Oncternal Therapeutics (ONCT) 10-K 15 Mar 16 2015 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2015	Mar. 09, 2016	Jun. 30, 2015
Document and Entity Information
Entity Registrant Name	GTX INC /DE/
Entity Central Index Key	1,260,990
Document Type	10-K
Document Period End Date	Dec. 31, 2015
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Public Float			$ 50,387,891
Entity Common Stock, Shares Outstanding		141,749,150
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	FY

BALANCE SHEETS

BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 14,056	$ 17,880
Short-term investments	15,200	31,415
Prepaid expenses and other current assets	2,633	856
Total current assets	31,889	50,151
Property and equipment, net	5	29
Intangible and other assets, net	137	471
Total assets	32,031	50,651
Current liabilities:
Accounts payable	382	512
Warrant liability	27,349	30,430
Accrued expenses and other current liabilities	2,441	1,850
Total current liabilities	$ 30,172	32,792
Other long-term liabilities		$ 30
Commitments and contingencies
Stockholders' equity:
Common stock, $0.001 par value: 400,000,000 shares and 200,000,000 shares authorized at December 31, 2015 and December 31, 2014, respectively; 140,374,112 and 140,325,643 shares issued and outstanding at December 31, 2015 and December 31, 2014, respectively	$ 141	$ 140
Additional paid-in capital	515,192	512,460
Accumulated deficit	(513,474)	(494,771)
Total stockholders' equity	1,859	17,829
Total liabilities and stockholders' equity	$ 32,031	$ 50,651

BALANCE SHEETS (Parenthetical)

BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2015	Dec. 31, 2014
BALANCE SHEETS
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	400,000,000	200,000,000
Common stock, shares issued	140,374,112	140,325,643
Common stock, shares outstanding	140,374,112	140,325,643

STATEMENTS OF OPERATIONS

STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Expenses:
Research and development expenses	$ 3,879	$ 3,824	$ 2,956	$ 2,948	$ 3,254	$ 3,362	$ 7,894	$ 6,360	$ 13,607	$ 20,870	$ 32,318
General and administrative expenses	2,079	2,039	2,005	2,111	2,203	1,594	3,052	2,629	8,234	9,478	11,281
Total expenses	5,958	5,863	4,961	5,059	5,457	4,956	10,946	8,989	21,841	30,348	43,599
Loss from operations	(5,958)	(5,863)	(4,961)	(5,059)	(5,457)	(4,956)	(10,946)	(8,989)	(21,841)	(30,348)	(43,599)
Other income (expense), net	(4)	9	25	27	(284)	21	2	2	57	(259)	1,488
Gain (loss) on change in fair value of warrant liability	2,729	40,720	(43,016)	2,648	(8,804)				3,081	(8,804)
Net loss	$ (3,233)	$ 34,866	$ (47,952)	$ (2,384)	$ (14,545)	$ (4,935)	$ (10,944)	$ (8,987)	$ (18,703)	$ (39,411)	$ (42,111)
Net loss per share:
Basic (in dollars per share)	$ (0.02)	$ 0.25	$ (0.34)	$ (0.02)					$ (0.13)	$ (0.48)	$ (0.67)
Diluted (in dollars per share)	$ (0.04)	$ (0.04)	$ (0.34)	$ (0.02)					$ (0.15)	$ (0.48)	$ (0.67)
Weighted average shares outstanding:
Basic (in shares)	140,374,112	140,374,112	140,374,112	140,335,875					140,364,684	81,807,706	63,057,142
Diluted (in shares)	149,529,197	154,852,127	140,374,112	140,335,875					147,774,040	81,807,706	63,057,142

STATEMENTS OF STOCKHOLDERS' EQU

STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common StockPrivate Placement, March 2014	Common StockPrivate Placement, November 2014	Common Stock	Additional Paid-in CapitalPrivate Placement, March 2014	Additional Paid-in CapitalPrivate Placement, November 2014	Additional Paid-in Capital	Accumulated Deficit	Private Placement, March 2014	Private Placement, November 2014	Total
Balance at Dec. 31, 2012			$ 63			$ 460,887	$ (413,249)			$ 47,701
Balance (in shares) at Dec. 31, 2012			62,818,424
Increase (Decrease) in Stockholders' Equity
Issuance of common stock under deferred compensation arrangements (in shares)			45,667
Exercise of employee stock options						1,226				1,226
Exercise of employee stock options (in shares)			321,298
Directors' deferred compensation						135				135
Share-based compensation						3,733				3,733
Net loss							(42,111)			(42,111)
Balance at Dec. 31, 2013			$ 63			465,981	(455,360)			10,684
Balance (in shares) at Dec. 31, 2013			63,185,389
Increase (Decrease) in Stockholders' Equity
Issuance of common stock and warrants in private placement, net of offering costs	$ 12	$ 64		$ 21,123	$ 21,420			$ 21,135	$ 21,484
Issuance of common stock in private placement (in shares)	11,976,048	64,311,112
Vesting of restricted stock units, net of shares withheld for tax payments			$ 1			(617)				(616)
Vesting of restricted stock units, net of shares withheld for tax payments (in shares)			853,094
Directors' deferred compensation						125				125
Share-based compensation						4,428				4,428
Net loss							(39,411)			(39,411)
Balance at Dec. 31, 2014			$ 140			512,460	(494,771)			$ 17,829
Balance (in shares) at Dec. 31, 2014			140,325,643							140,325,643
Increase (Decrease) in Stockholders' Equity
Issuance of common stock under deferred compensation arrangements (in shares)			48,469
Directors' deferred compensation			$ 1			112				$ 113
Share-based compensation						2,620				2,620
Net loss							(18,703)			(18,703)
Balance at Dec. 31, 2015			$ 141			$ 515,192	$ (513,474)			$ 1,859
Balance (in shares) at Dec. 31, 2015			140,374,112							140,374,112

STATEMENTS OF CASH FLOWS

STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities:
Net loss	$ (18,703)	$ (39,411)	$ (42,111)
Adjustments to reconcile net loss to net cash used in operating activities:
Gain (loss) on change in fair value of warrant liability	(3,081)	8,804
Private placement expenses recorded as other income (expense), net		297
Share-based compensation	2,620	4,428	3,733
Directors' deferred compensation	113	125	135
Depreciation and amortization	43	102	384
Gain on sale of property and equipment			(1,366)
Changes in assets and liabilities:
Prepaid expenses and other assets	(1,458)	(577)	399
Accounts payable	(130)	(296)	(899)
Accrued expenses and other liabilities	561	(2,231)	(4,246)
Net cash used in operating activities	(20,035)	(28,759)	(43,971)
Cash flows from investing activities:
Purchase of property and equipment	(4)	(5)	(32)
Proceeds from the sale of property and equipment			1,424
Purchase of short-term investments, held to maturity	(55,219)	(41,905)	(1,425)
Proceeds from maturities of short-term investments, held to maturity	71,434	10,690	9,270
Net cash provided by (used in) investing activities	16,211	(31,220)	9,237
Cash flows from financing activities:
Net proceeds from the issuance of common stock and warrants		63,949
Tax payments related to shares withheld for vested restricted stock units		(617)
Proceeds from exercise of employee stock options			1,226
Payments on capital lease and financed equipment obligations		(2)	(7)
Net cash provided by financing activities		63,330	1,219
Net (decrease) increase in cash and cash equivalents	(3,824)	3,351	(33,515)
Cash and cash equivalents, beginning of period	17,880	14,529	48,044
Cash and cash equivalents, end of period	$ 14,056	$ 17,880	$ 14,529

