Oncternal Therapeutics (ONCT) 10-K 16 Mar 20 2019 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Mar. 06, 2020	Jun. 30, 2019
Cover [Abstract]
Entity Registrant Name	Oncternal Therapeutics, Inc.
Entity Central Index Key	0001260990
Document Type	10-K
Document Period End Date	Dec. 31, 2019
Amendment Flag	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Trading Symbol	ONCT
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		15,387,242
Entity Public Float			$ 62.4
Entity File Number	000-50549
Entity Tax Identification Number	62-1715807
Entity Address, Address Line One	12230 El Camino Real
Entity Address, Address Line Two	Suite 300
Entity Address, City or Town	San Diego
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92130
City Area Code	858
Local Phone Number	434-1113
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common Stock, par value $0.001 per share
Security Exchange Name	NASDAQ
Entity Incorporation, State or Country Code	DE
Document Annual Report	true
Document Transition Report	false
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE Portions of the Registrant’s proxy statement to be filed with the Securities and Exchange Commission pursuant to Regulation 14A in connection with the Registrant’s 2020 Annual Meeting of Stockholders, which will be filed subsequent to the date hereof, are incorporated by reference into Part III of this Form 10-K. Such proxy statement will be filed with the Securities and Exchange Commission not later than 120 days following the end of the Registrant’s fiscal year ended December 31, 2019.

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 20,051	$ 20,645
Prepaid and other assets	736	565
Total current assets	20,787	21,210
Right-of-use asset	190
Other assets	767	752
Total assets	21,744	21,962
Current liabilities:
Accounts payable	871	3,440
Accrued liabilities	2,731	891
Deferred grant revenue	3,640
Current portion of lease liability	99
Total current liabilities	7,341	4,331
Preferred stock warrant liability	1,300	674
Lease liability	91
Commitments and contingencies (Notes 3 and 5)
Convertible preferred stock, $0.0001 par value; authorized shares - none and 130,100 at December 31, 2019 and 2018, respectively; issued and outstanding – none and 8,148 at December 31, 2019 and 2018, respectively; liquidation preference of none and $48,954 at December 31, 2019 and 2018, respectively		46,588
Stockholders’ equity (deficit):
Preferred stock, $0.001 par value, authorized shares – 5,000 and none at December 31, 2019 and 2018, respectively; issued and outstanding shares – none
Common stock, $0.001 par value; authorized shares – 60,000 and 200,000 at December 31, 2019 and 2018, respectively; issued and outstanding shares – 15,387 and 3,762 at December 31, 2019 and 2018, respectively	15	5
Additional paid-in capital	79,869	1,748
Accumulated deficit	(65,572)	(31,384)
Total stockholders’ equity (deficit)	14,312	(29,631)
Total liabilities and stockholders’ equity (deficit)	$ 21,744	$ 21,962

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	0
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	60,000,000	200,000,000
Common stock, shares issued	15,387,000	3,762,000
Common stock, shares outstanding	15,387,000	3,762,000
Convertible preferred stock
Convertible preferred stock, par value	$ 0.0001	$ 0.0001
Convertible preferred stock, shares authorized	0	130,100,000
Convertible preferred stock, shares issued	0	8,148,000
Convertible preferred stock, shares outstanding	0	8,148,000
Convertible preferred stock, liquidation preference	$ 0	$ 48,954,000

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Statement [Abstract]
Grant revenue	$ 2,425	$ 2,521
Operating expenses:
Research and development	10,159	8,287
In-process research and development	18,088
General and administrative	7,286	1,820
Total operating expenses	35,533	10,107
Loss from operations	(33,108)	(7,586)
Other income (expense):
Change in fair value of warrant liability	(1,268)	713
Other income		216
Interest expense		(1)
Interest income	188	79
Total other income (expense)	(1,080)	1,007
Net loss	$ (34,188)	$ (6,579)
Net loss per share, basic and diluted	$ (3.31)	$ (1.83)
Weighted-average shares outstanding, basic and diluted	10,329	3,591

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities
Net loss	$ (34,188)	$ (6,579)
Adjustments to reconcile net loss to net cash used in operating activities:
In-process research and development	18,088
Noncash other income		(216)
Stock-based compensation	507	180
Noncash interest expense		1
Noncash compensation expense		10
Change in fair value of preferred stock warrants liability	1,268	(713)
Noncash lease expense	92
Changes in operating assets and liabilities:
Prepaid and other assets	(44)	(436)
Accounts payable	(4,762)	2,242
Accrued liabilities	(1,255)	(4)
Change in operation lease liability	(92)
Deferred grant revenue	3,640	(1,902)
Net cash used in operating activities	(16,746)	(7,417)
Cash flows from investing activities
Cash acquired in connection with the Merger	18,292
Acquisition related costs paid	(2,155)
Net cash provided by investing activities	16,137
Cash flows from financing activities
Proceeds from exercise of stock options	14	1
Proceeds from exercise of common stock warrants	1
Proceeds from the issuance of convertible preferred stock, net		17,873
Net cash provided by financing activities	15	17,874
Net (decrease) increase in cash and cash equivalents	(594)	10,457
Cash and cash equivalents at beginning of period	20,645	10,188
Cash and cash equivalents at end of period	20,051	$ 20,645
Supplemental disclosure of non-cash investing and financing activities:
Conversion of convertible preferred stock into common stock	46,588
Issuance of common stock to GTx stockholders	29,049
Reclassification of preferred stock warrants liability to additional paid-in capital	1,942
Net liabilities assumed in Merger	$ 5,177

Consolidated Statements of Conv

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($)	Total	Convertible preferred stock	Common Stock	Additional Paid-in Capital	Accumulated Deficit
Balance at Dec. 31, 2017	$ (23,278,000)		$ 5,000	$ 1,522,000	$ (24,805,000)
Balance (in shares) at Dec. 31, 2017		5,653,000
Balance at Dec. 31, 2017		$ 28,715,000
Balance (in shares) at Dec. 31, 2017			3,745
Collection of stock subscription receivable		1,100,000
Issuance of Series C convertible preferred stock for cash, net of issuance costs	17,873,000	$ 16,773,000
Issuance of Series C convertible preferred stock for cash, net of issuance costs (in shares)		2,495
Exercise of stock options for cash	1,000			1,000
Exercise of stock options for cash (in shares)			2
Vesting related to repurchase liability	35,000			35,000
Issuance of restricted common shares	10,000			10,000
Issuance of restricted common shares, (in shares)			15
Stock-based compensation	180,000			180,000
Net loss	(6,579,000)				(6,579,000)
Balance at Dec. 31, 2018	(29,631,000)		$ 5,000	1,748,000	(31,384,000)
Balance (in shares) at Dec. 31, 2018		8,148,000
Balance at Dec. 31, 2018	$ 46,588,000	$ 46,588,000
Balance (in shares) at Dec. 31, 2018	3,762,000		3,762
Exercise of stock options for cash	$ 14,000		$ 19,000	14,000
Exercise of stock options for cash (in shares)	19,040
Exercise of warrants for cash	$ 1,000			1,000
Vesting related to repurchase liability	30,000			30,000
Issuance of common stock to former stockholders of GTx upon Merger	29,049,000		$ 2,000	29,047,000
Issuance of common stock to former stockholders of GTx upon Merger (in shares)			3,458
Conversion of convertible preferred stock into common stock upon Merger	46,588,000		$ 8,000	46,580,000
Conversion of convertible preferred stock into common stock upon merger (in shares)		(8,148)
Conversion of convertible preferred stock into common stock upon Merger		$ (46,588,000)
Conversion of convertible preferred stock into common stock upon Merger (in shares)			8,148
Reclassification of convertible preferred stock warrant	1,942,000			1,942,000
Stock-based compensation	507,000			507,000
Net loss	(34,188,000)				(34,188,000)
Balance at Dec. 31, 2019	$ 14,312,000		$ 15,000	$ 79,869,000	$ (65,572,000)
Balance (in shares) at Dec. 31, 2019		0
Balance (in shares) at Dec. 31, 2019	15,387,000		15,387

