Oncternal Therapeutics (ONCT) 10-Q 4 Nov 20 2020 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2020	Nov. 02, 2020
Cover [Abstract]
Entity Registrant Name	Oncternal Therapeutics, Inc.
Entity Central Index Key	0001260990
Document Type	10-Q
Document Period End Date	Sep. 30, 2020
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Trading Symbol	ONCT
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		22,346,766
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, $0.001 par value
Security Exchange Name	NASDAQ
Entity Incorporation, State or Country Code	DE
Document Quarterly Report	true
Document Transition Report	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 21,259	$ 20,051
Prepaid and other	1,448	736
Total current assets	22,707	20,787
Right-of-use	79	190
Other	766	767
Total assets	23,552	21,744
Current liabilities:
Accounts payable	977	871
Accrued liabilities	3,273	2,731
Deferred grant revenue	3,222	3,640
Lease, current	79	99
Total current liabilities	7,551	7,341
Payroll protection program loan payable	301
Lease, net of current	79	91
Commitments and contingencies (Note 3)
Stockholders’ equity:
Preferred stock, $0.001 par value, authorized shares – 5,000; issued and outstanding shares – none
Common stock, $0.001 par value; authorized shares – 60,000; issued and outstanding shares – 22,347 and 15,387 at September 30, 2020 and December 31, 2019, respectively	22	15
Additional paid-in capital	95,918	79,869
Accumulated deficit	(80,240)	(65,572)
Total stockholders’ equity	15,700	14,312
Total liabilities and stockholders’ equity	$ 23,552	$ 21,744

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
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	60,000,000
Common stock, shares issued	22,347,000	15,387,000
Common stock, shares outstanding	22,347,000	15,387,000

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Grant revenue	$ 585	$ 544	$ 1,787	$ 1,689
Operating expenses:
Research and development	3,047	3,108	9,558	7,591
In-process research and development				18,088
General and administrative	1,933	2,385	6,910	4,937
Total operating expenses	4,980	5,493	16,468	30,616
Loss from operations	(4,395)	(4,949)	(14,681)	(28,927)
Other income (expense):
Change in fair value of warrant liability				(1,268)
Interest income		57	13	163
Total other income (expense)		57	13	(1,105)
Net loss	$ (4,395)	$ (4,892)	$ (14,668)	$ (30,032)
Net loss per share, basic and diluted	$ (0.22)	$ (0.32)	$ (0.85)	$ (3.48)
Weighted-average shares outstanding, basic and diluted	20,126	15,340	17,251	8,636

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities
Net loss	$ (14,668)	$ (30,032)
Adjustments to reconcile net loss to net cash used in operating activities:
In-process research and development		18,088
Stock-based compensation	1,149	192
Noncash compensation expense		56
Change in fair value of preferred stock warrants liability		1,268
Noncash lease expense	111
Changes in operating assets and liabilities:
Prepaid and other	(711)	(268)
Accounts payable	106	(4,402)
Accrued liabilities	958	(1,555)
Change in lease liability	(111)	(56)
Deferred grant revenue	(418)	3,008
Net cash used in operating activities	(13,584)	(13,701)
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 payroll protection program loan payable	301
Proceeds from exercise of stock options	4	14
Proceeds from exercise of common stock warrants		1
Proceeds from issuance of common stock and common stock warrants, net	14,487
Net cash provided by financing activities	14,792	15
Net increase (decrease) in cash and cash equivalents	1,208	2,451
Cash and cash equivalents at beginning of period	20,051	20,645
Cash and cash equivalents at end of period	21,259	23,096
Supplemental disclosure of non-cash investing and financing activities:
Payment of 2019 bonus awards with stock options in lieu of cash	415
Fair value of warrants issued to placement agent	729
Conversion of convertible preferred stock into common stock		46,588
Reclassification of preferred stock warrants liability to additional paid-in capital		1,942
Net liabilities assumed in Merger		5,176
Deferred financing costs included in accrued liabilities	$ 8
GTx Inc.
Supplemental disclosure of non-cash investing and financing activities:
Payment of 2019 bonus awards with stock options in lieu of cash		$ 29,049

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Convertible preferred stock	Common Stock	Additional Paid-in Capital	Accumulated Deficit
Balance at Dec. 31, 2018	$ (29,631)		$ 5	$ 1,748	$ (31,384)
Balance (in shares) at Dec. 31, 2018		8,148,000
Balance at Dec. 31, 2018		$ 46,588
Balance (in shares) at Dec. 31, 2018			3,762,000
Exercise of stock options for cash	14			14
Exercise of stock options for cash (in shares)			19,000
Exercise of warrants for cash	1			1
Vesting related to unvested share liability	27			27
Issuance of common stock to former stockholders of GTx upon Merger	29,049		$ 2	29,047
Issuance of common stock to former stockholders of GTx upon Merger (in shares)			3,458,000
Conversion of convertible preferred stock into common stock upon Merger	46,588		$ 8	46,580
Conversion of convertible preferred stock into common stock upon Merger (in shares		(8,148,000)
Conversion of convertible preferred stock into common stock upon Merger		$ (46,588)
Conversion of convertible preferred stock into common stock upon Merger (in shares)			8,148,000
Reclassification of convertible preferred stock warrant	1,942			1,942
Stock-based compensation	192			192
Net loss	(30,032)				(30,032)
Balance at Sep. 30, 2019	18,150		$ 15	79,551	(61,416)
Balance (in shares) at Sep. 30, 2019			15,387,000
Balance at Jun. 30, 2019	22,936		$ 15	79,445	(56,524)
Balance (in shares) at Jun. 30, 2019			15,370,000
Exercise of stock options for cash	12			12
Exercise of stock options for cash (in shares)			17,000
Exercise of warrants for cash	1			1
Vesting related to unvested share liability	3			3
Stock-based compensation	90			90
Net loss	(4,892)				(4,892)
Balance at Sep. 30, 2019	18,150		$ 15	79,551	(61,416)
Balance (in shares) at Sep. 30, 2019			15,387,000
Balance at Dec. 31, 2019	$ 14,312		$ 15	79,869	(65,572)
Balance (in shares) at Dec. 31, 2019	15,387,000		15,387,000
Issuance of common stock and common stock warrants, net of issuance costs	$ 14,479		$ 7	14,472
Issuance of common stock and common stock warrants, net of issuance costs (in shares)			6,955,000
Exercise of stock options for cash	4			4
Exercise of stock options for cash (in shares)			5,000
Vesting related to unvested share liability	9			9
Stock-based compensation	1,149			1,149
Payment of 2019 bonus awards with stock options in lieu of cash	415			415
Net loss	(14,668)				(14,668)
Balance at Sep. 30, 2020	$ 15,700		$ 22	95,918	(80,240)
Balance (in shares) at Sep. 30, 2020	22,347,000		22,347,000
Balance at Jun. 30, 2020	$ 9,598		$ 17	85,426	(75,845)
Balance (in shares) at Jun. 30, 2020			17,336,000
Issuance of common stock and common stock warrants, net of issuance costs	10,087		$ 5	10,082
Issuance of common stock and common stock warrants, net of issuance costs (in shares)			5,011,000
Vesting related to unvested share liability	3			3
Stock-based compensation	407			407
Net loss	(4,395)				(4,395)
Balance at Sep. 30, 2020	$ 15,700		$ 22	$ 95,918	$ (80,240)
Balance (in shares) at Sep. 30, 2020	22,347,000		22,347,000