Business

Business	12 Months Ended
	Dec. 31, 2015
Business
Business	1. Business GTx, Inc. ("GTx" or the "Company"), a Delaware corporation incorporated on September 24, 1997 and headquartered in Memphis, Tennessee, is a biopharmaceutical company dedicated to the discovery, development and commercialization of small molecules for the treatment of cancer, including treatments for breast and prostate cancer, and other serious medical conditions. The Company is developing selective androgen receptor modulators ("SARMs"), including its lead product candidate, enobosarm (GTx-024). SARMs are a class of drugs that the Company believes have the potential to be used as a novel hormonal therapy for the treatment of advanced breast cancer, as well as the potential to treat other serious medical conditions. The Company announced during the second quarter of 2014 positive results from a Phase 2 proof-of-concept, open-label clinical trial evaluating a 9 mg oral daily dose of enobosarm for the treatment of patients with estrogen receptor ("ER") positive and androgen receptor ("AR") positive metastatic breast cancer who have previously responded to hormonal therapy. The Company commenced enrollment during 2015 in a Phase 2 proof-of-concept clinical trial designed to evaluate the efficacy and safety of enobosarm in patients with advanced AR positive triple-negative breast cancer. Additionally, during 2015, the Company commenced enrollment in a Phase 2 clinical trial evaluating enobosarm in patients whose advanced breast cancer is both ER positive and AR positive. The Company is also evaluating enobosarm and other compounds in its SARM portfolio for indications outside of oncology where unmet medical needs in muscle-related diseases may benefit from increasing muscle mass. In the first quarter of 2016, the Company initiated a Phase 2 proof-of-concept clinical trial of enobosarm to treat postmenopausal women with Stress Urinary Incontinence ("SUI"). The Company is also currently evaluating several SARM compounds, including enobosarm, in preclinical models of Duchenne Muscular Dystrophy ("DMD") where a SARM's ability to increase muscle mass may prove beneficial to patients suffering from DMD. The Company's evaluation of SARMs as a potential treatment for DMD is at an early stage, and the Company's ability to meaningfully advance development of SARMs as a potential treatment for DMD is subject to the Company's ability to obtain additional funding. In March 2015, the Company entered into an exclusive license agreement with the University of Tennessee Research Foundation ("UTRF") to develop UTRF's proprietary selective androgen receptor degrader ("SARD") technology which may have the potential to provide compounds that can degrade multiple forms of AR for those patients who do not respond or are resistant to current therapies to inhibit tumor growth in patients with progressive castration-resistant prostate cancer ("CRPC"). The Company's evaluation of the licensed SARD technology is at an early stage and to complete preclinical development of our SARD program through the requisite preclinical studies to support initial human clinical trials, the Company will require additional funding. The Company estimates that its current cash, cash equivalents and short-term investments, together with interest thereon, will be sufficient to meet its projected operating requirements through the end of 2016. Accordingly, the Company needs to raise substantial additional capital in the near term in order to fund its operations beyond the end of 2016 and to continue as a going concern thereafter. In addition, the Company has based its cash sufficiency estimates on its current business plan and its assumptions that may prove to be wrong. The Company could utilize its available capital resources sooner than it currently expects, and the Company could need additional funding to sustain its operations even sooner than currently anticipated. While the Company estimates that its current cash, cash equivalents and short-term investments, together with interest thereon, will be sufficient to meet its projected operating requirements through the end of 2016, during which time it expects to obtain results from the patients enrolled in the first stage of each of its ongoing open-label Phase 2 clinical trials of enobosarm in patients with AR positive advanced breast cancer and results from its recently initiated Phase 2 proof-of-concept clinical trial evaluating enobosarm to treat postmenopausal women with SUI, the Company will need to raise substantial additional capital in the near term in order to: • initiate and complete the second stage of both of the Company's ongoing open-label Phase 2 clinical trials of enobosarm in patients with AR positive advanced breast cancer; • meaningfully advance the preclinical development of the Company's licensed SARD program through the preclinical studies required to initiate human clinical studies; • undertake any further development of the Company's SARMs beyond its ongoing Phase 2 clinical trials of enobosarm in breast cancer and SUI and our ongoing preclinical development activities related to the development of SARMs as a potential treatment for DMD; and • fund the Company's operations and to continue as a going concern. In addition, these financial statements do not include any adjustments or charges that might be necessary should the Company be unable to continue as a going concern, such as charges related to impairment of its assets, the recoverability and classification of assets or the amounts and classification of liabilities or other similar adjustments.

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2015
Significant Accounting Policies
Significant Accounting Policies	2. Significant Accounting Policies Basis of Presentation The accompanying financial statements have been prepared in accordance with U.S. generally accepted accounting principles ("U.S. GAAP"). Additionally, GTx operates in one business segment. Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual amounts and results could differ from those estimates. Cash and Cash Equivalents The Company considers highly liquid investments with initial maturities of three months or less to be cash equivalents. Short-term Investments At December 31, 2015 and 2014, short-term investments consisted of Federal Deposit Insurance Corporation ("FDIC") insured certificates of deposit with original maturities of greater than three months and less than one year. Property and Equipment Property and equipment is stated at cost. Amortization of leasehold improvements is recognized over the shorter of the estimated useful life of the leasehold improvement or the lease term. Depreciation is computed using the straight-line method over the estimated useful lives as follows: Office equipment 3 to 5 years Leasehold improvements 3 to 7 years Furniture and fixtures 5 years Computer equipment and software 3 years Warrant Liability In November 2014, the Company issued warrants to purchase 64,311,112 shares of its common stock. The Company classifies the warrants as a liability on its balance sheet since the warrants contain certain terms that could require the Company (or its successor) to purchase the warrants for cash in an amount equal to the value (as calculated utilizing a contractually-agreed Black-Scholes-Merton option pricing valuation model ("Black-Scholes Model")) of the unexercised portion of the warrants in connection with certain change of control transactions occurring on or prior to December 31, 2016, with such cash payment capped at an amount equal to $0.125 per unexercised share underlying each warrant. In addition, each warrant was subject to net cash settlement if, at the time of any exercise, there was then an insufficient number of authorized and reserved shares of common stock to effect a share settlement of the warrant. Under the terms of the warrants, as of May 6, 2015, the net cash settlement feature of the warrants automatically became inoperative; accordingly, the warrants are exercisable only for shares of the Company's common stock. As a result of the provision of the warrant requiring cash settlement upon certain change of control transactions, the Company is required to account for these warrants as a liability at fair value and the estimated warrant liability is required to be revalued at each balance sheet date until the earlier of the exercise of the warrants, the modification to remove the provision that could require cash settlement upon certain change of control transactions or the expiration of such provision on December 31, 2016. Upon the earlier of the exercise of the warrants, the modification to remove the provision that could require cash settlement upon certain change of control transactions or the expiration of such provision on December 31, 2016, the fair value of the warrants will be reclassified from a liability to stockholders' equity on the Company's balance sheet and no further adjustment to the fair value would be made in subsequent periods. See Note 6, Stockholders' Equity , for further information regarding these warrants and the Company's valuation of the warrant liability. Fair Value of Financial Instruments and Warrant Liability The carrying amounts of the Company's financial instruments (which include cash, cash equivalents, short-term investments, and accounts payable) and its warrant liability approximate their fair values. The fair value of the warrant liability is estimated using the Black-Scholes Model. See Note 6, Stockholders' Equity , for additional disclosure on the valuation methodology and significant assumptions. The Company's financial assets and liabilities are classified within a three-level fair value hierarchy that prioritizes the inputs used to measure fair value, which is defined as follows: Level 1 — Quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date Level 2 — Inputs other than quoted prices in active markets that are observable for the asset or liability, either directly or indirectly Level 3 — Inputs that are unobservable for the asset or liability Asset and liabilities measured at fair value on a recurring basis as of December 31, 2015 and 2014 included only the Company's warrant liability of $27,349 and $30,430, respectively, which were classified within Level 3 of the hierarchy. A gain of $3,081 related to the change in the fair value of the warrant liability was recognized during the year ended December 31, 2015 as a non-cash gain in the Company's statement of operations. A loss of $8,804 related to the change in the fair value of the warrant liability was recognized during the year ended December 31, 2014 as a non-cash loss in the Company's statement of operations. Since the Company has the positive intent and ability to hold its certificates of deposit classified as short-term investments until maturity, these investments have been classified as held to maturity investments and are stated at cost, which approximates fair value. The Company considers these to be Level 2 investments as the fair values of these investments are determined using third-party pricing sources, which generally utilize observable inputs, such as interest rates and maturities of similar assets. Concentration of Risk Financial instruments that potentially subject the Company to a concentration of credit risk consist of cash and cash equivalents and short-term investments. The Company has established guidelines relating to diversification and maturities of its cash equivalents and short-term investments which are designed to manage risk. The Company's cash and cash equivalents consist of bank deposits, certificates of deposit, and money market mutual funds. Bank deposits may at times be in excess of FDIC insurance limits. The Company's short-term investments consist of FDIC insured certificates of deposit with original maturities of greater than three months and less than one year. Research and Development Expenses Research and development expenses include, but are not limited to, the Company's expenses for personnel, supplies, and facilities associated with research activities, screening and identification of product candidates, formulation and synthesis activities, manufacturing, preclinical studies, toxicology studies, clinical trials, regulatory and medical affairs activities, quality assurance activities and license fees. The Company expenses these costs in the period in which they are incurred. The Company estimates its liabilities for research and development expenses in order to match the recognition of expenses to the period in which the actual services are received. As such, accrued liabilities related to third party research and development activities are recognized based upon the Company's estimate of services received and degree of completion of the services in accordance with the specific third party contract. Patent Costs The Company expenses patent costs, including legal expenses, in the period in which they are incurred. Patent expenses are included in general and administrative expenses in the Company's statements of operations. Income Taxes The Company accounts for deferred taxes by recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements or tax returns. Under this method, deferred tax assets and liabilities are determined based on the difference between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. A valuation allowance is provided when it is more likely than not that some portion or all of the deferred tax assets will not be realized. Accordingly, at December 31, 2015 and December 31, 2014, net of the valuation allowance, the net deferred tax assets were reduced to zero. See Note 8, Income Taxes , for further discussion. Share-Based Compensation The Company has stock option and equity incentive plans that provide for the purchase or acquisition of the Company's common stock by certain of the Company's employees and non-employees. The Company recognizes compensation expense for its share-based payments based on the fair value of the awards over the period during which an employee or non-employee is required to provide service in exchange for the award. See Note 3, Share-Based Compensation , for further discussion. Other Income (Expense), Net Other income (expense), net consists of foreign currency transaction gains and losses, interest earned on the Company's cash, cash equivalents and short-term investments, interest expense, and other non-operating income or expense. Other income (expense), net for the year ended December 31, 2014 also included expenses related to the private placement of common stock and warrants completed in November 2014 as the warrants issued were accounted for as a liability. Other income (expense), net for the year ended December 31, 2013 also included a gain of $1,366 from the sale of research and development property and equipment sold subsequent to the workforce reduction that occurred in October 2013. Basic and Diluted Net Loss Per Share Basic and diluted net income (loss) per share attributable to common stockholders is calculated based on the weighted average number of common shares outstanding during the period. Diluted net income (loss) per share gives effect to the dilutive potential of common stock consisting of stock options, unvested restricted stock units ("RSUs") and common stock warrants. The calculation of diluted income (loss) per share also requires that, to the extent the average market price of the underlying shares for the reporting period exceeds the exercise price of the warrants and the presumed exercise of such warrants are dilutive to income (loss) per share for the period, adjustments to net income (loss) used in the calculation are required to remove the change in fair value of the warrant liability for the period. The following table sets forth the computation of the Company's net loss per share is as follows: Years Ended December 31, 2015 2014 2013 Basic and diluted net loss per share Numerator: Net loss — basic $ ) $ ) $ ) Adjustments for the gain on change in fair value of the warrant liability ) - - ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss — diluted ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Denominator: Weighted average shares outstanding — basic Dilutive warrants - - Dilutive restricted stock units - - Dilutive stock options - - ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average shares outstanding — diluted ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss per share: Basic $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Diluted $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average shares outstanding: Basic ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Diluted ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average potential shares of common stock of 8,387,455, 24,628,775, and 6,773,394 were excluded from the calculation of diluted net loss per share for the years ended December 31, 2015, 2014 and 2013, respectively, as inclusion of the potential shares would have had an anti-dilutive effect on the net loss per share for the periods. At December 31, 2015, the Company had 140,374,112 shares of common stock outstanding. Comprehensive Loss For all periods presented, there were no differences between net loss and comprehensive loss. Recent Accounting Pronouncements In November 2015, the Financial Accounting Standards Board issued Accounting Standards Update 2015-17, Balance Sheet Classification of Deferred Taxes . This guidance requires companies to classify all deferred tax assets and liabilities as noncurrent on the balance sheet rather than separating deferred taxes into current and noncurrent amounts. This guidance is effective for annual periods beginning after December 15, 2016, with early adoption permitted. The Company has early adopted this guidance on a prospective basis for the year ended December 31, 2015. This change did not have a material impact on the Company's financial position or results of operations for the year ended December 31, 2015. In August 2014, the Financial Accounting Standards Board issued Accounting Standard Update 2014-15, Disclosure of Uncertainties about an Entity's Ability to Continue as a Going Concern . The new guidance is intended to define management's responsibility to evaluate whether there is substantial doubt about an organization's ability to continue as a going concern within one year of the date the financial statements are issued and to provide related footnote disclosure. This new guidance is effective for the first annual period ending after December 15, 2016 and interim periods thereafter. Subsequent Events The Company has evaluated all events or transactions that occurred after December 31, 2015 up through the date the financial statements were issued. There were no material recognizable or nonrecognizable subsequent events during the period evaluated.

