Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2019	May 06, 2019
Document and Entity Information
Entity Registrant Name	GTX INC /DE/
Entity Central Index Key	0001260990
Document Type	10-Q
Document Period End Date	Mar. 31, 2019
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		24,051,844
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1

CONDENSED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 21,012	$ 28,258
Short-term Investments	175	200
Prepaid expenses and other current assets	1,347	2,750
Total current assets	22,534	31,208
Property and equipment, net	12	19
Intangible assets, net	90	94
Total assets	22,636	31,321
Current liabilities:
Accounts payable	609	3,279
Accrued expenses and other current liabilities	1,210	1,931
Total current liabilities	1,819	5,210
Commitments and contingencies
Stockholders' equity:
Common stock, $0.001 par value: 60,000,000 shares authorized at March 31, 2019 and December 31, 2018; 24,051,844 and 24,051,844 shares issued and outstanding at March 31, 2019 and December 31, 2018, respectively	24	24
Additional paid-in capital	626,650	626,142
Accumulated deficit	(605,857)	(600,055)
Total stockholders' equity	20,817	26,111
Total liabilities and stockholders' equity	$ 22,636	$ 31,321

CONDENSED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2019	Dec. 31, 2018
CONDENSED BALANCE SHEETS
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	60,000,000	60,000,000
Common stock, shares issued	24,051,844	24,051,844
Common stock, shares outstanding	24,051,844	24,051,844

CONDENSED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended
CONDENSED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	Mar. 31, 2019	Mar. 31, 2018
Expenses:
Research and development expenses	$ 2,434	$ 11,000
General and administrative expenses	3,507	2,688
Total expenses	5,941	13,688
Loss from operations	(5,941)	(13,688)
Other income, net	139	131
Net loss	$ (5,802)	$ (13,557)
Net loss per share:
Net loss per share -- basic and diluted (in dollars per share)	$ (0.24)	$ (0.62)
Weighted average shares outstanding:
Weighted average shares outstanding - basic and diluted (in shares)	24,051,844	21,967,805

CONDENSED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Total
Balance at Dec. 31, 2017	$ 22	$ 599,876	$ (561,637)	$ 38,261
Balance (in shares) at Dec. 31, 2017	21,541,909
Increase (Decrease) in Stockholders' Equity
Issuance of common stock upon exercise of warrants	$ 1	(1)
Issuance of common stock upon exercise of warrants (in shares)	674,579
Vesting of restricted stock units, net of share withheld for tax payments		(643)		(643)
Vesting of restricted stock units, net of share withheld for tax payments (in shares)	313,202
Directors' deferred compensation		42		42
Share-based compensation		646		646
Net loss			(13,557)	(13,557)
Balance at Mar. 31, 2018	$ 23	599,920	(575,194)	24,749
Balance (in shares) at Mar. 31, 2018	22,529,690
Balance at Dec. 31, 2018	$ 24	626,142	(600,055)	$ 26,111
Balance (in shares) at Dec. 31, 2018	24,051,844			24,051,844
Increase (Decrease) in Stockholders' Equity
Directors' deferred compensation		28		$ 28
Share-based compensation		480		480
Net loss			(5,802)	(5,802)
Balance at Mar. 31, 2019	$ 24	$ 626,650	$ (605,857)	$ 20,817
Balance (in shares) at Mar. 31, 2019	24,051,844			24,051,844

CONDENSED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
CONDENSED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	Mar. 31, 2019	Mar. 31, 2018
Cash flows from operating activities:
Net loss	$ (5,802)	$ (13,557)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	11	11
Share-based compensation	480	646
Directors' deferred compensation	28	42
Changes in assets and liabilities:
Prepaid expenses and other assets	1,403	111
Accounts payable	(2,670)	(865)
Accrued expenses and other liabilities	(721)	2,500
Net cash used in operating activities	(7,271)	(11,112)
Cash flows from investing activities:
Purchase of short-term investments, held to maturity	(175)	(5,106)
Proceeds from maturities of short-term investments, held to maturity	200	16,003
Net cash provided by investing activities	25	10,897
Cash flows from financing activities:
Tax payments related to shares withheld for vested restricted stock units		(643)
Net cash used in financing activities		(643)
Net decrease in cash and cash equivalents	(7,246)	(858)
Cash and cash equivalents, beginning of period	28,258	15,816
Cash and cash equivalents, end of period	$ 21,012	$ 14,958