Description of Business, Basis

Description of Business, Basis of Presentation and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Description of Business, Basis of Presentation and Summary of Significant Accounting Policies	1. Description of Basis of of Policies Description of Business Oncternal Therapeutics, Inc. (the “Company,” “Oncternal,” or the “combined company”), formerly known as GTx, Inc., was incorporated in Tennessee in September 1997 and reincorporated in Delaware in 2003 and is based in San Diego, California. The Company is a clinical-stage biopharmaceutical company focused on the development of novel oncology therapies for the treatment of cancers with critical unmet medical need. The Company’s clinical pipeline consists of its lead program, cirmtuzumab, a humanized monoclonal antibody that binds to ROR1 (Receptor-tyrosine kinase-like Orphan Receptor 1), and TK216, a small molecule inhibiting the biological activity of ETS-family transcription factor oncoproteins. The Company is also developing a CAR-T (chimeric antigen receptor T-cells) product candidate that targets ROR1. Merger On June 7, 2019, the Company, then operating as GTx, Inc. (“GTx”), completed its Agreement and Plan of Merger and Reorganization, as amended (the “Merger Agreement”), with privately-held Oncternal Therapeutics, Inc. (“Private Oncternal”) and Grizzly Merger Sub, Inc., a wholly-owned subsidiary of the Company (“Merger Sub”), dated March 6, 2019. Under the Merger Agreement, Merger Sub merged with and into Private Oncternal, with Private Oncternal surviving as a wholly-owned subsidiary of the Company (the “Merger”). GTx changed its name to Oncternal Therapeutics, Inc., and Private Oncternal, which remains as a wholly-owned subsidiary of the Company, changed its name to Oncternal Oncology, Inc. On June 10, 2019, the combined company’s common stock began trading on The Nasdaq Capital Market under the ticker symbol “ONCT.” Except as otherwise indicated, references herein to “Oncternal,” “the Company,” and the “combined company,” refer to Oncternal Therapeutics, Inc. on a post-Merger basis, and the term “Private Oncternal” refers to the business of privately-held Oncternal Therapeutics, Inc., prior to completion of the Merger. References to GTx refer to GTx, Inc. prior to completion of the Merger. Pursuant to the terms of the Merger Agreement, each outstanding share of Private Oncternal common stock outstanding immediately prior to the closing of the Merger was converted into approximately 0.073386 shares of Company common stock (the “Exchange Ratio”), after taking into account the Reverse Stock Split, as defined below. Immediately prior to the closing of the Merger, all shares of Private Oncternal preferred stock then outstanding were exchanged into shares of common stock of Private Oncternal. In addition, all outstanding options exercisable for common stock of Private Oncternal and warrants exercisable for convertible preferred stock of Private Oncternal became options and warrants exercisable for the same number of shares of common stock of the Company multiplied by the Exchange Ratio. Immediately following the Merger, stockholders of Private Oncternal owned approximately 77.5% of the outstanding common stock of the combined company. The transaction was accounted for as a reverse asset acquisition in accordance with generally accepted accounting principles in the United States of America (“GAAP”). Under this method of accounting, Private Oncternal was deemed to be the accounting acquirer for financial reporting purposes. This determination was primarily based on the facts that, immediately following the Merger: (i) Private Oncternal’s stockholders owned a substantial majority of the voting rights in the combined company, (ii) Private Oncternal designated a majority of the members of the initial board of directors of the combined company, and (iii) Private Oncternal’s senior management holds all key positions in the senior management of the combined company. As a result, as of the closing date of the Merger, the net assets of the Company were recorded at their acquisition-date relative fair values in the consolidated financial statements of the Company and the reported operating results prior to the Merger will be those of Private Oncternal. Reverse Stock Split and Exchange Ratio On June 7, 2019, in connection with, and prior to the completion of, the Merger, GTx effected a one-for-seven reverse stock split of its then outstanding common stock (the “Reverse Stock Split”). The par value and the authorized shares of the common stock were not adjusted as a result of the Reverse Stock Split. All of the Company’s issued and outstanding common stock have been retroactively adjusted to reflect this Reverse Stock Split for all periods presented. All issued and outstanding Private Oncternal common stock, preferred stock, options and warrants prior to the effective date of the Merger have been retroactively adjusted to reflect the Exchange Ratio for all periods presented. Principles of Consolidation The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries, Oncternal Oncology, Inc. and Oncternal, Inc. All intercompany accounts and transactions have been eliminated in the preparation of the consolidated financial statements. Liquidity and Going Concern From its inception through December 31, 2019, the Company has devoted substantially all of its efforts to organizational activities including raising capital, building infrastructure, acquiring assets, developing intellectual property, and conducting preclinical studies, clinical trials and product development activities. The Company has a limited operating history and the sales and income potential of the Company’s business and market are unproven. Since inception, the Company has experienced recurring net losses and negative cash flows from operating activities and expects to continue to incur losses into the foreseeable future. At December 31, 2019, the Company had an accumulated deficit of $65.6 million and had cash and cash equivalents of $20.1 million. The Company believes that its existing cash and cash equivalents will be sufficient to fund its operations into the third quarter of 2020. The Company will need to continue to raise a substantial amount of funds until it is able to generate revenues to fund its development activities and operations. The accompanying consolidated financial statements have been prepared assuming that the Company will continue as a going concern, wh ich contemplates the realization of assets and settlement of liabilities in the normal course of business. The Company plans to continue to fund its losses from operations and capital funding needs through a combination of equity offerings, debt financings, government funding, or other sources, including, potentially, collaborations, licenses and other similar arrangements. There can be no assurance that the Company will be able to obtain any sources of financing on acceptable terms, or at all. To the extent that the Company can raise additional funds by issuing equity securities, the Company’s stockholders may experience significant dilution. Any debt financing, if available, may involve restrictive covenants that impact the Company’s ability to conduct its business. Use of Estimates The Company’s consolidated financial statements accordance GAAP. of the Company’s consolidated financial statements and accompanying notes and assumptions that impact the amounts of liabilities, revenues and expenses and the disclosure of contingent and liabilities. Significant consist of those the value of the Company’s stock, stock liability , and those revenue and and development Although these on the Company’s knowledge of events and actions undertake the actual ultimately these and assumptions. Cash and Cash Equivalents The Company considers all highly liquid investments with maturities of three months or less when purchased to be cash equivalents. Cash and cash equivalents include cash in readily available checking accounts and money market accounts. Concentration of Credit Risk Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash and cash equivalents. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits. The Company has not experienced any losses in such accounts and believes it is not exposed to significant risk on its cash balances due to the financial position of the depository institution in which those deposits are held. Additionally, the Company established guidelines regarding approved investments and maturities of investments, which are designed to maintain safety and liquidity. Patent Costs Costs related to filing and pursuing patent applications are recorded as general and administrative expense and expensed as incurred since recoverability of such expenditures is uncertain. Research and Development Expenses and Accruals Research and development expenses consist of costs incurred for the Company’s own and for sponsored and collaborative research and development activities. Research and development costs are expensed as incurred and include manufacturing process development costs, manufacturing costs, costs associated with preclinical studies and clinical trials, regulatory and medical affairs activities, quality assurance activities, salaries and benefits, including stock-based compensation, fees paid to third-party consultants, license fees and overhead. The Company has entered into various research and development contracts with research institutions, clinical research organizations, clinical manufacturing organizations and other companies. Payments for these activities are based on the terms of the individual agreements, which may differ from the pattern of costs incurred, and payments made in advance of performance are reflected in the accompanying consolidated balance sheets as prepaid and other assets or accrued liabilities. The Company records accruals for estimated costs incurred for ongoing research and development activities. When evaluating the adequacy of the accrued liabilities, the Company analyzes progress of the services, including the phase or completion of events, invoices received and contracted costs. Significant judgments and estimates may be made in determining the prepaid or accrued balances at the end of any reporting period. Actual results could differ from the Company’s estimates. Preferred Stock Warrant Liability Prior to the Merger, Private Oncternal had outstanding freestanding warrants to purchase shares of its Series B-2 convertible preferred stock (the “Series B-2 warrants”). Because the underlying Series B-2 convertible preferred stock was classified as temporary equity, the Series B-2 warrants were classified as a liability in the accompanying consolidated balance sheets. Private Oncternal adjusted the carrying value of such Series B-2 warrants to their estimated fair value at each reporting date, with any related increases or decreases in the fair value recorded as an increase or decrease to other income (expense) in the consolidated statements of operations. Upon the completion of the Merger, the Series B-2 warrants were amended such that they were converted into warrants to purchase the Company’s common stock. As amended, warrant liability accounting is no longer required and the fair value of the warrant liability has been reclassified into stockholders’ equity. Fair Value Measurements The accounting guidance defines fair value, establishes a consistent framework for measuring fair value and expands disclosure for each major asset and liability category measured at fair value on either a recurring or non-recurring basis. Fair value is defined as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, the accounting guidance establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value as follows: Level 1: Observable inputs such as quoted prices in active markets. Level 2: Inputs, other than the quoted prices in active markets that are observable either directly or indirectly. Level 3: Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions. The carrying amounts of the Company’s current financial assets and liabilities are considered to be representative of their respective fair values because of the short-term nature of those instruments. The Company has no financial assets or liabilities, other than the preferred stock warrant liability described below, measured at fair value on a recurring basis. No transfers between levels have occurred during the periods presented. Liabilities measured at fair value on a recurring basis are as follows (in thousands): Fair Value Measurements at Reporting Date Using Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Total (Level 1) (Level 2) (Level 3) At December 31, 2018 Preferred stock warrant liability $ 674 $ — $ — $ 674 As of December 31, 2018, the preferred stock warrant liability was recorded at fair value utilizing the Black-Scholes option pricing model using significant unobservable inputs consistent with the inputs used for the Company’s stock-based compensation expense adjusted for the preferred stock warrants’ expected term and the fair value of the underlying preferred stock. The Company calculated the final remeasurement of the preferred stock warrant liability on June 7, 2019, the Merger closing date, using the closing price of GTx’s common stock on that date to determine the fair value of the warrants, and recorded a $1.3 million change in the fair value of the preferred stock warrant liability for the year ended December 31, 2019. The assumptions used in the Black-Scholes option pricing model to determine the fair value of the preferred stock warrant liability as of December 31, 2018 were as follows: Fair value of underlying preferred stock $ 0.29 Risk-free interest rate 2.4% — 2.7% Expected volatility 75.3% — 76.4% Expected term (in years) 3.7 — 4.0 Expected dividend yield —% The following table provides a reconciliation of the preferred stock warrant liability measured at fair value using Level 3 significant unobservable inputs (in thousands): Preferred Stock Warrant Liability Balance at December 31, 2018 $ 674 Change in fair value 1,268 Reclassification of preferred stock warrant liability to equity (1,942 ) Balance at December 31, 2019 $ — Revenue Recognition The Company currently generates revenue from the California Institute for Regenerative Medicine pursuant to a research subaward agreement (see Note 4), which provides the Company with payments in return for certain research and development activities over a contractually defined period. Revenue from such subaward is recognized in the period during which the related qualifying services are rendered and costs are incurred, provided that the applicable conditions under the subaward agreement have been met. The subaward agreement is on a best-effort basis and does not require scientific achievement as a performance obligation. All fees received under the agreement are non-refundable. The costs associated with the agreement are expensed as incurred and reflected as a component of research and development expense in the accompanying consolidated statements of operations. Funds received from the subaward agreement are recorded as revenue as the Company is the principal participant in the arrangement because the activities under the subaward are part of the Company’s development programs. In those instances where the Company first receives consideration in advance of providing underlying services, the Company classifies such consideration as deferred revenue until (or as) the Company provides the underlying services. In those instances where the Company first provides the underlying services prior to its receipt of consideration, the Company records a grant receivable. At December 31, 2019, the Company had deferred grant revenue of $3.6 million, and at December 31, 2018, the Company had a grant receivable of $0.1 million. Stock-Based Compensation Stock-based compensation expense represents the fair value of equity awards, on the grant date, recognized in the period using the Black- Scholes option pricing model. The Company recognizes expense for awards with graded vested schedules over the requisite service period of the awards (usually the vesting period) on a straight-line basis. For equity awards for which vesting is subject to performance-based milestones, the expense is recorded over the remaining service period after the point when the achievement of the milestone is probable or the performance condition has been achieved. Income Taxes The Company accounts for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements. Under this method, deferred tax assets and liabilities are determined on the basis of the differences between the financial statements and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date. The Company recognizes net deferred tax assets to the extent that the Company believes these assets are more likely than not to be realized. In making such a determination, management considers all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies, and results of recent operations. If management determines that the Company would be able to realize its deferred tax assets in the future in excess of their net recorded amount, management would make an adjustment to the deferred tax asset valuation allowance, which would reduce the provision for income taxes. Segment Reporting Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision-maker in making decisions regarding resource allocation and assessing performance. The Company views its operations and manages its business in one operating segment in the United States. Net Loss Per Share Basic net loss per share is computed by dividing the net loss by the weighted-average number of common shares outstanding for the period, without consideration for potentially dilutive securities and adjusted for the weighted-average number of common shares outstanding that are subject to repurchase. The Company has excluded weighted-average shares subject to repurchase of 56,000 shares and 164,000 shares from the weighted-average number of common shares outstanding for the years ended December 31, 2019 and 2018, respectively. Diluted net loss per share is computed by dividing the net loss by the weighted-average number of shares of common stock and dilutive common stock equivalents outstanding for the period determined using the treasury-stock and if-converted methods. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding as inclusion of the potentially dilutive securities would be antidilutive. Potentially dilutive securities not included in the calculation of diluted net loss per share, because to do so would be anti-dilutive, are as follows (in common stock equivalent shares; in thousands): December 31, 2019 2018 Redeemable convertible preferred stock — 8,148 Warrants to purchase convertible preferred stock — 372 Warrants to purchase common stock 841 — Common stock options 1,958 504 Common stock subject to repurchase 35 100 2,834 9,124 Recently Issued Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) or other standard setting bodies that are adopted by the Company as of the specified effective date. Unless otherwise discussed, the Company believes that the impact of recently issued standards that are not yet effective will not have a material impact on its consolidated financial position or results of operations upon adoption. In August 2018, the FASB issued Accounting Standards Update (“ASU”) Fair Value Measurement: Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement, no impact on the consolidated financial statements from the adoption of this standard Recently Adopted Accounting Pronouncements In February 2016, the FASB issued ASU 2016-02, Leases

Balance Sheet Details

Balance Sheet Details	12 Months Ended
	Dec. 31, 2019
Payables And Accruals [Abstract]
Balance Sheet Details	2. Balance Sheet Details Accrued liabilities consist of the following (in thousands): December 31, 2019 2018 Research and development $ 1,206 $ 720 Legal fees 424 20 Unvested share liability 24 54 Compensation 825 85 Other 252 12 $ 2,731 $ 891

