizes redeemable convertible preferred stock activity for the years ended

December 31, 2017,

2016

and

2015:

	Shares of
	Series A Preferred			Series B Preferred			Series C Preferred			Series D Preferred			Series D-1 Preferred			Total
Balance as of January 1, 2015		9,704,215			6,220,000			18,557,408			7,255,425			—			41,737,048
Issuance of Series D-1 preferred stock		—			—			—			—			3,200,000			3,200,000
Exercise of Series D preferred warrants		—			—			—			3,205			—			3,205
Effect of reverse stock split		(8,410,377	)		(5,390,766	)		(16,083,286	)		(6,290,844	)		(2,784,416	)		(38,959,689	)
Less: Conversion of preferred stock into common stock upon IPO		(1,293,838	)		(829,234	)		(2,474,122	)		(967,786	)		(415,584	)		(5,980,564	)
Balance as of December 31, 2015		—			—			—			—			—			—
Balance as of December 31, 2016		—			—			—			—			—			—
Balance as of December 31, 2017		—			—			—			—			—			—

Series D-

Redeemable Convertible Preferred Stock

February 2015,

the Company entered into a stock purchase

agreement with Cowen KP Investment LLC in which Cowen KP Investment LLC agreed to purchase and the Company agreed to sell

3,200,000

shares of the Company’s Series D-

redeemable convertible preferred stock for

$1.25

per share, or an aggregate of

$4.0

million. Upon completion of the IPO, these shares automatically converted into

415,584

shares of the Company’s common stock.

Warrants

As described in Note A, in

April 2015,

the Company completed an IPO of its common stock.

Upon completion of the IPO, warrants to purchase

15,499,324

shares of Series D preferred stock were reclassified into warrants to purchase

2,066,543

shares of the Company’s common stock.

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 Notes 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, 2017

Notes to Financial Statements

Stockholders' Equity Note Disclosure [Text Block]

J.	Common Stock and Warrants

Authorized, Issued, and Outstanding Common Shares

April 2015,

the Company amended and restated its Certificate of

Incorporation to increase the number of its authorized shares of common stock to

250,000,000

shares. Of the authorized shares,

14,657,430

and

14,646,982

shares of common stock were issued and outstanding as of

December 31, 2017

and

2016,

respectively.

As of

Dec

ember

31,

2017

and

2016,

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

	December 31,
	2017		2016
Conversion of Deerfield Convertible Notes		1,751,410		1,751,296
Conversion of 2021 Notes		5,040,914		5,040,914
Outstanding awards under equity incentive plans		2,853,924		1,990,260
Outstanding common stock warrants		2,027,763		2,087,477
Possible future issuances under equity incentive plans		944,700		1,244,671
Total common shares reserved for future issuance		12,618,711		12,114,618

Common Stock Activity

The following table summarizes common stock activity for the years ended

December 31, 2017,

2016

and

2015:

	Shares of
	Common Stock
Balance as of January 1, 2015		2,381,041
Issuance of common stock in connection with the IPO		5,854,545
Conversion of preferred stock to common stock in connection with the IPO		5,980,564
Common stock warrants exercised		270,038
Common stock options exercised		4,766
Balance as of December 31, 2015		14,490,954
Common stock warrants exercised		141,095
Common stock options exercised		14,933
Balance as of December 31, 2016		14,646,982
Common stock warrants exercised		698
Common stock options exercised		9,750
Balance as of December 31, 2017		14,657,430

The Company calculates the fair value of

common stock warrants using a Monte Carlo simulation. There were warrants exercised for an aggregate of

698,

141,095

and

270,038

shares of common stock during the years ended

December 31, 2017,

2016

and

2015,

respectively. 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.

As of

March 28, 2018,

the Company has sold

446,111

shares of common stock under the ATM Agreement, resulting in gross proceeds of

$2.9

million.

Note K - Stock-based Compensation

12 Months Ended

Dec. 31, 2017

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

3,432,183

as of

December 31, 2017.

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, 2018,

the common stock reserved for issuance under the

2014

Plan automatically increased by

586,297

shares.

During the years ended

December 31, 2017,

2016

and

2015,

stock options to acquire

9,750,

14,933

and

4,766

shares of common stock were exercised for approximately

$7,000,

$71,000

and

$28,000

with an intrinsic value of approximately

$32,000,

$169,000

and

$54,000,

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,
	2017		2016		2015
Research and development	$	1,304	$	1,051	$	610
General and administrative		3,258		3,639		1,759
Severance expense		—		1,910		—
Total stock-based compensation expense	$	4,562	$	6,600	$	2,369

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 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. 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, 2017,

2016

and

2015,

fair value was

$2.77,

$9.25

and

$10.63

per sha

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

	December 31,
	2017		2016		2015
Risk-free interest rate		1.88% - 2.26%		1.29% - 1.50%		1.40% - 1.99%
Expected term (in years)		5.12 - 7.00		5.50 - 6.26		4.33 - 6.25
Expected volatility		85.35% - 95.08%		77.38% - 94.78%		68.79% - 86.84%
Expected dividend yield		0%		0%		0%

The activity under the Incentive Stock Plan and the

2014

Plan

for the year ended

December 31, 2017,

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, 2017		1,990,260		$	13.64		8.27	$	26,400
Granted		919,000		$	3.59
Exercised		(9,750	)	$	0.75
Canceled or forfeited		(38,920	)	$	11.35
Expired		(6,666	)	$	4.65
Outsta nding balance as of December 31, 2017		2,853,924		$	10.50		7.90	$	471,539
Exercisable as of December 31, 2017		1,044,392		$	12.38		6.78	$	29,237
Vested and expected to vest as of December 31, 2017		2,760,447		$	10.62		7.87	$	440,178

Information regarding currently outstanding and exercisable options as of

December 31, 2017,

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	1,055,244	8.69	76,244	3.75
$5.01 to $10.00	366,447	5.77	345,146	5.72
$10.01 to $15.00	471,833	7.94	189,291	7.73
$15.01 to $20.00	612,600	7.89	259,811	7.76
$20.01 to $22.12	347,800	7.68	173,900	7.68
	2,853,924	7.90	1,044,392	6.78

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

December 31, 2017,

2016

and

2015,

was

$4.1

million,

$5.4

million and

$1.1

million, respectively.

Unvested stock options as of

December 31, 2017

and

2016,

were as follows:

	Number of Unvested Shares
	December 31,
Exercise Price	2017		2016
$2.75 to $5.00		979,000		99,000
$5.01 to $10.00		21,301		97,480
$10.01 to $15.00		282,542		378,500
$15.01 to $20.00		352,789		516,938
$20.01 to $22.12		173,900		260,850
Total number of unvested shares		1,809,532		1,352,768

As of

December 31, 2017,

there was

$8.5

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

2.06

years.

There was

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

December 31, 2017.

During the year ended

December 31, 2016,

the Company recognized

$44,000

of stock-based compensation expense r

elated to performance-based awards included in research and development expenses. These awards were in connection with the strategic initiatives set for the award that were achieved in

2016

exercisable for an aggregate of

13,333

shares of common stock during the year ended

December 31, 2016.

During the year ended

December 31, 2015,

the Company recognized

$0.7

million of stock-based compensation expense r

elated to performance-based awards included in general and administrative expenses and

$0.2

million of stock-based compensation expense related to performance-based awards included in research and development expenses. These awards were in connection with the grant of fully vested stock options exercisable for an aggregate of

163,998

shares of common stock during the year ended

December 31, 2015.

Note L - Fair Value of Financial Instruments

12 Months Ended

Dec. 31, 2017

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, approximate their respective fair values due to the short-term nature of such instruments.

The fair value of the Deerfield Convertible Notes

was

$11.0

million and

$10.2

million, respectively, as of

December 31, 2017

and

2016.

The fair value of the

2021

Notes was

$51.9

million and

$46.3

million, respectively, as of

December 31, 2017

and

2016.

Both the Deerfield Convertible Notes 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 Notes and

2021

Notes

as of

December 31, 2017

and

2016.

