Oncternal Therapeutics (ONCT) 10-Q 5 Aug 21 2021 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2021	Jul. 28, 2021
Cover [Abstract]
Entity Registrant Name	Oncternal Therapeutics, Inc.
Entity Central Index Key	0001260990
Document Type	10-Q
Document Period End Date	Jun. 30, 2021
Amendment Flag	false
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2
Trading Symbol	ONCT
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-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		49,385,247
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	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 103,663	$ 116,737
Prepaid and other	3,936	1,266
Total current assets	107,599	118,003
Right-of-use asset	162	40
Other assets	658	766
Total assets	108,419	118,809
Current liabilities:
Accounts payable	1,009	1,143
Accrued liabilities	2,493	3,042
Deferred grant revenue	2,236	1,633
Lease liability	162	40
Total current liabilities	5,900	5,858
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 – 120,000; issued and outstanding shares – 49,385 and 48,802 at June 30, 2021 and December 31, 2020, respectively	49	49
Additional paid-in capital	198,897	195,699
Accumulated deficit	(96,427)	(82,797)
Total stockholders’ equity	102,519	112,951
Total liabilities and stockholders’ equity	$ 108,419	$ 118,809

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2021	Dec. 31, 2020
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	120,000,000	120,000,000
Common stock, shares issued	49,385,000	48,802,000
Common stock, shares outstanding	49,385,000	48,802,000

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Statement [Abstract]
Grant revenue	$ 883	$ 623	$ 1,631	$ 1,201
Operating expenses:
Research and development	5,192	3,815	9,105	6,510
General and administrative	3,381	2,343	6,174	4,977
Total operating expenses	8,573	6,158	15,279	11,487
Loss from operations	(7,690)	(5,535)	(13,648)	(10,286)
Interest income	8		18	13
Net loss	$ (7,682)	$ (5,535)	$ (13,630)	$ (10,273)
Net loss per share, basic and diluted	$ (0.16)	$ (0.34)	$ (0.28)	$ (0.65)
Weighted-average shares outstanding, basic and diluted	49,364	16,241	49,230	15,798

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities
Net loss	$ (13,630)	$ (10,273)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	2,674	742
Non-cash lease expense	82	73
Changes in operating assets and liabilities:
Prepaid and other	(2,562)	(662)
Accounts payable	(134)	494
Accrued liabilities	(544)	1,275
Change in lease liability	(82)	(73)
Deferred grant revenue	603	167
Net cash used in operating activities	(13,593)	(8,257)
Cash flows from financing activities
Proceeds from payroll protection program loan payable		301
Proceeds from exercise of stock options	414	4
Proceeds from issuance of common stock and common stock warrants, net		4,518
Proceeds from the exercise of common stock warrants	105
Net cash provided by financing activities	519	4,823
Net decrease in cash and cash equivalents	(13,074)	(3,434)
Cash and cash equivalents at beginning of period	116,737	20,051
Cash and cash equivalents at end of period	103,663	16,617
Supplemental disclosure of non-cash financing activities:
Cashless exercise of warrants	$ 1,836
Payment of 2019 bonus awards with stock options in lieu of cash		415
Deferred financing costs included in accrued liabilities		126
Fair value of warrants issued to placement agent		$ 238

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders' Equity (Parenthetical) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2020
Statement Of Stockholders Equity [Abstract]
Common stock and common stock warrants, issuance cost	$ 602	$ 602

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit
Balance at Dec. 31, 2019	$ 14,312	$ 15	$ 79,869	$ (65,572)
Balance (in shares) at Dec. 31, 2019		15,387,000
Exercise of stock options for cash	4		4
Exercise of stock options for cash (in shares)		5,000
Issuance of common stock and common stock warrants, net of issuance costs of $602	4,392	$ 2	4,390
Issuance Of Common Stock And Warrants Net Of Issuance Costs Shares		1,944,000
Vesting related to unvested share liability	6		6
Stock-based compensation	742		742
Payment of 2019 bonus awards with stock options in lieu of cash	415		415
Net loss	(10,273)			(10,273)
Balance at Jun. 30, 2020	9,598	$ 17	85,426	(75,845)
Balance (in shares) at Jun. 30, 2020		17,336,000
Balance at Mar. 31, 2020	10,395	$ 15	80,690	(70,310)
Balance (in shares) at Mar. 31, 2020		15,392,000
Issuance of common stock and common stock warrants, net of issuance costs of $602	4,392	$ 2	4,390
Issuance Of Common Stock And Warrants Net Of Issuance Costs Shares		1,944,000
Vesting related to unvested share liability	3		3
Stock-based compensation	343		343
Net loss	(5,535)			(5,535)
Balance at Jun. 30, 2020	9,598	$ 17	85,426	(75,845)
Balance (in shares) at Jun. 30, 2020		17,336,000
Balance at Dec. 31, 2020	$ 112,951	$ 49	195,699	(82,797)
Balance (in shares) at Dec. 31, 2020	48,802,000	48,802,000
Exercise of stock options for cash	$ 414		414
Exercise of stock options for cash (in shares)	106,163	106,000
Exercise of warrants for cash	$ 105		105
Exercise of warrants for cash (in shares)		18,000
Vesting related to unvested share liability	5		5
Stock-based compensation	2,674		2,674
Net loss	(13,630)			(13,630)
Balance at Jun. 30, 2021	$ 102,519	$ 49	198,897	(96,427)
Balance (in shares) at Jun. 30, 2021	49,385,000	49,385,000
Cashless exercise of warrants		459,000
Balance at Mar. 31, 2021	$ 108,303	$ 49	196,999	(88,745)
Balance (in shares) at Mar. 31, 2021		49,366,000
Exercise of stock options for cash	56		56
Exercise of stock options for cash (in shares)		18,000
Exercise of warrants for cash	4		4
Exercise of warrants for cash (in shares)		1,000
Vesting related to unvested share liability	2		2
Stock-based compensation	1,836		1,836
Net loss	(7,682)			(7,682)
Balance at Jun. 30, 2021	$ 102,519	$ 49	$ 198,897	$ (96,427)
Balance (in shares) at Jun. 30, 2021	49,385,000	49,385,000