Pending Merger with Oncternal Therapeutics, Inc.	3 Months Ended
Pending Merger with Oncternal Therapeutics, Inc.	Mar. 31, 2019
Pending Merger with Oncternal Therapeutics, Inc.
Pending Merger with Oncternal Therapeutics, Inc.	1. Pending Merger with Oncternal Therapeutics, Inc. Merger Agreement On March 6, 2019, GTx, Inc. (“GTx” or the “Company”) entered into an Agreement and Plan of Merger and Reorganization, as amended by Amendment No. 1 to Agreement and Plan of Merger and Reorganization dated April 30, 2019 (the “Merger Agreement”), with Oncternal Therapeutics, Inc., a Delaware corporation (“Oncternal”), and Grizzly Merger Sub, Inc., a Delaware corporation and wholly-owned subsidiary of GTx (“Merger Sub”). Upon the terms and subject to the satisfaction of the conditions described in the Merger Agreement, including approval of the transaction by the Company's stockholders and Oncternal's stockholders, Merger Sub will be merged with and into Oncternal (the “Merger”), with Oncternal surviving the Merger as a wholly-owned subsidiary of the Company. Subject to the terms and conditions of the Merger Agreement, at the effective time of the Merger (the “Effective Time”): (i) each share of Oncternal common stock outstanding immediately prior to the Effective Time (excluding shares held by the Company, Merger Sub or Oncternal and dissenting shares) will be converted solely into the right to receive a number of shares of the Company's common stock equal to the exchange ratio described below, (ii) each outstanding Oncternal stock option will be assumed by the Company, and (iii) each outstanding Oncternal warrant will be assumed by the Company. Under the exchange ratio formula in the Merger Agreement, the former Oncternal stockholders immediately before the Merger are expected to own approximately 77.5% of the outstanding capital stock of the Company, and the stockholders of the Company immediately before the Merger are expected to own approximately 22.5% of the outstanding capital stock of the Company, subject to certain assumptions. The exchange ratio formula excludes Oncternal’s outstanding stock options and warrants and the Company's outstanding stock options and warrants. Under certain circumstances further described in the Merger Agreement, the ownership percentages may be adjusted upward or downward based on cash levels of the respective companies at the closing of the Merger (the "Closing"). The Merger Agreement contains customary representations, warranties and covenants made by the Company and Oncternal, including covenants relating to obtaining the requisite approvals of the stockholders of the Company and Oncternal, indemnification of directors and officers, the Company's and Oncternal's conduct of their respective businesses between the date of signing of the Merger Agreement and the Closing. The Closing is subject to satisfaction or waiver of certain conditions included in the Merger Agreement. Following the Closing, Oncternal's Chief Executive Officer, Chief Financial Officer, and Chief Operating Officer will serve in these positions for the Company. Additionally, following the Closing, the Company's board of directors will consist of nine directors, including two current GTx board members. The Merger Agreement also includes termination provisions for both the Company and Oncternal. In connection with a termination of the Merger Agreement under specified circumstances, either party may be required to pay the other party a termination fee ranging between $500 to $2,000. Contingent Value Rights Agreement At the Effective Time, the Company will enter into a Contingent Value Rights Agreement (the "CVR Agreement"). Pursuant to the CVR Agreement, for each share of the Company's common stock held, the Company's stockholders of record as of immediately prior to the Effective Time will receive one contingent value right ("CVR") entitling such holders to receive in the aggregate 75% of any net proceeds received during the 15-year period after the Closing from the grant, sale or transfer of rights to the Company’s selective androgen receptor degrader (“SARD”) or selective androgen receptor modulator (“SARM”) technology that occurs during the 10-year period after the Closing (or in the 11th year if based on a term sheet approved during the initial 10-year period) and, if applicable, to receive royalties on the sale of any SARD or SARM products by the combined company during the 15-year period after the Closing. The CVR Agreement will be effective prior to the Closing and will continue in effect until the payment of all amounts payable thereunder, unless terminated upon termination of the Merger Agreement.

