Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2016	Nov. 04, 2016
Document and Entity Information
Entity Registrant Name	GTX INC /DE/
Entity Central Index Key	0001260990
Document Type	10-Q
Document Period End Date	Sep. 30, 2016
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		159,199,764
Document Fiscal Year Focus	2016
Document Fiscal Period Focus	Q3

CONDENSED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 8,238	$ 14,056
Short-term investments	5,200	15,200
Prepaid expenses and other current assets	2,096	2,633
Total current assets	15,534	31,889
Property and equipment, net	89	5
Intangible asset, net	126	137
Total assets	15,749	32,031
Current liabilities:
Accounts payable	1,223	382
Warrant liability		27,349
Accrued expenses and other current liabilities	2,141	2,441
Total current liabilities	3,364	30,172
Commitments and contingencies
Stockholders' equity:
Common stock, $0.001 par value: 400,000,000 shares authorized at September 30, 2016 and December 31, 2015; 141,915,817 and 140,374,112 shares issued and outstanding at September 30, 2016 and December 31, 2015, respectively	142	141
Additional paid-in capital	536,577	515,192
Accumulated deficit	(524,334)	(513,474)
Total stockholders' equity	12,385	1,859
Total liabilities and stockholders' equity	$ 15,749	$ 32,031

CONDENSED BALANCE SHEETS (Parenthetical) - $ / shares	Sep. 30, 2016	Dec. 31, 2015
CONDENSED BALANCE SHEETS
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	400,000,000	400,000,000
Common stock, shares issued	141,915,817	140,374,112
Common stock, shares outstanding	141,915,817	140,374,112

CONDENSED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
CONDENSED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Expenses:
Research and development expenses	$ 4,614	$ 3,824	$ 12,643	$ 9,728
General and administrative expenses	2,313	2,039	6,426	6,155
Total expenses	6,927	5,863	19,069	15,883
Loss from operations	(6,927)	(5,863)	(19,069)	(15,883)
Other income, net	13	9	46	61
Gain on change in fair value of warrant liability		40,720	8,163	352
Net income (loss)	$ (6,914)	$ 34,866	$ (10,860)	$ (15,470)
Net income (loss) per share:
Basic (in dollars per share)	$ (0.05)	$ 0.25	$ (0.08)	$ (0.11)
Diluted (in dollars per share)	$ (0.05)	$ (0.04)	$ (0.08)	$ (0.11)
Weighted average shares outstanding:
Basic (in shares)	141,892,266	140,374,112	141,721,778	140,361,507
Diluted (in shares)	141,892,266	154,852,127	141,721,778	140,361,507

CONDENSED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
CONDENSED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	Sep. 30, 2016	Sep. 30, 2015
Cash flows from operating activities:
Net loss	$ (10,860)	$ (15,470)
Adjustments to reconcile net loss to net cash used in operating activities:
Gain on change in fair value of warrant liability	(8,163)	(352)
Depreciation and amortization	17	36
Share-based compensation	2,318	1,868
Directors' deferred compensation	92	85
Changes in assets and liabilities:
Prepaid expenses and other assets	537	(1,994)
Accounts payable	841	(328)
Accrued expenses and other liabilities	(300)	1,324
Net cash used in operating activities	(15,518)	(14,831)
Cash flows from investing activities:
Purchase of property and equipment	(90)	(4)
Purchase of short-term investments, held to maturity	(22,400)	(40,219)
Proceeds from maturities of short-term investments, held to maturity	32,400	48,971
Net cash provided by investing activities	9,910	8,748
Cash flows from financing activities:
Tax payments related to shares withheld for vested restricted stock units	(210)
Net cash used in financing activities	(210)
Net decrease in cash and cash equivalents	(5,818)	(6,083)
Cash and cash equivalents, beginning of period	14,056	17,880
Cash and cash equivalents, end of period	$ 8,238	$ 11,797

Business and Basis of Presentation

9 Months Ended

Sep. 30, 2016

Business and Basis of Presentation

Business and Basis of Presentation

1. Business and Basis of Presentation

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 has 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. Based on these results, the Company commenced enrollment in 2015 in a Phase 2 clinical trial designed to evaluate the efficacy and safety of enobosarm in patients whose advanced breast cancer is both ER positive and AR positive. During 2015, the Company also commenced enrollment 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 (“TNBC”).