Description of Business, Basis

Description of Business, Basis of Presentation and Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2021
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. (“Oncternal” or the “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. Oncternal 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 its Agreement and Plan of Merger and Reorganization, as amended (the “Merger Agreement”), with privately-held Oncternal Therapeutics, Inc. (“Private Oncternal”) and Grizzly Merger Sub, Inc., a wholly-owned subsidiary of the Company (“Merger Sub”), dated March 6, 2019. Under the Merger Agreement, Merger Sub merged with and into Private Oncternal, with Private Oncternal surviving as a wholly-owned subsidiary of the Company (the “Merger”). GTx changed its name to Oncternal Therapeutics, Inc., and Private Oncternal, which remains a wholly-owned subsidiary of the Company, changed its name to Oncternal Oncology, Inc. On June 10, 2019, the Company’s common stock began trading on The Nasdaq Capital Market under the ticker symbol “ONCT.” Except as otherwise indicated, references herein to “Oncternal,” and “the 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. 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 The Company follows Accounting Standards Codification (ASC) Topic 205-40, Presentation of Financial Statements—Going Concern The condensed consolidated financial statements have been prepared assuming the Company will continue as a going concern, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business. As of June 30, 2021, the Company had $103.7 million in cash and cash equivalents. The Company believes it has sufficient cash to fund its projected operating requirements for at least twelve months from the filing date of this Quarterly Report. From inception, the Company has devoted substantially all of its efforts to drug discovery and development and conducting preclinical studies and clinical trials. The Company has a limited operating history and the sales and income potential of the Company’s business and market are unproven. Successful transition to attaining profitable operations is dependent upon achieving a level of revenues adequate to support the Company’s cost structure. The Company has experienced net losses and negative cash flows from operating activities since its inception and has an accumulated deficit of $96.4 million as of June 30, 2021. The Company expects to continue to incur net losses for the foreseeable future and believes it will need to raise substantial additional capital to accomplish its business plan over the next several years. The Company plans to continue to fund its losses from operations and capital funding needs through a combination of equity offerings, debt financings or other sources, including potential collaborations, licenses and other similar arrangements. If the Company is unable to secure adequate additional funding, the Company may be forced to make reductions in spending, extend payment terms with suppliers, liquidate assets where possible, or suspend or curtail planned programs. Any of these actions could materially harm the Company’s business, results of operations and future prospects. There can be no assurance as to the availability or terms upon which such financing and capital might be available in the future. Basis of Presentation The accompanying interim condensed financial statements are unaudited. The unaudited condensed consolidated financial statements 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. 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, 2020, filed with the SEC on its Annual Report on Form 10-K/A on March 12, 2021. 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 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 consolidated balance sheets as prepaid expenses and other assets or accrued liabilities. The Company records accruals for estimated costs incurred for ongoing research and development activities and all clinical trial expenses are included in research and development expenses. 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. At June 30, 2021, the Company’s clinical trial accrual balance of $0.6 million is included in accrued liabilities. 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 (“CIRM”) 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 June 30, 2021, and December 31, 2020, the Company had deferred grant revenue of $2.2 million and $1.6 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 remaining service period after the point when the achievement of the milestone is deemed probable. The Company recognizes forfeitures for all awards as such forfeitures occur. Income Taxes The Company accounts for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements. Under this method, deferred tax assets and liabilities are determined on the basis of the differences between the financial statements and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date. The Company recognizes net deferred tax assets to the extent that the Company believes these assets are more likely than not to be realized. In making such a determination, management considers all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies, and results of recent operations. If management determines that the Company would be able to realize its deferred tax assets in the future in excess of their net recorded amount, management would make an adjustment to the deferred tax asset valuation allowance, which would reduce the provision for income taxes. Segment Reporting Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision-maker in making decisions regarding resource allocation and assessing performance. The Company views its operations and manages its business in one operating segment in the United States. Net Loss Per Share Basic net loss per share is computed by dividing the net loss by the weighted-average number of common shares outstanding for the period, without consideration for potentially dilutive securities and adjusted for the weighted-average number of common shares outstanding that are subject to repurchase. The Company has excluded weighted-average shares subject to repurchase of 8,000 shares and 27,000 shares from the weighted-average number of common shares outstanding for the three months ended June 30, 2021 and 2020, respectively. The Company has excluded weighted-average shares subject to repurchase of 11,000 shares and 30,000 shares from the weighted-average number of common shares outstanding for the six months ended June 30, 2021 and 2020, 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): June 30, 2021 2020 Warrants to purchase common stock 4,277 1,930 Common stock options 5,140 2,191 Common stock subject to repurchase 7 25 9,424 4,146