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, 2017

and

2016

(in thousands):

			Quoted Prices in
	Balance as of		Active Markets for		Significant Other		Significant
	December 31,		Identical Assets		Observable Inputs		Unobservable 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
Embedded Deerfield Note Put Option		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	$	—

			Quoted Prices in
	Balance as of		Active Markets for		Significant Other		Significant
	December 31,		Identical Assets		Observable Inputs		Unobservable Inputs
	2016		(Level 1)		(Level 2)		(Level 3)
Underwriter Warrant liability	$	16	$	—	$	—	$	16
Deerfield Warrant liability		4,231		—		—		4,231
Embedded Warrant Put Option		365		—		—		365
Fundamental change and make-whole interest provisions embedded in 2021 Notes		6						6
Total liabilities	$	4,618	$	—	$	—	$	4,618
Trading securities:
Certificates of deposit		7,788		7,788		—		—
U.S. Treasury securities		37,066		37,066		—		—
U.S. government-sponsored agency securities		14,349		—		14,349		—
Total assets	$	59,203	$	44,854	$	14,349	$	—

The Company

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

2021

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

December 31, 2017

and

2016,

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

2021

Notes 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. As of

December 31, 2017,

the embedded Deerfield Note Put Option is reported on the balance sheet in derivative and warrant liability. The Company used a Monte Carlo simulation to value the Underwriter Warrant liability, Deerfield Warrant liability, embedded Warrant Put Option and the fundamental change and make-whole interest provisions embedded in the

2021

Notes as of

December 31, 2017

and

2016.

The Company also used a Monte Carlo simulation to value the embedded Deerfield Note Put Option as of

December 31, 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 Underwriter Warrant liability, Deerfield

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

2021

Notes and the embedded Deerfield Note Put Option are reflected in the statements of operations as a

fair value adjustment.

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):

	2017		2016
Balance as of beginning of period	$	4,618	$	37,839
Exercise of warrants		—		(756	)
Adjustment to fair value		3,091		(32,465	)
Balance as of end of period	$	7,709	$	4,618

- 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, 2017

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

$43,000,

$15,000

and

$15,000

on a loss before income taxes of

$43.4

million,

$16.5

million and

$54.6

million for the years ended

December 31, 2017,

2016

and

2015,

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,
	2017			2016			2015
Federal statutory rate		34.00	%		34.00	%		34.00	%
Effect of:
Change in valuation allowance		13.38			(69.31	)		(19.25	)
Return to provision and deferred true-up		2.18			(23.83	)		—
Change in rate		(49.06	)		(14.63	)		—
State tax benefit (net of federal)		2.71			15.64			4.06
Warrant liability		(2.42	)		68.44			(15.28	)
State research and development credit		0.10			0.09			0.03
Federal research and development credit		1.50			5.65			0.84
Amortization		(1.22	)		(3.15	)		—
Conversion feature and put option on convertible notes		—			—			(1.68	)
Stock-based compensation		(1.03	)		(12.71	)		(1.28	)
Other		(0.04	)		(0.10	)		(1.49	)
Federal income tax benefit (provision) effective rate		0.10	%		0.09	%		(0.05	)%

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

	December 31,
	2017			2016			2015
Deferred tax assets relating to:
Net operating loss carryforwards	$	37,028		$	44,984		$	26,617
Research and development tax carryforward		3,788			3,166			2,254
Other deferred tax assets		2,409			715			232
Total gross deferred tax assets		43,225			48,865			29,103
Deferred tax liabilities relating to:
Property and equipment		260			89			80
Total gross deferred tax liabilities		260			89			80
Deferred tax assets less liabilities		42,965			48,776			29,023
Valuation allowance		(42,965	)		(48,776	)		(29,023	)
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.

Also on

December 22, 2017,

the SEC staff issued Staff Accounting Bulletin

No.

118

(“SAB

118”

), which provides guidance on accounting for the tax effects of the

2017

Tax Act. SAB

118

provides a measurement period that should

not

extend beyond

one

year from the

2017

Tax Act enactment date for companies to complete the accounting under ASC

740,

Income Taxes. As of

December 31, 2017,

the Company has

not

completed its accounting related to the enactment of the

2017

Tax Act.

However, the Company has made reasonable estimates of the effects on its income tax provision with respect to certain items, primarily the revaluation of its existing U.S. deferred tax balances as described above.

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, 2017 (

in thousands):

	Net Operating		Research
Year Incurred	Loss Carryforwards		Activities 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		16,265		894		2034
2015		24,126		598		2035
2016		40,715		745		2036
2017		33,828		652		2037
	$	137,331	$	3,788

The Company also has certain state net operating loss carryforwards totaling

$134.6

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, 2017

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,
	2017			2016			2015
Net loss - basic and diluted	$	(43,386	)	$	(16,516	)	$	(54,664	)
Weighted average number of shares of common stock - basic and diluted		14,652,898			14,597,053			7,368,681
Net loss per share - basic and diluted	$	(2.96	)	$	(1.13	)	$	(7.42	)

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,
	2017		2016		2015
Warrants to purchase common stock		2,027,763		2,087,477		2,325,383
Awards under equity incentive plans		2,853,924		1,990,260		1,397,511
Deerfield Convertible Notes		1,751,410		1,751,296		1,991,219
2021 Notes		5,040,914		5,040,914		—
Total securities excluded from the calculation of weighted average number of shares of common stock outstanding		11,674,011		10,869,947		5,714,113

Note O - Severance Expense

12 Months Ended

Dec. 31, 2017

Notes to Financial Statements

Restructuring and Related Activities Disclosure [Text Block]

O.	Severance Expense

September 15, 2016,

the Company announced its intention to defer its commercial operations and realign its financial resources and operational priorities towards its product development pipeline. The activities related to the deferral and realignment were completed during the year ended

December 31, 2016.

As part of these activities, the Company reduced its workforce by

three

employees. Personnel and other related charges of approximately

$1.1

million and stock compensation expense of approximately

$1.9

million related to the acceleration of vesting on certain stock options, related to the workforce reduction, were presented as severance expense in the statements of operations for the year ended

December 31, 2016.

As of

December 31, 2017,

the Company had

accrued severance expense recorded within accounts payable and accrued expenses.

Note P - Employee Benefit Plan

12 Months Ended

Dec. 31, 2017

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

$207,000,

$213,000

and

$113,000

for the years ended

December 31, 2017,

2016

and

2015,

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

2017,

2016

2015.

Note Q - Quarterly Results of Operations (Unaudited)

12 Months Ended

Dec. 31, 2017

Notes to Financial Statements

Quarterly Financial Information [Text Block]

Q.	Quarterly Results of Operations (unaudited)

The following tables set forth unaudited quarterly statements of operations data for each of the quarters indicated. The financial statements for each of these quarters have been prepared on the same basis as the audited financial statements included herein and, in the opinion of management, include all adjustments, consisting only of normal recurring adjustments, necessary for the fair statement of the results of operations for these perio

ds. You should read this information together with our financial statements and related notes included herein. These quarterly

operating results are

not

necessarily indicative of the results for any future period.

	Three-Months Ended
	Dec 31,			Sep 30,			Jun 30,			Mar 31,			Dec 31,			Sep 30,			Jun 30,			Mar 31,
	2017			2017			2017			2017			2016			2016			2016			2016
Revenue	$	—		$	—		$	—		$	—		$	—		$	—		$	—		$	—
Operating expenses:
Research and development		5,536			6,293			4,650			4,114			7,963			4,287			4,988			3,234
General and administrative		2,614			3,319			3,574			3,266			2,873			3,104			4,287			3,736
Severance expense		—			—			—			—			—			3,010			—			—
Total operating expenses		8,150			9,612			8,224			7,380			10,836			10,401			9,275			6,970
Loss from operations		(8,150	)		(9,612	)		(8,224	)		(7,380	)		(10,836	)		(10,401	)		(9,275	)		(6,970	)
Other (expense) income:
Loss on extinguishment of debt		—			—			—			—			—			—			—			(4,740	)
Interest expense related to amortization of debt issuance costs and discount		(390	)		(391	)		(390	)		(390	)		(391	)		(390	)		(393	)		(442	)
Interest expense on principal		(1,444	)		(1,448	)		(1,443	)		(1,441	)		(1,445	)		(1,441	)		(1,475	)		(1,150	)
Fair value adjustment related to derivative and warrant liability		(710	)		1,312			3,523			(7,216	)		2,723			(1,299	)		20,763			10,278
Interest and other income, net		97			154			13			101			9			98			144			102
Total other (expense) income		(2,447	)		(373	)		1,703			(8,946	)		896			(3,032	)		19,039			4,048
(Loss) income before income taxes		(10,597	)		(9,985	)		(6,521	)		(16,326	)		(9,940	)		(13,433	)		9,764			(2,922	)
Income tax benefit (expense)		31			4			4			4			4			19			4			(12	)
Net (loss) income	$	(10,566	)	$	(9,981	)	$	(6,517	)	$	(16,322	)	$	(9,936	)	$	(13,414	)	$	9,768		$	(2,934	)