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 is currently implementing an appropriate development program for SARDs and has selected lead SARD compounds that are undergoing further preclinical development, including formulation and pharmacokinetic studies, required to support initial human clinical trials. While the Company plans to initiate first in human clinical trials in 2017, the Company will require additional funding to initiate and complete any such clinical trials.

Based on its current business plan and assumptions, the Company estimates that its current cash, cash equivalents and short-term investments (which includes the net proceeds from the Company’s October 2016 registered direct offering completed on October 14, 2016, which is described further in the “Subsequent Events” section of these Notes), together with interest thereon, will be sufficient to meet its projected operating requirements into the third quarter of 2017. Accordingly, the Company will need to raise substantial additional capital in order to fund its operations through and beyond the third quarter of 2017 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 it could need additional funding to sustain its operations even sooner than currently anticipated. The Company believes, based on its current estimates of clinical trial expenditures and enrollment status, that the Company’s existing capital resources will be adequate to enable it to complete its ongoing open-label Phase 2 clinical trial of enobosarm in patients with ER positive, AR positive advanced breast cancer and its ongoing Phase 2 clinical trial of enobosarm in postmenopausal women with SUI. However, the Company’s existing capital resources may not be sufficient to allow it to complete its ongoing open-label Phase 2 clinical trial of enobosarm in patients with advanced AR positive TNBC and the Company will otherwise need to raise substantial additional capital in order to continue developing enobosarm for any of these indications. If the Company determines that its existing capital resources are not sufficient to enable it to complete its ongoing open-label Phase 2 clinical trial of enobosarm in patients with advanced AR positive TNBC, the Company may be unable or unwilling to enroll patients into the second stage of this trial even if the Company determines that the first stage milestone has been met. Accordingly, in order to enroll the second stage of and to complete this trial, the Company may need to obtain additional funding, which the Company may be unable to do. Also, the Company’s clinical trials may continue to encounter technical, enrollment or other difficulties that could increase its development costs beyond its current estimates or delay its development timelines, and the Company could otherwise exhaust its available financial resources sooner than the Company expects. In any event, the Company will need to raise substantial additional capital in order to:

potentially enroll the second stage of and complete the Company’s ongoing open-label Phase 2 clinical trial of enobosarm in patients with advanced AR positive TNBC;

undertake any further development of the Company’s SARMs beyond its ongoing Phase 2 clinical trials of enobosarm in breast cancer and SUI and its ongoing preclinical development activities related to the development of SARMs as a potential treatment for DMD;

initiate and complete human clinical studies of the Company’s licensed SARD program; and

fund the Company’s operations and to continue as a going concern.

In addition, these condensed 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.

Basis of Presentation

The accompanying unaudited condensed financial statements reflect, in the opinion of management, all adjustments (consisting of normal recurring adjustments) necessary for a fair presentation of GTx’s financial position, results of operations and cash flows for each period presented in accordance with accounting principles generally accepted in the United States for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States have been condensed or omitted from the accompanying condensed financial statements. These interim condensed financial statements should be read in conjunction with the audited financial statements and related notes thereto, which are included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2015. Operating results for the three and nine months ended September 30, 2016 are not necessarily indicative of the results that may be expected for the entire fiscal year ending December 31, 2016.

Use of Estimates

The preparation of condensed financial statements in conformity with accounting principles generally accepted in the United States 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 condensed financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual amounts and results could differ from those estimates.

Warrant Liability

In November 2014, the Company issued warrants to purchase 64,311,112 shares of its common stock. The Company classified these warrants as a liability on its balance sheet since the warrants contained certain terms that could have required 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. As a result of the provision of the warrants requiring cash settlement upon certain change of control transactions, the Company was required to account for these warrants as a liability at fair value and the estimated warrant liability was 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. Effective March 25, 2016, each of the warrants was amended by agreement of the warrant holders to remove the provision that could require cash settlement upon certain change of control transactions. These warrants were no longer accounted for as a liability as of March 31, 2016. The Company recorded a non-cash reclassification of the warrant fair value to stockholders’ equity based on the warrants’ fair value as of the March 25, 2016 modification date, with no further adjustments to the fair value of these warrants being required.

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 prior warrant liability approximate their fair values. The fair value of the warrant liability was estimated using the Black-Scholes-Merton Model. See Note 4, 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

There were no assets or liabilities measured at fair value on a recurring basis as of September 30, 2016. Liabilities measured at fair value on a recurring basis as of December 31, 2015 included only the Company’s warrant liability of $27,349, which was classified within Level 3 of the hierarchy. A non-cash gain of $8,163 related to the change in the fair value of the warrant liability was recognized during the nine months ended September 30, 2016 in the Company’s condensed statement of operations.