Business and Basis of Presentation	3 Months Ended
Business and Basis of Presentation	Mar. 31, 2019
Business and Basis of Presentation
Business and Basis of Presentation	2. Business and Basis of Presentation GTx, 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 medicines to treat serious and/or significant unmet medical conditions. In 2015, the Company entered into an exclusive license agreement with the University of Tennessee Research Foundation (“UTRF”) to develop UTRF’s proprietary SARD technology which the Company believes may have the potential to provide compounds that can degrade or antagonize multiple forms of androgen receptor to treat those patients who do not respond or are resistant to current androgen targeted therapies by inhibiting tumor growth in patients with progressive castration-resistant prostate cancer (“CRPC”). The Company has been conducting preclinical studies to determine if it can identify an appropriate SARD compound to move forward into additional preclinical studies required for the potential submission of an investigational new drug application (“IND”) to enable the initiation of a first-in-human clinical trial, if any. However, the Company recently received and evaluated new preclinical data from an independent laboratory of an academic researcher engaged by the Company, which, among other things, showed that at higher dose concentrations, the SARD compounds tested by the independent laboratory demonstrated partial androgen receptor agonist activity. The academic researcher pointed out that if these results translate to the clinical setting where there is little or no dose separation between antagonist activity and agonist activity, the future of the SARD program as an effective treatment of men with CRPC would likely not be viable. This information (the “Recent SARD Information”) was in conflict with other independent laboratory preclinical data previously received by GTx senior management and with internal preclinical data generated by the Company, that included: (1) conflicting in vitro data showing either partial agonist activity or no partial agonist activity, (2) in vivo data showing no evidence of agonist activity, and (3) data from another independent laboratory showing the dose-dependent suppression of enzalutamide-resistant prostate cancer tumors in a rat xenograft model. Considering this conflicting information, it was concluded that additional preclinical studies were required to better understand SARDs and their mechanism of action, and to reconcile the conflicting in vitro and in vivo findings. Accordingly, additional preclinical research would be required in order to determine whether an appropriate SARD compound can potentially be advanced into any IND-enabling preclinical studies. The Company had been developing SARMs, including enobosarm (GTx-024). Most recently, enobosarm was evaluated in post-menopausal women with stress urinary incontinence (“SUI”) compared to placebo. During the third quarter of 2018, the Company announced that the Phase 2 double-blind, placebo-controlled clinical trial of orally-administered enobosarm (3 mg or 1 mg) in post-menopausal women with SUI (the “ASTRID trial”) did not achieve statistical significance on the primary endpoint for the trial. The Company has completed the ASTRID trial, including its review of the full data sets from the clinical trial, and has determined that there is not a sufficient path forward to warrant additional clinical development of enobosarm to treat SUI. The Company has therefore discontinued further development of enobosarm to treat SUI, including discontinuing the related durability and open-label safety extension studies the Company initiated before it received topline data from the ASTRID trial. The Company has also discontinued any further development of its SARM technology generally. Following the announcement of the ASTRID trial results, the Company’s board of directors commenced a process of evaluating strategic alternatives to maximize stockholder value. To assist with this process, the Company’s board of directors engaged a financial advisory firm to help explore the Company’s available strategic alternatives, including possible mergers and business combinations, a sale of part or all of the Company’s assets, and collaboration and licensing arrangements. On March 6, 2019, the Company and Oncternal announced the signing of the Agreement and Plan of Merger and Reorganization, dated March 6, 2019, by and among the Company, Merger Sub and Oncternal (the “Original Merger Agreement”). See Note 1, Pending Merger with Oncternal Therapeutics, Inc., for further discussion regarding the Merger. On April 30, 2019, the Company entered into an Amendment No. 1 to the Original Merger Agreement (the “Merger Agreement Amendment”) with Oncternal and Merger Sub, as described in more detail in Note 2, Business and Basis of Presentation – Subsequent Events. At March 31, 2019, the Company had cash, cash equivalents and short-term investments of $21,187 compared to $28,458 at December 31, 2018. To conserve its cash resources, the Company has substantially reduced its workforce since November 2018 and has ceased its SARM development activities and all other operations except for day-to-day business operations, completing ongoing SARD preclinical studies and those activities necessary to complete the Merger. 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 filed with the Securities and Exchange Commission on March 18, 2019. Operating results for the three months ended March 31, 2019 are not necessarily indicative of the results that may be expected for the entire fiscal year ending December 31, 2019. 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. Fair Value of Financial Instruments The carrying amounts of the Company’s financial instruments (which include cash, cash equivalents, short-term investments, and accounts payable) approximate their fair values. 