Net (loss) income per share:
Basic	$	(0.72	)	$	(0.68	)	$	(0.44	)	$	(1.11	)	$	(0.68	)	$	(0.92	)	$	0.59		$	(0.20	)
Diluted	$	(0.72	)	$	(0.68	)	$	(0.44	)	$	(1.11	)	$	(0.68	)	$	(0.92	)	$	(0.58	)	$	(0.20	)

Note R - Subsequent Events (Unaudited)

12 Months Ended

Dec. 31, 2017

Notes to Financial Statements

Subsequent Events [Text Block]

R.	Subsequent Events

February 23, 2018,

the Company announced that the FDA approved its New Drug Application for APADAZ for the short-term (

more than

days) management of acute pain severe enough to require an opioid analgesic and for which alternative treatments are inadequate. APADAZ is an immediate-release combination of the Company's prodrug, benzhydrocodone, and acetaminophen. APADAZ was developed from the Company's proprietary LAT platform technology.

Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Basis of Accounting, Policy [Policy Text Block]

Organization

October

30,

2006

and reorganized in Delaware on

May 30, 2014.

Going Concern [Policy Text Block]

Going Concern

December 31, 2017.

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, marketable securities and trade date receivables, 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. The registration statement on Form S-

included a prospectus covering the offering up to

$20,000,000

of shares of common stock through an "at-the-market offering."

Stockholders' Equity, Policy [Policy Text Block]

Initial Public Offering and Reverse Stock Split

April 2015,

the Company completed an initial public offering ("IPO") of its common stock. Prior to the commencement of the IPO, the Company effected a

-for-

7.5

250,000,000

shares, designated as common stock, and

10,000,000

shares, designated as preferred stock, each with a par value of

$0.0001

per share.

Reclassification, Policy [Policy Text Block]

Reclassifications

Certain prior year amounts have been reclassified to conform with current year presentation.

During the

second

quarter of

2017,

the Company early adopted Accounting Standards Update ("ASU")

2016

18,

Statement of Cash Flows (Topic

230

): Restricted Cash

(“ASU

2016

18”

), which addresses the treatment of restricted cash and restricted cash equivalents in the statement of cash flows. The adoption of ASU

2016

reduced the Company’s net cash used in investing activities and net decrease in cash and cash equivalents on the statements of cash flows by

$1.1

million for the year ended

December 31, 2016,

as compared to the net cash used in investing activities and net decrease in cash and cash equivalents on the statements of cash flows if the Company had

not

early adopted ASU

2016

18.

This reclassification had

effect on the balance sheets, statements of operations or statements of changes in redeemable convertible preferred stock and stockholders' deficit. The Company did

not

have restricted cash for the year ended

December 31, 2015.

Common Stock Sales Agreement (ATM Agreement), Policy [Policy Text Block]

Entry into ATM Agreement

October 3, 2016,

the Company entered into a Common Stock Sales Agreement (the “ATM Agreement”) with Cowen and Company, LLC (“Cowen”) 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 Cowen as the Company's sales agent. The Company’s registration statement on Form S-

contemplated under the ATM Agreement was declared effective by the U.S. Securities and Exchange Commission ("SEC") on

October 17, 2016.

The registration statement on Form S-

included a prospectus covering the offering up to

$20,000,000

of shares of common stock in accordance with the ATM Agreement.

Cowen

may

sell common stock under the 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 or

1933,

may

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

three

percent (

3.0%

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

The Company is

not

December 31, 2017,

the Company had deferred offering costs recorded within other long-term assets in the amount of

$0.2

million.

As of

March 28, 2018,

the Company has sold

446,111

shares of common stock under the ATM Agreement, resulting in gross proceeds of

$2.9

million.

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, 2017,

2016

2015.

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, 2017

and

2016.

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

2013,

although carryforward attributes that were generated prior to

2013

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, 2017

and

2016.

New Accounting Pronouncements, 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

November 2015,

the FASB issued ASU

2015

17,

Income Taxes: Balance Sheet Classification of Deferred Taxes (Topic

740

)

(“ASU

2015

17”

December 15, 2016,

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

2015

did

not

have a material impact on the Company's financial statements and disclosures as the Company maintains a full valuation allowance over its deferred tax liabilities and assets.

March 2016,

the FASB issued ASU

2016

06,

Derivatives and Hedging (Topic

815

), Contingent Put and Call Options in Debt Instruments

(“ASU

2016

06”

2016

is effective for fiscal years beginning after

December 15, 2016,

including interim periods within those fiscal years, with early adoption permitted. The adoption of ASU

2016

did

not

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

March 2016,

the FASB issued ASU

2016

09,

Compensation–Stock Compensation (Topic

718

), Improvements to Employee Share-Based Payment Accounting

(“ASU

2016

09”

2016

is effective for fiscal years beginning after

December 15, 2016,

including interim periods within those fiscal years, with early adoption permitted. The adoption of ASU

2016

did

not

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

November 2016,

the FASB issued ASU

2016

18,

which

December 15, 2017,

and interim periods within those fiscal years. Early adoption is permitted, including adoption in an interim period.

The Company early adopted ASU

2016

in the

second

quarter of

2017.

Refer to Note A for discussion regarding the impact the adoption of ASU

2016

had on the Company's financial statements and disclosures.

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

Application of New or Revised Accounting Standards

—Not

Yet Adopted

May 2014,

the FASB issued guidance codified in ASC Topic

606,

Revenue Recognition—Revenue from Contracts with Customers

("ASC

606"

), which amends the guidance in former ASC

605,

Revenue Recognition

, and becomes effective beginning

January 1, 2018.

The Company does

not

currently expect this standard to have a material effect on its financial statements 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 Company does

not

currently expect ASU

2016

to have a material effect on its financial statements and disclosures upon adoption.

February 2016,

the FASB issued ASU

2016

02,

Leases (Topic

842

)

(“ASU

2016

02”

), which requires lessees to recognize assets and liabilities for operating leases with lease terms greater than

twelve

2016

is effective for fiscal years beginning after

December 15, 2018,

including interim periods within those fiscal years, with early adoption permitted.

The Company is currently evaluating the impact of the adoption of ASU

2016

on its 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 Company does

not

currently expect ASU

2016

to have a material effect on its financial statements and disclosures upon adoption.

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 Company does

not

currently expect ASU

2017

to have a material effect on its financial statements and disclosures upon adoption.

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,

2017

on its financial statements and disclosures.

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

12 Months Ended

Dec. 31, 2017

Notes Tables

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

	December 31,
	2017		2016
Prepaid insurance	$	202	$	333
Other receivables		76		58
Other prepaid expenses and current assets		1,384		98
Total prepaid expenses and other current assets	$	1,662	$	489

Note D - Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2017

Notes Tables

Property, Plant and Equipment [Table Text Block]

	December 31,
	2017			2016
Laboratory equipment	$	983		$	842
Furniture and office equipment		655			733
Computers and hardware		292			231
Leasehold improvements		1,003			769
Total property and equipment		2,933			2,575
Less: accumulated depreciation and amortization		(929	)		(605	)
Property and equipment, net	$	2,004		$	1,970

Schedule of Capital Leased Assets [Table Text Block]

	December 31,
	2017			2016
Laboratory equipment	$	366		$	271
Furniture and office equipment		541			537
Leasehold improvements		59			59
Total property and equipment financed under a capital lease agreement		966			867
Less: accumulated depreciation and amortization		(150	)		(31	)
Property and equipment financed under a capital lease agreement, net	$	816		$	836

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, 2017

Notes Tables

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

	December 31,
	2017		2016
Accrued interest	$	2,222	$	2,222
Accrued banking fees		700		700
Accrued severance		—		646
Accrued payroll		1,118		1,024
Accounts payable		2,177		469
Other accrued expenses		1,658		1,383
Total accounts payable and accrued expenses	$	7,875	$	6,444