Balance Sheet Details

Balance Sheet Details	6 Months Ended
	Jun. 30, 2021
Payables And Accruals [Abstract]
Balance Sheet Details	2. Balance Sheet Details Accrued liabilities consist of the following (in thousands): June 30, December 31, 2021 2020 Research and development $ 723 $ 412 Clinical trials 594 980 Legal fees 182 77 Compensation 988 1,528 Other 6 45 $ 2,493 $ 3,042

Commitments, Contingencies and

Commitments, Contingencies and Related Party Transactions	6 Months Ended
	Jun. 30, 2021
Commitments And Contingencies Disclosure [Abstract]
Commitments, Contingencies and Related Party Transactions	3. Commitments, Contingencies and Related Party Transactions Lease Liability Rent expense was $46,000 and $41,000 for the three months ended June 30, 2021 and 2020, respectively. Rent expense was $87,000 and $83,000 for the six months ended June 30, 2021 and 2020, respectively. On May 22, 2019, the Company entered into a sublease agreement for office space of 4,677 square feet in San Diego, California which expired on March 31, 2021. On March 17, 2021, the Company entered into a lease directly with the landlord for the same facility (the “San Diego Lease”) which expires on May 31, 2022. Base rent under the San Diego Lease is approximately $184,000 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 $ 162,000 Maturities of the lease liability due under this lease agreement as of June 30, 2021, are as follows (in thousands): Maturity of lease liability Operating Lease 2021 $ 92 2022 77 Total lease payments 169 Less imputed interest (7 ) Lease liability $ 162 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 three and six months ended June 30, 2021 and 2020, the Company paid insurance premiums of approximately $1.8 million and $1.4 million, for which the son earned commission of $79,000 and $57,000, 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 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 have executed and expect to continue to 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 a license and distribution agreement between the parties (see Note 4). The Company recorded amounts receivable from SPH USA related to statements of work totaling $0.4 million and $0.3 million as of June 30, 2021 and December 31, 2020, respectively. The Company has an agreement with SPH USA for certain rights to the greater China area (see Note 4). In connection with the securities purchase agreements and underwritten offerings described in Note 5, other investors included individuals or entities affiliated with David F. Hale, SPH USA, Daniel L. Kisner, Hazel M. Aker, and Michael G. Carter.

License, Collaboration and Rese

License, Collaboration and Research Subaward Agreements	6 Months Ended
	Jun. 30, 2021
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 June 30, 2021, 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. In July 2020, the Company entered into a research agreement with MD Anderson for certain services up to an aggregate cost of $293,000. The Company of none and $0.1 million for the three and six months ended June 30, 2021 and a nominal amount Agreements with the Regents of the University of California (the “Regents”) In March 2016, and as amended and restated in August 2018, and as amended in March and May 2019, 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 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) none and $25,000 in license maintenance fees as research and development expense for the three and six months ended June 30, 2021 and none for the three and six months ended June 30, 2020, and (ii) a nominal amount and $47,000 in patent costs as general and administrative expense for the three months ended June 30, 2021 and 2020, respectively, and $0.2 million and $1.0 million for six months ended June 30, 2021 and 2020, respectively. As of June 30, 2021, 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 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, and as amended, the Company and UTRF entered into a license agreement (the “SARD License Agreement”) pursuant to which the Company was granted exclusive worldwide rights in all existing selective androgen receptor degrader (“SARD”) technologies owned or controlled by UTRF, including all improvements thereto. Under the SARD License Agreement, the Company is obligated to employ active, diligent efforts to conduct preclinical research and development activities for the SARD program to advance one or more lead compounds into clinical development. The Company is also obligated to pay UTRF annual license maintenance fees, low single-digit royalties on net sales of products and additional royalties on sublicense revenues, depending on the state of development of a clinical product candidate at the time it is sublicensed. The Company recorded research and development expense under this agreement of $0.1 million and $10,000 million The California Institute for Regenerative Medicine (“CIRM”) Awards In August 2017, and as amended and restated in December 2020, researchers at UC San Diego 1.5 In October 2017, CIRM awarded a $5.8 million grant to the researchers at 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, and no contingency funds have been provided under such CIRM award for each of the three and six months ended June 30, 2021 and 2020. Clinical Trial and Supply Agreement In April 2018, and as amended, the Company entered into a Clinical Trial and Supply Agreement with Pharmacyclics, LLC, an AbbVie Company, to supply ibrutinib for the Company’s Phase 1/2 clinical trial evaluating cirmtuzumab in combination with ibrutinib. 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 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.