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 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 March 31, 2019 and December 31, 2018, 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 March 31, 2019 and December 31, 2018, 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 filed with the Securities and Exchange Commission on March 18, 2019. Other Income, net Other income, net consists of interest earned on the Company’s cash, cash equivalents and short-term investments, foreign currency transaction gains and losses, and other non-operating income or expense. Accounting Pronouncements Recently Adopted In February 2016, the Financial Accounting Standards Board issued Accounting Standard Update (“ASU”) 2016-02, Leases (Topic 842) (“ASU 2016-02”). This ASU requires that lessees recognize assets and liabilities on the balance sheet for the present value of the rights and obligations created by all leases with terms of more than 12 months. On January 1, 2019, the Company adopted the provisions of ASU 2016-02 under the transition method under which comparative financial information is not restated and continues to apply the provisions of the previous lease accounting standard in its financial disclosures for the comparative periods. The Company also elected the package of practical expedients permitted under the transition guidance, which among other things, allowed it to carry forward the historical lease classification. The Company leases office space under a lease that 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, which was accounted for as an operating lease. In March 2018, the Company amended the lease to extend the term of the lease for an additional 12-month term expiring on April 30, 2019. For this operating lease, the Company recorded a right-of-use asset and corresponding lease liability of $41, which were included in other current assets and other current liabilities, respectively, in the condensed balance sheet for the three months ended March 31, 2019. The adoption of ASU 2016-02 did not affect the Company’s condensed statement of operations or condensed statement of cash flows. The Company recorded lease expense of $121 in general and administrative expenses and paid cash in the amount of $121 during the three months ended March 31, 2019. Subsequent Events The Company has evaluated all events or transactions that occurred after March 31, 2019 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. Pending Merger with Oncternal In connection with the Company’s receipt of the Recent SARD Information and Oncternal’s evaluation of the Recent SARD Information, on April 30, 2019, the Company entered into Merger Agreement Amendment with Oncternal and Merger Sub. The Merger Agreement Amendment amended certain of the terms of the Original Merger Agreement by, among other things: (i) amending the exchange ratio formula such that the former Oncternal stockholders immediately before the Merger are expected to own approximately 77.5% of the outstanding capital stock of GTx rather than 75% as set forth in the Original Merger Agreement; (ii) amending the exchange ratio formula such that the GTx stockholders immediately before the Merger are expected to own approximately 22.5% of the outstanding capital stock of GTx rather than 25% as set forth in the Original Merger Agreement; (iii) amending the calculation of GTx’s cash balance at the Closing such that the cash balance will not be reduced by payments of GTx’s transaction expenses or any other costs or payments by GTx triggered by the transactions contemplated by the Merger Agreement or pursuant to any of GTx’s benefit plans; and (iv) amending GTx’s and Oncternal’s target cash amount used for purposes of determining whether there will be an adjustment to the ownership of GTx’s stockholders in the calculation of the exchange ratio formula. Except as set forth above, the material terms of the Merger Agreement are substantially the same as the terms of the Original Merger Agreement. On April 30, 2019, the form of the Contingent Value Rights Agreement to be entered into at the Effective Time was also amended in connection with the Merger Agreement Amendment (as such form has been amended, the “Amended Form CVR Agreement”). The original agreed upon form of the CVR Agreement (the “Original Form CVR Agreement”) was amended to provide, among other things: (i) that for each share of GTx common stock held, GTx’s stockholders of record as of immediately prior to the Effective Time will receive one contingent value right entitling such holders to receive in the aggregate 75% (rather than 50% as provided for in the Original Form CVR Agreement) of any net proceeds received during the 15-year period after the Closing from the grant, sale or transfer of rights to GTx’s SARD or SARM technology that occurs during the 10-year period after the Closing (or in the 11th year if based on a term sheet approved during the initial 10-year period); and (ii) that instead of using commercially reasonable efforts to develop SARD products, as provided in the Original Form of CVR Agreement, Oncternal (as successor in interest to GTx) will use commercially reasonable efforts, in its sole discretion, either to develop SARD products or to divest SARD technology, subject to certain limitations. Except as set forth above, the material terms of the Amended Form CVR Agreement are substantially the same as the terms of the Original Form CVR Agreement. Litigation Related to the Merger Between April 10, 2019 and May 7, 2019, six purported stockholder class action lawsuits were filed, naming as defendants the Company and the Company’s board of directors. Collectively, these lawsuits allege, among other things, violations of Sections 14(a) and 20(a) of the Exchange Act, as well as Rule 14a-9 promulgated thereunder, in connection with the filing of the registration statement on Form S-4 that the Company filed with the SEC in connection with the Merger. As relief, these lawsuits each separately seek an order, among other things, enjoining the defendants from closing the proposed transaction or taking any steps to consummate the Merger and/or awarding rescissory damages. The Company cannot predict the outcome of or estimate the possible loss or range of loss from any of these matters.