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020
Statement Of Stockholders Equity [Abstract]
Common stock and common stock warrants, issuance cost	$ 1,165	$ 1,767

Description of Business, Basis

Description of Business, Basis of Presentation and Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Description of Business, Basis of Presentation and Summary of Significant Accounting Policies	1. Description of Business, Basis of Presentation and Summary of Significant Accounting 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 includes, 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 the merger contemplated by the Agreement and Plan of Merger and Reorganization, dated March 6, 2019, 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”). 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”). 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. Principles of Consolidation The condensed 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 condensed consolidated financial statements. Liquidity and Going Concern From its inception through September 30, 2020, 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 September 30, 2020, the Company had an accumulated deficit of $80.2 million and had cash and cash equivalents of $21.3 million. 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 condensed 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. On May 21, 2020, the Company completed a registered direct offering pursuant to which it sold 1,943,636 shares of its common stock at a price of $2.5725 per share. The net proceeds to the Company from this offering were $4.4 million, after deducting placement agent fees and commissions and other offering expenses. Concurrently with the sale of shares of the Company’s common stock pursuant to the offering, the Company also sold warrants to purchase up to an aggregate of 971,818 On July 21, 2020, the Company completed a registered direct offering pursuant to which it sold 2,581,867 shares of its common stock at a price of $2.3825 per share. The net proceeds to the Company from this offering were $5.7 million, after deducting the placement agent fees and commissions and other offering expenses. Concurrently with the sale of shares of the Company’s common stock pursuant to the offering, the Company also sold warrants to purchase up to an aggregate of 1,290,933 shares of common stock (see Note 7). On September 1, 2020, the Company completed an underwritten offering pursuant to which it sold 2,428,886 shares of its common stock at a price of $2.10 per share. The net proceeds to the Company from this offering were $4.4 million, after deducting the underwriter discounts and commissions and other offering expenses (see Note 7). 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. Unaudited Interim Financial Information The unaudited condensed consolidated financial statements at September 30, 2020, and for the nine months ended September 30, 2020 and 2019, have been prepared in accordance with the rules and regulations of the Securities and Exchange Commission (“SEC”) and with generally accepted accounting principles in the United States of America (“GAAP”). These unaudited condensed consolidated financial statements have been prepared on the same basis as the audited consolidated financial statements and include all adjustments, consisting of only normal recurring accruals, which in the opinion of management are necessary to present fairly the Company’s financial position as of the interim date and results of operations for the interim periods presented. Interim results are not necessarily indicative of results for a full year or future periods. The preparation of financial statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. Actual results could differ materially from those estimates. These unaudited condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements for the year ended December 31, 2019, filed with the SEC on its Annual Report on Form 10-K on March 16, 2020. The results presented in these unaudited condensed consolidated financial statements are not necessarily indicative of the results expected for the full fiscal year or any other interim period or any future year or period. Use of Estimates The Company’s condensed consolidated financial statements are prepared in accordance with GAAP. The preparation of the Company’s condensed consolidated financial statements and accompanying notes requires it to make estimates and assumptions that impact the reported amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities. Significant estimates consist of those used to determine the fair value of the Company’s preferred stock, preferred stock warrant liability and stock-based awards, and those used to determine grant revenue and accruals for research and development costs. Although these estimates are based on the Company’s knowledge of current events and actions it may undertake in the future, actual results may ultimately materially differ from these estimates 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 condensed 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 condensed 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 condensed 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 current financial assets or liabilities measured at fair value on a recurring basis and no transfers between levels have occurred during the periods presented. 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 condensed 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 September 30, 2020 and December 31, 2019, the Company had deferred grant revenue of $3.2 million and $3.6 million, respectively. 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 vesting 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 service period when the achievement of the milestone is probable. 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 condensed consolidated 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 restricted common shares outstanding that are unvested and subject to repurchase (see Note 7). The Company has excluded weighted-average shares subject to repurchase of 23,000 shares and 27,000 shares from the weighted-average number of common shares outstanding for the three and nine months ended September 30, 2020, respectively. The Company has excluded weighted-average shares subject to repurchase of 42,000 shares and 63,000 shares from the weighted-average number of common shares outstanding for the three and nine months ended September 30, 2019, 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): September 30, 2020 2019 Warrants to purchase common stock 3,521 841 Common stock options 2,341 1,928 Common stock subject to repurchase 20 40 5,882 2,809 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,

Balance Sheet Details

Balance Sheet Details	9 Months Ended
	Sep. 30, 2020
Payables And Accruals [Abstract]
Balance Sheet Details	2. Balance Sheet Details Accrued liabilities consist of the following (in thousands): September 30, December 31, 2020 2019 Research and development $ 1,705 $ 1,206 Legal fees 203 424 Unvested share liability 14 24 Compensation 1,262 825 Other 89 252 $ 3,273 $ 2,731