As 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.

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.

Cash, Cash Equivalents and Short-term Investments

The Company considers highly liquid investments with initial maturities of three months or less to be cash equivalents.

At September 30, 2016 and December 31, 2015, short-term investments consisted of Federal Deposit Insurance Corporation insured certificates of deposit with original maturities of greater than three months and less than one year.

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 September 30, 2016 and December 31, 2015, net of the valuation allowance, the net deferred tax assets were reduced to zero. Income taxes are described more fully in Note 8 to the Company’s financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2015.

Other Income, net

Other income, net consists of foreign currency transaction gains and losses, interest earned on the Company’s cash, cash equivalents and short-term investments, and other non-operating income or expense.

Recent Accounting Pronouncements

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.

In March 2016, the Financial Accounting Standards Board issued Accounting Standard Update 2016-09, Improvements to Employee Share-Based Payment Accounting. The new guidance will require all income tax effects of awards to be recognized in the income statement when the awards vest or are settled. It will also allow an employer to repurchase more of an employee’s shares than it can today for tax withholding purposes without triggering liability accounting and to make a policy election to account for forfeitures as they occur. This new guidance is effective for fiscal years beginning after December 15, 2016 and interim periods within those years. The Company does not expect the adoption of the standard update to have a significant impact on its financial position or results of operations.

Subsequent Events

The Company has evaluated all events or transactions that occurred after September 30, 2016 up through the date the condensed financial statements were issued. Other than as set forth below, there were no material recognizable or nonrecognizable subsequent events during the period evaluated.

On October 14, 2016, the Company completed a registered direct offering of its common stock. Under the terms of the offering, the Company sold 17,283,947 shares of its common stock at a purchase price of $0.81 per share, which was the consolidated closing bid price of the Company’s common stock on October 11, 2016, the date that the Company entered into the definitive purchase agreements with the investors in the offering. The offering resulted in net proceeds to the Company of approximately $13,600, after deducting estimated offering expenses. The investors in the offering consisted of certain existing stockholders of the Company, including J.R. Hyde, III, its largest stockholder and the Lead Director of the Company’s Board of Directors (the “Board”), Robert J. Wills, the Board’s Executive Chairman, and Marc S. Hanover, the Company’s Chief Executive Officer and a member of the Board.

Share-Based Compensation

9 Months Ended

Sep. 30, 2016

Share-Based Compensation

Share-Based Compensation

2. Share-Based Compensation

Share-based payments include stock option grants and restricted stock units (“RSUs”) under the Company’s stock option and equity incentive plans and deferred compensation arrangements for the Company’s non-employee directors. 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 director is required to provide service in exchange for the award. The Company’s share-based compensation plans are described more fully in Note 3 to the Company’s financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2015.

The following table summarizes share-based compensation expense included within the condensed statements of operations for the three and nine months ended September 30, 2016 and 2015:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2016		2015		2016		2015
Research and development expenses	$	391	$	331	$	1,054	$	857
General and administrative expenses	461		423		1,356		1,096

Total share-based compensation	$	852	$	754	$	2,410	$	1,953

Share-based compensation expense recorded as general and administrative expense for the three months ended September 30, 2016 and 2015 included share-based compensation expense related to deferred compensation arrangements for the Company’s non-employee directors of $33 and $27, respectively. Share-based compensation expense recorded as general and administrative expense for the nine months ended September 30, 2016 and 2015 included share-based compensation expense related to deferred compensation arrangements for the Company’s non-employee directors of $92 and $85, respectively.

The Company uses the Black-Scholes Model to value stock options. The expected life of options is determined by calculating the average of the vesting term and the contractual term of the options. The expected price volatility is based on the Company’s historical stock price volatility. The risk-free interest rate is determined using U.S. Treasury rates where the term is consistent with the expected life of the stock options. Expected dividend yield is not considered as the Company has not made any dividend payments and has no plans of doing so in the foreseeable future. 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.