Stockholders' Equity

Stockholders' Equity	6 Months Ended
	Jun. 30, 2021
Equity [Abstract]
Stockholders' Equity	5 . Stockholders’ Equity Securities Purchase Agreements and Underwritten Offering In May 2020, the Company entered into a Securities Purchase Agreement (the “May Purchase Agreement”) with several institutional and individual investors 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. 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. An investor participating in the transaction included an entity affiliated with David F. Hale, the chairman of the Company’s board of directors. 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. 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 “August 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. 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 November 2020, the Company entered into an underwriting agreement (as amended and restated, the “November Underwriting Agreement”) with Wainwright for the sale of 7,258,065 shares of the Company’s common stock at a price to the public of $3.10 per share, resulting in net proceeds of $20.4 million, after deducting the underwriter’s discounts, commissions and other offering expenses. In addition, the Company issued warrants to purchase 435,484 shares of common stock at an exercise price of $3.875 per share to Wainwright as part of its compensation, which warrants were immediately exercisable upon issuance and terminate on November 17, 2025. In December 2020, the Company entered into an underwriting agreement (as amended and restated, the “December Underwriting Agreement”) with Wainwright for the sale of 19,161,667 shares of the Company’s common stock at a price to the public of $4.50 per share, resulting in net proceeds of $79.0 million, after deducting the underwriter’s discounts, commissions and other offering expenses In addition, the Company issued warrants to purchase 1,149,700 shares of common stock at an exercise price of $5.625 per share to Wainwright as part of its compensation, which warrants were immediately exercisable upon issuance and terminate on December 9, 2025. Common Stock Warrants A summary of warrant activity and changes in warrants outstanding is presented below: Number of Shares Underlying Warrants Weighted-Average Exercise Price Per Share Weighted-Average Remaining Contractual Term (in years) Balance at December 31, 2020 5,031,841 $ 9.25 4.40 Granted — $ — — Cancelled — $ — — Exercised (754,958 ) $ 2.57 4.34 Balance at June 30, 2021 4,276,883 $ 10.42 3.83 As of June 30, 2021, all warrants met the criteria for classification in stockholders’ equity. 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 upon cancellation 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 June 30, 2021, 2,400,691 shares remain available for future issuance under the 2019 Plan and Inducement Plan (as defined below). Weighted- Average Weighted- Remaining Average Contractual Aggregate Number of Exercise Price Term Intrinsic Shares Per Share (in years) Value Options outstanding 5,140,153 $ 5.53 8.85 $ 2,250,390 Options vested and expected to vest 5,140,153 $ 5.53 8.85 $ 2,250,390 Options exercisable 1,205,130 $ 3.67 6.75 $ 1,760,058 As of June 30, 2021, all 275,579 stock options previously outstanding under the 2013 Plan were cancelled and added to the 2019 Plan. At June 30, 2021, all former GTx stock option plans were terminated and there are no remaining outstanding stock options. 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 The 2019 Plan provides for the issuance of 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 stock options issued under the 2019 Plan expire ten years from the date of grant and vest over a four-year On February 11, 2021, the Company’s board of directors adopted the 2021 Employment Inducement Incentive Award Plan (the “Inducement Plan”). The Inducement Plan is a non-shareholder approved stock plan adopted pursuant to the “inducement exception” provided under Nasdaq listing rules. The Inducement Plan is used exclusively for the issuance of non-statutory stock options to certain new hires who satisfied the requirements to be granted inducement grants under Nasdaq rules as an inducement material to the individual’s entry into employment with the Company. The terms of the Inducement Plan are substantially similar to the terms of our 2019 Plan. As amended on May 25, 2021, the Company has reserved 2,050,000 shares of common stock under the Inducement Plan. A summary of the Company’s stock option activity under the 2019 Plan, Inducement Plan and 2015 Plan is as follows: Weighted- Number of Average Options Exercise Price Balance at December 31, 2020 2,107,625 $ 4.08 Granted 3,483,900 $ 6.38 Cancelled (345,209 ) $ 5.81 Exercised (106,163 ) $ 3.89 Balance at June 30, 2021 5,140,153 $ 5.53 The weighted average grant date fair value per share of option grants for the six months ended June 30, 2021 was $ 4.74 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 Six Months Ended June 30, June 30, 2021 2020 2021 2020 Risk-free interest rate 1.1 % 0.3 % 0.8 % 0.8 % Expected volatility 89.1 % 91.7 % 89.6 % 89.9 % Expected term (in years) 6.0 5.3 6.2 5.4 Expected dividend yield — % — % — % — % Expected volatility. Due to the lack of an adequate history of: (i) a public market for the trading of the Company’s common stock, and (ii) specific historical and implied volatility data, the Company has based its estimate of the historical volatility from a group of similar companies that are publicly traded. For these analyses, the Company has selected companies with comparable characteristics to it including enterprise value, risk profiles, position within the industry, and with historical share price information sufficient to meet the expected life of the stock-based awards. The Company computes the historical volatility data using the daily closing prices for the selected companies’ shares during the equivalent period of the calculated expected term of our stock-based awards. 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 the Company does not have historical exercise behavior, it determined the expected life assumption using the simplified method for employees, which is an average of the contractual term of the option and its vesting period. The expected term for nonemployee options is generally the remaining contractual term. Risk-free interest rate. The risk-free interest rate is based on the implied yield on the U.S. Treasury securities with a maturity date similar to the expected term of the associated stock option award. Expected dividend yield. The Company bases the expected dividend yield assumption on the fact that it has never paid cash dividends and has no present intention to pay cash dividends and, therefore, used an expected dividend yield of zero. Stock-based compensation expense recognized for all equity awards has been reported in the condensed consolidated statements of operations as follows (in thousands): Three Months Ended Six Months Ended June 30, June 30, 2021 2020 2021 2020 Research and development $ 703 $ 130 $ 1,177 $ 269 General and administrative 1,133 213 1,497 473 $ 1,836 $ 343 $ 2,674 $ 742 As of June 30, 2021, the total compensation cost related to non-vested awards not yet recognized was $16.1 million and the weighted-average period over which it is expected to be recognized was 3.4 years. Common Stock Reserved for Future Issuance Common stock reserved for future issuance is as follows (in thousands): June 30, 2021 Common stock warrants 4,277 Common stock options issued and outstanding 5,140 Common stock available for issuance under the Inducement Plan and 2019 Plan 2,401 11,818