Commitments, Contingencies and

Commitments, Contingencies and Related Party Transactions	9 Months Ended
	Sep. 30, 2020
Commitments And Contingencies Disclosure [Abstract]
Commitments, Contingencies and Related Party Transaction	3. Commitments, Contingencies and Related Party Transactions Lease Rent expense was $41,000 for each of On May 22, 2019, the Company entered into a sublease agreement for office space of 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 term of the lease. The San Diego Lease is included in the accompanying condensed 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 $ 79,000 Maturities of the lease liability due under this lease agreement as of September 30, 2020, are as follows (in thousands): Maturity of lease liability Operating Lease 2020 (3 months) $ 41 2021 41 Total lease payments 82 Less imputed interest (3 ) Total lease liability $ 79 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, is the Company’s agent at Newfront Insurance. During the nine months ended September 30, 2020 and 2019, the Company paid total related insurance policies of approximately $1.4 million and $1.2 million, for which the son earned a commission of $57,000 and $99,000, respectively. Effective in September 2019, the Company and Shanghai Pharmaceutical (USA) Inc. (“SPH USA”), the Company’s largest stockholder and an affiliate of two of the Company’s directors (Xin Nakanishi, PhD and Man Cho), entered into a Materials and Supply and Services Agreement (“SPH USA Services Agreement”). Pursuant to the SPH USA Services Agreement, 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 LDA. The Company recorded amounts receivable from SPH USA related to statements of work totaling $0.2 million as of September 30, 2020 and December 31, 2019, respectively (see Note 4). In connection with the securities purchase agreements and underwritten offering, other investors included individuals or entities affiliated with David F. Hale, SPH USA, Daniel L. Kisner, Hazel M. Aker, and Michael G. Carter (see Note 7). 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 (the “Delaware Actions”). In 2019, the Delaware Actions were voluntarily dismissed with prejudice. 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 (the “New York Actions”). The New York Actions name as defendants us and our former board of directors. The New York 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 our filing of the registration statement in connection with the Merger. 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 amended 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. On June 23, 2020, the court granted the defendants’ motion to dismiss, and the plaintiff did not amend his complaint by the July 14, 2020 deadline. On July 22, 2020, the plaintiff filed a notice of appeal to the United States Court of Appeals for the Second Circuit. On September 28, 2020, the plaintiff withdrew the appeal with prejudice, and the case is now dismissed. Zappia vs. GTx Incorporated On October 15, 2019, Joseph Zappia and Karen Zappia filed a lawsuit against the Company in the U.S. District Court for the District of Delaware. The complaint alleges that the Company’s 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. The Company believes that this lawsuit is without merit and intends to vigorously defend this matter. The Company 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	9 Months Ended
	Sep. 30, 2020
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 September 30, 2020, the Company had not 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. 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 Company of $0.2 million 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 fees as research and development expense for each of the three and nine months ended September 30, 2020 and 2019, (ii) $0.1 million and $0.2 million in patent costs as general and administrative expense for the three months ended September 30, 2020 and 2019, respectively, and (iii) $0.1 million and $0.3 million in patent costs for the nine months ended September 30, 2020 and 2019, respectively. As of September 30, 2020, the Company believes it has met its obligations under the Regents License Agreement. 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 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. The University of Tennessee Research Foundation (“UTRF”) In March 2015, GTx 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 $0.1 million $0.1 million The California Institute for Regenerative Medicine (“CIRM”) Awards In August 2017, CIRM awarded an $18.3 million grant to researchers at the University of California San Diego School of Medicine (“UC San Diego”) none 4.8 4.1 In October 2017, CIRM awarded a $5.8 million grant to 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, which expired in April 2020. The Company recorded no research and development expense under such CIRM award for the three and nine months ended September 30, 2020 and 2019. 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. SPH USA, a Related Party License and Development Agreement (“LDA”) In November 2018 , and as amended in August 2020 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 party in the event the other party declares insolvency or bankruptcy.

Debt

Debt	9 Months Ended
	Sep. 30, 2020
Debt Disclosure [Abstract]
Debt	5. Debt Payroll Protection Program Loan Payable In May 2020, the Company qualified for and received a loan pursuant to the Paycheck Protection Program (the “PPP”), a program implemented by the U.S. Small Business Administration (the “SBA”) under the Coronavirus Aid, Relief, and Economic Security Act (the “CARES Act”), for an aggregate principal amount of $0.3 million (the “PPP Loan”). The PPP Loan bears interest at a fixed rate of 1.0% per annum, with the first six months of interest deferred, has a term of two years, and is unsecured and guaranteed by the SBA. The principal amount of the PPP Loan is subject to forgiveness under the PPP upon the Company’s request to the extent that the PPP Loan proceeds are used to pay expenses permitted by the PPP, including payroll costs, covered rent and utility payments incurred by the Company. The Company applied November 2020 April 2022

Merger

Merger	9 Months Ended
	Sep. 30, 2020
Merger [Abstract]
Merger	6. Merger The Merger, which closed on June 7, 2019, was accounted for as a reverse asset acquisition, as substantially all of the fair value of the assets acquired were concentrated in a group of similar non-financial assets, and the acquired assets did not have outputs or employees. Because the assets had not yet received regulatory approval, the fair value attributable to these assets of $18.1 million was recorded as in-process research and development expenses in the Company’s condensed consolidated statement of operations in the nine September

