Document and Entity Information - shares	6 Months Ended
Document and Entity Information - shares	Jun. 30, 2019	Aug. 06, 2019
Document And Entity Information [Abstract]
Entity Registrant Name	Oncternal Therapeutics, Inc.
Entity Central Index Key	0001260990
Document Type	10-Q
Document Period End Date	Jun. 30, 2019
Amendment Flag	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
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		15,384,764
Entity File Number	000-50549
Entity Tax Identification Number	464137807
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

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 28,516	$ 20,645
Prepaid and other assets	1,355	565
Total current assets	29,871	21,210
Right-of-use asset	265
Other assets	767	752
Total assets	30,903	21,962
Current liabilities:
Accounts payable	2,765	3,440
Accrued liabilities	2,550	891
Deferred grant revenue	2,387
Current portion of lease liability	139
Total current liabilities	7,841	4,331
Preferred stock warrant liability	1,300	674
Lease liability	126
Commitments and contingencies (Notes 3 and 5)
Convertible preferred stock, $0.0001 par value; authorized shares - none and 130,100 at June 30, 2019 and December 31, 2018, respectively; issued and outstanding – none and 8,148 at June 30, 2019 and December 31, 2018, respectively; liquidation preference of $0 and $48,954 at June 30, 2019 and December 31, 2018, respectively		46,588
Stockholders’ equity (deficit):
Preferred stock, $0.001 par value, authorized shares – 5,000 shares and none at June 30, 2019 and December 31, 2018, respectively; issued and outstanding shares – none
Common stock, $0.001 par value; authorized shares – 60,000 and 200,000 shares at June 30, 2019 and December 31, 2018, respectively; issued and outstanding shares – 15,370 and 3,762 at June 30, 2019 and December 31, 2018, respectively	15	5
Additional paid-in capital	79,445	1,748
Accumulated deficit	(56,524)	(31,384)
Total stockholders’ equity (deficit)	22,936	(29,631)
Total liabilities and stockholders’ equity (deficit)	$ 30,903	$ 21,962

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($)	Jun. 30, 2019	Dec. 31, 2018
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	0
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	60,000,000	200,000,000
Common stock, shares issued	15,370,000	3,762,000
Common stock, shares outstanding	15,370,000	3,762,000
Convertible preferred stock
Convertible preferred stock, par value	$ 0.0001	$ 0.0001
Convertible preferred stock, shares authorized	0	130,100,000
Convertible preferred stock, shares issued	0	8,148,000
Convertible preferred stock, shares outstanding	0	8,148,000
Convertible preferred stock, liquidation preference	$ 0	$ 48,954,000

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Statement [Abstract]
Grant revenue	$ 674	$ 1,527	$ 1,144	$ 1,715
Operating expenses:
Research and development	2,587	3,513	4,483	4,802
In-process research and development	18,088		18,088
General and administrative	1,619	555	2,551	1,136
Total operating expenses	22,294	4,068	25,122	5,938
Loss from operations	(21,620)	(2,541)	(23,978)	(4,223)
Other income (expense):
Change in fair value of warrant liability	(1,285)	114	(1,268)	77
Other income				216
Interest expense				(1)
Interest income	59	15	106	28
Total other income (expense)	(1,226)	129	(1,162)	320
Net loss	$ (22,846)	$ (2,412)	$ (25,140)	$ (3,903)
Net loss per share, basic and diluted	$ (3.38)	$ (0.68)	$ (4.81)	$ (1.10)
Weighted-average shares outstanding, basic and diluted	6,765	3,573	5,229	3,555