The fair value of options granted was estimated using the following assumptions for the periods presented:

	Three Months Ended September 30,		Nine Months Ended September 30,
	2016	2015	2016	2015
Expected price volatility	89.4%	88.1%	91.3%	89.6%
Risk-free interest rate	1.2%	2.1%	2.0%	1.6%
Weighted average expected life in years	6.0 years	7.0 years	6.9 years	6.0 years

The following is a summary of stock option transactions for all of the Company’s stock option and equity incentive plans since the Company’s most recent fiscal year end:

	Number of Shares		Weighted Average Exercise Price Per Share
Options outstanding at December 31, 2015	7,983,168		$	3.88
Options granted	3,635,000		0.69
Options forfeited or expired	(487,501	)	4.38
Options exercised	—		—

Options outstanding at September 30, 2016	11,130,667		2.82

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 Company estimates the fair value of RSUs using the closing price of its stock on the grant date. The fair value of RSUs is amortized on a straight-line basis over the requisite service period of the awards. The following is a summary of the RSU transactions for all of the Company’s equity incentive plans since the Company’s most recent fiscal year end:

	Number of Shares
Nonvested RSUs at December 31, 2015	8,200,000
RSUs granted	110,000
RSUs vested	(1,840,001	)
RSUs forfeited	(380,000	)

Nonvested RSUs at September 30, 2016	6,089,999

- Definition

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.

+ References + Details

Basic and Diluted Net Loss Per Share

9 Months Ended

Sep. 30, 2016

Basic and Diluted Net Loss Per Share

Basic and Diluted Net Loss Per Share

3.Basic and Diluted Net Loss Per Share

Basic and diluted net loss per share attributable to common stockholders is calculated based on the weighted average number of common shares outstanding during the period. Diluted net loss per share gives effect to the dilutive potential of common stock consisting of stock options, unvested RSUs and common stock warrants. The calculation of diluted loss per share for the three months ended September 30, 2015 also required that since the average market price of the underlying shares for the reporting period exceeded the exercise price of the warrants and the presumed exercise of such warrants were dilutive to net income per share for the period, adjustments to net income were required to remove the change in fair value of the warrant liability for the period.

	Three Months Ended						Nine Months Ended
	September 30,						September 30,
	2016			2015			2016			2015
Basic and diluted net income (loss) per share
Numerator:

Net income (loss) — basic	$	(6,914	)	$	34,866		$	(10,860	)	$	(15,470	)
Adjustments for the gain on change in fair value of the warrant liability	—			(40,720		)	—			—

Net loss — diluted	(6,914		)	(5,854		)	(10,860		)	(15,470		)


Denominator:
Weighted average shares outstanding — basic	141,892,266			140,374,112			141,721,778			140,361,507
Dilutive warrants	—			11,955,547			—			—
Dilutive restricted stock units	—			2,499,629			—			—
Dilutive stock options	—			22,839			—			—

Weighted average shares outstanding — diluted	141,892,266			154,852,127			141,721,778			140,361,507


Net income (loss) per share:
Basic	$	(0.05	)	$	0.25		$	(0.08	)	$	(0.11	)

Diluted	$	(0.05	)	$	(0.04	)	$	(0.08	)	$	(0.11	)


Weighted average shares outstanding:
Basic	141,892,266			140,374,112			141,721,778			140,361,507

Diluted	141,892,266			154,852,127			141,721,778			140,361,507

Weighted average potential shares of common stock of 81,515,013 and 8,609,193 for the three months ended September 30, 2016 and 2015, respectively, and 81,697,936 and 81,364,457 for the nine months ended September 30, 2016 and 2015, respectively, were excluded from the calculations of diluted net loss per share as inclusion of the potential shares would have had an anti-dilutive effect on the net loss per share for the periods.

Stockholders' Equity	9 Months Ended
Stockholders' Equity	Sep. 30, 2016
Stockholders' Equity
Stockholders' Equity	4.Stockholders’ Equity 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, also contained certain terms that could have required 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 have required cash settlement upon certain change of control transactions, the Company was required to account for these warrants as a liability at fair value using the Black-Scholes Model and the estimated warrant liability was 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. Effective March 25, 2016, each of the warrants was amended by agreement of the warrant holders to remove the provision that could require cash settlement upon certain change of control transactions. These warrants were no longer accounted for as a liability at March 31, 2016. The Company recorded a non-cash reclassification of the warrant fair value to stockholders’ equity based on the warrants’ fair value as of the March 25, 2016 modification date, with no further adjustments to the fair value of these warrants being required. The fair value of the warrants on the March 25, 2016 modification date of $19,186 was estimated using the Black-Scholes Model with the following assumptions: expected volatility of 101%, risk-free interest rate of 1.1%, expected life of approximately 3.1 years and no dividends. 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 decrease in fair value from December 31, 2015 to March 25, 2016 of $8,163 was recorded as a non-cash gain on the change in fair value of warrant liability in the Company’s statement of operations for the nine months ended September 30, 2016. 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.