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2020
Equity [Abstract]
Stockholders' Equity	7. Stockholders’ Equity Convertible Preferred Stock In connection with the Merger, all of the then 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 was classified as temporary equity on the accompanying condensed consolidated statement of convertible preferred stock and stockholders’ equity (deficit) 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. Securities Purchase Agreements and Underwritten Offering In May 2020, the Company entered into a Securities Purchase Agreement (the “Purchase Agreement”) with several institutional and individual investors (including an entity affiliated with David F. Hale, the chairman of the Company’s board of directors) for the concurrent sale of: (i) 1,943,636 shares of the Company’s common stock in a registered direct offering, resulting in net proceeds of $4.4 million, after deducting the placement agent’s cash commissions and other offering expenses, and excluding the proceeds, if any, from the exercise of the warrants, and (ii) unregistered warrants to purchase up to an aggregate of 971,818 shares of common stock. The combined purchase price for one share and one warrant to purchase half of a share of common stock was $2.5725. The shares, but not the warrants or shares of common stock issuable upon exercise of the warrants, were offered and sold by the Company pursuant to an effective shelf registration statement on Form S-3, which was filed with the SEC on December 22, 2017 and subsequently declared effective on January 5, 2018 (the “Registration Statement”), and a related prospectus supplement. In addition, the Company issued warrants to purchase 116,618 shares of common stock at an exercise price of $3.2156 per share to the placement agent, H.C. Wainwright & Co., LLC (“Wainwright” or the “placement agent”) as part of its compensation, which warrants were immediately exercisable and expire on May 21, 2025 . In July 2020, the Company entered into a Securities Purchase Agreement (the “July Purchase Agreement”) with several institutional and individual investors for the concurrent sale of: (i) 2,581,867 shares of the Company’s common stock in a registered direct offering, resulting in net proceeds of $5.7 million, after deducting the placement agent’s cash commissions and other offering expenses, and excluding the proceeds, if any, from the exercise of the warrants, and (ii) unregistered warrants to purchase up to an aggregate of 1,290,933 shares of common stock. The combined purchase price for one share and one warrant to purchase half of a share of common stock was $2.3825. The warrants issued to investors were, subject to certain ownership limitations, immediately exercisable at an exercise price equal to $2.32 per share and expire on January 21, 2026. The shares, but not the warrants or shares of common stock issuable upon exercise of the warrants, were offered and sold by the Company pursuant to the Registration Statement and a related prospectus supplement. In addition, the Company issued warrants to purchase 154,912 shares of common stock at an exercise price of $2.9781 per share to the placement agent as part of its compensation, which warrants were immediately exercisable upon issuance and terminate on July 21, 2025. Other investors participating in the July Purchase Agreement included an entity affiliated with SPH USA, the Company’s largest stockholder, Daniel L. Kisner, a member of the Company’s board of directors, and Hazel M. Aker, the Company’s then General Counsel. In August 2020, the Company entered into an underwriting agreement (as amended and restated, the “Underwriting Agreement”) with Wainwright for the sale of 2,428,886 shares of the Company’s common stock at a price to the public of $2.10 per share, resulting in net proceeds of $4.4 million, after deducting the underwriter’s discounts, commissions and other offering expenses. The shares were offered and sold by the Company pursuant to the Registration Statement and a related prospectus supplement. In addition, the Company issued warrants to purchase 145,733 shares of common stock at an exercise price of $2.625 per share to Wainwright as part of its compensation, which warrants were immediately exercisable upon issuance and terminate on August 27, 2025. An investor participating in the transaction included Michael G. Carter, a member of the Company’s board of directors. In connection with the Securities Purchase Agreements above, the Company also agreed, on a best efforts basis, to: (i) maintain its listing on The Nasdaq Capital Market to provide for the resale of the shares of common stock issuable upon the exercise of the warrants, (ii) not enter into any agreement for the issuance of any shares of common stock through , 2020, and (iii) not enter into any agreement for the issuance of any shares of common stock involving a variable rate transaction before The Company also agreed, on a best efforts basis, to: (i) maintain its listing on The Nasdaq Capital Market to provide for the resale of the shares of common stock issuable upon the exercise of the warrants, and (ii) not enter into any agreement for the issuance of any shares of common stock involving a variable rate transaction before July 21, 2021. Common Stock Warrants On September 29, 2017, as adjusted for the Exchange Ratio, 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 In September, November and December 2017, as adjusted for the Exchange Ratio, 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 September 30, 2020, warrants to purchase 196 shares of common stock have been exercised. On May 21, 2020 in connection with the Purchase Agreement, the Company issued warrants to: (i) investors for the purchase of 971,818 shares of common stock. Subject to certain ownership limitations, the warrants are immediately exercisable at an exercise price equal to $2.51 per share , On July 21, 2020 in connection with the July Purchase Agreement, the Company issued warrants to: (i) investors for the purchase of 1,290,933 shares of common stock. Subject to certain ownership limitations, the warrants are immediately exercisable at an exercise price equal to $2.32 per share and expire on January 21, 2026, and (ii) the placement agent for the purchase of 154,912 shares of common stock, which were immediately exercisable at an exercise price of $2.9781 per share and expire on July 21, 2025. As of September 30, 2020, no such warrants have been exercised. On September 1, 2020 in connection with the U nderwriting A greement, the Company issued warrants to Wainwright for the purchase of 145,733 shares of common stock , which warrants were immediately exercisable at an exercise price of $2.625 per share and expire on August 27, 2025. As of September 30, 2020, no such warrants have been exercised . The Company assessed whether the above warrants require accounting as liabilities and determined that the warrants meet the criteria to be classified in stockholders’ equity. Restricted Common Stock and Unvested Share Liability Prior to the Merger, the Company 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 condensed consolidated balance sheets and is reclassified into common stock and additional paid-in capital as the shares vest. At September 30, 2020 and December 31, 2019, the unvested share liability was $14,000 and $24,000, respectively. A summary of the Company’s unvested shares is as follows (in thousands): Number of Shares Balance at December 31, 2019 35 Vested shares (15 ) Balance at September 30, 2020 20 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 September 30, 2020, 842,837 shares remain available for future issuance under the 2019 Plan. As of September 30, 2020, there were: (i) 111,415 outstanding and fully vested options, and (ii) 164,164 cancelled options from the 2013 Plan that were added back to the 2019 Plan. As of September 30, 2020, the former GTx stock option plans had an aggregate of 120,731 outstanding and fully vested and exercisable options with a weighted average exercise price of $77.63 and a weighted average remaining contractual term of 0.6 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 A summary of the Company’s stock option activity under the 2019 Plan and 2015 Plan is as follows: Weighted- Number of Average Options Exercise Price Balance at December 31, 2019 1,662,253 $ 4.17 Granted 569,260 $ 3.20 Cancelled (6,170 ) $ 2.82 Exercised (5,135 ) $ 0.77 Balance at September 30, 2020 2,220,208 $ 3.93 The aggregate intrinsic value of stock options exercised during the nine months ended September 30, 2020 was not significant. 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. 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: Three Months Ended Nine Months Ended September 30, September 30, 2020 2019 2020 2019 Risk-free interest rate 0.7 % 1.6 % 0.8 % 1.6 % Expected volatility 98.6 % 76.9 % 92.2 % 76.9 % Expected term (in years) 10.0 5.9 6.6 5.9 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, which is an average of the contractual term of the option and its vesting period. 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 condensed consolidated statements of operations as follows (in thousands): Three Months Ended Nine Months Ended September 30, September 30, 2020 2019 2020 2019 Research and development $ 129 $ 44 $ 398 $ 111 General and administrative 278 46 751 81 $ 407 $ 90 $ 1,149 $ 192 As of September 30, 2020, the total compensation cost related to non-vested awards not yet recognized was $3.9 million and the weighted-average period over which it is expected to be recognized was 2.8 years. Common Stock Reserved for Future Issuance Common stock reserved for future issuance is as follows (in thousands): September 30, 2020 Common stock warrants 3,521 Common stock options issued and outstanding 2,341 Common stock available for issuance under the 2019 Plan 843 6,705