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, 2017	$ (23,278)		$ 5	$ 1,522	$ (24,805)
Balance (in shares) at Dec. 31, 2017		5,653,000
Balance at Dec. 31, 2017		$ 28,715
Balance (in shares) at Dec. 31, 2017			3,745,000
Collection of stock subscription receivable		$ 1,100
Stock-based compensation	43			43
Net loss	(1,491)				(1,491)
Balance at Mar. 31, 2018	(24,726)		$ 5	1,565	(26,296)
Balance (in shares) at Mar. 31, 2018		5,653,000
Balance at Mar. 31, 2018		$ 29,815
Balance (in shares) at Mar. 31, 2018			3,745,000
Balance at Dec. 31, 2017	(23,278)		$ 5	1,522	(24,805)
Balance (in shares) at Dec. 31, 2017		5,653,000
Balance at Dec. 31, 2017		$ 28,715
Balance (in shares) at Dec. 31, 2017			3,745,000
Net loss	(3,903)
Balance at Jun. 30, 2018	(27,097)		$ 5	1,606	(28,708)
Balance (in shares) at Jun. 30, 2018		5,653,000
Balance at Jun. 30, 2018		$ 29,815
Balance (in shares) at Jun. 30, 2018			3,760,000
Balance at Mar. 31, 2018	(24,726)		$ 5	1,565	(26,296)
Balance (in shares) at Mar. 31, 2018		5,653,000
Balance at Mar. 31, 2018		$ 29,815
Balance (in shares) at Mar. 31, 2018			3,745,000
Issuance of restricted common shares (in shares)			15,000
Stock-based compensation	41			41
Net loss	(2,412)				(2,412)
Balance at Jun. 30, 2018	(27,097)		$ 5	1,606	(28,708)
Balance (in shares) at Jun. 30, 2018		5,653,000
Balance at Jun. 30, 2018		$ 29,815
Balance (in shares) at Jun. 30, 2018			3,760,000
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	$ 46,588
Balance (in shares) at Dec. 31, 2018	3,762,000		3,762,000
Exercise of stock options for cash	$ 2			2
Exercise of stock options for cash (in shares)			2,000
Vesting related to repurchase liability	4			4
Stock-based compensation	39			39
Net loss	(2,294)				(2,294)
Balance at Mar. 31, 2019	(31,880)		$ 5	1,793	(33,678)
Balance (in shares) at Mar. 31, 2019		8,148,000
Balance at Mar. 31, 2019		$ 46,588
Balance (in shares) at Mar. 31, 2019			3,764,000
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	$ 46,588
Balance (in shares) at Dec. 31, 2018	3,762,000		3,762,000
Net loss	$ (25,140)
Balance at Jun. 30, 2019	$ 22,936		$ 15	79,445	(56,524)
Balance (in shares) at Jun. 30, 2019		0
Balance (in shares) at Jun. 30, 2019	15,370,000		15,370,000
Balance at Mar. 31, 2019	$ (31,880)		$ 5	1,793	(33,678)
Balance (in shares) at Mar. 31, 2019		8,148,000
Balance at Mar. 31, 2019		$ 46,588
Balance (in shares) at Mar. 31, 2019			3,764,000
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
Vesting related to repurchase liability	20			20
Stock-based compensation	63			63
Net loss	(22,846)				(22,846)
Balance at Jun. 30, 2019	$ 22,936		$ 15	$ 79,445	$ (56,524)
Balance (in shares) at Jun. 30, 2019		0
Balance (in shares) at Jun. 30, 2019	15,370,000		15,370,000

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019	Jun. 30, 2018
Cash flows from operating activities
Net loss		$ (25,140)	$ (3,903)
Adjustments to reconcile net loss to net cash used in operating activities:
In-process research and development	$ 18,088	18,088
Noncash lease expense		13
Noncash other income			(216)
Stock-based compensation		102	84
Noncash compensation expense		24
Noncash interest expense			1
Change in fair value of preferred stock warrants liability	1,285	1,268	(77)
Prepaid expenses and other assets		(663)	(2,599)
Accounts payable		(4,435)	2,543
Change in operating lease liability		(13)
Accrued liabilities		(1,503)	130
Deferred grant revenue		2,387	(1,246)
Net cash used in operating activities		(9,872)	(5,283)
Cash flows from investing activities
Cash acquired in connection with the Merger		18,292
Acquisition related costs paid		(551)
Net cash provided by investing activities		17,741
Cash flows from financing activities
Proceeds from exercise of stock options		2
Proceeds from convertible preferred stock subscription			1,100
Net cash provided by financing activities		2	1,100
Net increase (decrease) in cash and cash equivalents		7,871	(4,183)
Cash and cash equivalents at beginning of period		20,645	10,188
Cash and cash equivalents at end of period	$ 28,516	28,516	$ 6,005
Supplemental disclosure of non-cash investing and financing activities:
Conversion of convertible preferred stock into common stock		46,588
Issuance of common stock to GTx stockholders		29,049
Reclassification of preferred stock warrants liability to additional paid-in capital		1,942
Net liabilities assumed in Merger		5,177
Acquisition related costs included in accounts payable and accrued liabilities		$ 1,604