Commitments, Contingencies and

Commitments, Contingencies and Related Party Transactions	12 Months Ended
	Dec. 31, 2019
Commitments And Contingencies Disclosure [Abstract]
Commitments, Contingencies and Related Party Transactions	3. Commitments, Contingencies and Related Party Transactions Lease Rent expense was $0.1 million and $12,000 for the years ended December 31, 2019 and 2018, respectively. On May 22, 2019, the Company entered into an office sublease agreement for 4,677 square feet in San Diego, California (“San Diego Lease”) which expires on March 31, 2021. Base rent is approximately $166,000 annually and the monthly rent expense is being recognized on a straight-line basis over the lease term. The San Diego Lease is included in the accompanying consolidated balance sheet at the present value of the lease payments. As the San Diego Lease does not have an implicit interest rate, the present value reflects a 10.0% discount rate which is the estimated rate of interest that the Company would have to pay in order to borrow an amount equal to the lease payments on a collateralized basis over a similar term and in a similar economic environment. The Company recognized a net operating lease right-of-use asset and an aggregate lease liability of $0.2 million as of December 31, 2019, in the accompanying consolidated balance sheet. The weighted average remaining lease term was 1.25 years. Maturities of lease liabilities due under this lease agreement as of December 31, 2019, are as follows (in thousands): Maturity of lease liabilities Operating Leases 2020 $ 166 2021 41 Total lease payments 207 Less imputed interest (17 ) Total operating lease liabilities 190 Less current portion of lease liability (99 ) Lease liability $ 91 Related Party Transactions In January 2019, the Company engaged Newfront Insurance as its primary insurance broker. The son of Richard Vincent, the Company’s Chief Financial Officer, acted as the Company’s agent at Newfront Insurance. The Company paid total related policy premiums of approximately $1.2 million during the year ending December 31, 2019, for which Mr. Vincent’s son received a commission of approximately $0.1 million. In September 2019, the Company entered into a consulting agreement with Robert J. Wills. Ph.D., a member of the Company’s Board of Directors, whereby Dr. Wills will provide services related to the potential out-licensing or sale of the SARM and/or SARD technology. The Company recorded approximately $3,500 in related services during the year ended December 31, 2019. Effective in September 2019, the Company and Shanghai Pharmaceutical (USA) Inc. (“SPH USA”) entered into a Materials Supply and Services Agreement (“SPH USA Services Agreement”), pursuant to which the Company and SPH USA will execute various statements of work for the transfer to SPH USA of key reagents and other materials, and for the supply of certain services by the Company to SPH USA, as contemplated under and in furtherance of the License and Development Agreement between the Company and SPH USA effective as of November 2018. During the year ended December 31, 2019, the Company recorded amounts receivable from SPH USA related to statements of work totaling $0.2 million. See Notes 4 and 6. Litigation Related to the Merger Between April 10 and May 1, 2019, three putative class action lawsuits and one individual lawsuit were filed in the U.S. District Court for the District of Delaware: Wheby v. GTx, Inc. et al., Miller v. GTx, Inc. et al., Tabb v. GTx, Inc. et al., and Living Seas LLC v. GTx, Inc. et al. (collectively, the “Delaware Actions”). On April 11 and 23, 2019, two putative class actions were filed in the U.S. District Court for the Southern District of New York: Kopanic v. GTx, Inc. et al. and Cooper v. GTx, Inc. et al. (collectively, the “New York Actions” and, together with the Delaware Actions, the “Actions”). The Actions name as defendants the Company and its former board of directors, and, in the case of the Wheby and Miller actions, Private Oncternal and Merger Sub. The Actions allege that defendants violated Sections 14(a) and 20(a) of the Exchange Act, as well as Rule 14a-9 promulgated thereunder, in connection with the company's filing of the Registration Statement in connection with the Merger. The Delaware Actions have now been voluntarily dismissed with prejudice: the Wheby action on June 12, 2019; the Miller action on July 15, 2019; the Living Seas action on June 26, 2019; and the Tabb action on October 21, 2019. On September 16, 2019, Plaintiffs in the New York Actions filed an amended complaint, alleging violations of Sections 14(a) and 20(a) of the Exchange Act related to the value GTx’s stockholders received in the Merger. The complaint seeks damages and other unspecified relief. On January 10, 2020, the defendants filed their motion to dismiss the amended complaint, on January 31, 2020, the plaintiffs filed their opposition to defendants’ motion to dismiss, and on February 14, 2020, the defendants filed a reply in support of their motion to dismiss. The defendants’ motion to dismiss is pending. The Company believes that the New York Actions are without merit and intends to vigorously defend these actions. The Company cannot predict the outcome of or estimate the possible loss or range of loss from any of these matters. Zappia vs. GTx Incorporated On October 15, 2019, Joseph Zappia and Karen Zappia filed a lawsuit against us in the U.S. District Court for the District of Delaware. The complaint alleges that our former management (prior to the Merger) engaged in illegal insider trading and false, manipulative and deceptive practices in violation of Sections 10(b) (and Rule 10b-5 promulgated thereunder), with respect to the timing of the disclosure of failed clinical trial results of GTx’s enobosarm product candidate in September 2018. The plaintiffs seek damages, interest, costs, attorneys' fees. We believe that this lawsuit is without merit and intend to vigorously defend this matter. We cannot predict the outcome of or estimate the possible loss or range of loss from this matter.

License, Collaboration and Rese

License, Collaboration and Research Subaward Agreements	12 Months Ended
	Dec. 31, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
License, Collaboration and Research Subaward Agreements	4. License, Collaboration and Research Subaward Agreements Georgetown University (“Georgetown”) In March 2014, the Company entered into an Exclusive License Agreement (the “Georgetown License Agreement”) with Georgetown, pursuant to which the Company: (i) licensed the exclusive worldwide right to patents and technologies for the development and commercialization of certain product candidates targeting EWS-FLI1 as an anti-tumor therapy for therapeutic, diagnostics, or research tool purposes, (ii) is solely responsible for all development and commercialization activities and costs, and (iii) is responsible for all costs related to the filing, prosecution and maintenance of the licensed patent rights. Under the terms of the Georgetown License Agreement, commencing in 2015, the Company: (i) shall pay and has paid an annual license maintenance fee of $10,000 until the first commercial sale occurs, (ii) is required to make up to $0.2 million in aggregate milestone payments upon the achievement of certain regulatory milestones, and (iii) will be required to pay low single digit royalties based on annual net product sales. The Company accounted for the licensed technology as an asset acquisition because it did not meet the definition of a business. All milestone payments under the Georgetown License Agreement will be recognized as research and development expense upon completion of the required events, as the triggering events are not considered to be probable until they are achieved. As of December 31, 2019, the Company had not triggered or made any milestone payments under the Georgetown License Agreement. The Georgetown License Agreement may be terminated by either party upon material breach or may be terminated by the Company as to one or more countries with 90 days written notice of termination. The term of the Georgetown License Agreement will continue until the expiration of the last valid claim within the patent rights covering the product. Georgetown may terminate the agreement in the event: (i) the Company fails to pay any amount and fails to cure such failure within 30 days after receipt of notice, (ii) the Company defaults in its obligation to obtain and maintain insurance and fails to remedy such breach within 60 days after receipt of notice, or (iii) the Company declares insolvency or bankruptcy. The Company may terminate the Georgetown License Agreement at any time upon at least 60 days’ written notice. In 2017, the Company entered into a research agreement with Georgetown for up to $150,000. The Company recorded research and development expense under this agreement of $27,000 and $53,000 for the years ended December 31, 2019 and 2018, respectively. The University of Texas MD Anderson Cancer Center (“MD Anderson”) In December 2014, the Company entered into a collaboration agreement (as amended, the “Collaboration”) with MD Anderson, which provides for the conduct of preclinical and clinical research for TK216 in exchange for certain program payments. If MD Anderson successfully completes all the requirements of the Collaboration in full and the program is successfully commercialized, the Company will be required to pay aggregate milestone payments of $1.0 million based on net product sales. The amounts recorded as research and development expense for the years ended December 31, 2019 and 2018 were not significant. Agreements with the Regents of the University of California (the “Regents”) In March 2016, and as amended and restated in August 2018 in connection with the spin-off transactions described below, the Company entered into a license agreement (as amended, the “Regents License Agreement”) for the development, manufacturing and distribution rights related to the development and commercialization of ROR1 related naked antibodies, antibody fragments or synthetic antibodies, and genetically engineered cellular therapy. The Regents License Agreement was amended on March 25, 2019 and May 15, 2019, to update the patents covered under the agreement. The Regents License Agreement provides for the following: (i) in May 2016, an upfront license fee of $0.5 million was paid and 107,108 shares of common stock were issued, (ii) $25,000 in annual license maintenance fees commencing in 2017, (iii) reimbursement of certain annual patent costs, (iv) certain development and regulatory milestones aggregating from $10.0 million to $12.5 million, on a per product basis, (v) certain worldwide sales milestones based on achievement of tiered revenue levels aggregating $75.0 million, (vi) low single-digit royalties, including potential future minimum annual royalties, on net sales of each target, and (vii) minimum diligence to advance licensed assets consisting of at least $1.0 million in development spend annually through 2021. Under the Regents License Agreement, the Company recorded: (i) $25,000 in license maintenance and development expense for each of the million and patent costs and administrative expense In July 2016, and as modified by the amended and restated Regents License Agreement in August 2018, the Company entered into a Research Agreement (the “Research Agreement”) with the Regents for further research on a ROR1 therapeutic development program. Under this five-year agreement, the Regents will have an aggregate budget of $3.6 million, with $125,000 payable quarterly. The Company recorded $0.5 million in research and development expense under this agreement for each of the years ended December 31, 2019 and 2018. Such costs are includable as part of the Company’s annual diligence obligations under the Regents License Agreement. The Regents License Agreement will expire upon the later of the expiration date of the longest-lived patent rights or the fifteenth anniversary of the first commercial sale of a licensed product. The Regents may terminate the Regents License Agreement if: (i) a material breach by the Company is not cured within a reasonable time, (ii) the Company files a claim asserting the Regents licensed patent rights are invalid or unenforceable and (iii) the Company files for bankruptcy. The Company may terminate the agreement at any time upon at least 60 days’ written notice. University of Tennessee Research Foundation (“UTRF”) In July 2007, the Company and UTRF entered into a consolidated, amended and restated license agreement (the “SARM License Agreement”), pursuant to which the Company was granted exclusive worldwide rights in all existing selective androgen receptor modulator (“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 recorded research and development expense under this agreement of $0.1 million and none for the years ended December 31, 2019 and 2018, respectively. On December 31, 2019, the Company provided UTRF notice of termination of the SARM License Agreement by and between the Company and UTRF, which termination will be effective three months following such notice. Following termination, the Company will no longer have the obligation to make further payments under the SARM License Agreement, and will no longer have any rights to develop or sublicense the SARM Technology. In March 2015, the Company and UTRF entered into a license agreement (the “SARD License Agreement”) pursuant to which the Company was granted exclusive worldwide rights in all existing selective androgen receptor degrader (“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. The Company recorded research and development expense under this agreement of $0.2 million and none for the years ended December 31, 2019 and 2018, respectively. As of December 31, 2019, the Company believes it has met its obligations under each of the UTRF agreements. Velos Biopharma Holdings, LLC (“VBH”) and VelosBio, Inc. (“VelosBio”) Spin-off Transactions In November 2017, the Company formed VBH and in December 2017, made an in-kind tax-free distribution of 100% of its interest in VBH to the Company’s stockholders, option holders and warrant holders of record. On February 6, 2018, the Company licensed and assigned its rights to two preclinical product candidates, previously under the Regents License Agreement, to VBH. In consideration for the license, the Company: (i) received a promissory note receivable from VBH of $0.1 million, with an annual interest rate of 2.64% and a due date of 10 years, and (ii) made a partial assignment of its March 2016 Regents License Agreement. Pursuant to the partial assignment, VBH assumed certain obligations related to the licensed products under the Regents License Agreement as follows: (i) reimbursement of certain historical and future patent costs related to the licensed products, (ii) certain development and milestones advancing licensed low single-digit royalties, including potential minimum annual royalties, on net of licensed be allocated the Company and and obligations the licensed minimum diligence obligations to advance licensed assets under the equal million development spend annually through 2021, and obligations equal million annually commencing 1, 2018. the high uncertainty of the of ever repaying the note receivable and associated the Company provided valuation allowance these amounts of . In December 2017, VelosBio was incorporated with VBH being its sole stockholder. On February 6, 2018, VBH sublicensed and assigned its intellectual property rights to its two preclinical product candidates to VelosBio. In consideration for the license, VelosBio agreed to use commercially reasonable efforts to develop the licensed products as well as the following payment obligations: (i) the assumption of each of the VBH assumed obligations under the partial assignment between the Company and VBH as outlined above, and (ii) certain tiered development milestone and royalty payments to VBH. In August 2018, the Company entered into the amended and restated Regents License Agreement and VelosBio entered into their own license agreement directly with the Regents. There is no common control overlap between the companies. Also on February 6, 2018, the Company and VelosBio entered into: (i) an asset purchase agreement whereby VelosBio purchased the Company’s right, title and interest in the Company’s nominal assets related to the two preclinical product candidates and assumed the Company’s $0.2 million convertible note payable and related $16,000 of accrued interest which has been recorded as other income, and (ii) a transition services agreement whereby the Company agreed to provide VelosBio with certain transition services, as follows: (a) access to certain common laboratory equipment at the Company’s lab facility, (b) certain named employees were to devote up to 80% of their time supporting VelosBio related activities, (c) cirmtuzumab manufacturing, process optimization and ancillary activities until VelosBio was able to establish their own, and (d) agreement to cost share the purchase of certain antibody materials with VelosBio. Such services were to be provided at cost or cost plus. During the year ended December 31, 2018, the Company incurred $3.0 million, of costs on behalf of VelosBio that were substantially reimbursed and recorded on a net basis within operating expenses in the accompanying consolidated statements of operations. As of December 31, 2018, there were no ongoing rights or commitments under the asset purchase or transition services agreements. In February 2020, the Company entered into a sublicense agreement with VelosBio pursuant to which it granted certain sublicenses to VelosBio under the Selexis License Agreement. The California Institute for Regenerative Medicine (“CIRM”) Award In August 2017, CIRM awarded an $18.3 million grant to researchers at UC San Diego to advance the Company’s Phase 1/2 clinical trial evaluating cirmtuzumab in combination with ibrutinib for the treatment of patients with B-cell lymphoid malignancies, including chronic lymphocytic leukemia and mantle cell lymphoma. The Company: (i) is conducting this study in collaboration with UC San Diego, (ii) estimates it will receive approximately $14.0 million in development milestones under research subaward agreements throughout the award project period, estimated to be from October 1, 2017 to March 31, 2022, (iii) is committed to certain co-funding requirements, (iv) received subaward payments of $6.2 million and $0.5 million in the years ended December 31, 2019 and 2018, respectively, and (v) is required to provide UC San Diego progress and financial update reports throughout the award period. The subaward does not bear a royalty payment commitment, nor is the subaward otherwise refundable. For the years ended December 31, 2019 and 2018, the Company recorded revenue of $2.4 million and $2.5 million, respectively. Related qualifying subaward costs for the years ended December 31, 2019 and 2018 were $5.4 million and $4.6 million, respectively. As of December 31, 2019, the Company believes it has met its obligations under the CIRM award and UC San Diego subawards. In October 2017, CIRM awarded a $5.8 million grant to the researchers at the University of California San Diego School of Medicine (“UC San Diego”) to develop a novel anti-cancer stem cell targeted therapy for patients with advanced solid and hematological malignancies. In connection with such CIRM award, the Company agreed to provide up to $1.0 million in contingency funds if required during the grant period. The Company recorded no research and development expense under such CIRM award for the years ended December 31, 2019 and 2018. Clinical Trial and Supply Agreement In April 2018, the Company entered into a Clinical Trial and Supply Agreement with Pharmacyclics, LLC, an AbbVie Company (“Pharmacyclics”) to supply ibrutinib for the Company’s Phase 1/2 clinical trial evaluating cirmtuzumab in combination with ibrutinib, which agreement was amended in August 2019. Such agreement does not bear any upfront costs, inventory purchase costs, milestone or royalty payment commitments or other financial obligations. License and Development Agreement with SPH USA, a Related Party In November 2018, the Company entered into a License and Development Agreement (“LDA”) with SPH USA for: (i) the territory of the People’s Republic of China, Hong Kong, Macau, and Taiwan (“Greater China”), and (ii) rights to manufacture, develop, market, distribute and sell all of the Company’s product candidates under the Georgetown License Agreement and the Regents License Agreement (exclusive to Greater China only). Under the LDA, SPH USA is solely responsible for: (a) all preclinical and clinical development activities required in order to obtain regulatory approval in Greater China for such product candidates, (b) any third-party license milestone or royalty payments owed under the Georgetown License Agreement and the Regents License Agreement, and (c) paying the Company a low single digit royalty on net sales in the territory. The LDA will expire upon the expiration of the last royalty term for the last licensed product. The LDA may be terminated by: (i) SPH USA on a country by country or product by product basis with 180 days written notice, (ii) either party upon material breach that is not cured within 90 days, and (iii) either the event the other insolvency or bankruptcy.