COVID-19 Pandemic and CARES Act

COVID-19 Pandemic and CARES Act	9 Months Ended
	Sep. 30, 2020
C O V I D19 Pandemic And C A R E S Act [Abstract]
COVID-19 Pandemic and CARES Act	8. COVID-19 Pandemic and CARES Act A novel strain of coronavirus (SAR-CoV-2) causing a severe respiratory disease (“COVID-19”), was declared a global pandemic by the World Health Organization in March 2020. COVID-19 has presented substantial public health and economic challenges and is affecting economies, financial markets and business operations around the world. International and U.S. governmental authorities in impacted regions are taking action in an effort to slow the spread of COVID-19, including issuing varying forms of “stay-at-home” orders, and restricting business functions outside of one’s home. In response, the Company has put restrictions on employee travel and working from its executive offices with many employees continuing their work remotely. While the Company is currently continuing the clinical trials it has underway in sites across the U.S., the Company expects that COVID-19 precautions may directly or indirectly impact the timeline for some of its clinical trials. For example, some of its clinical trial sites, including those located in areas severely impacted by the pandemic, have placed new patient enrollment into clinical trials on hold or, for patients travelling from out-of-state, have implemented a 14-day self-quarantine before appointments. Additionally, the Company’s expectations for the timing of first-in-human dosing of its ROR1 CAR-T therapy in China has been delayed. The Company considered the impacts of COVID-19 on the assumptions and estimates used to prepare its condensed consolidated financial statements and determined that there were no material adverse impacts on the Company’s results of operations and financial position at September 30, 2020. The full extent to which the COVID-19 pandemic will directly or indirectly impact the Company’s business results of operations and financial condition, will depend on future development that are highly uncertain, including as a result of new information that may emerge concerning COVID-19 and the actions taken to contain or treat it, as well as the economic impact on local, regional, national and international markets. In response to the COVID-19 pandemic, the CARES Act was signed into law on March 27, 2020. The CARES Act, among other things, includes tax provisions relating to refundable payroll tax credits, deferment of employer’s social security payments, net operating loss utilization and carryback periods, modifications to the net interest deduction limitations and technical corrections to tax depreciation methods for qualified improvement property (QIP), and authorized the PPP (see Note 5). The CARES Act had no material impact on the Company’s income tax provision for the nine months ended September 30, 2020. The Company continues to evaluate the impact of the CARES Act on its condensed consolidated financial position, results of operations and cash flows.

Description of Business, Basi_2

Description of Business, Basis of Presentation and Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Merger	Merger On June 7, 2019, the Company, then operating as GTx, Inc. (“GTx”), completed the merger contemplated by the Agreement and Plan of Merger and Reorganization, dated March 6, 2019, 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”). 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”). 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.
Principles of Consolidation	Principles of Consolidation The condensed 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 condensed consolidated financial statements.
Liquidity and Going Concern	Liquidity and Going Concern From its inception through September 30, 2020, 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 September 30, 2020, the Company had an accumulated deficit of $80.2 million and had cash and cash equivalents of $21.3 million. 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 condensed 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. On May 21, 2020, the Company completed a registered direct offering pursuant to which it sold 1,943,636 shares of its common stock at a price of $2.5725 per share. The net proceeds to the Company from this offering were $4.4 million, after deducting placement agent fees and commissions and other offering expenses. Concurrently with the sale of shares of the Company’s common stock pursuant to the offering, the Company also sold warrants to purchase up to an aggregate of 971,818 On July 21, 2020, the Company completed a registered direct offering pursuant to which it sold 2,581,867 shares of its common stock at a price of $2.3825 per share. The net proceeds to the Company from this offering were $5.7 million, after deducting the placement agent fees and commissions and other offering expenses. Concurrently with the sale of shares of the Company’s common stock pursuant to the offering, the Company also sold warrants to purchase up to an aggregate of 1,290,933 shares of common stock (see Note 7). On September 1, 2020, the Company completed an underwritten offering pursuant to which it sold 2,428,886 shares of its common stock at a price of $2.10 per share. The net proceeds to the Company from this offering were $4.4 million, after deducting the underwriter discounts and commissions and other offering expenses (see Note 7). 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.
Unaudited Interim Financial Information	Unaudited Interim Financial Information The unaudited condensed consolidated financial statements at September 30, 2020, and for the nine months ended September 30, 2020 and 2019, have been prepared in accordance with the rules and regulations of the Securities and Exchange Commission (“SEC”) and with generally accepted accounting principles in the United States of America (“GAAP”). These unaudited condensed consolidated financial statements have been prepared on the same basis as the audited consolidated financial statements and include all adjustments, consisting of only normal recurring accruals, which in the opinion of management are necessary to present fairly the Company’s financial position as of the interim date and results of operations for the interim periods presented. Interim results are not necessarily indicative of results for a full year or future periods. The preparation of financial statements requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. Actual results could differ materially from those estimates. These unaudited condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements for the year ended December 31, 2019, filed with the SEC on its Annual Report on Form 10-K on March 16, 2020. The results presented in these unaudited condensed consolidated financial statements are not necessarily indicative of the results expected for the full fiscal year or any other interim period or any future year or period.
Use of Estimates	Use of Estimates The Company’s condensed consolidated financial statements are prepared in accordance with GAAP. The preparation of the Company’s condensed consolidated financial statements and accompanying notes requires it to make estimates and assumptions that impact the reported amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities. Significant estimates consist of those used to determine the fair value of the Company’s preferred stock, preferred stock warrant liability and stock-based awards, and those used to determine grant revenue and accruals for research and development costs. Although these estimates are based on the Company’s knowledge of current events and actions it may undertake in the future, actual results may ultimately materially differ from these estimates 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 condensed 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 condensed 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 condensed 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 current financial assets or liabilities measured at fair value on a recurring basis and no transfers between levels have occurred during the periods presented.
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 condensed 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 September 30, 2020 and December 31, 2019, the Company had deferred grant revenue of $3.2 million and $3.6 million, respectively.
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 vesting 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 service period when the achievement of the milestone is probable.
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 condensed consolidated 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 restricted common shares outstanding that are unvested and subject to repurchase (see Note 7). The Company has excluded weighted-average shares subject to repurchase of 23,000 shares and 27,000 shares from the weighted-average number of common shares outstanding for the three and nine months ended September 30, 2020, respectively. The Company has excluded weighted-average shares subject to repurchase of 42,000 shares and 63,000 shares from the weighted-average number of common shares outstanding for the three and nine months ended September 30, 2019, 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): September 30, 2020 2019 Warrants to purchase common stock 3,521 841 Common stock options 2,341 1,928 Common stock subject to repurchase 20 40 5,882 2,809
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,