Share-Based Compensation

3 Months Ended

Mar. 31, 2019

Share-Based Compensation

Share-Based Compensation

3. Share-Based Compensation

Share-based payments consist of stock option grants 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 filed with the Securities and Exchange Commission on March 18, 2019.

The following table summarizes share-based compensation expense included within the condensed statements of operations for the three months ended March 31, 2019 and 2018:


	Three Months Ended
	March 31,
	2019		2018
Research and development expenses	$	105	$	281
General and administrative expenses		403		407
Total share-based compensation	$	508	$	688

Share-based compensation expense recorded as general and administrative expense for the three months ended March 31, 2019 and 2018 included share-based compensation expense related to deferred compensation arrangements for the Company's non-employee directors of $28 and $42 , 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 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:


		Weighted Average
		Exercise Price Per
	Number of Shares	Share
Options outstanding at December 31, 2018	2,335,447	$	11.67
Options granted	—		—
Options forfeited or expired	(16,800)		25.30
Options outstanding at March 31, 2019	2,318,647		11.57

Basic and Diluted Net Income (Loss) Per Share	3 Months Ended
Basic and Diluted Net Income (Loss) Per Share	Mar. 31, 2019
Basic and Diluted Net Income (Loss) Per Share
Basic and Diluted Net Income (Loss) Per Share	4. Basic and Diluted Net Income (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 RSUs and common stock warrants. Weighted average potential shares of common stock of 10,940,932 and 11,862,772 for the three months ended March 31, 2019 and 2018, respectively, were excluded from the calculations of diluted income (loss) per share as inclusion of the potential shares would have had an anti-dilutive effect on the net income (loss) per share for the periods.

Stockholders' Equity	3 Months Ended
Stockholders' Equity	Mar. 31, 2019
Stockholders' Equity
Stockholders' Equity	5. Stockholders’ Equity On February 9, 2018, the Company entered into an At-the-Market Equity OfferingSM Sales Agreement (the “ATM Sales Agreement”) with Stifel, Nicolaus & Company, Incorporated, as sales agent (“Stifel”), pursuant to which the Company may offer and sell, from time to time, through Stifel, shares of the Company’s common stock, having an aggregate offering price of up to $50,000. In May 2018, the Company sold 1,501,501 shares of its common stock under the ATM Sales Agreement for net proceeds of $24,474. As of March 31, 2019, the Company had approximately $25,000 of common stock remaining available to be sold under the ATM Sales Agreement. On September 29, 2017, the Company completed a private placement of units consisting of an aggregate of 5,483,320 shares of common stock and warrants to purchase an aggregate of 3,289,988 shares of its common stock for net proceeds of $45,648, after deducting placement agent fees and other offering expenses. The purchasers in the registered direct offering consisted solely of accredited investors that included certain institutional and existing stockholders, including a member of the Company’s board of directors. The warrants, which have five year terms expiring on September 29, 2022, are immediately exercisable and have a per share exercise price of $9.02. The Company assessed whether the warrants require accounting as derivatives. The Company determined that the warrants were indexed to the Company’s own stock. As such, the Company has concluded the warrants meet the scope exception for determining whether the instruments require accounting as derivatives and are classified in stockholders’ equity. The fair value of the warrants was estimated at $21,069 using the Black-Scholes Model with the following assumptions: expected volatility of 97%, risk free interest rate of 1.92%, expected life of five years and no dividends. The net proceeds from the private placement were allocated to the common stock and warrants based upon their relative fair values. On November 14, 2014, the Company completed a private placement of units consisting of an aggregate of 6,431,111 shares of common stock and warrants to purchase an aggregate of 6,430,948 shares of its common stock for net proceeds of $42,814, after deducting offering expenses. 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. During the three months ended March 31, 2018, certain holders of warrants issued in November 2014 exercised 1,111,082 warrants in a cashless exercise for which the Company issued an aggregate of 674,579 shares of common stock upon exercise. The remaining unissued warrants, which had a four year term, expired unexercised on May 6, 2019.

University of Tennessee Research Foundation License Agreements	3 Months Ended
	Mar. 31, 2019
University of Tennessee Research Foundation License Agreements
University of Tennessee Research Foundation License Agreements	6. University of Tennessee Research Foundation License Agreements The Company and 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.