Merger

Merger	12 Months Ended
	Dec. 31, 2019
Merger [Abstract]
Merger	5. Merger The Merger, which closed on June 7, 2019, was accounted for as a reverse asset acquisition pursuant to Topic 805, Business Combinations Pursuant to the Merger Agreement on June 7, 2019, the Company, a representative of holders of the contingent value rights (“CVRs”), and Computershare, Inc. as rights agent entered into a Contingent Value Rights Agreement (the “CVR Agreement”). Pursuant to the CVR Agreement, the Company’s stockholders of record as of immediately prior to the Merger received one CVR for each share of the Company’s common stock held immediately prior to the Merger. CVR holders are entitled to receive 75% of the aggregate amount of any net proceeds received by the Company during the 15-year period after the closing of the Merger from the grant, sale or transfer of rights to the Company’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, if applicable, to receive royalties on the sale of any SARD or SARM products by the Company during the 15-year period after the closing. The CVR Agreement will continue in effect until the payment of all amounts payable thereunder. As of the June 7, 2019 closing date and December 31, 2019, no milestones had been accrued as there were no potential milestones yet considered probable. The total purchase price paid in the Merger has been allocated to the net assets acquired and liabilities assumed based on their fair values as of the completion of the Merger. The following summarizes the purchase price paid in the Merger (in thousands, except share and per share amounts): Number of shares of the combined organization owned by the Company’s pre-Merger stockholders 3,458,170 Multiplied by the fair value per share of GTx common stock (1) $ 8.40 Fair value of consideration issued to effect the Merger $ 29,049 Transaction costs 2,154 Purchase price $ 31,203 (1) Based on the last reported sale price of the Company’s common stock on the Nasdaq Capital Market on June 7, 2019, the closing date of the Merger, and gives effect to the Reverse Stock Split. The allocation of the purchase price is as follows: Cash acquired $ 18,292 Net liabilities assumed (5,177 ) IPR&D (2) 18,088 Purchase price $ 31,203 (2) Represents the research and development projects of GTx which were in-process, but not yet completed, and which the Company plans to advance, consisting primarily of GTx’s preclinical SARD technology. Current accounting standards require that the fair value of IPR&D projects acquired in an asset acquisition with no alternative future use be allocated a portion of the consideration transferred and charged to expense on the acquisition date. The acquired assets did not have outputs or employees.

Stockholders' Equity (Deficit)

Stockholders' Equity (Deficit)	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Stockholders' Equity (Deficit)	6. Stockholders’ Equity (Deficit) Amended and Restated Articles of Incorporation On June 7, 2019, the Company’s certificate of incorporation was amended and restated to authorize 60,000,000 shares of common stock and 5,000,000 shares of undesignated preferred stock, each with a par value of $0.001 per share. Convertible Preferred Stock In connection with the Merger, all of the outstanding shares of Private Oncternal’s convertible preferred stock were converted into 8,148,268 shares of the Company’s common stock. As of December 31, 2018, Private Oncternal’s convertible preferred stock is classified as temporary equity on the accompanying consolidated balance sheets in accordance with authoritative guidance for the classification and measurement of potentially redeemable securities whose redemption is based upon certain change in control events outside of Private Oncternal’s control, including liquidation, sale or transfer of control of Private Oncternal. Private Oncternal did not adjust the carrying values of the convertible preferred stock to the liquidation preferences of such shares because the occurrence of any such change of control event was not deemed probable. Sales of Convertible Preferred Stock In September, November and December 2017, Private Oncternal issued an aggregate of 1,662,494 shares of Series B-2 preferred stock at a per share purchase price of $6.13, raising net cash proceeds of $8.9 million, of which $1.1 million was collected in February 2018. In November 2018, contemporaneous with entering into the LDA, Private Oncternal issued 2,495,114 shares of Series C preferred stock to SPH USA, at a per share purchase price of $6.81, raising net cash proceeds of $16.8 million. Private Oncternal concluded that the shares were issued at fair value and therefore no value was ascribed to the LDA. Common Stock Warrants In September, November and December 2017, Private Oncternal issued warrants to purchase of 371,624 shares of Series B-2 preferred stock, which converted into rights to purchase common stock of the Company at the Merger closing, at an exercise price of $6.13 per share. The warrants expire on various dates in September, November and December 2022. As of December 31, 2019, warrants to purchase 196 shares of common stock have been exercised. On September 29, 2017, the Company completed a private placement transaction that included warrants to purchase an aggregate of 469,996 shares of the Company’s common stock at an exercise price of $63.14 per share. The five-year warrants expire on September 29, 2022. As of December 31, 2019, no such warrants have been exercised. The Company assessed whether the above warrants require accounting as derivatives after the Merger closing. 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 warrant liabilities. Common Stock and Unvested Share Liability The Company has issued restricted common stock subject to vesting and repurchase by the Company. For employee and non-employee awards, the issuance date fair value is recognized over the requisite service period of the award (usually the vesting period) on a straight-line basis. In addition, the Company has outstanding unvested shares related to the early exercise of stock options. The Company has the right, but not the obligation, to repurchase any unvested shares at the original purchase price upon any voluntary or involuntary termination. The consideration received in exchange for unvested shares is recorded as an unvested share liability on the accompanying consolidated balance sheets and is reclassified into common stock and additional paid-in capital as the shares vest. At December 31, 2019 and 2018, the unvested share liability was $24,000 and $54,000, respectively. A summary of the Company’s unvested shares is as follows (in thousands): Number of Shares Balance at December 31, 2018 100 Vested shares (65 ) Balance at December 31, 2019 35 Equity Incentive Plans Contemporaneous with the Merger closing: (i) Private Oncternal’s 2015 Equity Incentive Plan, as amended (the “2015 Plan”) was assumed by the Company, and (ii) the Company adopted the 2019 Incentive Award Plan (“2019 Plan”) under which the sum of: (a) 1,678,571 shares of common stock, (b) up to 275,579 shares of common stock which were subject to outstanding awards under the GTx 2013 Equity Incentive Plan (the “2013 Plan”) as of June 7, 2019, that are subsequently cancelled will become available for issuance under the 2019 Plan, and (c) an annual increase on the first day of each calendar year beginning January 1, 2020, and ending on and including January 1, 2029, equal to the lesser of (A) 5% of the aggregate number of shares of common stock outstanding on the final day of the immediately preceding calendar year and (B) such smaller number of shares of common stock as is determined by the Board, are reserved for issuance. At December 31, 2019, 494,583 shares remain available for future issuance under the 2019 Plan (see Note 9). Number of Shares Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (in years) Aggregate Intrinsic Value December 31, 2019: Options outstanding 1,662,253 $ 4.17 9.2 $ 1,460 Options vested and expected to vest 1,662,253 $ 4.17 9.2 $ 1,460 Options exercisable 244,170 $ 1.16 7.2 $ 718 As of December 31, 2019 under the 2013 Plan, there were: (i) 257,067 outstanding and fully vested options with a weighted average exercise price of $59.98 per share, and (ii) 18,512 cancelled options that were added back to the 2019 Plan as of December 31, 2019. As of December 31, 2019, the former GTx stock option plans had an aggregate of 295,414 outstanding and fully vested and exercisable options with a weighted average exercise price of $71.34 and a weighted average remaining contractual term of 0.7 years. In July 2015, Private Oncternal adopted the 2015 Plan which provided for the issuance of up to 631,120 shares of common stock for incentive stock options, non-statutory stock options, restricted stock awards, restricted stock unit awards and other stock awards to its employees, members of its board of directors and consultants. In general, the options issued under the 2015 Plan expire ten years from the date of grant and vest over a four-year period. Certain grants vest based on the achievement of development or regulatory milestones. The 2015 Plan allowed for the early exercise of all stock option grants if authorized by the board of directors at the time of grant. The Company has the option to repurchase any unvested shares at the original purchase price upon any voluntary or involuntary termination. No further awards will be made under the 2015 Plan, which was terminated in June 2019. A summary of the Company’s stock option activity under the 2019 Plan and 2015 Plan is as follows: Number of Options Weighted- Average Exercise Price Balance at December 31, 2018 504,019 $ 0.81 Granted 1,230,000 $ 5.47 Cancelled (52,726 ) $ 3.38 Exercised (19,040 ) $ 0.69 Balance at December 31, 2019 1,662,253 $ 4.17 Information about the Company’s outstanding stock options under the 2019 Plan and 2015 Plan is as follows (in thousands, except share and per share data and contractual term): The weighted average grant date fair value per share of option grants for the years ended December 31, 2019 and 2018 was $3.69 and $0.55 per share, respectively. The aggregate intrinsic value used in the above table of options at December 31, 2019 is based on the Company’s closing market price per common share on December 31, 2019 of $3.95. The intrinsic value is calculated as the difference between the fair value of the Company’s common stock at the time of the option exercise and the exercise price of that stock option. The aggregate intrinsic value of stock options exercised during the years ended December 31, 2019 and 2018 was not material. Stock-Based Compensation Expense The weighted-average assumptions used in the Black-Scholes option pricing model to determine the fair value of stock option grants were as follows: Years Ended December 31, 2019 2018 Risk-free interest rate 1.6 % 2.9 % Expected volatility 77.6 % 64.7 % Expected term (in years) 6.0 6.1 Expected dividend yield — % — % Expected volatility. Prior to the Merger, Private Oncternal did not have a trading history for its common stock. Accordingly, the expected volatility assumption is based on volatilities of a peer group of similar companies whose share prices are publicly available. The peer group was developed based on companies in the life sciences industry. The Company will continue to apply this process until a sufficient amount of historical information regarding the volatility of its own stock price becomes available. Expected term. The expected term represents the period of time that options are expected to be outstanding. Because Private Oncternal did not have historical exercise behavior, it determined the expected life assumption using the simplified method for employees, which is an average of the contractual term of the option and its vesting period. The expected term for nonemployee options is generally the remaining contractual term. Risk-free interest rate. The risk-free interest rate is based on the implied yield on the U.S. Treasury securities with a maturity date similar to the expected term of the associated stock option award. Expected dividend yield. The Company bases the expected dividend yield assumption on the fact that it has never paid cash dividends and has no present intention to pay cash dividends and, therefore, used an expected dividend yield of zero. Stock-based compensation expense recognized for all equity awards has been reported in the statements of operations as follows (in thousands): Years Ended December 31, 2019 2018 Research and development $ 237 $ 141 General and administrative 270 39 $ 507 $ 180 At December 31, 2019, the total compensation cost related to nonvested awards not yet recognized was $4.2 million and the weighted-average period over which it is expected to be recognized was 3.5 years. Common Stock Reserved for Future Issuance Common stock reserved for future issuance is as follows (in thousands): December 31, 2019 2018 Redeemable convertible preferred stock — 8,148 Warrants to purchase convertible preferred stock — 372 Common stock warrants 841 — Common stock options issued and outstanding 1,958 504 Common stock available for issuance under equity plans 495 80 3,294 9,104