Description of Business, Basi_3

Description of Business, Basis of Presentation and Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
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): September 30, 2020 2019 Warrants to purchase common stock 3,521 841 Common stock options 2,341 1,928 Common stock subject to repurchase 20 40 5,882 2,809

Balance Sheet Details (Tables)

Balance Sheet Details (Tables)	9 Months Ended
	Sep. 30, 2020
Payables And Accruals [Abstract]
Summary of Accrued Liabilities	Accrued liabilities consist of the following (in thousands): September 30, December 31, 2020 2019 Research and development $ 1,705 $ 1,206 Legal fees 203 424 Unvested share liability 14 24 Compensation 1,262 825 Other 89 252 $ 3,273 $ 2,731

Commitments, Contingencies an_2

Commitments, Contingencies and Related Party Transactions (Tables)	9 Months Ended
	Sep. 30, 2020
Commitments And Contingencies Disclosure [Abstract]
Summary of Maturities of Lease Liabilities	Maturities of the lease liability due under this lease agreement as of September 30, 2020, are as follows (in thousands): Maturity of lease liability Operating Lease 2020 (3 months) $ 41 2021 41 Total lease payments 82 Less imputed interest (3 ) Total lease liability $ 79

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2020
Summary of Unvested Shares	A summary of the Company’s unvested shares is as follows (in thousands): Number of Shares Balance at December 31, 2019 35 Vested shares (15 ) Balance at September 30, 2020 20
Summary of Stock Option Activity	A summary of the Company’s stock option activity under the 2019 Plan and 2015 Plan is as follows: Weighted- Number of Average Options Exercise Price Balance at December 31, 2019 1,662,253 $ 4.17 Granted 569,260 $ 3.20 Cancelled (6,170 ) $ 2.82 Exercised (5,135 ) $ 0.77 Balance at September 30, 2020 2,220,208 $ 3.93
Summary of Share-Based Compensation Expense	Stock-based compensation expense recognized for all equity awards has been reported in the condensed consolidated statements of operations as follows (in thousands): Three Months Ended Nine Months Ended September 30, September 30, 2020 2019 2020 2019 Research and development $ 129 $ 44 $ 398 $ 111 General and administrative 278 46 751 81 $ 407 $ 90 $ 1,149 $ 192
Common Stock Reserved for Future Issuance	Common stock reserved for future issuance is as follows (in thousands): September 30, 2020 Common stock warrants 3,521 Common stock options issued and outstanding 2,341 Common stock available for issuance under the 2019 Plan 843 6,705
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: Three Months Ended Nine Months Ended September 30, September 30, 2020 2019 2020 2019 Risk-free interest rate 0.7 % 1.6 % 0.8 % 1.6 % Expected volatility 98.6 % 76.9 % 92.2 % 76.9 % Expected term (in years) 10.0 5.9 6.6 5.9 Expected dividend yield — % — % — % — %

Description of Business, Basi_4

Description of Business, Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Details) $ / shares in Units, $ in Thousands	Sep. 01, 2020USD ($)$ / sharesshares	Jul. 21, 2020USD ($)$ / sharesshares	May 21, 2020USD ($)$ / sharesshares	Jun. 07, 2019	Sep. 30, 2020USD ($)shares	Sep. 30, 2019shares	Sep. 30, 2020USD ($)segmentshares	Sep. 30, 2019shares	Dec. 31, 2019USD ($)shares
Description Of Business Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Accumulated deficit					$ (80,240)		$ (80,240)		$ (65,572)
Cash and cash equivalents					$ 21,259		$ 21,259		$ 20,051
Common stock, shares issued | shares					22,347,000		22,347,000		15,387,000
Net proceeds from Offering							$ 14,487
Deferred grant revenue					$ 3,222		$ 3,222		$ 3,640
Number of operating segments | segment							1
Weighted-average shares subject to repurchase | shares					23,000	42,000	27,000	63,000
Direct Offering
Description Of Business Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Common stock, shares issued | shares		2,581,867	1,943,636
Price per Share | $ / shares		$ 2.3825	$ 2.5725
Net proceeds from Offering		$ 5,700	$ 4,400
Direct Offering | Warrant
Description Of Business Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Common stock, shares issued | shares		1,290,933	971,818
Direct Offering
Description Of Business Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Common stock, shares issued | shares	2,428,886
Price per Share | $ / shares	$ 2.10
Net proceeds from Offering	$ 4,400
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 Potentially Dilutive Securities Excluded from Calculation of Diluted Net Loss per Share Would Be Anti-dilutive (Detail) - shares	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities	5,882	2,809
Warrants to purchase common stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities	3,521	841
Stock Option Grants
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities	2,341	1,928
Common Stock Subject to Repurchase
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities	20	40