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SAB Topic 4.E)
-URI http://asc.fasb.org/extlink&oid=27010918&loc=d3e74567-122707

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21484-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21488-112644

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
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-Paragraph 1
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+ Details

University of Tennessee Research Foundation License Agreements	9 Months Ended
	Sep. 30, 2016
University of Tennessee Research Foundation License Agreements
University of Tennessee Research Foundation License Agreements	5.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 was 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. The Company and UTRF also entered into a license agreement (the “SARD 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. 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.

Business and Basis of Presentation (Policies)	9 Months Ended
Business and Basis of Presentation (Policies)	Sep. 30, 2016
Business and Basis of Presentation
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed financial statements reflect, in the opinion of management, all adjustments (consisting of normal recurring adjustments) necessary for a fair presentation of GTx’s financial position, results of operations and cash flows for each period presented in accordance with accounting principles generally accepted in the United States for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States have been condensed or omitted from the accompanying condensed financial statements. These interim condensed financial statements should be read in conjunction with the audited financial statements and related notes thereto, which are included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2015. Operating results for the three and nine months ended September 30, 2016 are not necessarily indicative of the results that may be expected for the entire fiscal year ending December 31, 2016.
Use of Estimates	Use of Estimates The preparation of condensed financial statements in conformity with accounting principles generally accepted in the United States 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 condensed financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual amounts and results could differ from those estimates.
Warrant Liability	Warrant Liability In November 2014, the Company issued warrants to purchase 64,311,112 shares of its common stock. The Company classified these warrants as a liability on its balance sheet since the warrants contained certain terms that could have required 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. As a result of the provision of the warrants requiring cash settlement upon certain change of control transactions, the Company was required to account for these warrants as a liability at fair value and the estimated warrant liability was 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. Effective March 25, 2016, each of the warrants was amended by agreement of the warrant holders to remove the provision that could require cash settlement upon certain change of control transactions. These warrants were no longer accounted for as a liability as of March 31, 2016. The Company recorded a non-cash reclassification of the warrant fair value to stockholders’ equity based on the warrants’ fair value as of the March 25, 2016 modification date, with no further adjustments to the fair value of these warrants being required.
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 prior warrant liability approximate their fair values. The fair value of the warrant liability was estimated using the Black-Scholes-Merton Model. See Note 4, 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 There were no assets or liabilities measured at fair value on a recurring basis as of September 30, 2016. Liabilities measured at fair value on a recurring basis as of December 31, 2015 included only the Company’s warrant liability of $27,349, which was classified within Level 3 of the hierarchy. A non-cash gain of $8,163 related to the change in the fair value of the warrant liability was recognized during the nine months ended September 30, 2016 in the Company’s condensed statement of operations. As 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.
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.
Cash, Cash Equivalents and Short-term Investments	Cash, Cash Equivalents and Short-term Investments The Company considers highly liquid investments with initial maturities of three months or less to be cash equivalents. At September 30, 2016 and December 31, 2015, short-term investments consisted of Federal Deposit Insurance Corporation insured certificates of deposit with original maturities of greater than three months and less than one year.
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 September 30, 2016 and December 31, 2015, net of the valuation allowance, the net deferred tax assets were reduced to zero. Income taxes are described more fully in Note 8 to the Company’s financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2015.
Other Income, net	Other Income, net Other income, net consists of foreign currency transaction gains and losses, interest earned on the Company’s cash, cash equivalents and short-term investments, and other non-operating income or expense.
Recent Accounting Pronouncements	Recent Accounting Pronouncements 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. In March 2016, the Financial Accounting Standards Board issued Accounting Standard Update 2016-09, Improvements to Employee Share-Based Payment Accounting. The new guidance will require all income tax effects of awards to be recognized in the income statement when the awards vest or are settled. It will also allow an employer to repurchase more of an employee’s shares than it can today for tax withholding purposes without triggering liability accounting and to make a policy election to account for forfeitures as they occur. This new guidance is effective for fiscal years beginning after December 15, 2016 and interim periods within those years. The Company does not expect the adoption of the standard update to have a significant impact on its financial position or results of operations.
Subsequent Events	Subsequent Events The Company has evaluated all events or transactions that occurred after September 30, 2016 up through the date the condensed financial statements were issued. Other than as set forth below, there were no material recognizable or nonrecognizable subsequent events during the period evaluated. On October 14, 2016, the Company completed a registered direct offering of its common stock. Under the terms of the offering, the Company sold 17,283,947 shares of its common stock at a purchase price of $0.81 per share, which was the consolidated closing bid price of the Company’s common stock on October 11, 2016, the date that the Company entered into the definitive purchase agreements with the investors in the offering. The offering resulted in net proceeds to the Company of approximately $13,600, after deducting estimated offering expenses. The investors in the offering consisted of certain existing stockholders of the Company, including J.R. Hyde, III, its largest stockholder and the Lead Director of the Company’s Board of Directors (the “Board”), Robert J. Wills, the Board’s Executive Chairman, and Marc S. Hanover, the Company’s Chief Executive Officer and a member of the Board.