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	7. Income Taxes A reconciliation of the Company’s effective tax rate and federal statutory tax rate is as follows (in thousands): Years Ended December 31, 2019 2018 Federal income taxes $ (7,179 ) $ (1,379 ) State income taxes, net of federal benefit (968 ) (500 ) Permanent items 873 (147 ) In-process research and development 3,354 Research and development credit carryforwards (217 ) (468 ) Other, net 18 51 Change in valuation allowance 4,119 2,443 Provision for income taxes $ — $ — Significant components of the Company’s net deferred tax assets are as follows (in thousands): December 31, 2019 2018 Deferred tax assets: Net operating loss carryforwards $ 18,108 $ 8,321 Research and development credit carryforwards 1,446 1,231 Accrued expenses 214 24 Capitalized research and development costs 7,688 — Other, net 143 288 Total deferred tax assets 27,599 9,864 Valuation allowance (27,546 ) (9,864 ) 53 — Deferred tax liabilities: Right of use asset (53 ) — Total deferred tax liabilities (53 ) — Net deferred tax assets $ — $ — Based on the Company’s history of operating losses, the Company is unable to conclude that it is more likely than not that the benefit of its deferred tax assets will be realized. Accordingly, the Company has provided a full valuation allowance for its deferred tax assets as of December 31, 2019 and 2018. As a result of the Merger in 2019, the Company recorded deferred tax assets of $13.1 million which are fully offset by a valuation allowance. The $13.1 million net deferred tax assets do not include federal and state net operating loss carryforwards and federal research and development credit carryforwards that are estimated to expire under Internal Revenue Code Sections 382 and 383 as a result of the Merger. At December 31, 2019, the Company had federal and state net operating loss (NOL) carryforwards of approximately $70.0 million and $48.7 million, respectively. Of the federal net operating losses at December 31, 2019, $44.2 million do not expire, and the remaining federal and state net operating loss carryforwards will begin expiring in 2034 and 2030, respectively, unless previously utilized. At December 31, 2019, the Company also had federal and state research and development credit carryforwards of approximately $0.9 million and $0.7 million, respectively. The federal research and development credit carryforwards will begin expiring in 2034 unless previously utilized. The state research and development credits do not expire. Pursuant to Internal Revenue Code Sections 382 and 383, annual use of the Company’s net operating loss and research and development tax credit carryforwards may be limited in the event a cumulative change in ownership of more than 50% occurs within a three-year period. The Company has not completed a Section 382 study to assess whether an ownership change has occurred or whether there have been multiple ownership changes since the Company’s formation due to the complexity and cost associated with such a study and the fact that there may be additional such ownership changes in the future. If eliminated, the related asset would be removed from the deferred tax asset schedule with a corresponding reduction in the valuation allowance. Due to the existence of the valuation allowance, limitations created by future ownership changes, if any, will not impact the Company’s effective tax rate. The Company recognizes a tax benefit from an uncertain tax position when it is more likely than not that the position will be sustained upon examination, including resolutions of any related appeals or litigation processes, based on the technical merits. Income tax positions must meet a more likely than not recognition at the effective date to be recognized. At December 31, 2019 and 2018, there were no unrecognized tax benefits recorded in the consolidated financial statements. The Company does not expect any material changes to unrecognized tax benefits within the next twelve months. The Company is subject to taxation in the United States federal and state jurisdictions. The Company’s 2013 through 2019 federal income tax and state income tax returns are subject to examination by federal and state tax authorities due to the carryforward of unutilized net operating losses and research and development credits. The Company is not currently under examination by any tax authority. The Company’s policy is to recognize interest and penalties related to income tax matters in income tax expense. The Company has not recognized interest or penalties in its consolidated statements of operations since inception. The Company adopted Accounting Standards Codification Topic 842 – Leases, on January 1, 2019. Under Topic 842, the Company is required to recognize a right-of-use asset and a lease liability, initially measured at the present value of the lease payments for operating leases on the balance sheet. Upon adoption, no change in retained earnings was recorded related to income taxes as the Company maintains a full valuation allowance. As of the implementation date, an adjustment of $0.1 million was recorded as a deferred tax liability and an adjustment of $0.1 million was recorded as a deferred tax asset.