Share-Based Compensation

Share-Based Compensation	12 Months Ended
	Dec. 31, 2015
Share-Based Compensation
Share-Based Compensation	3. Share-Based Compensation Share-based payments include stock option and RSU grants under the Company's stock option and equity incentive plans and deferred compensation arrangements for the Company's non-employee directors. The Company has granted and continues to grant to employees and non-employees options to purchase common stock under various plans at prices equal to the fair market value of its common stock on the dates the options are granted as determined in accordance with the terms of the applicable plan. The options have a term of ten years from the grant date and generally vest over three years from the grant date for director and non-employee options and over periods of up to five years from the grant date for employee options. Under the terms of the Company's stock option and equity incentive plans, employees generally have three months after the employment relationship ends to exercise all vested options except in the case of voluntary retirement, disability or death, where post-termination exercise periods are generally longer. The Company issues new shares of common stock upon the exercise of options. The Company estimates the fair value of stock option awards as of the date of the grant by applying the Black-Scholes Model. The application of this valuation model involves assumptions that are judgmental and highly sensitive in the determination of compensation expense. The fair value of each stock option is amortized into compensation expense on a straight-line basis between the grant date for the award and each vesting date. The amount of share-based compensation expense recognized is reduced ratably over the vesting period by an estimate of the percentage of options granted that are expected to be forfeited or canceled before becoming fully vested. Additionally, the Company periodically grants RSUs to its employees. The Company estimates the fair value of RSUs using the closing price of its common stock on the grant date. The fair value of the RSUs is amortized on a straight-line basis over the requisite service period of the awards. The amount of share-based compensation expense recognized is reduced ratably over the vesting period by an estimate of the percentage of RSUs granted that are expected to be forfeited or canceled before becoming fully vested. The following table summarizes share-based compensation expense included within the statements of operations for each of the three years in the period ended December 31, 2015: Years Ended December 31, 2015 2014 2013 Research and development expenses $ $ $ General and administrative expenses ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total share-based compensation $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Share-based compensation expense recorded in the statement of operations as general and administrative expense for the years ended December 31, 2015, 2014 and 2013 included share-based compensation expense related to deferred compensation arrangements for the Company's non-employee directors of $113, $125 and $135, respectively. See Note 9, Directors' Deferred Compensation Plan , for further discussion of deferred compensation arrangements for the Company's non-employee directors. For the years ended December 31, 2015, 2014 and 2013, the weighted average grant date fair value per share of stock options granted was $0.57, $1.04 and $2.13, respectively. The key assumptions used in determining the grant date fair value of options granted in 2015, 2014 and 2013, and a summary of the methodology applied to develop each assumption is as follows: Years Ended December 31, 2015 2014 2013 Expected price volatility Risk-free interest rate Weighted average expected life in years 6.0 years 6.9 years 5.9 years Dividend yield Expected Price Volatility — This is a measure of the amount by which a price has fluctuated or is expected to fluctuate. The Company based its determination of expected volatility on its historical stock price volatility. An increase in the expected price volatility will increase compensation expense. Risk-Free Interest Rate — This is determined using U.S. Treasury rates where the term is consistent with the expected life of the stock options. An increase in the risk-free interest rate will increase compensation expense. Expected Life — This is the period of time over which the options granted are expected to remain outstanding and is determined by calculating the average of the vesting term and the contractual term of the options. The Company has utilized this method due to the lack of historical option exercise information related to the Company's stock option and equity incentive plans. Options granted have a maximum term of ten years. An increase in the expected life will increase compensation expense. Dividend Yield — The Company has not made any dividend payments nor does it have plans to pay dividends in the foreseeable future. An increase in the dividend yield will decrease compensation expense. The following is a summary of stock option transactions for all of the Company's stock option and equity incentive plans for the three year period ended December 31, 2015: Number of Shares Weighted Average Exercise Price Per Share Options outstanding at January 1, 2013 $ Options granted Options forfeited or expired ) Options exercised ) ​ ​ ​ ​ ​ ​ ​ ​ Options outstanding at December 31, 2013 Options granted Options forfeited or expired ) Options exercised - - ​ ​ ​ ​ ​ ​ ​ ​ Options outstanding at December 31, 2014 Options granted Options forfeited or expired ) Options exercised - - ​ ​ ​ ​ ​ ​ ​ ​ Options outstanding at December 31, 2015 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options vested and expected to vest at December 31, 2015 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The following table summarizes information about stock options outstanding at December 31, 2015: Options Outstanding Options Exercisable Exercise Price Number Outstanding Weighted Average Remaining Contractual Life (years) Weighted Average Exercise Price Number Exercisable Weighted Average Exercise Price $0.61 - $1.33 2,782,000 $ 33,334 $ $1.42 - $3.36 2,786,500 2,068,802 $3.44 - $20.40 2,414,668 2,002,472 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 7,983,168 4,104,608 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ At December 31, 2015, the aggregate intrinsic value of all outstanding options was $3 with a weighted average remaining contractual term of 6.51 years. Of the Company's outstanding options, 4,104,608 options were exercisable and had a weighted average remaining contractual term of 4.94 years and an aggregate intrinsic value of $2. Additionally, the Company's vested and expected to vest options had a weighted average remaining contractual term of 6.48 years and an aggregate intrinsic value of $3. There were no options exercised during the years ended December 31, 2015 and 2014. The total intrinsic value of options exercised during the year ended December 31, 2013 was $688. At December 31, 2015, the total compensation cost related to non-vested options not yet recognized was $3,346, with a weighted average expense recognition period of 2.99 years. Shares available for future issuance under the Company's stock option and equity incentive plans were 3,013,965 at December 31, 2015. On January 1, 2016, shares available for future issuance under the 2013 equity incentive plan and 2013 non-employee director equity incentive plan increased by an aggregate of 6,114,964 shares in accordance with the automatic increase provisions of such plans. During the year ended December 31, 2015, the Company granted 8,200,000 RSUs to employees of which a portion of each award vests annually over a three year period from the date of grant. The non-vested RSUs had a weighted average grant date fair value per share of $0.72. At December 31, 2015, all of these RSUs remained unvested and the total compensation cost related to non-vested RSUs not yet recognized was $4,111, with a weighted average expense recognition period of 1.65 years. Additionally, in the fourth quarter of 2013, the Company granted RSUs to employees that vested in full June 1, 2014. At December 31, 2013, the Company had 1,225,000 unvested RSUs outstanding with a weighted average grant date fair value per share of $1.87. All of these RSUs vested during the second quarter of 2014 and no RSUs were outstanding as of December 31, 2014. The number of RSUs vested included 371,906 shares that were withheld on behalf of the Company's employees to satisfy the statutory tax withholding requirements.