Note F - Debt Obligations (Tables)

12 Months Ended

Dec. 31, 2017

Notes Tables

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

	Convertible
Year Ending December 31,	Notes
2018	$	3,333
2019		3,333
2020		3,334
2021		86,250
Total minimum principal payments		96,250
Less: debt issuance costs and discount		(3,519	)
Convertible notes, net	$	92,731

Note G - Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2017

Notes Tables

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

	Capital			Operating
Year Ending December 31,	Leases			Leases
2018	$	242		$	688
2019		231			604
2020		231			499
2021		151			449
2022		11			461
Thereafter		—			1,376
Total minimum lease payments		866		$	4,077
Less: amounts representing interest		(115	)
Total minimum capital lease principal payments	$	751

Note I - Preferred Stock and Warrants (Tables)

12 Months Ended

Dec. 31, 2017

Notes Tables

Temporary Equity [Table Text Block]

	Shares of
	Series A Preferred			Series B Preferred			Series C Preferred			Series D Preferred			Series D-1 Preferred			Total
Balance as of January 1, 2015		9,704,215			6,220,000			18,557,408			7,255,425			—			41,737,048
Issuance of Series D-1 preferred stock		—			—			—			—			3,200,000			3,200,000
Exercise of Series D preferred warrants		—			—			—			3,205			—			3,205
Effect of reverse stock split		(8,410,377	)		(5,390,766	)		(16,083,286	)		(6,290,844	)		(2,784,416	)		(38,959,689	)
Less: Conversion of preferred stock into common stock upon IPO		(1,293,838	)		(829,234	)		(2,474,122	)		(967,786	)		(415,584	)		(5,980,564	)
Balance as of December 31, 2015		—			—			—			—			—			—
Balance as of December 31, 2016		—			—			—			—			—			—
Balance as of December 31, 2017		—			—			—			—			—			—

Note J - Common Stock and Warrants (Tables)

12 Months Ended

Dec. 31, 2017

Notes Tables

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

	December 31,
	2017		2016
Conversion of Deerfield Convertible Notes		1,751,410		1,751,296
Conversion of 2021 Notes		5,040,914		5,040,914
Outstanding awards under equity incentive plans		2,853,924		1,990,260
Outstanding common stock warrants		2,027,763		2,087,477
Possible future issuances under equity incentive plans		944,700		1,244,671
Total common shares reserved for future issuance		12,618,711		12,114,618

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

	Shares of
	Common Stock
Balance as of January 1, 2015		2,381,041
Issuance of common stock in connection with the IPO		5,854,545
Conversion of preferred stock to common stock in connection with the IPO		5,980,564
Common stock warrants exercised		270,038
Common stock options exercised		4,766
Balance as of December 31, 2015		14,490,954
Common stock warrants exercised		141,095
Common stock options exercised		14,933
Balance as of December 31, 2016		14,646,982
Common stock warrants exercised		698
Common stock options exercised		9,750
Balance as of December 31, 2017		14,657,430

Note K - Stock-based Compensation (Tables)

12 Months Ended

Dec. 31, 2017

Notes Tables

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

	Year Ended December 31,
	2017		2016		2015
Research and development	$	1,304	$	1,051	$	610
General and administrative		3,258		3,639		1,759
Severance expense		—		1,910		—
Total stock-based compensation expense	$	4,562	$	6,600	$	2,369

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

	December 31,
	2017		2016		2015
Risk-free interest rate		1.88% - 2.26%		1.29% - 1.50%		1.40% - 1.99%
Expected term (in years)		5.12 - 7.00		5.50 - 6.26		4.33 - 6.25
Expected volatility		85.35% - 95.08%		77.38% - 94.78%		68.79% - 86.84%
Expected dividend yield		0%		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, 2017		1,990,260		$	13.64		8.27	$	26,400
Granted		919,000		$	3.59
Exercised		(9,750	)	$	0.75
Canceled or forfeited		(38,920	)	$	11.35
Expired		(6,666	)	$	4.65
Outsta nding balance as of December 31, 2017		2,853,924		$	10.50		7.90	$	471,539
Exercisable as of December 31, 2017		1,044,392		$	12.38		6.78	$	29,237
Vested and expected to vest as of December 31, 2017		2,760,447		$	10.62		7.87	$	440,178

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	1,055,244	8.69	76,244	3.75
$5.01 to $10.00	366,447	5.77	345,146	5.72
$10.01 to $15.00	471,833	7.94	189,291	7.73
$15.01 to $20.00	612,600	7.89	259,811	7.76
$20.01 to $22.12	347,800	7.68	173,900	7.68
	2,853,924	7.90	1,044,392	6.78

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

	Number of Unvested Shares
	December 31,
Exercise Price	2017		2016
$2.75 to $5.00		979,000		99,000
$5.01 to $10.00		21,301		97,480
$10.01 to $15.00		282,542		378,500
$15.01 to $20.00		352,789		516,938
$20.01 to $22.12		173,900		260,850
Total number of unvested shares		1,809,532		1,352,768

Note L - Fair Value of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2017

Notes Tables

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

			Quoted Prices in
	Balance as of		Active Markets for		Significant Other		Significant
	December 31,		Identical Assets		Observable Inputs		Unobservable 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
Embedded Deerfield Note Put Option		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	$	—

			Quoted Prices in
	Balance as of		Active Markets for		Significant Other		Significant
	December 31,		Identical Assets		Observable Inputs		Unobservable Inputs
	2016		(Level 1)		(Level 2)		(Level 3)
Underwriter Warrant liability	$	16	$	—	$	—	$	16
Deerfield Warrant liability		4,231		—		—		4,231
Embedded Warrant Put Option		365		—		—		365
Fundamental change and make-whole interest provisions embedded in 2021 Notes		6						6
Total liabilities	$	4,618	$	—	$	—	$	4,618
Trading securities:
Certificates of deposit		7,788		7,788		—		—
U.S. Treasury securities		37,066		37,066		—		—
U.S. government-sponsored agency securities		14,349		—		14,349		—
Total assets	$	59,203	$	44,854	$	14,349	$	—

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

	2017		2016
Balance as of beginning of period	$	4,618	$	37,839
Exercise of warrants		—		(756	)
Adjustment to fair value		3,091		(32,465	)
Balance as of end of period	$	7,709	$	4,618

Note M - Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Notes Tables

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

	Year ended December 31,
	2017			2016			2015
Federal statutory rate		34.00	%		34.00	%		34.00	%
Effect of:
Change in valuation allowance		13.38			(69.31	)		(19.25	)
Return to provision and deferred true-up		2.18			(23.83	)		—
Change in rate		(49.06	)		(14.63	)		—
State tax benefit (net of federal)		2.71			15.64			4.06
Warrant liability		(2.42	)		68.44			(15.28	)
State research and development credit		0.10			0.09			0.03
Federal research and development credit		1.50			5.65			0.84
Amortization		(1.22	)		(3.15	)		—
Conversion feature and put option on convertible notes		—			—			(1.68	)
Stock-based compensation		(1.03	)		(12.71	)		(1.28	)
Other		(0.04	)		(0.10	)		(1.49	)
Federal income tax benefit (provision) effective rate		0.10	%		0.09	%		(0.05	)%

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

	December 31,
	2017			2016			2015
Deferred tax assets relating to:
Net operating loss carryforwards	$	37,028		$	44,984		$	26,617
Research and development tax carryforward		3,788			3,166			2,254
Other deferred tax assets		2,409			715			232
Total gross deferred tax assets		43,225			48,865			29,103
Deferred tax liabilities relating to:
Property and equipment		260			89			80
Total gross deferred tax liabilities		260			89			80
Deferred tax assets less liabilities		42,965			48,776			29,023
Valuation allowance		(42,965	)		(48,776	)		(29,023	)
Net deferred tax asset (liability)	$	—		$	—		$	—

Summary of Operating Loss Carryforwards [Table Text Block]

	Net Operating		Research
Year Incurred	Loss Carryforwards		Activities 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		16,265		894		2034
2015		24,126		598		2035
2016		40,715		745		2036
2017		33,828		652		2037
	$	137,331	$	3,788