Balance Sheet Details - Accrued

Balance Sheet Details - Accrued Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Payables And Accruals [Abstract]
Research and development	$ 1,705	$ 1,206
Legal fees	203	424
Unvested share liability	14	24
Compensation	1,262	825
Other	89	252
Total accrued liabilities	$ 3,273	$ 2,731

Commitments, Contingencies an_3

Commitments, Contingencies and Related Party Transactions - Additional Information (Details)	1 Months Ended	3 Months Ended		9 Months Ended
	May 22, 2019USD ($)ft²	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2019USD ($)	Dec. 31, 2019USD ($)
Commitments And Contingencies [Line Items]
Insurance policies				$ 1,400,000	$ 1,200,000
Shanghai Pharmaceutical (USA) Inc.
Commitments And Contingencies [Line Items]
Accounts Receivable, Related Parties		$ 200,000		200,000		$ 200,000
Agent
Commitments And Contingencies [Line Items]
Insurance commissions				57,000	99,000
San Diego, California | Office Space
Commitments And Contingencies [Line Items]
Rent expense		$ 41,000	$ 41,000	$ 124,000	75,000
Rentable area | ft²	4,677
Lease expiration date	Mar. 31, 2021
Annual base rent	$ 166,000,000
Lease discount rate		10.00%		10.00%
Operating lease liability			$ 79,000,000		$ 79,000,000
Weighted average remaining lease term		6 months		6 months

Commitments, Contingencies an_4

Commitments, Contingencies and Related Party Transactions - Summary of Maturities of Lease Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Operating Lease Liabilities Payments Due [Abstract]
2020 (3 months)	$ 41
2021	41
Total lease payments	82
Less imputed interest	(3)
Lease, net of current	$ 79	$ 91

License, Collaboration and Re_2

License, Collaboration and Research Subaward Agreements - Additional Information (Details) - USD ($)	1 Months Ended			3 Months Ended		9 Months Ended		12 Months Ended
	Oct. 31, 2017	Aug. 31, 2017	May 31, 2016	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2017	Dec. 31, 2015	Dec. 31, 2014
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research and development expense				$ 200,000	$ 0	$ 200,000	$ 0
Patent costs as general and administrative expense				1,933,000	2,385,000	6,910,000	4,937,000
Grant revenue				585,000	544,000	1,787,000	1,689,000
Regents of the University of California
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research and development expense				25,000	25,000	25,000	25,000
Upfront license fees paid			$ 500,000
Common stock, shares, issued			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				100,000	200,000	100,000	300,000
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				0	1,200,000	1,400,000	4,800,000
Grant revenue				600,000	500,000	1,800,000	1,700,000
Related qualifying subaward costs				1,300,000	1,100,000	4,100,000	3,200,000
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
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
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
Exclusive License Agreement | Maximum | Georgetown University
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Potential milestone payments									$ 200,000
Collaboration Agreement | 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				100,000	100,000	$ 400,000	400,000
Research agreement term						5 years
Aggregate research agreement budget						$ 3,600,000
Research amount payable quarterly						$ 125,000
Regents License Agreement | Regents of the University of California
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Written notice of termination, period						60 days
License Agreement | University Of Tennessee Research Foundation
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research and development expense				$ 100,000	$ 100,000	$ 200,000	$ 100,000

Debt - Additional Information (

Debt - Additional Information (Details) - Unsecured Debt - Paycheck Protection Program - USD ($) $ in Millions	1 Months Ended	9 Months Ended
	May 31, 2020	Sep. 30, 2020
Debt Instrument [Line Items]
Loan amount	$ 0.3
Interest rate, stated percentage	1.00%	1.00%
Interest payment, initial deferred period	6 months
Loan term	2 years
Interest payment, start date		Nov. 30, 2020
Maturity Date		Apr. 30, 2022

Merger - Additional Information

Merger - Additional Information (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019USD ($)
Merger [Abstract]
In-process research and development	$ 18,088

Stockholders' Equity - Converti

Stockholders' Equity - 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 - Securiti

Stockholders' Equity - Securities Purchase Agreements and Underwritten Offering (Details) - USD ($) $ / shares in Units, $ in Thousands	Sep. 01, 2020	Jul. 21, 2020	May 21, 2020	Sep. 29, 2017	Aug. 31, 2020	Jul. 31, 2020	May 31, 2020	Sep. 30, 2020	Dec. 31, 2017
Schedule Of Capitalization Equity [Line Items]
Proceeds from issuance of common stock and common stock warrants, net								$ 14,487
Warrants to purchase common stock
Schedule Of Capitalization Equity [Line Items]
Warrant exercise price per share				$ 63.14					$ 6.13
Warrants to purchase common stock | Placement Agent
Schedule Of Capitalization Equity [Line Items]
Common stock warrants expiration date				Sep. 29, 2022
Purchase Agreement | Warrants to purchase common stock
Schedule Of Capitalization Equity [Line Items]
Warrants issued		1,290,933	971,818
Combined purchase price of share and warrant per unit							$ 2.5725
Warrant exercise price per share		$ 2.32	$ 2.51
Common stock warrants expiration date		Jan. 21, 2026	Nov. 21, 2025
Purchase Agreement | Warrants to purchase common stock | Maximum
Schedule Of Capitalization Equity [Line Items]
Warrants issued							971,818
Purchase Agreement | Warrants to purchase common stock | Placement Agent
Schedule Of Capitalization Equity [Line Items]
Warrants issued		154,912	116,618				116,618
Warrant exercise price per share		$ 2.9781	$ 3.2156				$ 3.2156
Common stock warrants expiration date		Jul. 21, 2025	May 21, 2025				May 21, 2025
Purchase Agreement | Common Stock
Schedule Of Capitalization Equity [Line Items]
Common stock, shares, issued							1,943,636
Proceeds from issuance of common stock and common stock warrants, net							$ 4,400
July Purchase Agreement | Warrants to purchase common stock
Schedule Of Capitalization Equity [Line Items]
Combined purchase price of share and warrant per unit						$ 2.3825
Warrant exercise price per share						$ 2.32
Common stock warrants expiration date						Jan. 21, 2026
July Purchase Agreement | Warrants to purchase common stock | Maximum
Schedule Of Capitalization Equity [Line Items]
Warrants issued						1,290,933
July Purchase Agreement | Warrants to purchase common stock | Placement Agent
Schedule Of Capitalization Equity [Line Items]
Warrants issued						154,912
Warrant exercise price per share						$ 2.9781
Common stock warrants expiration date						Jul. 21, 2025
July Purchase Agreement | Common Stock
Schedule Of Capitalization Equity [Line Items]
Common stock, shares, issued						2,581,867
Proceeds from issuance of common stock and common stock warrants, net						$ 5,700
Direct Offering
Schedule Of Capitalization Equity [Line Items]
Proceeds from issuance of common stock and common stock warrants, net	$ 4,400
Direct Offering | Warrants to purchase common stock
Schedule Of Capitalization Equity [Line Items]
Combined purchase price of share and warrant per unit					$ 2.10
Warrant exercise price per share					$ 2.625
Common stock warrants expiration date					Aug. 27, 2025
Direct Offering | Warrants to purchase common stock | Maximum
Schedule Of Capitalization Equity [Line Items]
Warrants issued					145,733
Direct Offering | Common Stock
Schedule Of Capitalization Equity [Line Items]
Common stock, shares, issued					2,428,886
Proceeds from issuance of common stock and common stock warrants, net					$ 4,400