Workforce Reduction	3 Months Ended
Workforce Reduction	Mar. 31, 2019
Workforce Reduction
Workforce Reduction	7. Workforce Reduction In the first quarter of 2019, due to the entry into the Original Merger Agreement with Oncternal, the Company's board of directors committed to reducing its workforce by seven employees. All employees affected by the workforce reduction were eligible to receive, among other things, specified severance payments based on the applicable employee's level and years of service with the Company and the continuation of group health insurance coverage. In addition, the affected employees were eligible for full vesting acceleration of their outstanding stock options as well as an extension of the post-termination exercise period for their outstanding stock options. As a result of the workforce reduction and prior termination of three employees earlier in the first quarter of 2019, the Company incurred severance-related cash expenses of $1,017, all of which was included in research and development expenses for the three months ended March 31, 2019. Additional cash severance of up to $500 in total for these employees is contingent upon the closing of the Merger. The Company did not record a non-cash charge related to the modification of outstanding stock options in connection with the workforce reduction.

Business and Basis of Presentation (Policies)	3 Months Ended
Business and Basis of Presentation (Policies)	Mar. 31, 2019
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 filed with the Securities and Exchange Commission on March 18, 2019. Operating results for the three months ended March 31, 2019 are not necessarily indicative of the results that may be expected for the entire fiscal year ending December 31, 2019.
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.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The carrying amounts of the Company’s financial instruments (which include cash, cash equivalents, short-term investments, and accounts payable) approximate their fair values. 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 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 March 31, 2019 and December 31, 2018, 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 March 31, 2019 and December 31, 2018, 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 filed with the Securities and Exchange Commission on March 18, 2019.
Other Income, net	Other Income, net Other income, net consists of interest earned on the Company’s cash, cash equivalents and short-term investments, foreign currency transaction gains and losses, and other non-operating income or expense.
Accounting Pronouncements Recently Adopted	Accounting Pronouncements Recently Adopted In February 2016, the Financial Accounting Standards Board issued Accounting Standard Update (“ASU”) 2016-02, Leases (Topic 842) (“ASU 2016-02”). This ASU requires that lessees recognize assets and liabilities on the balance sheet for the present value of the rights and obligations created by all leases with terms of more than 12 months. On January 1, 2019, the Company adopted the provisions of ASU 2016-02 under the transition method under which comparative financial information is not restated and continues to apply the provisions of the previous lease accounting standard in its financial disclosures for the comparative periods. The Company also elected the package of practical expedients permitted under the transition guidance, which among other things, allowed it to carry forward the historical lease classification. The Company leases office space under a lease that 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, which was accounted for as an operating lease. In March 2018, the Company amended the lease to extend the term of the lease for an additional 12-month term expiring on April 30, 2019. For this operating lease, the Company recorded a right-of-use asset and corresponding lease liability of $41, which were included in other current assets and other current liabilities, respectively, in the condensed balance sheet for the three months ended March 31, 2019. The adoption of ASU 2016-02 did not affect the Company’s condensed statement of operations or condensed statement of cash flows. The Company recorded lease expense of $121 in general and administrative expenses and paid cash in the amount of $121 during the three months ended March 31, 2019.
Subsequent Events	Subsequent Events The Company has evaluated all events or transactions that occurred after March 31, 2019 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. Pending Merger with Oncternal In connection with the Company’s receipt of the Recent SARD Information and Oncternal’s evaluation of the Recent SARD Information, on April 30, 2019, the Company entered into Merger Agreement Amendment with Oncternal and Merger Sub. The Merger Agreement Amendment amended certain of the terms of the Original Merger Agreement by, among other things: (i) amending the exchange ratio formula such that the former Oncternal stockholders immediately before the Merger are expected to own approximately 77.5% of the outstanding capital stock of GTx rather than 75% as set forth in the Original Merger Agreement; (ii) amending the exchange ratio formula such that the GTx stockholders immediately before the Merger are expected to own approximately 22.5% of the outstanding capital stock of GTx rather than 25% as set forth in the Original Merger Agreement; (iii) amending the calculation of GTx’s cash balance at the Closing such that the cash balance will not be reduced by payments of GTx’s transaction expenses or any other costs or payments by GTx triggered by the transactions contemplated by the Merger Agreement or pursuant to any of GTx’s benefit plans; and (iv) amending GTx’s and Oncternal’s target cash amount used for purposes of determining whether there will be an adjustment to the ownership of GTx’s stockholders in the calculation of the exchange ratio formula. Except as set forth above, the material terms of the Merger Agreement are substantially the same as the terms of the Original Merger Agreement. On April 30, 2019, the form of the Contingent Value Rights Agreement to be entered into at the Effective Time was also amended in connection with the Merger Agreement Amendment (as such form has been amended, the “Amended Form CVR Agreement”). The original agreed upon form of the CVR Agreement (the “Original Form CVR Agreement”) was amended to provide, among other things: (i) that for each share of GTx common stock held, GTx’s stockholders of record as of immediately prior to the Effective Time will receive one contingent value right entitling such holders to receive in the aggregate 75% (rather than 50% as provided for in the Original Form CVR Agreement) of any net proceeds received during the 15-year period after the Closing from the grant, sale or transfer of rights to GTx’s SARD or SARM technology that occurs during the 10-year period after the Closing (or in the 11th year if based on a term sheet approved during the initial 10-year period); and (ii) that instead of using commercially reasonable efforts to develop SARD products, as provided in the Original Form of CVR Agreement, Oncternal (as successor in interest to GTx) will use commercially reasonable efforts, in its sole discretion, either to develop SARD products or to divest SARD technology, subject to certain limitations. Except as set forth above, the material terms of the Amended Form CVR Agreement are substantially the same as the terms of the Original Form CVR Agreement. Litigation Related to the Merger Between April 10, 2019 and May 7, 2019, six purported stockholder class action lawsuits were filed, naming as defendants the Company and the Company’s board of directors. Collectively, these lawsuits allege, among other things, violations of Sections 14(a) and 20(a) of the Exchange Act, as well as Rule 14a-9 promulgated thereunder, in connection with the filing of the registration statement on Form S-4 that the Company filed with the SEC in connection with the Merger. As relief, these lawsuits each separately seek an order, among other things, enjoining the defendants from closing the proposed transaction or taking any steps to consummate the Merger and/or awarding rescissory damages. The Company cannot predict the outcome of or estimate the possible loss or range of loss from any of these matters.