Share-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2016

Share-Based Compensation

Summary of share-based compensation expense

	Three Months Ended September 30,				Nine Months Ended September 30,
	2016		2015		2016		2015
Research and development expenses	$	391	$	331	$	1,054	$	857
General and administrative expenses	461		423		1,356		1,096

Total share-based compensation	$	852	$	754	$	2,410	$	1,953

Schedule of assumptions used to estimate fair value of options

	Three Months Ended September 30,		Nine Months Ended September 30,
	2016	2015	2016	2015
Expected price volatility	89.4%	88.1%	91.3%	89.6%
Risk-free interest rate	1.2%	2.1%	2.0%	1.6%
Weighted average expected life in years	6.0 years	7.0 years	6.9 years	6.0 years

Summary of stock option transactions

	Number of Shares		Weighted Average Exercise Price Per Share
Options outstanding at December 31, 2015	7,983,168		$	3.88
Options granted	3,635,000		0.69
Options forfeited or expired	(487,501	)	4.38
Options exercised	—		—

Options outstanding at September 30, 2016	11,130,667		2.82

Summary of RSU transactions

	Number of Shares
Nonvested RSUs at December 31, 2015	8,200,000
RSUs granted	110,000
RSUs vested	(1,840,001	)
RSUs forfeited	(380,000	)

Nonvested RSUs at September 30, 2016	6,089,999

Basic and Diluted Net Loss Per Share (Tables)

9 Months Ended

Sep. 30, 2016

Basic and Diluted Net Loss Per Share

Schedule of basic and diluted net income (loss) per share

	Three Months Ended						Nine Months Ended
	September 30,						September 30,
	2016			2015			2016			2015
Basic and diluted net income (loss) per share
Numerator:

Net income (loss) — basic	$	(6,914	)	$	34,866		$	(10,860	)	$	(15,470	)
Adjustments for the gain on change in fair value of the warrant liability	—			(40,720		)	—			—

Net loss — diluted	(6,914		)	(5,854		)	(10,860		)	(15,470		)


Denominator:
Weighted average shares outstanding — basic	141,892,266			140,374,112			141,721,778			140,361,507
Dilutive warrants	—			11,955,547			—			—
Dilutive restricted stock units	—			2,499,629			—			—
Dilutive stock options	—			22,839			—			—

Weighted average shares outstanding — diluted	141,892,266			154,852,127			141,721,778			140,361,507


Net income (loss) per share:
Basic	$	(0.05	)	$	0.25		$	(0.08	)	$	(0.11	)

Diluted	$	(0.05	)	$	(0.04	)	$	(0.08	)	$	(0.11	)


Weighted average shares outstanding:
Basic	141,892,266			140,374,112			141,721,778			140,361,507

Diluted	141,892,266			154,852,127			141,721,778			140,361,507

Business and Basis of Presentation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	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
Gain on change in fair value of warrant liability	$ (40,720)	$ (8,163)	$ (352)
Income Taxes
Net deferred tax assets		0		0
Fair Value Measurements, Recurring
Income Taxes
Assets measured at fair value		0
Liabilities measured at fair value		0
Fair Value Measurements, Recurring \| Level 3
Warrant Liability
Warrant liability				$ 27,349
Gain on change in fair value of warrant liability		$ (8,163)