Property and Equipment, Net

Property and Equipment, Net	12 Months Ended
	Dec. 31, 2015
Property and Equipment, Net
Property and Equipment, Net	4. Property and Equipment, Net Property and equipment, net consisted of the following: December 31, 2015 2014 Computer equipment and software $ $ Furniture and fixtures Leasehold improvements Office equipment ​ ​ ​ ​ ​ ​ ​ ​ Less: accumulated depreciation ) ) ​ ​ ​ ​ ​ ​ ​ ​ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Depreciation and amortization expense for the years ended December 31, 2015, 2014 and 2013 was $27, $88, and $369, respectively. Of these amounts, $1, $1 and $169, respectively, were included in research and development expenses in the statements of operations.

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	12 Months Ended
	Dec. 31, 2015
Accrued Expenses and Other Current Liabilities
Accrued Expenses and Other Current Liabilities	5. Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consisted of the following: December 31, 2015 2014 Clinical trials $ $ General and administrative Research and development Employee compensation Net deferred income tax liabilities - ​ ​ ​ ​ ​ ​ ​ ​ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2015
Stockholders' Equity
Stockholders' Equity	6. Stockholders' Equity Authorized Capital On May 6, 2015, the Company filed a Certificate of Amendment to the Company's Restated Certificate of Incorporation with the Secretary of State of the State of Delaware to increase the number of authorized shares of the Company's common stock, par value $0.001 per share, from 200,000,000 shares to 400,000,000 shares. The Company's certificate of incorporation currently authorizes the Company to issue 400,000,000 shares of common stock, $0.001 par value per share, and 5,000,000 shares of preferred stock, $0.001 par value per share. Common Stock and Associated Warrant Liability On November 14, 2014, the Company completed a private placement of units consisting of an aggregate of 64,311,112 shares of common stock and warrants to purchase an aggregate of 64,311,112 shares of its common stock for net proceeds of $42,814, after deducting offering expenses. The purchasers in the private placement included certain existing GTx stockholders and certain members of the GTx management team and board of directors. The net proceeds from the private placement were allocated to the common stock and warrants based upon the fair value method. Similarly, the offering expenses were allocated between the common stock and warrants with the portion allocated to common stock offset against the proceeds allocated to stockholders' equity, whereas the portion allocated to the warrants was expensed immediately. The warrants have a per share exercise price of $0.85, became exercisable on May 6, 2015 and will continue to be exercisable for four years thereafter. Prior to May 6, 2015, each warrant was subject to net cash settlement if, at the time of any exercise, there was then an insufficient number of authorized and reserved shares of common stock to effect a share settlement of the warrant. Under the terms of the warrants, as of May 6, 2015, the net cash settlement feature of the warrants automatically became inoperative; accordingly, the warrants are exercisable only for shares of the Company's common stock. The warrants, however, contain certain terms that could require the Company (or its successor) to purchase the warrants for cash in an amount equal to the value (as calculated utilizing a contractually-agreed Black-Scholes Model) of the unexercised portion of the warrants in connection with certain change of control transactions occurring on or prior to December 31, 2016, with the cash payment capped at an amount equal to $0.125 per unexercised share underlying each warrant. Due to the provision of the warrants that could require cash settlement upon certain change of control transactions, the Company is required to account for these warrants as a liability at fair value using the Black-Scholes Model and the estimated warrant liability is required to be revalued at each balance sheet date until the earlier of the exercise of the warrants, the modification to remove the provision that could require cash settlement upon certain change of control transactions or the expiration of such provision on December 31, 2016. The fair value of the warrants at December 31, 2015 of $27,349 was estimated using the Black-Scholes Model with the following assumptions: expected volatility of 98%, risk-free interest rate of 1.4%, expected life of approximately 3.4 years and no dividends. The fair value of the warrants at December 31, 2014 of $30,430 was estimated using the Black-Scholes Model with the following assumptions: expected volatility of 91%, risk-free interest rate of 1.5%, expected life of approximately 4.5 years and no dividends. The decrease in fair value from December 31, 2014 of $3,081 was recorded as a non-cash gain on the change in fair value of warrant liability in the Company's statement of operations. Significant changes to the Company's market price for its common stock will impact the implied and/or historical volatility used to fair value the warrants. Any significant increases in the Company's stock price will likely create an increase to the fair value of the warrant liability. Similarly, any significant decreases in the Company's stock price will likely create a decrease to the fair value of the warrant liability. On March 6, 2014, the Company completed a private placement of units consisting of an aggregate of 11,976,048 shares of common stock and warrants to purchase an aggregate of 10,179,642 shares of its common stock for net proceeds of $21,135, after deducting offering expenses. The net proceeds from the private placement were allocated to the common stock and warrants based upon their relative fair values. The warrants, which had a one year term, expired unexercised on March 6, 2015.

License Agreements

License Agreements	12 Months Ended
	Dec. 31, 2015
License Agreements
License Agreements	7. License Agreements University of Tennessee Research Foundation License Agreements The Company and the University of Tennessee Research Foundation ("UTRF") are parties to a consolidated, amended and restated license agreement (the "SARM License Agreement") pursuant to which the Company has been granted exclusive worldwide rights in all existing SARM technologies owned or controlled by UTRF, including all improvements thereto, and exclusive rights to future SARM technology that may be developed by certain scientists at the University of Tennessee or subsequently licensed to UTRF under certain existing inter-institutional agreements with The Ohio State University. Under the SARM License Agreement, the Company is obligated to pay UTRF annual license maintenance fees, low single-digit royalties on net sales of products and mid single-digit royalties on sublicense revenues. In accordance with the terms of the SARM License Agreement that the Company entered into with UTRF in July 2007, the Company paid a one-time up-front fee of $290, which was recorded as an intangible asset by the Company. This intangible asset, net at December 31, 2015 and 2014 was $137 and $152, respectively. The Company and UTRF also entered into a license agreement in March 2015 pursuant to which the Company was granted exclusive worldwide rights in all existing SARD technologies owned or controlled by UTRF, including all improvements thereto (the "SARD License Agreement"). Under the SARD License Agreement, the Company is obligated to employ active, diligent efforts to conduct preclinical research and development activities for the SARD program to advance one or more lead compounds into clinical development. The Company is also obligated to pay UTRF annual license maintenance fees, low single-digit royalties on net sales of products and additional royalties on sublicense revenues, depending on the state of development of a clinical product candidate at the time it is sublicensed.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2015
Income Taxes
Income Taxes	8. Income Taxes Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. The principal components of the Company's net deferred income tax assets and liabilities consisted of the following: December 31, 2015 2014 Deferred income tax assets: Net federal and state operating loss carryforwards $ $ Research and development credits Share-based compensation Depreciation and amortization Other ​ ​ ​ ​ ​ ​ ​ ​ Total deferred tax assets ​ ​ ​ ​ ​ ​ ​ ​ Deferred income tax liabilities: Other ​ ​ ​ ​ ​ ​ ​ ​ Total deferred tax liabilities ​ ​ ​ ​ ​ ​ ​ ​ Net deferred tax assets Valuation allowance ) ) ​ ​ ​ ​ ​ ​ ​ ​ $ - $ - ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Realization of deferred income tax assets is dependent upon future earnings, if any, the timing and amount of which are uncertain. Accordingly, due to the Company's history of net operating losses, the net deferred tax assets have been fully offset by a valuation allowance. The valuation allowance increased by $8,101, $9,648 and $17,318 in 2015, 2014 and 2013, respectively. At December 31, 2015, the Company had net federal operating loss carryforwards of approximately $377,710, which expire from 2018 to 2035 if not utilized. The Company had state operating loss carryforwards of approximately $353,519, which expire from 2016 to 2035 if not utilized. The Company also had research and development credits at December 31, 2015 of approximately $13,245, which expire from 2020 to 2035 if not utilized. Both of the net federal and state operating loss carryforwards include approximately $2,301 of deductions related to the exercise of stock options. This amount represents an excess tax benefit and has not been included in the gross deferred income tax asset reflected for net federal and state operating loss carryforwards. If utilized, the benefits from these deductions will be recorded as an adjustment to additional paid in capital. The Company will recognize the impact of a tax position in the financial statements if that position is more likely than not of being sustained on audit based on the technical merits of the position. As of December 31, 2015, the Company had no unrecognized tax benefits. Utilization of the Company's net operating loss carryforwards may be subject to a substantial annual limitation due to ownership change limitations provided by Section 382 of the Internal Revenue Code of 1986, as amended, and similar state provisions. The annual limitations may result in the expiration of net operating loss carryforwards before utilization. The Company completed a study of its net operating losses through December 31, 2014 to determine whether such amounts are likely to be limited by Section 382. As a result of this study and its analysis of subsequent ownership changes, the Company does not currently believe any Section 382 limitation exists through December 31, 2015. However, any future ownership changes under Section 382 may limit the Company's ability to fully utilize these tax benefits. The Company has not yet conducted an in-depth study of its research and development credits, although the Company periodically reviews assumptions used in its calculations to reflect its best estimate of expected credit. An in-depth study may result in an increase or decrease to the Company's research and development credits and until such study is conducted of the Company's research and development credits, no amounts are being presented as an uncertain tax position. The Company's net deferred income tax assets have been fully offset by a valuation allowance. Therefore, future changes to the Company's unrecognized tax benefits would be offset by an adjustment to the valuation allowance and there would be no impact on the Company's balance sheet, statement of operations, or cash flows. The Company does not expect its unrecognized tax benefits to change significantly over the next 12 months. The Company is currently open to audit under the statute of limitations by the Internal Revenue Service and the appropriate state income taxing authorities for all years due to the net loss carryforwards from those years. The Company is currently not under examination by the Internal Revenue Service or any other taxing authorities. The Company has not recorded any interest and penalties on any unrecognized tax benefits since its inception.