Share-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2019

Share-Based Compensation

Summary of share-based compensation expense


	Three Months Ended
	March 31,
	2019		2018
Research and development expenses	$	105	$	281
General and administrative expenses		403		407
Total share-based compensation	$	508	$	688

Summary of stock option transactions


		Weighted Average
		Exercise Price Per
	Number of Shares	Share
Options outstanding at December 31, 2018	2,335,447	$	11.67
Options granted	—		—
Options forfeited or expired	(16,800)		25.30
Options outstanding at March 31, 2019	2,318,647		11.57

Pending Merger with Oncternal Therapeutics, Inc. (Details) $ in Thousands	Mar. 06, 2019 USD ($) director item
Merger Agreement
Pending Merger with Oncternal Therapeutics, Inc.
Ownership percentage of stockholders upon closing of the merger	22.50%
Number of directors on the Board of Directors upon closing of the merger \| director	9
Number of GTx designees on the Board of Directors upon closing of the merger \| director	2
Merger Agreement \| Minimum
Pending Merger with Oncternal Therapeutics, Inc.
Potential termination fee payable upon termination of the merger agreement \| $	$ 500
Merger Agreement \| Maximum
Pending Merger with Oncternal Therapeutics, Inc.
Potential termination fee payable upon termination of the merger agreement \| $	$ 2,000
Merger Agreement \| Oncternal Therapeutics Inc. stockholders
Pending Merger with Oncternal Therapeutics, Inc.
Ownership percentage of stockholders upon closing of the merger	77.50%
CVR Agreement
Pending Merger with Oncternal Therapeutics, Inc.
Contingent value right per common stock \| item	1
Percentage of net proceeds entitled to be received per CVR	75.00%
Period from closing during which payment of percentage of net proceeds would be payable under the CVR	15 years
Period from closing during which the grant, sale or transfer of rights to the Company's SARD or SARM technology could trigger a payment under the CVR Agreement	10 years

Business and Basis of Presentation (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Business
Cash, cash equivalents and short-term investments	$ 21,187	$ 28,458
Income Taxes
Net deferred tax assets	$ 0	$ 0

Business and Basis of Presentation - Accounting Pronouncements Recently Adopted (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)
Accounting Pronouncements Recently Adopted
Lease expense paid in cash	$ 121
General and administrative expenses
Accounting Pronouncements Recently Adopted
Lease expense	$ 121
ASU 2016-02
Accounting Pronouncements Recently Adopted
Package of practical expedients	true
Lease term	3 years
Option to extend the lease	true
Option to extend the lease, additional term	3 years
Amended lease extended term	12 months
Operating lease right-of-use asset	$ 41
Operating lease liability	$ 41