Stockholders' Equity - Common S

Stockholders' Equity - Common Stock Warrants (Details) - $ / shares	Jul. 21, 2020	May 21, 2020	Sep. 29, 2017	May 31, 2020	Dec. 31, 2017	Sep. 30, 2020
Placement Agent
Class Of Stock [Line Items]
Number of common stock warrants exercised			0
Warrants to purchase common stock
Class Of Stock [Line Items]
Warrant exercise price per share			$ 63.14		$ 6.13
Common stock warrants expiration date					The warrants expire on various dates in September, November and December 2022
Number of common stock warrants exercised					196
Warrants to purchase common stock | Purchase Agreement
Class Of Stock [Line Items]
Warrants issued	1,290,933	971,818
Warrant exercise price per share	$ 2.32	$ 2.51
Number of common stock warrants exercised						0
Common stock warrants expiration date	Jan. 21, 2026	Nov. 21, 2025
Warrants to purchase common stock | Placement Agent
Class Of Stock [Line Items]
Warrants issued to purchase shares under private placement			469,996
Warrant term			5 years
Common stock warrants expiration date			Sep. 29, 2022
Warrants to purchase common stock | Placement Agent | Purchase Agreement
Class Of Stock [Line Items]
Warrants issued	154,912	116,618		116,618
Warrant exercise price per share	$ 2.9781	$ 3.2156		$ 3.2156
Common stock warrants expiration date	Jul. 21, 2025	May 21, 2025		May 21, 2025
Warrants to purchase common stock | Series B2 Convertible Preferred Stock
Class Of Stock [Line Items]
Warrants issued					371,624

Stockholders' Equity - Restrict

Stockholders' Equity - Restricted Common Stock and Unvested Share Liability (Details) - USD ($)	Sep. 30, 2020	Dec. 31, 2019
Equity [Abstract]
Unvested share liability	$ 14,000	$ 24,000

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Unvested Shares (Details)	9 Months Ended
	Sep. 30, 2020shares
Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Number Of Shares Roll Forward
Number of shares unvested, beginning balance	35,000
Number of shares, vested shares	(15,000)
Number of shares unvested, ending balance	20,000

Stockholders' Equity - Equity I

Stockholders' Equity - Equity Incentive Plans (Details) - $ / shares	Jun. 07, 2019	Jul. 31, 2015	Sep. 30, 2020
Class Of Stock [Line Items]
Number of common stock shares provided for issuance of stock awards to its employees			6,705,000
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			842,837
Number of options cancelled			164,164
2013 plan
Class Of Stock [Line Items]
Number of options outstanding and fully vested			111,415
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			120,731
Weighted average exercise price of options outstanding and fully vested and exercisable			$ 77.63
Weighted average remaining contractual term of options outstanding and fully vested and exercisable			7 months 6 days

Stockholders' Equity - Summar_2

Stockholders' Equity - Summary of Stock Option Activity (Details) - 2019 Incentive Award Plan and 2015 Equity Incentive Plan	9 Months Ended
	Sep. 30, 2020$ / sharesshares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of options, beginning balance | shares	1,662,253
Number of options, granted | shares	569,260
Number of options, cancelled | shares	(6,170)
Number of options, exercised | shares	(5,135)
Number of options, ending balance | shares	2,220,208
Weighted average exercise price, beginning balance | $ / shares	$ 4.17
Weighted average exercise price, granted | $ / shares	3.20
Weighted average exercise price, cancelled | $ / shares	2.82
Weighted average exercise price, exercised | $ / shares	0.77
Weighted average exercise price, ending balance | $ / shares	$ 3.93

Stockholders' Equity - Schedule

Stockholders' Equity - Schedule of Assumptions Used to Estimate Fair Value of Stock Option Grants (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Risk-free interest rate	0.70%	1.60%	0.80%	1.60%
Expected volatility	98.60%	76.90%	92.20%	76.90%
Expected term (in years)	10 years	5 years 10 months 24 days	6 years 7 months 6 days	5 years 10 months 24 days

Stockholders' Equity - Share-Ba

Stockholders' Equity - Share-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 407	$ 90	$ 1,149	$ 192
Research and development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	129	44	398	111
General and administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 278	$ 46	$ 751	$ 81

Stockholders' Equity - Stock-Ba

Stockholders' Equity - Stock-Based Compensation Expense (Details) $ in Millions	9 Months Ended
	Sep. 30, 2020USD ($)
Equity [Abstract]
Compensation cost related to non-vested awards not yet recognized	$ 3.9
Remaining weighted-average period	2 years 9 months 18 days

Stockholders' Equity - Common_2

Stockholders' Equity - Common Stock Reserved for Future Issuance (Details)	Sep. 30, 2020shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock warrants	3,521,000
Common stock options issued and outstanding	2,341,000
Number of common stock shares provided for issuance of stock awards to its employees	6,705,000
2019 incentive award plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of common stock shares provided for issuance of stock awards to its employees	842,837