Directors' Deferred Compensatio

Directors' Deferred Compensation Plan	12 Months Ended
	Dec. 31, 2015
Directors' Deferred Compensation Plan
Directors' Deferred Compensation Plan	9. Directors' Deferred Compensation Plan Non-employee directors may defer all or a portion of their fees under the Company's Directors' Deferred Compensation Plan until termination of their status as directors. Deferrals can be made into a cash account, a stock account, or a combination of both. Stock accounts will be paid out in the form of Company common stock, except that any fractional shares will be paid out in cash valued at the then current market price of the Company's common stock. Cash accounts and stock accounts under the Directors' Deferred Compensation Plan are credited with interest or the value of any cash and stock dividends, respectively. Non-employee directors are fully vested in any amounts that they elect to defer under the Directors' Deferred Compensation Plan. For the years ended December 31, 2015, 2014 and 2013, the Company incurred non-employee director fee expense of $229, $247 and $259, respectively, of which $113, $125 and $135 was deferred into stock accounts and will be paid in common stock following separation from service as a director. At December 31, 2015, 361,005 shares of the Company's common stock had been credited to individual director stock accounts under the Directors' Deferred Compensation Plan, and no amounts had been credited to individual director cash accounts under the Directors' Deferred Compensation Plan.

401(k) Plan

401(k) Plan	12 Months Ended
	Dec. 31, 2015
401(k) Plan
401(k) Plan	10. 401(k) Plan The Company sponsors a 401(k) retirement savings plan that is available to all eligible employees. The plan is intended to qualify under Section 401(k) of the Internal Revenue Code of 1986, as amended. The plan provides that each participant may contribute up to a statutory limit of their pre-tax compensation which was $18 for employees under age 50 and $24 for employees 50 and older in calendar year 2015. Employee contributions are held in the employees' name and invested by the plan's trustee. The plan also permits the Company to make matching contributions, subject to established limits. The Company elected to match a portion of employee's contributions to the plan in the amount of $189, $200 and $338 in 2015, 2014 and 2013, respectively.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies
Commitments and Contingencies	11. Commitments and Contingencies Operating Lease Commitments The Company previously leased laboratory facilities and office space pursuant to a sublease, which had been accounted for as an operating lease. Subsequent to the reduction in force implemented in October 2013, this lease was cancelled effective December 31, 2013. Prior to April 30, 2015, the Company subleased office space under a sublease that was accounted for as an operating lease. Upon expiration of this lease, the Company entered into a new office lease with respect to the Company's current office space. The new office lease term commenced on May 1, 2015 with a three year term ending on April 30, 2018, with an option to extend the lease for an additional three years. Total rent expense under the operating leases was approximately $501, $513 and $674 for the years ended December 31, 2015, 2014 and 2013, respectively. As of December 31, 2015, future annual minimum payments under operating lease arrangements were $466, $475, and $159 for the year ended December 31, 2016, 2017, and 2018, respectively.

Quarterly Financial Data (Unaud

Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Data (Unaudited)
Quarterly Financial Data (Unaudited)	12. Quarterly Financial Data (Unaudited) The following is a summary of the quarterly results of operations for the years ended December 31, 2015 and 2014: 2015 Quarters Ended March 31 June 30 September 30 December 31 Expenses: Research and development expenses $ $ $ $ General and administrative expenses ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total expenses ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Loss from operations ) ) ) ) Other income (expense), net ) Gain (loss) on change in fair value of warrant liability (a) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss $ ) $ ) $ $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income (loss) per share: Basic $ ) $ ) $ $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Diluted $ ) $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average shares outstanding: Basic ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Diluted ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2014 Quarters Ended March 31 June 30 September 30 December 31 Expenses: Research and development expenses $ $ $ $ General and administrative expenses ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total expenses ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Loss from operations ) ) ) ) Other income (expense), net ) Loss on change in fair value of warrant liability (a) - - - ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss $ ) $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss per share — basic and diluted $ ) $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average shares outstanding: Basic and diluted ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (a) The gain (loss) on change in fair value of warrant liability is related to the private placement of warrants completed in November 2014. See Note 6, Stockholder's Equity , for further information.