Note N - Net Loss Per Share (Tables)

12 Months Ended

Dec. 31, 2017

Notes Tables

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

	Year ended December 31,
	2017			2016			2015
Net loss - basic and diluted	$	(43,386	)	$	(16,516	)	$	(54,664	)
Weighted average number of shares of common stock - basic and diluted		14,652,898			14,597,053			7,368,681
Net loss per share - basic and diluted	$	(2.96	)	$	(1.13	)	$	(7.42	)

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

	December 31,
	2017		2016		2015
Warrants to purchase common stock		2,027,763		2,087,477		2,325,383
Awards under equity incentive plans		2,853,924		1,990,260		1,397,511
Deerfield Convertible Notes		1,751,410		1,751,296		1,991,219
2021 Notes		5,040,914		5,040,914		—
Total securities excluded from the calculation of weighted average number of shares of common stock outstanding		11,674,011		10,869,947		5,714,113

Note Q - Quarterly Results of Operations (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2017

Notes Tables

Quarterly Financial Information [Table Text Block]

	Three-Months Ended
	Dec 31,			Sep 30,			Jun 30,			Mar 31,			Dec 31,			Sep 30,			Jun 30,			Mar 31,
	2017			2017			2017			2017			2016			2016			2016			2016
Revenue	$	—		$	—		$	—		$	—		$	—		$	—		$	—		$	—
Operating expenses:
Research and development		5,536			6,293			4,650			4,114			7,963			4,287			4,988			3,234
General and administrative		2,614			3,319			3,574			3,266			2,873			3,104			4,287			3,736
Severance expense		—			—			—			—			—			3,010			—			—
Total operating expenses		8,150			9,612			8,224			7,380			10,836			10,401			9,275			6,970
Loss from operations		(8,150	)		(9,612	)		(8,224	)		(7,380	)		(10,836	)		(10,401	)		(9,275	)		(6,970	)
Other (expense) income:
Loss on extinguishment of debt		—			—			—			—			—			—			—			(4,740	)
Interest expense related to amortization of debt issuance costs and discount		(390	)		(391	)		(390	)		(390	)		(391	)		(390	)		(393	)		(442	)
Interest expense on principal		(1,444	)		(1,448	)		(1,443	)		(1,441	)		(1,445	)		(1,441	)		(1,475	)		(1,150	)
Fair value adjustment related to derivative and warrant liability		(710	)		1,312			3,523			(7,216	)		2,723			(1,299	)		20,763			10,278
Interest and other income, net		97			154			13			101			9			98			144			102
Total other (expense) income		(2,447	)		(373	)		1,703			(8,946	)		896			(3,032	)		19,039			4,048
(Loss) income before income taxes		(10,597	)		(9,985	)		(6,521	)		(16,326	)		(9,940	)		(13,433	)		9,764			(2,922	)
Income tax benefit (expense)		31			4			4			4			4			19			4			(12	)
Net (loss) income	$	(10,566	)	$	(9,981	)	$	(6,517	)	$	(16,322	)	$	(9,936	)	$	(13,414	)	$	9,768		$	(2,934	)

Net (loss) income per share:
Basic	$	(0.72	)	$	(0.68	)	$	(0.44	)	$	(1.11	)	$	(0.68	)	$	(0.92	)	$	0.59		$	(0.20	)
Diluted	$	(0.72	)	$	(0.68	)	$	(0.44	)	$	(1.11	)	$	(0.68	)	$	(0.92	)	$	(0.58	)	$	(0.20	)

Note A - Description of Business and Basis of Presentation (Details Textual)	1 Months Ended	12 Months Ended			18 Months Ended
	Apr. 30, 2015 $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2015 USD ($)	Mar. 22, 2018 USD ($) shares	Oct. 17, 2016 USD ($)	Oct. 03, 2016 USD ($)
Sale of Securities, Value, Available to Issue		$ 150,000,000
Sale of Stock, Value, Available to Issue		$ 20,000,000
Common Stock, Shares Authorized \| shares	250,000,000	250,000,000	250,000,000
Preferred Stock, Shares Authorized \| shares	10,000,000	10,000,000	10,000,000
Common Stock, Par or Stated Value Per Share \| $ / shares	$ 0.0001	$ 0.0001	$ 0.0001
Net Cash Provided by (Used in) Investing Activities		$ 27,412,000	$ (45,847,000)	$ (19,137,000)
Restricted Cash				0
Preferred Stock, Par or Stated Value Per Share \| $ / shares	$ 0.0001	$ 0.0001	$ 0.0001
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect		$ (5,891,000)	$ (14,456,000)	$ 22,063,000
Other Noncurrent Assets [Member]
Deferred Offering Costs		$ 200,000
Cowen and Company, LLC [Member]
Sale of Stock, Authorized Offering Price						$ 20,000,000
Sale of Stock, Commission Fee						3.00%
Cowen and Company, LLC [Member] \| Subsequent Event [Member]
Stock Issued During Period, Shares, New Issues \| shares					446,111
Proceeds from Issuance of Common Stock					$ 2,900,000
Cowen and Company, LLC [Member] \| Maximum [Member]
Sale of Stock, Authorized Offering Price							$ 50,000,000
Accounting Standards Update 2016-18 [Member] \| Restatement Adjustment [Member]
Net Cash Provided by (Used in) Investing Activities			1,100,000
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect			$ 1,100,000
Reverse Stock Split [Member]
Stockholders' Equity Note, Stock Split, Conversion Ratio	7.5

Note B - Summary of Significant Accounting Policies (Details Textual) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Asset Impairment Charges	$ 0	$ 0	$ 0
Unrecognized Tax Benefits	$ 0	$ 0
Number of Operating Segments	1
Number of Reportable Segments	1
Earliest Tax Year [Member]
Open Tax Year	2013
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, 2017	Dec. 31, 2016
Prepaid insurance	$ 202	$ 333
Other receivables	76	58
Other prepaid expenses and current assets	1,384	98
Total prepaid expenses and other current assets	$ 1,662	$ 489

Note D - Property and Equipment (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Depreciation, Depletion and Amortization	$ 336,000	$ 175,000	$ 84,000

Note D - Property and Equipment - Components of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property and equipment, gross	$ 2,933	$ 2,575
Less: accumulated depreciation and amortization	(929)	(605)
Property and equipment, net	2,004	1,970
Laboratory Equipment [Member]
Property and equipment, gross	983	842
Furniture and Fixtures [Member]
Property and equipment, gross	655	733
Computer and Hardware [Member]
Property and equipment, gross	292	231
Leasehold Improvements [Member]
Property and equipment, gross	$ 1,003	$ 769

Note D - Property and Equipment - Assets Under Capital Leases Included in Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Capital leased assets, gross	$ 966	$ 867
Less: accumulated depreciation and amortization	(150)	(31)
Property and equipment financed under a capital lease agreement, net	816	836
Laboratory Equipment [Member]
Capital leased assets, gross	366	271
Furniture and Fixtures [Member]
Capital leased assets, gross	541	537
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, 2017
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, 2017	Dec. 31, 2016
Accrued interest	$ 2,222	$ 2,222
Accrued banking fees	700	700
Accrued severance		646
Accrued payroll	1,118	1,024
Accounts payable	2,177	469
Other accrued expenses	1,658	1,383
Total accounts payable and accrued expenses	$ 7,875	$ 6,444

Note F - Debt Obligations (Details Textual) - USD ($)			1 Months Ended	12 Months Ended
Note F - Debt Obligations (Details Textual) - USD ($)	Feb. 09, 2016	Jun. 02, 2014	Jan. 31, 2018	Dec. 31, 2017	Jun. 30, 2016	Apr. 30, 2015	Dec. 31, 2013
Series D Redeemable Convertible Preferred Stock [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights						15,499,324	1,079,453
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	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
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 5.85
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
Long-term Line of Credit				$ 0
Third Line of Credit Agreement [Member] \| City National Bank of Florida [Member] \| Prime Rate [Member]
Debt Instrument, Interest Rate, Stated Percentage				3.36%
Debt Instrument, Basis Spread on Variable Rate				2.00%
Third Line of Credit Agreement [Member] \| City National Bank of Florida [Member] \| Subsequent Event [Member]
Line of Credit Facility, Expiration Period			2 years