Business and Basis of Presentation - Subsequent Events (Details) - Subsequent Events		1 Months Ended
	Apr. 30, 2019 item	May 07, 2019 lawsuit
Subsequent Events
Number of purported stockholder class action lawsuits were filed \| lawsuit		6
Amended Merger Agreement
Subsequent Events
Ownership percentage of stockholders upon closing of the merger	22.50%
Amended Merger Agreement \| Oncternal Therapeutics Inc. stockholders
Subsequent Events
Ownership percentage of stockholders upon closing of the merger	77.50%
Original Merger Agreement
Subsequent Events
Ownership percentage of stockholders upon closing of the merger	25.00%
Original Merger Agreement \| Oncternal Therapeutics Inc. stockholders
Subsequent Events
Ownership percentage of stockholders upon closing of the merger	75.00%
Amended Form CVR Agreement
Subsequent Events
Contingent value right per common stock \| item	1
Percentage of net proceeds entitled to be received per CVR	75.00%
Period from closing during which payment of percentage of net proceeds would be payable under the CVR	15 years
Period Which Grant Sale Or Transfer Of Rights To Company Sard Or Sarm Technology Could Trigger Payment Under CVR Agreement	10 years
Original Form CVR Agreement
Subsequent Events
Percentage of net proceeds entitled to be received per CVR	50.00%

Share-Based Compensation - Share-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Share-based compensation expense
Total share-based compensation	$ 508	$ 688
Share-based compensation expense related to deferred compensation arrangements for non-employee directors	28	42
Research and development expenses
Share-based compensation expense
Total share-based compensation	105	281
General and administrative expenses
Share-based compensation expense
Total share-based compensation	403	407
Director \| General and administrative expenses
Share-based compensation expense
Share-based compensation expense related to deferred compensation arrangements for non-employee directors	$ 28	$ 42

Share-Based Compensation - Stock Option Activity (Details)	3 Months Ended
	Mar. 31, 2019 $ / shares shares
Number of Shares
Options outstanding at the beginning of the period (in shares) \| shares	2,335,447
Options forfeited or expired (in shares) \| shares	(16,800)
Options outstanding at the end of the period (in shares) \| shares	2,318,647
Weighted Average Exercise Price Per Share
Options outstanding at the beginning of the period (in dollars per share) \| $ / shares	$ 11.67
Options forfeited or expired (in dollars per share) \| $ / shares	25.30
Options outstanding at the end of the period (in dollars per share) \| $ / shares	$ 11.57

Basic and Diluted Net Income (Loss) Per Share (Details) - shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Basic and Diluted Net Income (Loss) Per Share
Weighted average potential shares of common stock excluded from calculation of diluted net income (loss) per share	10,940,932	11,862,772

Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands				1 Months Ended
	May 06, 2019	Sep. 29, 2017	Nov. 14, 2014	May 31, 2018	Mar. 31, 2018	Mar. 31, 2019	Feb. 09, 2018
At-The-Market Equity Offering
Common Stock
Common stock value that may be sold under the At-the-Market Equity Offering Sales Agreement							$ 50,000
Common stock sold under the ATM Sales Agreement				1,501,501
Net proceeds from the issuance of common stock and warrants				$ 24,474
Remaining common stock value that is available and may be sold under the At-the-Market Equity Offering Sales Agreement						$ 25,000
Private Placement, September 2017
Common Stock
Proceeds from issue of new stock or shares (in shares)		5,483,320
Warrants issued to purchase shares under private placement		3,289,988
Net proceeds from private placement after deducting offering expenses		$ 45,648
Warrant term		5 years
Exercise price (in dollars per share)		$ 9.02
Estimated fair value of warrants		$ 21,069
Expected volatility of warrants (as a percent)		97.00%
Risk-free interest rate of warrants (as a percent)		1.92%
Expected life of warrants		5 years
Expected dividends on warrants (in dollars per share)		$ 0
Private Placement, November 2014
Common Stock
Proceeds from issue of new stock or shares (in shares)			6,431,111
Warrants issued to purchase shares under private placement			6,430,948
Net proceeds from private placement after deducting offering expenses			$ 42,814
Common stock issued upon exercise of warrants					674,579
Warrants exercised					1,111,082
Remaining unissued warrants - expired unexercised	4 years

Workforce Reduction (Details) $ in Thousands	3 Months Ended
Workforce Reduction (Details) $ in Thousands	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($) employee
Number of employees terminated upon entry into the merger agreement \| employee		7
Number of employees terminated prior to the merger agreement \| employee		3
Severance-related charges \| $		$ 1,017
Forecast \| Maximum
Severance-related charges \| $	$ 500