COVID-19 Pandemic and CARES Act

COVID-19 Pandemic and CARES Act	6 Months Ended
	Jun. 30, 2021
C O V I D19 Pandemic And C A R E S Act [Abstract]
COVID-19 Pandemic and CARES Act	6 . COVID-19 Pandemic and CARES Act The current COVID-19 pandemic 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 have taken actions 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, many Company employees continue to work remotely. While the Company is currently continuing the clinical trials it has underway in sites across the U.S., COVID-19 precautions have directly or indirectly impacted the timeline for some of its clinical trials. Additionally, the Company’s expectations for the timing of first-in-human dosing of its ROR1 CAR-T therapy has been delayed to the first half of 2022. 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 June 30, 2021. The full extent to which the COVID-19 pandemic will continue to 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, the success or failure of vaccination programs, the emergence and spread of variants of COVID-19, 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, and authorized the Paycheck Protection Program. The CARES Act had no material impact on the Company’s income tax provision for the six months ended June 30, 2021. The Company continues to monitor changes and revisions to the CARES Act and its impact on the Company’s 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)	6 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
Merger	Merger On June 7, 2019, the Company, then operating as GTx, Inc. (“GTx”), completed the merger contemplated by its Agreement and Plan of Merger and Reorganization, as amended (the “Merger Agreement”), with privately-held Oncternal Therapeutics, Inc. (“Private Oncternal”) and Grizzly Merger Sub, Inc., a wholly-owned subsidiary of the Company (“Merger Sub”), dated March 6, 2019. Under the Merger Agreement, Merger Sub merged with and into Private Oncternal, with Private Oncternal surviving as a wholly-owned subsidiary of the Company (the “Merger”). GTx changed its name to Oncternal Therapeutics, Inc., and Private Oncternal, which remains a wholly-owned subsidiary of the Company, changed its name to Oncternal Oncology, Inc. On June 10, 2019, the Company’s common stock began trading on The Nasdaq Capital Market under the ticker symbol “ONCT.” Except as otherwise indicated, references herein to “Oncternal,” and “the 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.
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 The Company follows Accounting Standards Codification (ASC) Topic 205-40, Presentation of Financial Statements—Going Concern The condensed consolidated financial statements have been prepared assuming the Company will continue as a going concern, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business. As of June 30, 2021, the Company had $103.7 million in cash and cash equivalents. The Company believes it has sufficient cash to fund its projected operating requirements for at least twelve months from the filing date of this Quarterly Report. From inception, the Company has devoted substantially all of its efforts to drug discovery and development and conducting preclinical studies and clinical trials. The Company has a limited operating history and the sales and income potential of the Company’s business and market are unproven. Successful transition to attaining profitable operations is dependent upon achieving a level of revenues adequate to support the Company’s cost structure. The Company has experienced net losses and negative cash flows from operating activities since its inception and has an accumulated deficit of $96.4 million as of June 30, 2021. The Company expects to continue to incur net losses for the foreseeable future and believes it will need to raise substantial additional capital to accomplish its business plan over the next several years. The Company plans to continue to fund its losses from operations and capital funding needs through a combination of equity offerings, debt financings or other sources, including potential collaborations, licenses and other similar arrangements. If the Company is unable to secure adequate additional funding, the Company may be forced to make reductions in spending, extend payment terms with suppliers, liquidate assets where possible, or suspend or curtail planned programs. Any of these actions could materially harm the Company’s business, results of operations and future prospects. There can be no assurance as to the availability or terms upon which such financing and capital might be available in the future.
Basis of Presentation	Basis of Presentation The accompanying interim condensed financial statements are unaudited. The unaudited condensed consolidated financial statements 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. 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, 2020, filed with the SEC on its Annual Report on Form 10-K/A on March 12, 2021. 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 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 consolidated balance sheets as prepaid expenses and other assets or accrued liabilities. The Company records accruals for estimated costs incurred for ongoing research and development activities and all clinical trial expenses are included in research and development expenses. 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. At June 30, 2021, the Company’s clinical trial accrual balance of $0.6 million is included in accrued liabilities.
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 (“CIRM”) 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 June 30, 2021, and December 31, 2020, the Company had deferred grant revenue of $2.2 million and $1.6 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 remaining service period after the point when the achievement of the milestone is deemed probable. The Company recognizes forfeitures for all awards as such forfeitures occur.
Income Taxes	Income Taxes The Company accounts for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements. Under this method, deferred tax assets and liabilities are determined on the basis of the differences between the financial statements and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date. The Company recognizes net deferred tax assets to the extent that the Company believes these assets are more likely than not to be realized. In making such a determination, management considers all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies, and results of recent operations. If management determines that the Company would be able to realize its deferred tax assets in the future in excess of their net recorded amount, management would make an adjustment to the deferred tax asset valuation allowance, which would reduce the provision for income taxes.
Segment Reporting	Segment Reporting Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision-maker in making decisions regarding resource allocation and assessing performance. The Company views its operations and manages its business in one operating segment in the United States.
Net Loss Per Share	Net Loss Per Share Basic net loss per share is computed by dividing the net loss by the weighted-average number of common shares outstanding for the period, without consideration for potentially dilutive securities and adjusted for the weighted-average number of common shares outstanding that are subject to repurchase. The Company has excluded weighted-average shares subject to repurchase of 8,000 shares and 27,000 shares from the weighted-average number of common shares outstanding for the three months ended June 30, 2021 and 2020, respectively. The Company has excluded weighted-average shares subject to repurchase of 11,000 shares and 30,000 shares from the weighted-average number of common shares outstanding for the six months ended June 30, 2021 and 2020, 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): June 30, 2021 2020 Warrants to purchase common stock 4,277 1,930 Common stock options 5,140 2,191 Common stock subject to repurchase 7 25 9,424 4,146