Note F - Debt Obligations - Future Minimum Payments (Details) $ in Thousands	Dec. 31, 2017 USD ($)
2018	$ 3,333
2019	3,333
2020	3,334
2021	86,250
Total minimum principal payments	96,250
Less: debt issuance costs and discount	(3,519)
Convertible notes, net	$ 92,731

Note G - Commitments and Contingencies (Details Textual) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Loss Contingency Accrual	$ 0	$ 0
Operating and Capital Leases, Rent Expense, Net	$ 600	$ 600	$ 300
Capital Lease One [Member]
Capital Lease, Interest Rate	7.19%
Capital Lease Two [Member]
Capital Lease, Interest Rate	8.05%
Iowa [Member]
Lessee, Operating Lease, Renewal Term	1 year
Florida [Member]
Lessee, Operating Lease, Renewal Term	5 years
Number of Units Leased	2
Lessee Leasing Arrangements, Operating Leases, Number of Lease Renewals	2
North Carolina [Member]
Lessee, Operating Lease, Renewal Term	3 years

Note G - Commitment and Contingencies - Future Minimum Lease Payments Under Capital Leases and Non-cancelable Operating Leases (Details) $ in Thousands	Dec. 31, 2017 USD ($)
2018	$ 242
2018	688
2019	231
2019	604
2020	231
2020	499
2021	151
2021	449
2022	11
2022	461
Thereafter
Thereafter	1,376
Total minimum lease payments	866
Total minimum lease payments	4,077
Less: amounts representing interest	(115)
Total minimum capital lease principal payments	$ 751

Note H - Supply Arrangement (Details Textual) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Number of Manufacturing Arrangements	1
Supply Arrangement Expense	$ 0	$ 0	$ 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		1 Months Ended		12 Months Ended
	Jun. 02, 2014	Apr. 30, 2015	Feb. 28, 2015	Dec. 31, 2015	Dec. 31, 2013	Dec. 31, 2017	Dec. 31, 2016
Preferred Stock, Shares Authorized		10,000,000				10,000,000	10,000,000
Preferred Stock, Par or Stated Value Per Share		$ 0.0001				$ 0.0001	$ 0.0001
Preferred Stock, Shares Outstanding						0	0
Conversion of Preferred Stock to Common Stock Upon Initial Public Offering Shares				5,980,564
2013 Warrants [Member]
Class of Warrant or Right Issued					1,079,453
Deerfield Warrant [Member]
Class of Warrant or Right Issued	14,423,076
Convertible Notes Payable [Member]
Debt Instrument, Face Amount					$ 3.8
Series D-1 Redeemable Convertible Preferred Stock [Member]
Conversion of Preferred Stock to Common Stock Upon Initial Public Offering Shares				415,584
Series D-1 Redeemable Convertible Preferred Stock [Member] \| Cowen KP Investment LLC [Member]
Temporary Equity Shares Issuance			3,200,000
Sale of Stock, Price Per Share			$ 1.25
Proceeds from Issuance of Redeemable Convertible Preferred Stock			$ 4.0
Conversion of Preferred Stock to Common Stock Upon Initial Public Offering Shares			415,584
Series D Redeemable Convertible Preferred Stock [Member]
Conversion of Preferred Stock to Common Stock Upon Initial Public Offering Shares				967,786
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		15,499,324			1,079,453
Common Stock [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		2,066,543			143,466
Class of Warrant or Right, Exercise Price of Warrants or Rights					$ 5.85
Common Stock [Member] \| Deerfield Warrant [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
Common Stock [Member] \| IPO [Member]
Stock Issued During Period, Shares, Conversion of Convertible Securities		5,980,564		5,980,564

Note I - Preferred Stock and Warrants - Summary of Redeemable Convertible Preferred Stock Activity (Details) - shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2014
Balance (in shares)
Less: Conversion of preferred stock into common stock upon IPO (in shares)	(5,980,564)
Scenario, Previously Reported [Member]
Balance (in shares)				41,737,048
Temporary Equity Shares Issuance	3,200,000
Exercise of Series D preferred warrants (in shares)	3,205
Restatement Adjustment [Member]
Effect of reverse stock split (in shares)	(38,959,689)
Series A Redeemable Convertible Preferred Stock [Member]
Balance (in shares)
Less: Conversion of preferred stock into common stock upon IPO (in shares)	(1,293,838)
Series A Redeemable Convertible Preferred Stock [Member] \| Scenario, Previously Reported [Member]
Balance (in shares)				9,704,215
Temporary Equity Shares Issuance
Exercise of Series D preferred warrants (in shares)
Series A Redeemable Convertible Preferred Stock [Member] \| Restatement Adjustment [Member]
Effect of reverse stock split (in shares)	(8,410,377)
Series B Redeemable Convertible Preferred Stock [Member]
Balance (in shares)
Less: Conversion of preferred stock into common stock upon IPO (in shares)	(829,234)
Series B Redeemable Convertible Preferred Stock [Member] \| Scenario, Previously Reported [Member]
Balance (in shares)				6,220,000
Temporary Equity Shares Issuance
Exercise of Series D preferred warrants (in shares)
Series B Redeemable Convertible Preferred Stock [Member] \| Restatement Adjustment [Member]
Effect of reverse stock split (in shares)	(5,390,766)
Series C Redeemable Convertible Preferred Stock [Member]
Balance (in shares)
Less: Conversion of preferred stock into common stock upon IPO (in shares)	(2,474,122)
Series C Redeemable Convertible Preferred Stock [Member] \| Scenario, Previously Reported [Member]
Balance (in shares)				18,557,408
Temporary Equity Shares Issuance
Exercise of Series D preferred warrants (in shares)
Series C Redeemable Convertible Preferred Stock [Member] \| Restatement Adjustment [Member]
Effect of reverse stock split (in shares)	(16,083,286)
Series D Redeemable Convertible Preferred Stock [Member]
Balance (in shares)
Less: Conversion of preferred stock into common stock upon IPO (in shares)	(967,786)
Series D Redeemable Convertible Preferred Stock [Member] \| Scenario, Previously Reported [Member]
Balance (in shares)				7,255,425
Temporary Equity Shares Issuance
Exercise of Series D preferred warrants (in shares)	3,205
Series D Redeemable Convertible Preferred Stock [Member] \| Restatement Adjustment [Member]
Effect of reverse stock split (in shares)	(6,290,844)
Series D-1 Redeemable Convertible Preferred Stock [Member]
Balance (in shares)
Less: Conversion of preferred stock into common stock upon IPO (in shares)	(415,584)
Series D-1 Redeemable Convertible Preferred Stock [Member] \| Scenario, Previously Reported [Member]
Balance (in shares)
Temporary Equity Shares Issuance	3,200,000
Exercise of Series D preferred warrants (in shares)
Series D-1 Redeemable Convertible Preferred Stock [Member] \| Restatement Adjustment [Member]
Effect of reverse stock split (in shares)	(2,784,416)

Note J - Common Stock and Warrants (Details Textual) - USD ($)	12 Months Ended			18 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Mar. 22, 2018	Apr. 30, 2015	Dec. 31, 2012
Common Stock, Shares Authorized	250,000,000	250,000,000			250,000,000
Common Stock, Shares, Issued	14,657,430	14,646,982
Common Stock Issued During Period from Warrants Exercised	698	141,095	270,038
Subsequent Event [Member] \| Cowen and Company, LLC [Member]
Stock Issued During Period, Shares, New Issues				446,111
Proceeds from Issuance of Common Stock				$ 2,900,000
Private Placement [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights						595,920

Note J - Common Stock and Warrants - Reserved Authorized Shares of Common Stock for Future Issuance (Details) - shares	Dec. 31, 2017	Dec. 31, 2016
Common shares reserved for future issuance (in shares)	12,618,711	12,114,618
Warrant [Member]
Common shares reserved for future issuance (in shares)	2,027,763	2,087,477
Stock Compensation Plan [Member]
Common shares reserved for future issuance (in shares)	2,853,924	1,990,260
Possible Future Issuances Under Equity Incentive Plans [Member]
Common shares reserved for future issuance (in shares)	944,700	1,244,671
2021 Notes [Member]
Common shares reserved for future issuance (in shares)	5,040,914	5,040,914
Convertible Notes Payable [Member]
Common shares reserved for future issuance (in shares)	1,751,410	1,751,296