Description of Business, Basi_2

Description of Business, Basis of Presentation and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Merger	Merger On June 7, 2019, the Company, then operating as GTx, Inc. (“GTx”), completed its Agreement and Plan of Merger and Reorganization, as amended (the “Merger Agreement”), with privately-held Oncternal Therapeutics, Inc. (“Private Oncternal”) and Grizzly Merger Sub, Inc., a wholly-owned subsidiary of the Company (“Merger Sub”), dated March 6, 2019. Under the Merger Agreement, Merger Sub merged with and into Private Oncternal, with Private Oncternal surviving as a wholly-owned subsidiary of the Company (the “Merger”). GTx changed its name to Oncternal Therapeutics, Inc., and Private Oncternal, which remains as a wholly-owned subsidiary of the Company, changed its name to Oncternal Oncology, Inc. On June 10, 2019, the combined company’s common stock began trading on The Nasdaq Capital Market under the ticker symbol “ONCT.” Except as otherwise indicated, references herein to “Oncternal,” “the Company,” and the “combined company,” refer to Oncternal Therapeutics, Inc. on a post-Merger basis, and the term “Private Oncternal” refers to the business of privately-held Oncternal Therapeutics, Inc., prior to completion of the Merger. References to GTx refer to GTx, Inc. prior to completion of the Merger. Pursuant to the terms of the Merger Agreement, each outstanding share of Private Oncternal common stock outstanding immediately prior to the closing of the Merger was converted into approximately 0.073386 shares of Company common stock (the “Exchange Ratio”), after taking into account the Reverse Stock Split, as defined below. Immediately prior to the closing of the Merger, all shares of Private Oncternal preferred stock then outstanding were exchanged into shares of common stock of Private Oncternal. In addition, all outstanding options exercisable for common stock of Private Oncternal and warrants exercisable for convertible preferred stock of Private Oncternal became options and warrants exercisable for the same number of shares of common stock of the Company multiplied by the Exchange Ratio. Immediately following the Merger, stockholders of Private Oncternal owned approximately 77.5% of the outstanding common stock of the combined company. The transaction was accounted for as a reverse asset acquisition in accordance with generally accepted accounting principles in the United States of America (“GAAP”). Under this method of accounting, Private Oncternal was deemed to be the accounting acquirer for financial reporting purposes. This determination was primarily based on the facts that, immediately following the Merger: (i) Private Oncternal’s stockholders owned a substantial majority of the voting rights in the combined company, (ii) Private Oncternal designated a majority of the members of the initial board of directors of the combined company, and (iii) Private Oncternal’s senior management holds all key positions in the senior management of the combined company. As a result, as of the closing date of the Merger, the net assets of the Company were recorded at their acquisition-date relative fair values in the consolidated financial statements of the Company and the reported operating results prior to the Merger will be those of Private Oncternal.
Reverse Stock Split and Exchange Ratio	Reverse Stock Split and Exchange Ratio On June 7, 2019, in connection with, and prior to the completion of, the Merger, GTx effected a one-for-seven reverse stock split of its then outstanding common stock (the “Reverse Stock Split”). The par value and the authorized shares of the common stock were not adjusted as a result of the Reverse Stock Split. All of the Company’s issued and outstanding common stock have been retroactively adjusted to reflect this Reverse Stock Split for all periods presented. All issued and outstanding Private Oncternal common stock, preferred stock, options and warrants prior to the effective date of the Merger have been retroactively adjusted to reflect the Exchange Ratio for all periods presented.
Principles of Consolidation	Principles of Consolidation The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries, Oncternal Oncology, Inc. and Oncternal, Inc. All intercompany accounts and transactions have been eliminated in the preparation of the consolidated financial statements.
Liquidity and Going Concern	Liquidity and Going Concern From its inception through December 31, 2019, the Company has devoted substantially all of its efforts to organizational activities including raising capital, building infrastructure, acquiring assets, developing intellectual property, and conducting preclinical studies, clinical trials and product development activities. The Company has a limited operating history and the sales and income potential of the Company’s business and market are unproven. Since inception, the Company has experienced recurring net losses and negative cash flows from operating activities and expects to continue to incur losses into the foreseeable future. At December 31, 2019, the Company had an accumulated deficit of $65.6 million and had cash and cash equivalents of $20.1 million. The Company believes that its existing cash and cash equivalents will be sufficient to fund its operations into the third quarter of 2020. The Company will need to continue to raise a substantial amount of funds until it is able to generate revenues to fund its development activities and operations. The accompanying consolidated financial statements have been prepared assuming that the Company will continue as a going concern, wh ich contemplates the realization of assets and settlement of liabilities in the normal course of business. The Company plans to continue to fund its losses from operations and capital funding needs through a combination of equity offerings, debt financings, government funding, or other sources, including, potentially, collaborations, licenses and other similar arrangements. There can be no assurance that the Company will be able to obtain any sources of financing on acceptable terms, or at all. To the extent that the Company can raise additional funds by issuing equity securities, the Company’s stockholders may experience significant dilution. Any debt financing, if available, may involve restrictive covenants that impact the Company’s ability to conduct its business.
Use of Estimates	Use of Estimates The Company’s consolidated financial statements accordance GAAP. of the Company’s consolidated financial statements and accompanying notes and assumptions that impact the amounts of liabilities, revenues and expenses and the disclosure of contingent and liabilities. Significant consist of those the value of the Company’s stock, stock liability , and those revenue and and development Although these on the Company’s knowledge of events and actions undertake the actual ultimately these and assumptions.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments with maturities of three months or less when purchased to be cash equivalents. Cash and cash equivalents include cash in readily available checking accounts and money market accounts.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash and cash equivalents. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits. The Company has not experienced any losses in such accounts and believes it is not exposed to significant risk on its cash balances due to the financial position of the depository institution in which those deposits are held. Additionally, the Company established guidelines regarding approved investments and maturities of investments, which are designed to maintain safety and liquidity.
Patent Costs	Patent Costs Costs related to filing and pursuing patent applications are recorded as general and administrative expense and expensed as incurred since recoverability of such expenditures is uncertain.
Research and Development Expenses and Accruals	Research and Development Expenses and Accruals Research and development expenses consist of costs incurred for the Company’s own and for sponsored and collaborative research and development activities. Research and development costs are expensed as incurred and include manufacturing process development costs, manufacturing costs, costs associated with preclinical studies and clinical trials, regulatory and medical affairs activities, quality assurance activities, salaries and benefits, including stock-based compensation, fees paid to third-party consultants, license fees and overhead. The Company has entered into various research and development contracts with research institutions, clinical research organizations, clinical manufacturing organizations and other companies. Payments for these activities are based on the terms of the individual agreements, which may differ from the pattern of costs incurred, and payments made in advance of performance are reflected in the accompanying consolidated balance sheets as prepaid and other assets or accrued liabilities. The Company records accruals for estimated costs incurred for ongoing research and development activities. When evaluating the adequacy of the accrued liabilities, the Company analyzes progress of the services, including the phase or completion of events, invoices received and contracted costs. Significant judgments and estimates may be made in determining the prepaid or accrued balances at the end of any reporting period. Actual results could differ from the Company’s estimates.
Preferred Stock Warrant Liability	Preferred Stock Warrant Liability Prior to the Merger, Private Oncternal had outstanding freestanding warrants to purchase shares of its Series B-2 convertible preferred stock (the “Series B-2 warrants”). Because the underlying Series B-2 convertible preferred stock was classified as temporary equity, the Series B-2 warrants were classified as a liability in the accompanying consolidated balance sheets. Private Oncternal adjusted the carrying value of such Series B-2 warrants to their estimated fair value at each reporting date, with any related increases or decreases in the fair value recorded as an increase or decrease to other income (expense) in the consolidated statements of operations. Upon the completion of the Merger, the Series B-2 warrants were amended such that they were converted into warrants to purchase the Company’s common stock. As amended, warrant liability accounting is no longer required and the fair value of the warrant liability has been reclassified into stockholders’ equity.
Fair Value Measurements	Fair Value Measurements The accounting guidance defines fair value, establishes a consistent framework for measuring fair value and expands disclosure for each major asset and liability category measured at fair value on either a recurring or non-recurring basis. Fair value is defined as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, the accounting guidance establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value as follows: Level 1: Observable inputs such as quoted prices in active markets. Level 2: Inputs, other than the quoted prices in active markets that are observable either directly or indirectly. Level 3: Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions. The carrying amounts of the Company’s current financial assets and liabilities are considered to be representative of their respective fair values because of the short-term nature of those instruments. The Company has no financial assets or liabilities, other than the preferred stock warrant liability described below, measured at fair value on a recurring basis. No transfers between levels have occurred during the periods presented. Liabilities measured at fair value on a recurring basis are as follows (in thousands): Fair Value Measurements at Reporting Date Using Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Total (Level 1) (Level 2) (Level 3) At December 31, 2018 Preferred stock warrant liability $ 674 $ — $ — $ 674 As of December 31, 2018, the preferred stock warrant liability was recorded at fair value utilizing the Black-Scholes option pricing model using significant unobservable inputs consistent with the inputs used for the Company’s stock-based compensation expense adjusted for the preferred stock warrants’ expected term and the fair value of the underlying preferred stock. The Company calculated the final remeasurement of the preferred stock warrant liability on June 7, 2019, the Merger closing date, using the closing price of GTx’s common stock on that date to determine the fair value of the warrants, and recorded a $1.3 million change in the fair value of the preferred stock warrant liability for the year ended December 31, 2019. The assumptions used in the Black-Scholes option pricing model to determine the fair value of the preferred stock warrant liability as of December 31, 2018 were as follows: Fair value of underlying preferred stock $ 0.29 Risk-free interest rate 2.4% — 2.7% Expected volatility 75.3% — 76.4% Expected term (in years) 3.7 — 4.0 Expected dividend yield —% The following table provides a reconciliation of the preferred stock warrant liability measured at fair value using Level 3 significant unobservable inputs (in thousands): Preferred Stock Warrant Liability Balance at December 31, 2018 $ 674 Change in fair value 1,268 Reclassification of preferred stock warrant liability to equity (1,942 ) Balance at December 31, 2019 $ —
Revenue Recognition	Revenue Recognition The Company currently generates revenue from the California Institute for Regenerative Medicine pursuant to a research subaward agreement (see Note 4), which provides the Company with payments in return for certain research and development activities over a contractually defined period. Revenue from such subaward is recognized in the period during which the related qualifying services are rendered and costs are incurred, provided that the applicable conditions under the subaward agreement have been met. The subaward agreement is on a best-effort basis and does not require scientific achievement as a performance obligation. All fees received under the agreement are non-refundable. The costs associated with the agreement are expensed as incurred and reflected as a component of research and development expense in the accompanying consolidated statements of operations. Funds received from the subaward agreement are recorded as revenue as the Company is the principal participant in the arrangement because the activities under the subaward are part of the Company’s development programs. In those instances where the Company first receives consideration in advance of providing underlying services, the Company classifies such consideration as deferred revenue until (or as) the Company provides the underlying services. In those instances where the Company first provides the underlying services prior to its receipt of consideration, the Company records a grant receivable. At December 31, 2019, the Company had deferred grant revenue of $3.6 million, and at December 31, 2018, the Company had a grant receivable of $0.1 million.
Stock-Based Compensation	Stock-Based Compensation Stock-based compensation expense represents the fair value of equity awards, on the grant date, recognized in the period using the Black- Scholes option pricing model. The Company recognizes expense for awards with graded vested schedules over the requisite service period of the awards (usually the vesting period) on a straight-line basis. For equity awards for which vesting is subject to performance-based milestones, the expense is recorded over the remaining service period after the point when the achievement of the milestone is probable or the performance condition has been achieved.
Income Taxes	Income Taxes The Company accounts for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements. Under this method, deferred tax assets and liabilities are determined on the basis of the differences between the financial statements and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date. The Company recognizes net deferred tax assets to the extent that the Company believes these assets are more likely than not to be realized. In making such a determination, management considers all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies, and results of recent operations. If management determines that the Company would be able to realize its deferred tax assets in the future in excess of their net recorded amount, management would make an adjustment to the deferred tax asset valuation allowance, which would reduce the provision for income taxes.
Segment Reporting	Segment Reporting Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision-maker in making decisions regarding resource allocation and assessing performance. The Company views its operations and manages its business in one operating segment in the United States.
Net Loss Per Share	Net Loss Per Share Basic net loss per share is computed by dividing the net loss by the weighted-average number of common shares outstanding for the period, without consideration for potentially dilutive securities and adjusted for the weighted-average number of common shares outstanding that are subject to repurchase. The Company has excluded weighted-average shares subject to repurchase of 56,000 shares and 164,000 shares from the weighted-average number of common shares outstanding for the years ended December 31, 2019 and 2018, respectively. Diluted net loss per share is computed by dividing the net loss by the weighted-average number of shares of common stock and dilutive common stock equivalents outstanding for the period determined using the treasury-stock and if-converted methods. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding as inclusion of the potentially dilutive securities would be antidilutive. Potentially dilutive securities not included in the calculation of diluted net loss per share, because to do so would be anti-dilutive, are as follows (in common stock equivalent shares; in thousands): December 31, 2019 2018 Redeemable convertible preferred stock — 8,148 Warrants to purchase convertible preferred stock — 372 Warrants to purchase common stock 841 — Common stock options 1,958 504 Common stock subject to repurchase 35 100 2,834 9,124
Recently Accounting Pronouncements	Recently Issued Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) or other standard setting bodies that are adopted by the Company as of the specified effective date. Unless otherwise discussed, the Company believes that the impact of recently issued standards that are not yet effective will not have a material impact on its consolidated financial position or results of operations upon adoption. In August 2018, the FASB issued Accounting Standards Update (“ASU”) Fair Value Measurement: Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement, no impact on the consolidated financial statements from the adoption of this standard Recently Adopted Accounting Pronouncements In February 2016, the FASB issued ASU 2016-02, Leases

Description of Business, Basi_3

Description of Business, Basis of Presentation and Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2019
Schedule of Liabilities Measured at Fair Value on Recurring Basis	Liabilities measured at fair value on a recurring basis are as follows (in thousands): Fair Value Measurements at Reporting Date Using Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Unobservable Inputs Total (Level 1) (Level 2) (Level 3) At December 31, 2018 Preferred stock warrant liability $ 674 $ — $ — $ 674
Schedule of Reconciliation of Warrant Liability Measured at Fair Value Using Level 3 Significant Unobservable Inputs	The following table provides a reconciliation of the preferred stock warrant liability measured at fair value using Level 3 significant unobservable inputs (in thousands): Preferred Stock Warrant Liability Balance at December 31, 2018 $ 674 Change in fair value 1,268 Reclassification of preferred stock warrant liability to equity (1,942 ) Balance at December 31, 2019 $ —
Schedule of Potentially Dilutive Securities Excluded from Calculation of Diluted Net Loss per Share Would Be Anti-dilutive	Potentially dilutive securities not included in the calculation of diluted net loss per share, because to do so would be anti-dilutive, are as follows (in common stock equivalent shares; in thousands): December 31, 2019 2018 Redeemable convertible preferred stock — 8,148 Warrants to purchase convertible preferred stock — 372 Warrants to purchase common stock 841 — Common stock options 1,958 504 Common stock subject to repurchase 35 100 2,834 9,124
Preferred Stock Warrants
Schedule of Assumptions Used to Determine Fair Value	The assumptions used in the Black-Scholes option pricing model to determine the fair value of the preferred stock warrant liability as of December 31, 2018 were as follows: Fair value of underlying preferred stock $ 0.29 Risk-free interest rate 2.4% — 2.7% Expected volatility 75.3% — 76.4% Expected term (in years) 3.7 — 4.0 Expected dividend yield —%

Balance Sheet Details (Tables)

Balance Sheet Details (Tables)	12 Months Ended
	Dec. 31, 2019
Payables And Accruals [Abstract]
Summary of Accrued Liabilities	Accrued liabilities consist of the following (in thousands): December 31, 2019 2018 Research and development $ 1,206 $ 720 Legal fees 424 20 Unvested share liability 24 54 Compensation 825 85 Other 252 12 $ 2,731 $ 891