Description of Business, Basi_3

Description of Business, Basis of Presentation and Summary of Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2021
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): June 30, 2021 2020 Warrants to purchase common stock 4,277 1,930 Common stock options 5,140 2,191 Common stock subject to repurchase 7 25 9,424 4,146

Balance Sheet Details (Tables)

Balance Sheet Details (Tables)	6 Months Ended
	Jun. 30, 2021
Payables And Accruals [Abstract]
Summary of Accrued Liabilities	Accrued liabilities consist of the following (in thousands): June 30, December 31, 2021 2020 Research and development $ 723 $ 412 Clinical trials 594 980 Legal fees 182 77 Compensation 988 1,528 Other 6 45 $ 2,493 $ 3,042

Commitments, Contingencies an_2

Commitments, Contingencies and Related Party Transactions (Tables)	6 Months Ended
	Jun. 30, 2021
Commitments And Contingencies Disclosure [Abstract]
Summary of Maturities of Lease Liabilities	Maturities of the lease liability due under this lease agreement as of June 30, 2021, are as follows (in thousands): Maturity of lease liability Operating Lease 2021 $ 92 2022 77 Total lease payments 169 Less imputed interest (7 ) Lease liability $ 162

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	6 Months Ended
	Jun. 30, 2021
Summary Of Warrant Activity And Changes In Warrants Outstanding	A summary of warrant activity and changes in warrants outstanding is presented below: Number of Shares Underlying Warrants Weighted-Average Exercise Price Per Share Weighted-Average Remaining Contractual Term (in years) Balance at December 31, 2020 5,031,841 $ 9.25 4.40 Granted — $ — — Cancelled — $ — — Exercised (754,958 ) $ 2.57 4.34 Balance at June 30, 2021 4,276,883 $ 10.42 3.83
Summary of Stock Option Outstanding, Vested and Expected to Vest and Exercisable	Weighted- Average Weighted- Remaining Average Contractual Aggregate Number of Exercise Price Term Intrinsic Shares Per Share (in years) Value Options outstanding 5,140,153 $ 5.53 8.85 $ 2,250,390 Options vested and expected to vest 5,140,153 $ 5.53 8.85 $ 2,250,390 Options exercisable 1,205,130 $ 3.67 6.75 $ 1,760,058
Summary of Stock Option Activity	A summary of the Company’s stock option activity under the 2019 Plan, Inducement Plan and 2015 Plan is as follows: Weighted- Number of Average Options Exercise Price Balance at December 31, 2020 2,107,625 $ 4.08 Granted 3,483,900 $ 6.38 Cancelled (345,209 ) $ 5.81 Exercised (106,163 ) $ 3.89 Balance at June 30, 2021 5,140,153 $ 5.53
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 Six Months Ended June 30, June 30, 2021 2020 2021 2020 Research and development $ 703 $ 130 $ 1,177 $ 269 General and administrative 1,133 213 1,497 473 $ 1,836 $ 343 $ 2,674 $ 742
Common Stock Reserved for Future Issuance	Common stock reserved for future issuance is as follows (in thousands): June 30, 2021 Common stock warrants 4,277 Common stock options issued and outstanding 5,140 Common stock available for issuance under the Inducement Plan and 2019 Plan 2,401 11,818
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 Six Months Ended June 30, June 30, 2021 2020 2021 2020 Risk-free interest rate 1.1 % 0.3 % 0.8 % 0.8 % Expected volatility 89.1 % 91.7 % 89.6 % 89.9 % Expected term (in years) 6.0 5.3 6.2 5.4 Expected dividend yield — % — % — % — %