Business and Basis of Presentation - Subsequent Events (Details) - Subsequent Event - Common Stock - Registered direct offering $ / shares in Units, $ in Thousands	Oct. 14, 2016 USD ($) $ / shares shares
Subsequent Events
Number of shares sold \| shares	17,283,947
Share price (in dollars per share) \| $ / shares	$ 0.81
Net cash proceeds from registered direct offering after deducting estimated offering expenses \| $	$ 13,600

Share-Based Compensation - Share-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Share-based compensation expense
Total share-based compensation	$ 852	$ 754	$ 2,410	$ 1,953
Share-based compensation expense related to deferred compensation arrangements for non-employee directors			92	85
Research and development expenses
Share-based compensation expense
Total share-based compensation	391	331	1,054	857
General and administrative expenses
Share-based compensation expense
Total share-based compensation	461	423	1,356	1,096
Director \| General and administrative expenses
Share-based compensation expense
Share-based compensation expense related to deferred compensation arrangements for non-employee directors	$ 33	$ 27	$ 92	$ 85

Share-Based Compensation - Stock Option Activity (Details) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Fair value of options granted
Expected price volatility (as a percent)	89.40%	88.10%	91.30%	89.60%
Risk-free interest rate (as a percent)	1.20%	2.10%	2.00%	1.60%
Weighted average expected life in years	6 years	7 years	6 years 10 months 24 days	6 years
Number of Shares
Options outstanding at the beginning of the period (in shares)			7,983,168
Options granted (in shares)			3,635,000
Options forfeited or expired (in shares)			(487,501)
Options outstanding at the end of the period (in shares)	11,130,667		11,130,667
Weighted Average Exercise Price Per Share
Options outstanding at the beginning of the period (in dollars per share)			$ 3.88
Options granted (in dollars per share)			0.69
Options forfeited or expired (in dollars per share)			4.38
Options outstanding at the end of the period (in dollars per share)	$ 2.82		$ 2.82

Share-Based Compensation - RSU Activity - (Details) - Restricted Stock Units (RSUs) - shares	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Number of Shares
Vesting period	3 years
Nonvested RSUs at the beginning of the period (in shares)	8,200,000
RSUs granted (in shares)	110,000	8,200,000
RSUs vested (in shares)	(1,840,001)
RSUs forfeited (in shares)	(380,000)
Nonvested RSUs at the end of the period (in shares)	6,089,999	8,200,000

Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Numerator:
Net income (loss) -- basic	$ (6,914)	$ 34,866	$ (10,860)	$ (15,470)
Adjustments for the gain on change in fair value of the warrant liability		(40,720)
Net loss -- diluted	$ (6,914)	$ (5,854)	$ (10,860)	$ (15,470)
Denominator:
Weighted average shares outstanding - basic	141,892,266	140,374,112	141,721,778	140,361,507
Dilutive warrants (in shares)		11,955,547
Dilutive restricted stock units (in shares)		2,499,629
Dilutive stock options (in shares)		22,839
Weighted average shares outstanding - diluted	141,892,266	154,852,127	141,721,778	140,361,507
Net income (loss) per share
Basic (in dollars per share)	$ (0.05)	$ 0.25	$ (0.08)	$ (0.11)
Diluted (in dollars per share)	$ (0.05)	$ (0.04)	$ (0.08)	$ (0.11)
Weighted average shares outstanding:
Basic (in shares)	141,892,266	140,374,112	141,721,778	140,361,507
Diluted (in shares)	141,892,266	154,852,127	141,721,778	140,361,507
Weighted average potential shares of common stock excluded from calculation of diluted net loss per share	81,515,013	8,609,193	81,697,936	81,364,457

Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands				3 Months Ended	9 Months Ended		12 Months Ended
	Mar. 25, 2016	Nov. 14, 2014	Mar. 06, 2014	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
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
Gain on change in fair value of warrant liability				$ 40,720	$ 8,163	$ 352
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 registered direct offering after deducting estimated 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	$ 19,186						$ 27,349
Expected volatility of warrants (as a percent)	101.00%						98.00%
Risk free interest rate of warrants (as a percent)	1.10%						1.40%
Expected life of warrants	3 years 1 month 6 days						3 years 4 months 24 days
Expected dividends on warrants	$ 0						$ 0
Gain on change in fair value of warrant liability					$ 8,163
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 registered direct offering after deducting estimated offering expenses			$ 21,135
Warrant term			1 year