Note J - Common Stock and Warrants - Common Stock Activity (Details) - shares	1 Months Ended	12 Months Ended
	Apr. 30, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Balance (in shares)		14,646,982	14,490,954	2,381,041
Common stock warrants exercised (in shares)		698	141,095	270,038
Common stock options exercised (in shares)		9,750	14,933	4,766
Balance (in shares)		14,657,430	14,646,982	14,490,954
Common Stock [Member] \| IPO [Member]
Issuance of common stock in connection with the IPO (in shares)				5,854,545
Conversion of preferred stock to common stock in connection with the IPO (in shares)	5,980,564			5,980,564

Note K - Stock-based Compensation (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Increase in Common Stock Reserved for Issuance	586,297
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	9,750	14,933	4,766
Stock Issued During Period, Value, Stock Options Exercised	$ 7,000	$ 71,000	$ 28,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value	$ 32,000	$ 169,000	$ 54,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Weighted Average Grant Date Fair Value	$ 2.77	$ 9.25	$ 10.63
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value	$ 4,100,000	$ 5,400,000	$ 1,100,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	$ 8,500,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	2 years 21 days
Allocated Share-based Compensation Expense	$ 4,562,000	$ 6,600,000	$ 2,369,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Number of Shares		13,333	163,998
Research and Development Expense [Member]
Allocated Share-based Compensation Expense	1,304,000	$ 1,051,000	$ 610,000
General and Administrative Expense [Member]
Allocated Share-based Compensation Expense	3,258,000	3,639,000	1,759,000
Performance Shares [Member]
Allocated Share-based Compensation Expense	$ 0
Performance Shares [Member] \| Research and Development Expense [Member]
Allocated Share-based Compensation Expense		$ 44,000	200,000
Performance Shares [Member] \| General and Administrative Expense [Member]
Allocated Share-based Compensation Expense			$ 700,000
2014 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	3,432,183
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, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock based compensation expense	$ 4,562	$ 6,600	$ 2,369
Research and Development Expense [Member]
Stock based compensation expense	1,304	1,051	610
General and Administrative Expense [Member]
Stock based compensation expense	3,258	3,639	1,759
Severance Expense [Member]
Stock based compensation expense		$ 1,910

Note K - Stock-based Compensation - Black-Scholes Option-pricing Model (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Expected dividend yield	0.00%	0.00%	0.00%
Minimum [Member]
Risk-free interest rate	1.88%	1.29%	1.40%
Expected term (in years) (Year)	5 years 43 days	5 years 182 days	4 years 120 days
Expected volatility	85.35%	77.38%	68.79%
Maximum [Member]
Risk-free interest rate	2.26%	1.50%	1.99%
Expected term (in years) (Year)	7 years	6 years 94 days	6 years 91 days
Expected volatility	95.08%	94.78%	86.84%

Note K - Stock-based Compensation - Schedule of Stock Option Activity (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Outstanding, number of options (in shares)	1,990,260
Outstanding, weighted average exercise price (in dollars per share)	$ 13.64
Outstanding, weighted average remaining contractual term (Year)	7 years 328 days	8 years 98 days
Outstanding, aggregate intrinsic value	$ 471,539	$ 26,400
Granted, number of options (in shares)	919,000
Granted, weighted average exercise price (in dollars per share)	$ 3.59
Exercised, number of options (in shares)	(9,750)	(14,933)	(4,766)
Exercised, weighted average exercise price (in dollars per share)	$ 0.75
Canceled or forfeited, number of options (in shares)	(38,920)
Canceled or forfeited, weighted average exercise price (in dollars per share)	$ 11.35
Expired, number of options (in shares)	(6,666)
Expired, weighted average exercise price (in dollars per share)	$ 4.65
Outstanding, number of options (in shares)	2,853,924	1,990,260
Outstanding, weighted average exercise price (in dollars per share)	$ 10.50	$ 13.64
Exercisable, number of options (in shares)	1,044,392
Exercisable, weighted average exercise price (in dollars per share)	$ 12.38
Exercisable, weighted average remaining contractual term (Year)	6 years 284 days
Exercisable, aggregate intrinsic value	$ 29,237
Vested and expected to vest, number of options (in shares)	2,760,447
Vested and expected to vest, weighted average exercise price (in dollars per share)	$ 10.62
Vested and expected to vest, weighted average remaining contractual term (Year)	7 years 317 days
Vested and expected to vest, aggregate intrinsic value	$ 440,178

Note K - Stock-based Compensation - Information Regarding Currently Outstanding and Exercisable Options (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Options outstanding, number of shares (in shares)	2,853,924	1,990,260
Outstanding, weighted average remaining contractual term (Year)	7 years 328 days	8 years 98 days
Exercisable, number of options (in shares)	1,044,392
Exercisable, weighted average remaining contractual term (Year)	6 years 284 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)	1,055,244
Outstanding, weighted average remaining contractual term (Year)	8 years 251 days
Exercisable, number of options (in shares)	76,244
Exercisable, weighted average remaining contractual term (Year)	3 years 273 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)	366,447
Outstanding, weighted average remaining contractual term (Year)	5 years 281 days
Exercisable, number of options (in shares)	345,146
Exercisable, weighted average remaining contractual term (Year)	5 years 262 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)	7 years 343 days
Exercisable, number of options (in shares)	189,291
Exercisable, weighted average remaining contractual term (Year)	7 years 266 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)	612,600
Outstanding, weighted average remaining contractual term (Year)	7 years 324 days
Exercisable, number of options (in shares)	259,811
Exercisable, weighted average remaining contractual term (Year)	7 years 277 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)	7 years 248 days
Exercisable, number of options (in shares)	173,900
Exercisable, weighted average remaining contractual term (Year)	7 years 248 days

Note K - Stock-based Compensation - Nonvested Stock Option Awards (Details) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Number of unvested shares (in shares)	1,809,532	1,352,768
Exercise Price Range One [Member]
Number of unvested shares (in shares)	979,000	99,000
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)	21,301	97,480
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)	282,542	378,500
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)	352,789	516,938
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)	173,900	260,850
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, 2017	Dec. 31, 2016
Deerfield Convertible Notes [Member]
Long-term Debt, Fair Value	$ 11.0	$ 10.2
Term Notes [Member]
Long-term Debt, Fair Value	$ 51.9	$ 46.3

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, 2017	Dec. 31, 2016
Balance as of beginning of period	$ 4,618	$ 37,839
Exercise of warrants		(756)
Adjustment to fair value	3,091	(32,465)
Balance as of end of period	$ 7,709	$ 4,618

Note M - Income Taxes (Details Textual) - USD ($)	3 Months Ended								12 Months Ended
Note M - Income Taxes (Details Textual) - USD ($)	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
State and Local Income Tax Expense (Benefit), Continuing Operations									$ (43,000)	$ (15,000)	$ (15,000)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	$ (10,597,000)	$ (9,985,000)	$ (6,521,000)	$ (16,326,000)	$ (9,940,000)	$ (13,433,000)	$ 9,764,000	$ (2,922,000)	(43,429,000)	$ (16,531,000)	$ (54,638,000)
Operating Loss Carryforwards	137,331,000								137,331,000
Increase (Decrease) in Deferred Tax Assets									(21.30)
State and Local Jurisdiction [Member]
Operating Loss Carryforwards	$ 134,600,000								$ 134,600,000
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, 2017	Dec. 31, 2016	Dec. 31, 2015
Federal statutory rate	34.00%	34.00%	34.00%
Change in valuation allowance	13.38%	(69.31%)	(19.25%)
Return to provision and deferred true-up	2.18%	(23.83%)
Change in rate	(49.06%)	(14.63%)
State tax benefit (net of federal)	2.71%	15.64%	4.06%
Warrant liability	(2.42%)	68.44%	(15.28%)
Amortization	(1.22%)	(3.15%)
Conversion feature and put option on convertible notes			(1.68%)
Stock-based compensation	(1.03%)	(12.71%)	(1.28%)
Other	(0.04%)	(0.10%)	(1.49%)
Federal income tax benefit (provision) effective rate	0.10%	0.09%	(0.05%)
State and Local Jurisdiction [Member]
Research and development credit	0.10%	0.09%	0.03%
Domestic Tax Authority [Member]
Research and development credit	1.50%	5.65%	0.84%