Description of Business, Basi_4

Description of Business, Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021USD ($)shares	Jun. 30, 2020shares	Jun. 30, 2021USD ($)segmentshares	Jun. 30, 2020shares	Dec. 31, 2020USD ($)
Accounting Policies [Abstract]
Accumulated deficit	$ (96,427)		$ (96,427)		$ (82,797)
Cash and cash equivalents	103,663		103,663		116,737
Accrued Clinical Trials	594		594		980
Deferred grant revenue	$ 2,236		$ 2,236		$ 1,633
Number of operating segments | segment			1
Weighted-average shares subject to repurchase | shares	8,000	27,000	11,000	30,000

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	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities	9,424	4,146
Warrants to purchase common stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities	4,277	1,930
Stock Option Grants
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities	5,140	2,191
Common Stock Subject to Repurchase
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities	7	25

Balance Sheet Details - Accrued

Balance Sheet Details - Accrued Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Payables And Accruals [Abstract]
Research and development	$ 723	$ 412
Accrued Clinical Trials	594	980
Legal fees	182	77
Compensation	988	1,528
Other	6	45
Total accrued liabilities	$ 2,493	$ 3,042

Commitments, Contingencies an_3

Commitments, Contingencies and Related Party Transactions - Additional Information (Details)	Mar. 17, 2021USD ($)	May 22, 2019USD ($)ft²	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Dec. 31, 2020USD ($)
Commitments And Contingencies [Line Items]
Insurance premiums			$ 1,800,000	$ 1,400,000	$ 1,800,000	$ 1,400,000
Agent
Commitments And Contingencies [Line Items]
Insurance commissions			79,000	57,000	79,000	57,000
Shanghai Pharmaceutical (USA) Inc.
Commitments And Contingencies [Line Items]
Amounts receivable			400,000		400,000		$ 300,000
San Diego, California | Office Space
Commitments And Contingencies [Line Items]
Rent expense			$ 46,000	$ 41,000	$ 87,000	$ 83,000
Rentable area | ft²		4,677
Lease expiration date	May 31, 2022	Mar. 31, 2021
Annual base rent	$ 184,000	$ 184,000
Lease discount rate			10.00%		10.00%
Operating lease liability			$ 162,000		$ 162,000
Weighted average remaining lease term			10 months 24 days		10 months 24 days

Commitments, Contingencies an_4

Commitments, Contingencies and Related Party Transactions - Summary of Maturities of Lease Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Operating Lease Liabilities Payments Due [Abstract]
2021	$ 92
2022	77
Total lease payments	169
Less imputed interest	(7)
Lease liability	$ 162	$ 40

License, Collaboration and Re_2

License, Collaboration and Research Subaward Agreements - Additional Information (Details) - USD ($)	1 Months Ended			3 Months Ended			6 Months Ended		12 Months Ended
	Oct. 31, 2017	Aug. 31, 2017	May 31, 2016	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2017	Dec. 31, 2015	Jul. 31, 2020	Dec. 31, 2014
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research and development expense				$ 0		$ 0	$ 0	$ 0
Patent costs as general and administrative expense				3,381,000		2,343,000	6,174,000	4,977,000
Grant revenue				883,000		623,000	1,631,000	1,201,000
MD Anderson Cancer Center
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research and development expense				0			100,000
Aggregate cost											$ 293,000,000
Regents of the University of California
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research and development expense				0		0	25,000	0
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						47,000	200,000	1,000,000
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 sub award agreements throughout award project period		$ 14,000,000
Subaward payments received				2,200,000		1,400,000	2,200,000	1,400,000
Grant revenue				900,000		600,000	1,600,000	1,600,000
Related qualifying subaward costs				1,800,000		1,500,000	3,300,000	2,800,000
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	$ 300,000	300,000
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		$ 10,000	$ 100,000	$ 100,000

Stockholders' Equity - Securiti

Stockholders' Equity - Securities Purchase Agreements and Underwritten Offering (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended					6 Months Ended
	Dec. 31, 2020	Nov. 30, 2020	Aug. 31, 2020	Jul. 31, 2020	May 31, 2020	Jun. 30, 2020	Jun. 30, 2021
Schedule Of Capitalization Equity [Line Items]
Proceeds from issuance of common stock and common stock warrants, net						$ 4,518
Warrants issued	5,031,841						4,276,883
Warrant exercise price per share	$ 9.25						$ 10.42
Warrants to purchase common stock
Schedule Of Capitalization Equity [Line Items]
Combined purchase price of share and warrant per unit	4.50	$ 3.10	$ 2.10
Warrant exercise price per share	$ 5.625	$ 3.875	$ 2.625
Common stock warrants exercisable and expiration date	Dec. 9, 2025	Nov. 17, 2025	Aug. 27, 2025
Warrants to purchase common stock | Maximum
Schedule Of Capitalization Equity [Line Items]
Warrants issued	1,149,700	435,484	145,733
Common Stock
Schedule Of Capitalization Equity [Line Items]
Common stock, shares, issued	19,161,667	7,258,065	2,428,886
Proceeds from issuance of common stock and common stock warrants, net	$ 79,000	$ 20,400	$ 4,400
Purchase Agreement | Warrants to purchase common stock
Schedule Of Capitalization Equity [Line Items]
Combined purchase price of share and warrant per unit					$ 2.5725
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					116,618
Warrant exercise price per share					$ 3.2156
Common stock warrants exercisable and expiration date					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 exercisable and 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