Commitments, Contingencies an_2

Commitments, Contingencies and Related Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2019
Commitments And Contingencies Disclosure [Abstract]
Summary of Maturities of Lease Liabilities	Maturities of lease liabilities due under this lease agreement as of December 31, 2019, are as follows (in thousands): Maturity of lease liabilities Operating Leases 2020 $ 166 2021 41 Total lease payments 207 Less imputed interest (17 ) Total operating lease liabilities 190 Less current portion of lease liability (99 ) Lease liability $ 91

Merger - (Tables)

Merger - (Tables)	12 Months Ended
	Dec. 31, 2019
Merger [Abstract]
Summary of Purchase Price Paid in Merger	The following summarizes the purchase price paid in the Merger (in thousands, except share and per share amounts): Number of shares of the combined organization owned by the Company’s pre-Merger stockholders 3,458,170 Multiplied by the fair value per share of GTx common stock (1) $ 8.40 Fair value of consideration issued to effect the Merger $ 29,049 Transaction costs 2,154 Purchase price $ 31,203 (1) Based on the last reported sale price of the Company’s common stock on the Nasdaq Capital Market on June 7, 2019, the closing date of the Merger, and gives effect to the Reverse Stock Split.
Summary of Allocation of Purchase Price	The allocation of the purchase price is as follows: Cash acquired $ 18,292 Net liabilities assumed (5,177 ) IPR&D (2) 18,088 Purchase price $ 31,203 (2) Represents the research and development projects of GTx which were in-process, but not yet completed, and which the Company plans to advance, consisting primarily of GTx’s preclinical SARD technology. Current accounting standards require that the fair value of IPR&D projects acquired in an asset acquisition with no alternative future use be allocated a portion of the consideration transferred and charged to expense on the acquisition date. The acquired assets did not have outputs or employees.

Stockholders' Equity (Deficit)

Stockholders' Equity (Deficit) (Tables)	12 Months Ended
	Dec. 31, 2019
Summary of Unvested Shares	A summary of the Company’s unvested shares is as follows (in thousands): Number of Shares Balance at December 31, 2018 100 Vested shares (65 ) Balance at December 31, 2019 35
Summary of Stock Option Outstanding, Vested and Expected to Vest and Exercisable	Number of Shares Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (in years) Aggregate Intrinsic Value December 31, 2019: Options outstanding 1,662,253 $ 4.17 9.2 $ 1,460 Options vested and expected to vest 1,662,253 $ 4.17 9.2 $ 1,460 Options exercisable 244,170 $ 1.16 7.2 $ 718
Summary of Stock Option Activity	A summary of the Company’s stock option activity under the 2019 Plan and 2015 Plan is as follows: Number of Options Weighted- Average Exercise Price Balance at December 31, 2018 504,019 $ 0.81 Granted 1,230,000 $ 5.47 Cancelled (52,726 ) $ 3.38 Exercised (19,040 ) $ 0.69 Balance at December 31, 2019 1,662,253 $ 4.17
Summary of Share-Based Compensation Expense	Stock-based compensation expense recognized for all equity awards has been reported in the statements of operations as follows (in thousands): Years Ended December 31, 2019 2018 Research and development $ 237 $ 141 General and administrative 270 39 $ 507 $ 180
Common Stock Reserved for Future Issuance	Common stock reserved for future issuance is as follows (in thousands): December 31, 2019 2018 Redeemable convertible preferred stock — 8,148 Warrants to purchase convertible preferred stock — 372 Common stock warrants 841 — Common stock options issued and outstanding 1,958 504 Common stock available for issuance under equity plans 495 80 3,294 9,104
Stock Option Grants
Schedule of Assumptions Used to Determine Fair Value	The weighted-average assumptions used in the Black-Scholes option pricing model to determine the fair value of stock option grants were as follows: Years Ended December 31, 2019 2018 Risk-free interest rate 1.6 % 2.9 % Expected volatility 77.6 % 64.7 % Expected term (in years) 6.0 6.1 Expected dividend yield — % — %

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Summary of Reconciliation of Effective Tax Rate and Federal Statutory Tax Rate	A reconciliation of the Company’s effective tax rate and federal statutory tax rate is as follows (in thousands): Years Ended December 31, 2019 2018 Federal income taxes $ (7,179 ) $ (1,379 ) State income taxes, net of federal benefit (968 ) (500 ) Permanent items 873 (147 ) In-process research and development 3,354 Research and development credit carryforwards (217 ) (468 ) Other, net 18 51 Change in valuation allowance 4,119 2,443 Provision for income taxes $ — $ —
Summary of Significant Components of Net Deferred Tax Assets	Significant components of the Company’s net deferred tax assets are as follows (in thousands): December 31, 2019 2018 Deferred tax assets: Net operating loss carryforwards $ 18,108 $ 8,321 Research and development credit carryforwards 1,446 1,231 Accrued expenses 214 24 Capitalized research and development costs 7,688 — Other, net 143 288 Total deferred tax assets 27,599 9,864 Valuation allowance (27,546 ) (9,864 ) 53 — Deferred tax liabilities: Right of use asset (53 ) — Total deferred tax liabilities (53 ) — Net deferred tax assets $ — $ —

Description of Business, Basi_4

Description of Business, Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Details) $ in Thousands	Jun. 07, 2019	Dec. 31, 2019USD ($)segmentshares	Dec. 31, 2018USD ($)shares
Description Of Business Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Accumulated deficit		$ 65,572	$ 31,384
Cash and cash equivalents		20,051	20,645
Preferred stock warrant liability		1,300	674
Deferred grant revenue		$ 3,640
Grants receivable			$ 100
Number of operating segments | segment		1
Weighted-average shares subject to repurchase | shares		56,000	164,000
Merger Agreement
Description Of Business Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Reverse stock split of common stock	7
Merger Agreement | Combined organization's
Description Of Business Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Common stock and preferred stock exchange ratio	0.073386
Ownership percentage of stockholders upon closing of merger	77.50%

Description of Business, Basi_5

Description of Business, Basis of Presentation and Summary of Significant Accounting Policies - Schedule of Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Preferred stock warrant liability	$ 1,300	$ 674
Fair Value, Measurements, Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Preferred stock warrant liability		674
Level 3 | Fair Value, Measurements, Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Preferred stock warrant liability		$ 674

Description of Business, Basi_6

Description of Business, Basis of Presentation and Summary of Significant Accounting Policies - Schedule of Assumptions Used to Determine Fair Value of Preferred Stock Warrant Liability (Detail)	12 Months Ended
	Dec. 31, 2018$ / shares
Accounting Policies [Abstract]
Fair value of underlying preferred stock	$ 0.29
Risk-free interest rate, minimum	2.40%
Risk-free interest rate, maximum	2.70%
Expected volatility, minimum	75.30%
Expected volatility, maximum	76.40%
Expected term, minimum (in years)	3 years 8 months 12 days
Expected term, maximum (in years)	4 years

Description of Business, Basi_7

Description of Business, Basis of Presentation and Summary of Significant Accounting Policies - Schedule of Reconciliation of Warrant Liability Measured at Fair Value Using Level 3 Significant Unobservable Inputs (Details) - Level 3 - Preferred Stock Warrants $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 674
Change in fair value	1,268
Reclassification of preferred stock warrant liability to equity	$ (1,942)

Description of Business, Basi_8

Description of Business, Basis of Presentation and Summary of Significant Accounting Policies - Schedule of Potentially Dilutive Securities Excluded from Calculation of Diluted Net Loss per Share Would Be Anti-dilutive (Detail) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities	2,834	9,124
Redeemable Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities		8,148
Warrants to Purchase Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities		372
Warrants to purchase common stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities	841
Common Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities	1,958	504
Common Stock Subject to Repurchase
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities	35	100

Balance Sheet Details - Accrued

Balance Sheet Details - Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Payables And Accruals [Abstract]
Research and development	$ 1,206	$ 720
Legal fees	424	20
Unvested share liability	24	54
Compensation	825	85
Other	252	12
Total accrued liabilities	$ 2,731	$ 891

Commitments, Contingencies an_3

Commitments, Contingencies and Related Party Transactions - Additional Information (Details)	May 22, 2019USD ($)ft²	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Commitments And Contingencies [Line Items]
Rent expense		$ 100,000	$ 12,000
Operating lease liability		190,000
Insurance premium		1,200,000
Shanghai Pharmaceutical (USA) Inc.
Commitments And Contingencies [Line Items]
Amounts receivable		200,000
Agent
Commitments And Contingencies [Line Items]
Insurance commissions		100,000
Board of Directors
Commitments And Contingencies [Line Items]
Expense on services related to potential out-licensing or sale of technology		$ 3,500
San Diego, California | Office Space
Commitments And Contingencies [Line Items]
Rentable area | ft²	4,677
Lease expiration date	Mar. 31, 2021
Annual base rent	$ 166,000,000
Lease discount rate		10.00%
Operating lease liability		$ 200,000
Weighted average remaining lease term		1 year 3 months

Commitments, Contingencies an_4

Commitments, Contingencies and Related Party Transactions - Summary of Maturities of Lease Liabilities (Details) $ in Thousands	Dec. 31, 2019USD ($)
Operating Lease Liabilities Payments Due [Abstract]
2020	$ 166
2021	41
Total lease payments	207
Less imputed interest	(17)
Operating lease liability	190
Less current portion of lease liability	(99)
Lease liability	$ 91

License, Collaboration and Re_2

License, Collaboration and Research Subaward Agreements - Additional Information (Details)	Feb. 06, 2018USD ($)Product	Oct. 31, 2017USD ($)	Aug. 31, 2017USD ($)	May 31, 2015USD ($)shares	Dec. 31, 2019USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research and development expense						$ 0	$ 0
Patent costs as general and administrative expense						7,286,000	1,820,000
Loss from operations						(33,108,000)	(7,586,000)
Grant revenue						2,425,000	2,521,000
Regents of the University of California
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research and development expense						25,000	25,000
Upfront license fees paid				$ 500,000
Common stock, shares, issued | shares				107,108
Annual license maintenance fees				$ 25,000
Worldwide sales milestones based on achievement of tiered revenue levels				75,000,000
Patent costs as general and administrative expense						200,000	100,000
Velos Biopharma Holdings, LLC
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of preclinical product candidates licensed and assigned | Product	2
University of California San Diego School of Medicine | The California Institute for Regenerative Medicine ("CIRM") Award
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Grants awarded to researchers		$ 5,800,000	$ 18,300,000
Development milestones to be received under research subaward agreements throughout award project period			$ 14,000,000
Subaward payments received						6,200,000	500,000
Grant revenue						2,400,000	2,500,000
Related qualifying subaward costs						5,400,000	4,600,000
Exclusive License Agreement | Georgetown University
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Annual license maintenance fee to be paid and payment made									$ 10,000
Potential milestone payments					$ 0	$ 0
Written notice of termination, period						90 days
Days after receipt of notice, to pay failure amount						30 days
Days after receipt of notice for default in payment						60 days
Minimum period in days of written notice to terminate license agreement						60 days
Research and development expense						$ 27,000	53,000
Collaborative Arrangement | MD Anderson Cancer Center
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Potential regulatory milestone payments										$ 1,000,000
Research Agreement | Regents of the University of California
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research and development expense						$ 500,000
Research agreement term						5 years
Aggregate research agreement budget						$ 3,600,000
Research amount payable quarterly						$ 125,000
Regents License Agreement | Velos Biopharma Holdings, LLC | Spin-off Transactions
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Percentage of tax free interest distribution								100.00%
Number of preclinical product candidates licensed and assigned | Product	2
Promissory note receivable	$ 100,000
Annual interest rate	2.64%
Promissory note maturity period	10 years
Payment obligations to advance licensed assets	$ 500,000
Research agreement obligation	$ 500,000
Regents License Agreement | Regents of the University of California
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Written notice of termination, period						60 days
SARM License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research and development expense						$ 100,000	0
SARD License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research and development expense					$ 200,000		0
Asset Purchase Agreement | Velos Biopharma Holdings, LLC
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of preclinical product candidates licensed and assigned | Product	2
Convertible note payable	$ 200,000
Accrued interest of convertible note payable	$ 16,000
Percentage of devoting business activities						80.00%
Loss from operations							$ 3,000,000
Maximum | The California Institute for Regenerative Medicine ("CIRM") Award
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Amount agreed to be provided in contingency funds		$ 1,000,000
Maximum | Regents of the University of California
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Potential regulatory milestone payments				12,500,000
Maximum | Exclusive License Agreement | Georgetown University
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Potential milestone payments									$ 200,000
Collaborative agreement research funding amount								$ 150,000
Minimum [Member] | Regents of the University of California
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Potential regulatory milestone payments				10,000,000
Advance licensed assets				$ 1,000,000