Significant Accounting Polici19

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2015
Significant Accounting Policies
Basis of Presentation	Basis of Presentation The accompanying financial statements have been prepared in accordance with U.S. generally accepted accounting principles ("U.S. GAAP"). Additionally, GTx operates in one business segment.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual amounts and results could differ from those estimates.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers highly liquid investments with initial maturities of three months or less to be cash equivalents.
Short-term Investments	Short-term Investments At December 31, 2015 and 2014, short-term investments consisted of Federal Deposit Insurance Corporation ("FDIC") insured certificates of deposit with original maturities of greater than three months and less than one year.
Property and Equipment	Property and Equipment Property and equipment is stated at cost. Amortization of leasehold improvements is recognized over the shorter of the estimated useful life of the leasehold improvement or the lease term. Depreciation is computed using the straight-line method over the estimated useful lives as follows: Office equipment 3 to 5 years Leasehold improvements 3 to 7 years Furniture and fixtures 5 years Computer equipment and software 3 years
Warrant Liability	Warrant Liability In November 2014, the Company issued warrants to purchase 64,311,112 shares of its common stock. The Company classifies the warrants as a liability on its balance sheet since the warrants contain certain terms that could require the Company (or its successor) to purchase the warrants for cash in an amount equal to the value (as calculated utilizing a contractually-agreed Black-Scholes-Merton option pricing valuation model ("Black-Scholes Model")) of the unexercised portion of the warrants in connection with certain change of control transactions occurring on or prior to December 31, 2016, with such cash payment capped at an amount equal to $0.125 per unexercised share underlying each warrant. In addition, each warrant was subject to net cash settlement if, at the time of any exercise, there was then an insufficient number of authorized and reserved shares of common stock to effect a share settlement of the warrant. Under the terms of the warrants, as of May 6, 2015, the net cash settlement feature of the warrants automatically became inoperative; accordingly, the warrants are exercisable only for shares of the Company's common stock. As a result of the provision of the warrant requiring cash settlement upon certain change of control transactions, the Company is required to account for these warrants as a liability at fair value and the estimated warrant liability is required to be revalued at each balance sheet date until the earlier of the exercise of the warrants, the modification to remove the provision that could require cash settlement upon certain change of control transactions or the expiration of such provision on December 31, 2016. Upon the earlier of the exercise of the warrants, the modification to remove the provision that could require cash settlement upon certain change of control transactions or the expiration of such provision on December 31, 2016, the fair value of the warrants will be reclassified from a liability to stockholders' equity on the Company's balance sheet and no further adjustment to the fair value would be made in subsequent periods. See Note 6, Stockholders' Equity , for further information regarding these warrants and the Company's valuation of the warrant liability.
Fair Value of Financial Instruments and Warrant Liability	Fair Value of Financial Instruments and Warrant Liability The carrying amounts of the Company's financial instruments (which include cash, cash equivalents, short-term investments, and accounts payable) and its warrant liability approximate their fair values. The fair value of the warrant liability is estimated using the Black-Scholes Model. See Note 6, Stockholders' Equity , for additional disclosure on the valuation methodology and significant assumptions. The Company's financial assets and liabilities are classified within a three-level fair value hierarchy that prioritizes the inputs used to measure fair value, which is defined as follows: Level 1 — Quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date Level 2 — Inputs other than quoted prices in active markets that are observable for the asset or liability, either directly or indirectly Level 3 — Inputs that are unobservable for the asset or liability Asset and liabilities measured at fair value on a recurring basis as of December 31, 2015 and 2014 included only the Company's warrant liability of $27,349 and $30,430, respectively, which were classified within Level 3 of the hierarchy. A gain of $3,081 related to the change in the fair value of the warrant liability was recognized during the year ended December 31, 2015 as a non-cash gain in the Company's statement of operations. A loss of $8,804 related to the change in the fair value of the warrant liability was recognized during the year ended December 31, 2014 as a non-cash loss in the Company's statement of operations. Since the Company has the positive intent and ability to hold its certificates of deposit classified as short-term investments until maturity, these investments have been classified as held to maturity investments and are stated at cost, which approximates fair value. The Company considers these to be Level 2 investments as the fair values of these investments are determined using third-party pricing sources, which generally utilize observable inputs, such as interest rates and maturities of similar assets.
Concentration of Risk	Concentration of Risk Financial instruments that potentially subject the Company to a concentration of credit risk consist of cash and cash equivalents and short-term investments. The Company has established guidelines relating to diversification and maturities of its cash equivalents and short-term investments which are designed to manage risk. The Company's cash and cash equivalents consist of bank deposits, certificates of deposit, and money market mutual funds. Bank deposits may at times be in excess of FDIC insurance limits. The Company's short-term investments consist of FDIC insured certificates of deposit with original maturities of greater than three months and less than one year.
Research and Development Expenses	Research and Development Expenses Research and development expenses include, but are not limited to, the Company's expenses for personnel, supplies, and facilities associated with research activities, screening and identification of product candidates, formulation and synthesis activities, manufacturing, preclinical studies, toxicology studies, clinical trials, regulatory and medical affairs activities, quality assurance activities and license fees. The Company expenses these costs in the period in which they are incurred. The Company estimates its liabilities for research and development expenses in order to match the recognition of expenses to the period in which the actual services are received. As such, accrued liabilities related to third party research and development activities are recognized based upon the Company's estimate of services received and degree of completion of the services in accordance with the specific third party contract.
Patent Costs	Patent Costs The Company expenses patent costs, including legal expenses, in the period in which they are incurred. Patent expenses are included in general and administrative expenses in the Company's statements of operations.
Income Taxes	Income Taxes The Company accounts for deferred taxes by recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements or tax returns. Under this method, deferred tax assets and liabilities are determined based on the difference between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. A valuation allowance is provided when it is more likely than not that some portion or all of the deferred tax assets will not be realized. Accordingly, at December 31, 2015 and December 31, 2014, net of the valuation allowance, the net deferred tax assets were reduced to zero. See Note 8, Income Taxes , for further discussion.
Share-Based Compensation	Share-Based Compensation The Company has stock option and equity incentive plans that provide for the purchase or acquisition of the Company's common stock by certain of the Company's employees and non-employees. The Company recognizes compensation expense for its share-based payments based on the fair value of the awards over the period during which an employee or non-employee is required to provide service in exchange for the award. See Note 3, Share-Based Compensation , for further discussion.
Other Income (Expense), Net	Other Income (Expense), Net Other income (expense), net consists of foreign currency transaction gains and losses, interest earned on the Company's cash, cash equivalents and short-term investments, interest expense, and other non-operating income or expense. Other income (expense), net for the year ended December 31, 2014 also included expenses related to the private placement of common stock and warrants completed in November 2014 as the warrants issued were accounted for as a liability. Other income (expense), net for the year ended December 31, 2013 also included a gain of $1,366 from the sale of research and development property and equipment sold subsequent to the workforce reduction that occurred in October 2013.
Basic and Diluted Net Loss Per Share	Basic and Diluted Net Loss Per Share Basic and diluted net income (loss) per share attributable to common stockholders is calculated based on the weighted average number of common shares outstanding during the period. Diluted net income (loss) per share gives effect to the dilutive potential of common stock consisting of stock options, unvested restricted stock units ("RSUs") and common stock warrants. The calculation of diluted income (loss) per share also requires that, to the extent the average market price of the underlying shares for the reporting period exceeds the exercise price of the warrants and the presumed exercise of such warrants are dilutive to income (loss) per share for the period, adjustments to net income (loss) used in the calculation are required to remove the change in fair value of the warrant liability for the period. The following table sets forth the computation of the Company's net loss per share is as follows: Years Ended December 31, 2015 2014 2013 Basic and diluted net loss per share Numerator: Net loss — basic $ ) $ ) $ ) Adjustments for the gain on change in fair value of the warrant liability ) - - ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss — diluted ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Denominator: Weighted average shares outstanding — basic Dilutive warrants - - Dilutive restricted stock units - - Dilutive stock options - - ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average shares outstanding — diluted ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss per share: Basic $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Diluted $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average shares outstanding: Basic ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Diluted ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average potential shares of common stock of 8,387,455, 24,628,775, and 6,773,394 were excluded from the calculation of diluted net loss per share for the years ended December 31, 2015, 2014 and 2013, respectively, as inclusion of the potential shares would have had an anti-dilutive effect on the net loss per share for the periods. At December 31, 2015, the Company had 140,374,112 shares of common stock outstanding.
Comprehensive Loss	Comprehensive Loss For all periods presented, there were no differences between net loss and comprehensive loss.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In November 2015, the Financial Accounting Standards Board issued Accounting Standards Update 2015-17, Balance Sheet Classification of Deferred Taxes . This guidance requires companies to classify all deferred tax assets and liabilities as noncurrent on the balance sheet rather than separating deferred taxes into current and noncurrent amounts. This guidance is effective for annual periods beginning after December 15, 2016, with early adoption permitted. The Company has early adopted this guidance on a prospective basis for the year ended December 31, 2015. This change did not have a material impact on the Company's financial position or results of operations for the year ended December 31, 2015. In August 2014, the Financial Accounting Standards Board issued Accounting Standard Update 2014-15, Disclosure of Uncertainties about an Entity's Ability to Continue as a Going Concern . The new guidance is intended to define management's responsibility to evaluate whether there is substantial doubt about an organization's ability to continue as a going concern within one year of the date the financial statements are issued and to provide related footnote disclosure. This new guidance is effective for the first annual period ending after December 15, 2016 and interim periods thereafter.
Subsequent Events	Subsequent Events The Company has evaluated all events or transactions that occurred after December 31, 2015 up through the date the financial statements were issued. There were no material recognizable or nonrecognizable subsequent events during the period evaluated.

Significant Accounting Polici20

Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2015
Significant Accounting Policies
Schedule of estimated useful lives of property and equipment	Office equipment 3 to 5 years Leasehold improvements 3 to 7 years Furniture and fixtures 5 years Computer equipment and software 3 years
Schedule of basic and diluted net income (loss) per share	Years Ended December 31, 2015 2014 2013 Basic and diluted net loss per share Numerator: Net loss — basic $ ) $ ) $ ) Adjustments for the gain on change in fair value of the warrant liability ) - - ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss — diluted ) ) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Denominator: Weighted average shares outstanding — basic Dilutive warrants - - Dilutive restricted stock units - - Dilutive stock options - - ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average shares outstanding — diluted ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss per share: Basic $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Diluted $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average shares outstanding: Basic ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Diluted ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Share-Based Compensation (Table

Share-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2015
Share-Based Compensation
Summary of share-based compensation expense	Years Ended December 31, 2015 2014 2013 Research and development expenses $ $ $ General and administrative expenses ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total share-based compensation $ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule of assumptions used to estimate fair value of options	Years Ended December 31, 2015 2014 2013 Expected price volatility Risk-free interest rate Weighted average expected life in years 6.0 years 6.9 years 5.9 years Dividend yield
Summary of stock option transactions	Number of Shares Weighted Average Exercise Price Per Share Options outstanding at January 1, 2013 $ Options granted Options forfeited or expired ) Options exercised ) ​ ​ ​ ​ ​ ​ ​ ​ Options outstanding at December 31, 2013 Options granted Options forfeited or expired ) Options exercised - - ​ ​ ​ ​ ​ ​ ​ ​ Options outstanding at December 31, 2014 Options granted Options forfeited or expired ) Options exercised - - ​ ​ ​ ​ ​ ​ ​ ​ Options outstanding at December 31, 2015 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Options vested and expected to vest at December 31, 2015 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​
Schedule of stock option activity by exercise price range	Options Outstanding Options Exercisable Exercise Price Number Outstanding Weighted Average Remaining Contractual Life (years) Weighted Average Exercise Price Number Exercisable Weighted Average Exercise Price $0.61 - $1.33 2,782,000 $ 33,334 $ $1.42 - $3.36 2,786,500 2,068,802 $3.44 - $20.40 2,414,668 2,002,472 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 7,983,168 4,104,608 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2015
Property and Equipment, Net
Schedule of property and equipment, net	December 31, 2015 2014 Computer equipment and software $ $ Furniture and fixtures Leasehold improvements Office equipment ​ ​ ​ ​ ​ ​ ​ ​ Less: accumulated depreciation ) ) ​ ​ ​ ​ ​ ​ ​ ​ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Accrued Expenses and Other Cu23

Accrued Expenses and Other Current Liabilities (Tables)	12 Months Ended
	Dec. 31, 2015
Accrued Expenses and Other Current Liabilities
Schedule of accrued expenses and other current liabilities	December 31, 2015 2014 Clinical trials $ $ General and administrative Research and development Employee compensation Net deferred income tax liabilities - ​ ​ ​ ​ ​ ​ ​ ​ $ $ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2015
Income Taxes
Schedule of principal components of the Company's net deferred income tax assets and liabilities	December 31, 2015 2014 Deferred income tax assets: Net federal and state operating loss carryforwards $ $ Research and development credits Share-based compensation Depreciation and amortization Other ​ ​ ​ ​ ​ ​ ​ ​ Total deferred tax assets ​ ​ ​ ​ ​ ​ ​ ​ Deferred income tax liabilities: Other ​ ​ ​ ​ ​ ​ ​ ​ Total deferred tax liabilities ​ ​ ​ ​ ​ ​ ​ ​ Net deferred tax assets Valuation allowance ) ) ​ ​ ​ ​ ​ ​ ​ ​ $ - $ - ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