Stockholders' Equity - Summary

Stockholders' Equity - Summary Of Warrant Activity And Changes In Warrants Outstanding (Details) - $ / shares	6 Months Ended	12 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Equity [Abstract]
Options outstanding, Number of Warrant	5,031,841
Number of Shares Underlying Warrants Exercised	(754,958)
Options outstanding, Number of Warrant	4,276,883	5,031,841
Weighted-Average Exercise Price	$ 9.25
Exercised	2.57
Weighted-Average Exercise Price	$ 10.42	$ 9.25
Weighted-Average Remaining Contractual Term	3 years 9 months 29 days	4 years 4 months 24 days
Weighted-Average Remaining Contractual Term, Exercised	4 years 4 months 2 days

Stockholders' Equity - Equity I

Stockholders' Equity - Equity Incentive Plans (Details) - $ / shares	Jun. 07, 2019	Jul. 31, 2015	Jun. 30, 2021	Feb. 11, 2021
Class Of Stock [Line Items]
Number of common stock shares provided for issuance of stock awards to its employees			11,818,000
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%
2019 incentive award plan and inducement plan
Class Of Stock [Line Items]
Number of common stock shares provided for issuance of stock awards to its employees			2,400,691
2013 plan
Class Of Stock [Line Items]
Number of options outstanding and fully vested and exercisable			275,579
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			0
2019 plan
Class Of Stock [Line Items]
Options expiration term		10 years
Options vesting period		4 years
Inducement Plan
Class Of Stock [Line Items]
Number of common stock shares provided for issuance of stock awards to its employees				2,050,000
2019 and 2015 plan
Class Of Stock [Line Items]
Weighted average grant date fair value per share of option grants			$ 4.74
Intrinsic value of stock options exercised			$ 3.89

Stockholders' Equity - Summar_2

Stockholders' Equity - Summary of Stock Option Outstanding, Vested and Expected to Vest and Exercisable (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options outstanding, Number of Shares	5,140,153	2,107,625
Options vested and expected to vest, Number of Shares	5,140,153
Options exercisable, Number of Shares	1,205,130
Options outstanding, Weighted Average Exercise Price	$ 5.53	$ 4.08
Options outstanding, Weighted Average Exercise Price	5.53
Options outstanding, Weighted Average Exercise Price	$ 3.67
Options outstanding, Weighted Average Remaining Contractual Term	3 years 4 months 24 days
Options outstanding, Aggregate Intrinsic Value	$ 2,250,390
Options outstanding, Aggregate Intrinsic Value	2,250,390
Options outstanding, Aggregate Intrinsic Value	$ 1,760,058
Equity incentive plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options outstanding, Weighted Average Remaining Contractual Term	8 years 10 months 6 days
Options outstanding, Weighted Average Remaining Contractual Term	8 years 10 months 6 days
Options outstanding, Weighted Average Remaining Contractual Term	6 years 9 months

Stockholders' Equity - Summar_3

Stockholders' Equity - Summary of Stock Option Activity (Details)	6 Months Ended
	Jun. 30, 2021$ / sharesshares
Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Roll Forward
Number of options, beginning balance | shares	2,107,625
Number of options, granted | shares	3,483,900
Number of options, cancelled | shares	(345,209)
Number of options, exercised | shares	(106,163)
Number of options, ending balance | shares	5,140,153
Weighted average exercise price, beginning balance | $ / shares	$ 4.08
Weighted average exercise price, granted | $ / shares	6.38
Weighted average exercise price, cancelled | $ / shares	5.81
Weighted average exercise price, exercised | $ / shares	3.89
Weighted average exercise price, ending balance | $ / shares	$ 5.53

Stockholders' Equity - Schedule

Stockholders' Equity - Schedule of Assumptions Used to Estimate Fair Value of Stock Option Grants (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Risk-free interest rate	1.10%	0.30%	0.80%	0.80%
Expected volatility	89.10%	91.70%	89.60%	89.90%
Expected term (in years)	6 years	5 years 3 months 18 days	6 years 4 months 24 days	5 years 4 months 24 days

Stockholders' Equity - Share-Ba

Stockholders' Equity - Share-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 1,836	$ 343	$ 2,674	$ 742
Research and development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	703	130	1,177	269
General and administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 1,133	$ 213	$ 1,497	$ 473

Stockholders' Equity - Stock-Ba

Stockholders' Equity - Stock-Based Compensation Expense (Details) $ in Millions	6 Months Ended
	Jun. 30, 2021USD ($)
Equity [Abstract]
Compensation cost related to non-vested awards not yet recognized	$ 16.1
Remaining weighted-average period	3 years 4 months 24 days

Stockholders' Equity - Common S

Stockholders' Equity - Common Stock Reserved for Future Issuance (Details)	Jun. 30, 2021shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock warrants	4,277,000
Common stock options issued and outstanding	5,140,000
Common stock available for future issuance	11,818,000
2019 incentive award plan and inducement plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock available for future issuance	2,400,691