Merger - Additional Information

Merger - Additional Information (Details) - CVR Agreement	Jun. 07, 2019CVR
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Contingent value right per common stock	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

Merger - Summary of Purchase Pr

Merger - Summary of Purchase Price Paid in Merger (Details) $ / shares in Units, $ in Thousands	Jun. 07, 2019USD ($)$ / sharesshares
Asset Acquisitions [Line Items]
Number of shares of the combined organization owned by the Company’s pre-Merger stockholders | shares	3,458,170
Fair value of consideration issued to effect the Merger	$ 29,049
Transaction costs	2,154
Purchase price	$ 31,203
GTx
Asset Acquisitions [Line Items]
Multiplied by the fair value per share of GTx common stock | $ / shares	$ 8.40

Merger - Summary of Allocation

Merger - Summary of Allocation of Purchase Price (Details) - USD ($) $ in Thousands	Jun. 07, 2019	Dec. 31, 2019
Merger [Abstract]
Cash acquired	$ 18,292	$ 18,292
Net liabilities assumed	(5,177)
In-process research and development	18,088	$ 18,088
Purchase price	$ 31,203

Stockholders' Equity (Deficit_2

Stockholders' Equity (Deficit) - Amended and Restated Articles of Incorporation (Details) - $ / shares	Dec. 31, 2019	Jun. 07, 2019	Dec. 31, 2018
Equity [Abstract]
Common stock, shares authorized	60,000,000	60,000,000	200,000,000
Preferred stock, shares authorized	5,000,000	5,000,000	0
Preferred stock, par value	$ 0.001	$ 0.001	$ 0.001

Stockholders' Equity (Deficit_3

Stockholders' Equity (Deficit) - Convertible Preferred Stock (Details)	Jun. 07, 2019shares
Private Oncternal
Class Of Stock [Line Items]
Convertible preferred stock converted into common stock shares	8,148,268

Stockholders' Equity (Deficit_4

Stockholders' Equity (Deficit) - Sales of Convertible Preferred Stock (Details) - USD ($)	1 Months Ended	4 Months Ended	12 Months Ended
	Nov. 30, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2019	Jun. 07, 2019	Feb. 28, 2018
Class Of Stock [Line Items]
Preferred stock, shares issued			0	0
Preferred stock, par value			$ 0.001	$ 0.001	$ 0.001
Net cash proceeds from issuance of preferred stock			$ 17,873,000
Series B-2 Convertible Preferred Stock | Private Oncternal
Class Of Stock [Line Items]
Preferred stock, shares issued		1,662,494
Preferred stock, par value		$ 6.13
Net cash proceeds from issuance of preferred stock		$ 8,900,000
Preferred stock, value collected						$ 1,100,000
Series C Convertible Preferred Stock | Private Oncternal
Class Of Stock [Line Items]
Preferred stock, shares issued	2,495,114
Preferred stock, par value	$ 6.81
Net cash proceeds from issuance of preferred stock	$ 16,800,000
Preferred stock, value collected	$ 0

Stockholders' Equity (Deficit_5

Stockholders' Equity (Deficit) - Common Stock Warrants (Details) - Warrants to purchase common stock - $ / shares	Sep. 29, 2017	Sep. 30, 2017	Dec. 31, 2019
Class Of Stock [Line Items]
Warrants exercise price per share	$ 63.14	$ 6.13
Warrants issued expiration period			The warrants expire on various dates in September, November and December 2022.
Number of common stock warrants exercised			196
Private Placement, September 2017
Class Of Stock [Line Items]
Number of common stock warrants exercised			0
Warrants issued to purchase shares under private placement	469,996
Warrant term	5 years
Common stock warrants expiration date	Sep. 29, 2022
Series B-2 Convertible Preferred Stock
Class Of Stock [Line Items]
Warrants issued		371,624

Stockholders' Equity (Deficit_6

Stockholders' Equity (Deficit) - Common Stock and Unvested Share Liability (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Equity [Abstract]
Unvested share liability	$ 24,000	$ 54,000

Stockholders' Equity (Deficit_7

Stockholders' Equity (Deficit) - Summary of Unvested Shares (Details)	12 Months Ended
	Dec. 31, 2019shares
Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Number Of Shares Roll Forward
Number of shares unvested, beginning balance	100,000
Number of shares, vested shares	(65,000)
Number of shares unvested, ending balance	35,000

Stockholders' Equity (Deficit_8

Stockholders' Equity (Deficit) - Equity Incentive Plans (Details) - $ / shares	Jun. 07, 2019	Jul. 31, 2015	Dec. 31, 2019	Dec. 31, 2018
Class Of Stock [Line Items]
Number of common stock shares provided for issuance of stock awards to its employees			3,294,000	9,104,000
Number of options cancelled			52,726
Fair value of underlying preferred stock				$ 0.29
2019 incentive award plan
Class Of Stock [Line Items]
Shares of common stock reserved for issuance	1,678,571
Maximum number of shares of common stock a participant may receive	275,579
Percentage of annual increase in shares reserved for issuance	5.00%
Number of common stock shares provided for issuance of stock awards to its employees			494,583
Number of options cancelled			18,512
2013 plan
Class Of Stock [Line Items]
Number of options outstanding and fully vested			257,067
Weighted average exercise price of options outstanding and fully vested			$ 59.98
2015 plan
Class Of Stock [Line Items]
Options expiration term		10 years
Options vesting period		4 years
2015 plan | Private Oncternal
Class Of Stock [Line Items]
Number of common stock shares provided for issuance of stock awards to its employees		631,120
GTx Stock Option Plans
Class Of Stock [Line Items]
Number of options outstanding and fully vested and exercisable			295,414
Weighted average exercise price of options outstanding and fully vested and exercisable			$ 71.34
Weighted average remaining contractual term of options outstanding and fully vested and exercisable			8 months 12 days
2019 and 2015 plan
Class Of Stock [Line Items]
Fair value of underlying preferred stock			$ 3.69	$ 0.55
Closing market price per common share			$ 3.95

Stockholders' Equity (Deficit_9

Stockholders' Equity (Deficit) - Summary of Stock Option Outstanding, Vested and Expected to Vest and Exercisable (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options outstanding, Number of Shares	1,662,253	504,019
Options outstanding, Weighted Average Exercise Price	$ 4.17	$ 0.81
Options outstanding, Weighted Average Remaining Contractual Term	3 years 6 months
Equity incentive plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options outstanding, Number of Shares	1,662,253
Options vested and expected to vest, Number of Shares	1,662,253
Options exercisable, Number of Shares	244,170
Options outstanding, Weighted Average Exercise Price	$ 4.17
Options outstanding, Weighted Average Exercise Price	4.17
Options outstanding, Weighted Average Exercise Price	$ 1.16
Options outstanding, Weighted Average Remaining Contractual Term	9 years 2 months 12 days
Options outstanding, Weighted Average Remaining Contractual Term	9 years 2 months 12 days
Options outstanding, Weighted Average Remaining Contractual Term	7 years 2 months 12 days
Options outstanding, Aggregate Intrinsic Value	$ 1,460
Options outstanding, Aggregate Intrinsic Value	1,460
Options outstanding, Aggregate Intrinsic Value	$ 718

Stockholders' Equity (Defici_10

Stockholders' Equity (Deficit) - Summary of Stock Option Activity (Details)	12 Months Ended
	Dec. 31, 2019$ / sharesshares
Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Roll Forward
Number of options, beginning balance | shares	504,019
Number of options, granted | shares	1,230,000
Number of options, cancelled | shares	(52,726)
Number of options, exercised | shares	(19,040)
Number of options, ending balance | shares	1,662,253
Weighted average exercise price, beginning balance | $ / shares	$ 0.81
Weighted average exercise price, granted | $ / shares	5.47
Weighted average exercise price, cancelled | $ / shares	3.38
Weighted average exercise price, exercised | $ / shares	0.69
Weighted average exercise price, ending balance | $ / shares	$ 4.17

Stockholders' Equity (Defici_11

Stockholders' Equity (Deficit) - Schedule of Assumptions Used to Estimate Fair Value of Stock Option Grants (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Risk-free interest rate	1.60%	2.90%
Expected volatility	77.60%	64.70%
Expected term (in years)	6 years	6 years 1 month 6 days

Stockholders' Equity (Defici_12

Stockholders' Equity (Deficit) - Share-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 507	$ 180
Research and development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	237	141
General and administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 270	$ 39

Stockholders' Equity (Defici_13

Stockholders' Equity (Deficit) - Stock-Based Compensation Expense (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)
Equity [Abstract]
Compensation cost related to nonvested awards not yet recognized	$ 4.2
Remaining weighted-average period	3 years 6 months

Stockholders' Equity (Defici_14

Stockholders' Equity (Deficit) - Common Stock Reserved for Future Issuance (Details) - shares shares in Thousands	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Redeemable convertible preferred stock		8,148
Warrants to purchase convertible preferred stock		372
Common stock warrants	841
Common stock options issued and outstanding	1,958	504
Common stock available for future issuance	3,294	9,104
Equity incentive plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock available for future issuance	495	80

Income Taxes - Summary of Recon

Income Taxes - Summary of Reconciliation of Effective Tax Rate and Federal Statutory Tax Rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Federal income taxes	$ (7,179)	$ (1,379)
State income taxes, net of federal benefit	(968)	(500)
Permanent items	873	(147)
In-process research and development	3,354
Research and development credit carryforwards	(217)	(468)
Other, net	18	51
Change in valuation allowance	$ 4,119	$ 2,443

Income Taxes - Summary of Signi

Income Taxes - Summary of Significant Components of Net Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Net operating loss carryforwards	$ 18,108	$ 8,321
Research and development credit carryforwards	1,446	1,231
Accrued expenses	214	24
Capitalized research and development costs	7,688
Other, net	143	288
Total deferred tax assets	27,599	9,864
Valuation allowance	(27,546)	$ (9,864)
Net deferred tax assets and liabilities	53
Deferred tax liabilities:
Right of use asset	(53)
Total deferred tax liabilities	$ (53)

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	Jan. 01, 2019	Dec. 31, 2019	Dec. 31, 2018
Income Taxes [Line Items]
Deferred tax assets, fully offset by valuation allowance		$ 13,100,000
Net deferred tax assets		13,100,000
Research and development credit carryforward		$ 1,446,000	$ 1,231,000
Cumulative changes in ownership percentage		50.00%
Period for cumulative change in ownership		3 years
Unrecognized Tax Benefits		$ 0	$ 0
Interest and penalties		0
Change in retained earnings	$ 0
Adjustment in deferred tax liability	100,000
Adjustment in deferred tax assets	$ 100,000
Federal
Income Taxes [Line Items]
Net operating loss carryforwards		70,000,000
Operating loss carryforwards non expire portion		$ 44,200,000
Operating loss carryforwards expiration year		2034
Research and development credit carryforward		$ 900,000
Research and development credit carryforward expiration year		2034
State
Income Taxes [Line Items]
Net operating loss carryforwards		$ 48,700,000
Operating loss carryforwards expiration year		2030
Research and development credit carryforward		$ 700,000