Quarterly Financial Data (Una25

Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Data (Unaudited)
Summary of the quarterly results of operations	2015 Quarters Ended March 31 June 30 September 30 December 31 Expenses: Research and development expenses $ $ $ $ General and administrative expenses ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total expenses ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Loss from operations ) ) ) ) Other income (expense), net ) Gain (loss) on change in fair value of warrant liability (a) ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss $ ) $ ) $ $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net income (loss) per share: Basic $ ) $ ) $ $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Diluted $ ) $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average shares outstanding: Basic ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Diluted ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2014 Quarters Ended March 31 June 30 September 30 December 31 Expenses: Research and development expenses $ $ $ $ General and administrative expenses ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total expenses ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Loss from operations ) ) ) ) Other income (expense), net ) Loss on change in fair value of warrant liability (a) - - - ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss $ ) $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss per share — basic and diluted $ ) $ ) $ ) $ ) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average shares outstanding: Basic and diluted ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (a) The gain (loss) on change in fair value of warrant liability is related to the private placement of warrants completed in November 2014. See Note 6, Stockholder's Equity , for further information.

Significant Accounting Polici26

Significant Accounting Policies - Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2015item
Significant Accounting Policies
Number of business segments	1
Office Equipment | Minimum
Property and equipment
Estimated useful lives	3 years
Office Equipment | Maximum
Property and equipment
Estimated useful lives	5 years
Leasehold Improvements | Minimum
Property and equipment
Estimated useful lives	3 years
Leasehold Improvements | Maximum
Property and equipment
Estimated useful lives	7 years
Furniture and Fixtures
Property and equipment
Estimated useful lives	5 years
Computer Equipment and Software
Property and equipment
Estimated useful lives	3 years

Significant Accounting Polici27

Significant Accounting Policies - Warrant Liability (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended					12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Nov. 14, 2014
Warrant Liability
Warrants issued to purchase shares under private placement									64,311,112
Maximum contingent per share cash settlement price (in dollars per share)									$ 0.125
Warrant liability	$ 27,349				$ 30,430	$ 27,349	$ 30,430
Gain (loss) on change in fair value of warrant liability	2,729	$ 40,720	$ (43,016)	$ 2,648	(8,804)	3,081	(8,804)
Income Taxes
Net deferred tax assets	0				0	0	0
Other Income (Expense), Net
Gain on sale of property and equipment								$ 1,366
Level 3 | Fair Value Measurements, Recurring
Warrant Liability
Warrant liability	$ 27,349				$ 30,430	$ 27,349	$ 30,430

Significant Accounting Polici28

Significant Accounting Policies - Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Numerator:
Net loss - basic	$ (3,233)	$ 34,866	$ (47,952)	$ (2,384)	$ (14,545)	$ (4,935)	$ (10,944)	$ (8,987)	$ (18,703)	$ (39,411)	$ (42,111)
Adjustments for the gain on change in fair value of warrant liability									(3,081)
Net loss - diluted									$ (21,784)	$ (39,411)	$ (42,111)
Denominator:
Weighted average shares outstanding - basic	140,374,112	140,374,112	140,374,112	140,335,875					140,364,684	81,807,706	63,057,142
Dilutive warrants (in shares)									5,563,723
Dilutive restricted stock units (in shares)									1,843,786
Dilutive stock options (in shares)									1,847
Weighted average shares outstanding - diluted	149,529,197	154,852,127	140,374,112	140,335,875					147,774,040	81,807,706	63,057,142
Net loss per share
Basic (in dollars per share)	$ (0.02)	$ 0.25	$ (0.34)	$ (0.02)					$ (0.13)	$ (0.48)	$ (0.67)
Diluted (in dollars per share)	$ (0.04)	$ (0.04)	$ (0.34)	$ (0.02)					$ (0.15)	$ (0.48)	$ (0.67)
Weighted average shares outstanding:
Basic (in shares)	140,374,112	140,374,112	140,374,112	140,335,875					140,364,684	81,807,706	63,057,142
Diluted (in shares)	149,529,197	154,852,127	140,374,112	140,335,875					147,774,040	81,807,706	63,057,142
Weighted average potential shares of common stock excluded from calculation of diluted net loss per share									8,387,455	24,628,775	6,773,394
Common stock, shares outstanding	140,374,112				140,325,643				140,374,112	140,325,643

Share-Based Compensation - Shar

Share-Based Compensation - Share-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based compensation expense
Total share-based compensation	$ 2,733	$ 4,553	$ 3,868
Share-based compensation expense related to deferred compensation arrangements for non-employee directors	113	125	135
Research and development expenses
Share-based compensation expense
Total share-based compensation	1,210	2,512	1,875
General and administrative expenses
Share-based compensation expense
Total share-based compensation	1,523	2,041	1,993
Director
Share-based compensation expense
Share-based compensation expense related to deferred compensation arrangements for non-employee directors	113	125	135
Director | General and administrative expenses
Share-based compensation expense
Share-based compensation expense related to deferred compensation arrangements for non-employee directors	$ 113	$ 125	$ 135
Stock Options
Share-based compensation expense
Term of options from the grant date	10 years
Stock Options | Maximum
Share-based compensation expense
Term of options from the grant date	10 years
Stock Options | Director
Share-based compensation expense
Vesting period	3 years
Stock Options | Employees
Share-based compensation expense
Period available to exercise all vested options after end of employment relationship	3 months
Stock Options | Employees | Maximum
Share-based compensation expense
Vesting period	5 years

Share-Based Compensation - Stoc

Share-Based Compensation - Stock Option Activity (Details) - Stock Options - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based compensation
Weighted average grant date fair value (in dollars per share)	$ 0.57	$ 1.04	$ 2.13
Fair value of options granted
Expected price volatility (as a percent)	89.60%	86.50%	82.90%
Risk-free interest rate (as a percent)	1.60%	2.30%	1.27%
Weighted average expected life in years	6 years	6 years 10 months 24 days	5 years 10 months 24 days
Dividend yield (as a percent)	0.00%	0.00%	0.00%
Option term	10 years
Number of Shares
Options outstanding at the beginning of the period (in shares)	8,104,434	6,445,342	5,382,859
Options granted (in shares)	365,000	3,094,500	2,784,200
Options forfeited or expired (in shares)	(486,266)	(1,435,408)	(1,400,419)
Options exercised (in shares)	0		(321,298)
Options outstanding at the end of the period (in shares)	7,983,168	8,104,434	6,445,342
Options vested and expected to vest at the end of the period (in shares)	7,834,923
Weighted Average Exercise Price Per Share
Options outstanding at the beginning of the period (in dollars per share)	$ 4.24	$ 6.58	$ 7.96
Options granted (in dollars per share)	0.77	1.34	3.12
Options forfeited or expired (in dollars per share)	7.54	8.50	5.86
Options exercised (in dollars per share)			3.81
Options outstanding at the end of the period (in dollars per share)	3.88	$ 4.24	$ 6.58
Options vested and expected to vest at the end of the period (in dollars per share)	$ 3.93
Maximum
Fair value of options granted
Option term	10 years

Share-Based Compensation - St31

Share-Based Compensation - Stock Options Outstanding (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Jan. 01, 2016
Additional information
Shares available for future issuance under the Company's stock option and equity incentive plans	3,013,965
Increase to shares available for future issuance in accordance with annual automatic increase provisions				6,114,964
Stock Options
Information about stock options outstanding
Options Outstanding, Number Outstanding (in shares)	7,983,168
Options Outstanding, Weighted Average Remaining Contractual Life	6 years 6 months 4 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 3.88
Options Exercisable, Number Exercisable (in shares)	4,104,608
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 5.93
Additional information
Aggregate intrinsic value of all outstanding options (in dollars)	$ 3
Options exercisable, weighted average remaining contractual term	4 years 11 months 9 days
Options exercisable, aggregate intrinsic value (in dollars)	$ 2
Vested and expected to vest options, weighted average remaining contractual term	6 years 5 months 23 days
Vested and expected to vest options, intrinsic value (in dollars)	$ 3
Options exercised (in shares)	0		321,298
Intrinsic value of options exercised (in dollars)			$ 688
Compensation cost related to non-vested options not yet recognized	$ 3,346
Weighted average expense recognition period related to non-vested options not yet recognized		2 years 11 months 27 days
Stock Options | $0.61 - $1.33
Information about stock options outstanding
Low end of range of exercise prices (in dollars per share)	$ 0.61
High end of range of exercise prices (in dollars per share)	$ 1.33
Options Outstanding, Number Outstanding (in shares)	2,782,000
Options Outstanding, Weighted Average Remaining Contractual Life	8 years 6 months 22 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 1.23
Options Exercisable, Number Exercisable (in shares)	33,334
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 0.72
Stock Options | $1.42 - $3.36
Information about stock options outstanding
Low end of range of exercise prices (in dollars per share)	1.42
High end of range of exercise prices (in dollars per share)	$ 3.36
Options Outstanding, Number Outstanding (in shares)	2,786,500
Options Outstanding, Weighted Average Remaining Contractual Life	6 years 8 months 1 day
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 2.26
Options Exercisable, Number Exercisable (in shares)	2,068,802
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 2.32
Stock Options | $3.44 - $20.40
Information about stock options outstanding
Low end of range of exercise prices (in dollars per share)	3.44
High end of range of exercise prices (in dollars per share)	$ 20.40
Options Outstanding, Number Outstanding (in shares)	2,414,668
Options Outstanding, Weighted Average Remaining Contractual Life	3 years 11 months 23 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 8.81
Options Exercisable, Number Exercisable (in shares)	2,002,472
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 9.76