Note M - Income Taxes - Components of Net Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net operating loss carryforwards	$ 37,028	$ 44,984	$ 26,617
Research and development tax carryforward	3,788	3,166	2,254
Other deferred tax assets	2,409	715	232
Total gross deferred tax assets	43,225	48,865	29,103
Property and equipment	260	89	80
Total gross deferred tax liabilities	260	89	80
Deferred tax assets less liabilities	42,965	48,776	29,023
Valuation allowance	(42,965)	(48,776)	(29,023)
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, 2017	Dec. 31, 2016	Dec. 31, 2015
Net Operating Loss Carryforwards	$ 137,331
Research Activities Tax Credit	$ 3,788	$ 3,166	$ 2,254
Expiration
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	$ 16,265
Research Activities Tax Credit	$ 894
Expiration	2034
Tax Year 2015 [Member]
Net Operating Loss Carryforwards	$ 24,126
Research Activities Tax Credit	$ 598
Expiration	2035
Tax Year 2016 [Member]
Net Operating Loss Carryforwards	$ 40,715
Research Activities Tax Credit	$ 745
Expiration	2036
Tax Year 2017 [Member]
Net Operating Loss Carryforwards	$ 33,828
Research Activities Tax Credit	$ 652
Expiration	2037

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	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net loss - basic and diluted	$ (10,566)	$ (9,981)	$ (6,517)	$ (16,322)	$ (9,936)	$ (13,414)	$ 9,768	$ (2,934)	$ (43,386)	$ (16,516)	$ (54,664)
Weighted average number of shares of common stock - basic and diluted (in shares)									14,652,898	14,597,053	7,368,681
Net loss per share - basic and diluted (in dollars per share)									$ (2.96)	$ (1.13)	$ (7.42)

Note N - Net Loss Per Share - Anti-dilutive Securities (Details) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Antidilutive securities (in shares)	11,674,011	10,869,947	5,714,113
Warrants to Purchase Common Stock [Member]
Antidilutive securities (in shares)	2,027,763	2,087,477	2,325,383
Stock Compensation Plan [Member]
Antidilutive securities (in shares)	2,853,924	1,990,260	1,397,511
Convertible Debt Securities [Member]
Antidilutive securities (in shares)	1,751,410	1,751,296	1,991,219
2021 Notes [Member]
Antidilutive securities (in shares)	5,040,914	5,040,914

Note O - Severance Expense (Details Textual) $ in Thousands	12 Months Ended
Note O - Severance Expense (Details Textual) $ in Thousands	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Restructuring and Related Cost, Number of Positions Eliminated		3
Allocated Share-based Compensation Expense	$ 4,562	$ 6,600	$ 2,369
Severance Expense [Member]
Allocated Share-based Compensation Expense		1,910
Employee Severance [Member] \| Accounts Payable and Accrued Liabilities [Member]
Restructuring Reserve	$ 0
Employee Severance [Member] \| Severance Expense [Member]
Restructuring Charges		1,100
Allocated Share-based Compensation Expense		$ 1,900

Note P - Employee Benefit Plan (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Retirement Plan [Member]
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	4.00%
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 207,000	$ 213,000	$ 113,000
Profit Sharing Plan [Member]
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 0	$ 0	$ 0
Defined Contribution Plan, Requisite Service Period	3 years

Note Q - Quarterly Results of Operations (Unaudited) - Schedule of Quarterly Operating Results (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue
Operating expenses:
Research and development	5,536	6,293	4,650	4,114	7,963	4,287	4,988	3,234	20,593	20,472	13,931
General and administrative	2,614	3,319	3,574	3,266	2,873	3,104	4,287	3,736	12,773	14,000	8,883
Severance expense						3,010				3,010
Total operating expenses	8,150	9,612	8,224	7,380	10,836	10,401	9,275	6,970	33,366	37,482	22,814
Loss from operations	(8,150)	(9,612)	(8,224)	(7,380)	(10,836)	(10,401)	(9,275)	(6,970)	(33,366)	(37,482)	(22,814)
Other (expense) income:
Loss on extinguishment of debt								(4,740)		(4,740)
Interest expense related to amortization of debt issuance costs and discount	(390)	(391)	(390)	(390)	(391)	(390)	(393)	(442)	(1,561)	(1,616)	(1,909)
Interest expense on principal	(1,444)	(1,448)	(1,443)	(1,441)	(1,445)	(1,441)	(1,475)	(1,150)	(5,776)	(5,511)	(2,671)
Fair value adjustment related to derivative and warrant liability	(710)	1,312	3,523	(7,216)	2,723	(1,299)	20,763	10,278	(3,091)	32,465	(27,276)
Interest and other income, net	97	154	13	101	9	98	144	102	365	353	32
Total other (expense) income	(2,447)	(373)	1,703	(8,946)	896	(3,032)	19,039	4,048	(10,063)	20,951	(31,824)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	(10,597)	(9,985)	(6,521)	(16,326)	(9,940)	(13,433)	9,764	(2,922)	(43,429)	(16,531)	(54,638)
Income tax benefit (expense)	31	4	4	4	4	19	4	(12)	43	15	(26)
Net loss - basic and diluted	$ (10,566)	$ (9,981)	$ (6,517)	$ (16,322)	$ (9,936)	$ (13,414)	$ 9,768	$ (2,934)	$ (43,386)	$ (16,516)	$ (54,664)
Net loss per share:
Basic (in dollars per share)	$ (0.72)	$ (0.68)	$ (0.44)	$ (1.11)	$ (0.68)	$ (0.92)	$ 0.59	$ (0.20)
Diluted (in dollars per share)	$ (0.72)	$ (0.68)	$ (0.44)	$ (1.11)	$ (0.68)	$ (0.92)	$ (0.58)	$ (0.20)

Note L - Fair Value of Financial Instruments - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Financial liabilities measured at fair value on recurring basis	$ 7,709,000	$ 4,618,000
Financial assets measured at fair value on recurring basis	34,608,000	59,203,000
Certificates of Deposit [Member]
Financial assets measured at fair value on recurring basis	5,616,000	7,788,000
US Treasury Securities [Member]
Financial assets measured at fair value on recurring basis	25,988,000	37,066,000
US Government Corporations and Agencies Securities [Member]
Financial assets measured at fair value on recurring basis	3,004,000	14,349,000
Fair Value, Inputs, Level 1 [Member]
Financial liabilities measured at fair value on recurring basis
Financial assets measured at fair value on recurring basis	31,604,000	44,854,000
Fair Value, Inputs, Level 1 [Member] \| Certificates of Deposit [Member]
Financial assets measured at fair value on recurring basis	5,616,000	7,788,000
Fair Value, Inputs, Level 1 [Member] \| US Treasury Securities [Member]
Financial assets measured at fair value on recurring basis	25,988,000	37,066,000
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
Financial assets measured at fair value on recurring basis	3,004,000	14,349,000
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	3,004,000	14,349,000
Fair Value, Inputs, Level 3 [Member]
Financial liabilities measured at fair value on recurring basis	7,709,000	4,618,000
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	5,115,000	4,231,000
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	5,115,000	4,231,000
Underwriter Warrant Liability [Member]
Financial liabilities measured at fair value on recurring basis		16,000
Underwriter Warrant Liability [Member] \| Fair Value, Inputs, Level 1 [Member]
Financial liabilities measured at fair value on recurring basis
Underwriter Warrant Liability [Member] \| Fair Value, Inputs, Level 2 [Member]
Financial liabilities measured at fair value on recurring basis
Underwriter Warrant Liability [Member] \| Fair Value, Inputs, Level 3 [Member]
Financial liabilities measured at fair value on recurring basis		16,000
Embedded Put Option [Member]
Financial liabilities measured at fair value on recurring basis	365,000	365,000
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	365,000	365,000
Fundamental Change and Make-Whole Interest Provisions Embedded in 2021 Notes [Member]
Financial liabilities measured at fair value on recurring basis	14,000	6,000
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	14,000	$ 6,000
Embedded Deerfield Note Put Option [Member]
Financial liabilities measured at fair value on recurring basis	2,215,000
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	$ 2,215