Share-Based Compensation - RSU

Share-Based Compensation - RSU Activity (Details) - Restricted Stock Units (RSUs) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Jun. 30, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Number of Shares
Restricted stock units granted (in shares)		8,200,000
Vesting period		3 years
Unvested awards outstanding (in shares)			0	1,225,000
Vested shares withheld to satisfy statutory tax withholding requirements	371,906
Weighted Average Grant Date Fair Value Per Share
Weighted average grant date fair value per share (in dollars per share)		$ 0.72		$ 1.87
Share-based compensation additional disclosure
Compensation cost related to non-vested restricted stock units not yet recognized		$ 4,111
Weighted average expense recognition period related to restricted stock units not yet recognized		1 year 7 months 24 days

Property and Equipment, Net (De

Property and Equipment, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property and equipment
Property and Equipment, gross	$ 2,854	$ 3,776
Less: accumulated depreciation	(2,849)	(3,747)
Property and Equipment, Net	5	29
Depreciation and amortization expense	27	88	$ 369
Research and development expenses
Property and equipment
Depreciation and amortization expense	1	1	$ 169
Computer Equipment and Software
Property and equipment
Property and Equipment, gross	1,435	2,128
Furniture and Fixtures
Property and equipment
Property and Equipment, gross	853	1,032
Leasehold Improvements
Property and equipment
Property and Equipment, gross	355	355
Office Equipment
Property and equipment
Property and Equipment, gross	$ 211	$ 261

Accrued Expenses and Other Cu34

Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Accrued Expenses and Other Current Liabilities
Clinical trials	$ 1,899	$ 929
General and administrative	281	379
Research and development	246	63
Employee compensation	15	160
Net deferred income tax liabilities		319
Accrued expenses and other current liabilities	$ 2,441	$ 1,850

Stockholders' Equity (Details)

Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	Nov. 14, 2014	Mar. 06, 2014	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	May. 06, 2015	May. 05, 2015
Authorized Capital
Common stock, shares authorized			400,000,000				200,000,000	400,000,000	200,000,000	400,000,000	200,000,000
Common stock, par value (in dollars per share)			$ 0.001				$ 0.001	$ 0.001	$ 0.001
Preferred stock shares authorized			5,000,000					5,000,000
Par value per share (in dollars per share)			$ 0.001					$ 0.001
Common Stock and Associated Warrant Liability
Warrants issued to purchase shares under private placement	64,311,112
Maximum contingent per share cash settlement price (in dollars per share)	$ 0.125
Fair value of warrant liability			$ 27,349				$ 30,430	$ 27,349	$ 30,430
Gain (loss) on change in fair value of warrant liability			2,729	$ 40,720	$ (43,016)	$ 2,648	(8,804)	3,081	(8,804)
Private Placement, November 2014
Common Stock and Associated Warrant Liability
Shares issued	64,311,112
Warrants issued to purchase shares under private placement	64,311,112
Net cash proceeds from public offering after deducting underwriting discounts and commissions and other offering expenses	$ 42,814
Exercise price (in dollars per share)	$ 0.85
Warrant term	4 years
Maximum contingent per share cash settlement price (in dollars per share)	$ 0.125
Fair value of warrant liability			$ 27,349				$ 30,430	$ 27,349	$ 30,430
Expected volatility of warrants (as a percent)								98.00%	91.00%
Risk free interest rate of warrants (as a percent)								1.40%	1.50%
Expected life of warrants								3 years 4 months 24 days	4 years 6 months
Expected dividends on warrants								$ 0	$ 0
Private Placement, March 2014
Common Stock and Associated Warrant Liability
Shares issued		11,976,048
Warrants issued to purchase shares under private placement		10,179,642
Net cash proceeds from public offering after deducting underwriting discounts and commissions and other offering expenses		$ 21,135
Warrant term		1 year

License Agreements (Details)

License Agreements (Details) - SARM License Agreement - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Jul. 31, 2007
Intangible assets, net
One-time up-front fee			$ 290
Intangible asset, net	$ 137	$ 152

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Deferred income tax assets:
Net federal and state operating loss carryforwards	$ 146,433	$ 139,126
Research and development credits	13,245	12,754
Share-based compensation	7,088	6,800
Depreciation and amortization	58	89
Other	37	69
Total deferred tax assets	166,861	158,838
Deferred income tax liabilities:
Other	251	329
Total deferred tax liabilities	251	329
Net deferred tax assets	166,610	158,509
Valuation allowance	(166,610)	(158,509)
Net deferred tax assets and liabilities	0	0
Valuation allowance disclosure
Increase in valuation allowance	8,101	$ 9,648	$ 17,318
Tax credits
Unrecognized tax benefits	0
Federal
Operating loss carryforwards
Net operating loss carryforwards	377,710
State
Operating loss carryforwards
Net operating loss carryforwards	353,519
Federal and State
Operating loss carryforwards
Deductions related to the exercise of stock options	$ 2,301

Directors' Deferred Compensat38

Directors' Deferred Compensation Plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Directors' deferred compensation plan
Non-employee director fee expense which was deferred into stock accounts	$ 113	$ 125	$ 135
Director
Directors' deferred compensation plan
Non-employee director fee expense	229	247	259
Non-employee director fee expense which was deferred into stock accounts	$ 113	$ 125	$ 135
Shares of common stock credited to individual director stock accounts under the Directors' Deferred Compensation Plan	361,005
Amount credited to individual director cash accounts under the Directors' Deferred Compensation Plan	$ 0

401(k) Plan (Details)

401(k) Plan (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)item	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
401(k) Plan
Maximum annual contribution per employee who is under the specified age in the current calendar year	$ 18
Age specified for current calendar year to determine employee's contribution | item	50
Maximum annual contribution per employee who is equal to specified age and older in the current calendar year	$ 24
Company's matching contribution to the plan	$ 189	$ 200	$ 338

Commitments and Contingencies (

Commitments and Contingencies (Details) - USD ($) $ in Thousands	May. 01, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Commitments and Contingencies
Initial term of lease arrangement	3 years
Rent expense under operating leases		$ 501	$ 513	$ 674
Option to extend lease	3 years
Operating Lease Commitments
2,016		466
2,017		475
2,018		$ 159

Quarterly Financial Data (Una41

Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Expenses:
Research and development expenses	$ 3,879	$ 3,824	$ 2,956	$ 2,948	$ 3,254	$ 3,362	$ 7,894	$ 6,360	$ 13,607	$ 20,870	$ 32,318
General and administrative expenses	2,079	2,039	2,005	2,111	2,203	1,594	3,052	2,629	8,234	9,478	11,281
Total expenses	5,958	5,863	4,961	5,059	5,457	4,956	10,946	8,989	21,841	30,348	43,599
Loss from operations	(5,958)	(5,863)	(4,961)	(5,059)	(5,457)	(4,956)	(10,946)	(8,989)	(21,841)	(30,348)	(43,599)
Other income (expense), net	(4)	9	25	27	(284)	21	2	2	57	(259)	1,488
Gain (loss) on change in fair value of warrant liability	2,729	40,720	(43,016)	2,648	(8,804)				3,081	(8,804)
Net loss	$ (3,233)	$ 34,866	$ (47,952)	$ (2,384)	$ (14,545)	$ (4,935)	$ (10,944)	$ (8,987)	$ (18,703)	$ (39,411)	$ (42,111)
Net income (loss) per share:
Basic (in dollars per share)	$ (0.02)	$ 0.25	$ (0.34)	$ (0.02)					$ (0.13)	$ (0.48)	$ (0.67)
Diluted (in dollars per share)	$ (0.04)	$ (0.04)	$ (0.34)	$ (0.02)					$ (0.15)	$ (0.48)	$ (0.67)
Net loss per share - basic and diluted (in dollars per share)					$ (0.13)	$ (0.06)	$ (0.15)	$ (0.14)
Weighted average shares outstanding:
Basic (in shares)	140,374,112	140,374,112	140,374,112	140,335,875					140,364,684	81,807,706	63,057,142
Diluted (in shares)	149,529,197	154,852,127	140,374,112	140,335,875					147,774,040	81,807,706	63,057,142
Basic and diluted (in shares)					108,869,121	76,014,531	75,433,302	66,512,069