Description of Business, Basis of Presentation and Summary of Significant Accounting Policies

6 Months Ended

Jun. 30, 2019

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 developing first-in-class product candidates for cancers with critical unmet medical need. The Company’s clinical pipeline consists of its lead program, cirmtuzumab, a humanized monoclonal antibody that binds to ROR1 (Receptor-tyrosine kinase-like Orphan Receptor 1), and TK216, a small molecule inhibiting the biological activity of ETS-family transcription factor oncoproteins targeting patients with Ewing sarcoma. The Company is also developing a CAR-T (chimeric antigen receptor T-cells) product candidate that targets ROR1.

Merger

On March 6, 2019, the Company, then operating as GTx, Inc. (“GTx”), entered into an 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”). 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”). On June 7, 2019, the Merger was completed. 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,” the “combined company,” “we,” “us,” and “our,” refer to Oncternal Therapeutics, Inc. on a post-Merger basis, and the term “Private Oncternal” refers to the business of privately-held Oncternal Therapeutics, Inc., prior to completion of the Merger. References to GTx refer to GTx, Inc. prior to completion of the Merger.

Pursuant to the terms of the Merger Agreement, each outstanding share of Private Oncternal common stock outstanding immediately prior to the closing of the Merger was converted into approximately 0.073386 shares of Company common stock (the “Exchange Ratio”), after taking into account the Reverse Stock Split, as defined below. Immediately prior to the closing of the Merger, all shares of Private Oncternal preferred stock then outstanding were exchanged into shares of common stock of Private Oncternal. In addition, all outstanding options exercisable for common stock of Private Oncternal and warrants exercisable for convertible preferred stock of Private Oncternal became options and warrants exercisable for the same number of shares of common stock of the Company multiplied by the Exchange Ratio. Immediately following the Merger, stockholders of Private Oncternal owned approximately 77.5% of the outstanding common stock of the combined company.

The transaction was accounted for as a reverse asset acquisition in accordance with generally accepted accounting principles in the United States of America (“GAAP”). Under this method of accounting, Private Oncternal was deemed to be the accounting acquirer for financial reporting purposes. This determination was primarily based on the facts that, immediately following the Merger: (i) Private Oncternal’s stockholders owned a substantial majority of the voting rights in the combined company, (ii) Private Oncternal designated a majority of the members of the initial board of directors of the combined company, and (iii) Private Oncternal’s senior management holds all key positions in the senior management of the combined company. As a result, as of the closing date of the Merger, the net assets of the Company were recorded at their acquisition-date relative fair values in the condensed consolidated financial statements of the Company and the reported operating results prior to the Merger will be those of Private Oncternal.

Reverse Stock Split and Exchange Ratio

On June 7, 2019, in connection with, and prior to the completion of, the Merger, the Company effected a one-for-seven reverse stock split of its then outstanding common stock (the “Reverse Stock Split”). The par value and the authorized shares of the common stock were not adjusted as a result of the Reverse Stock Split. All of the Company’s issued and outstanding common stock have been retroactively adjusted to reflect this Reverse Stock Split for all periods presented. All issued and outstanding Private Oncternal common stock, preferred stock, options and warrants prior to the effective date of the Merger have been retroactively adjusted to reflect the Exchange Ratio for all periods presented.

Principles of Consolidation

The 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 June 30, 2019, the Company has devoted substantially all of its efforts to organizational activities including raising capital, building infrastructure, acquiring assets, developing intellectual property, and conducting preclinical studies, clinical trials and product development activities. The Company has a limited operating history and the sales and income potential of the Company’s business and market are unproven. Since inception, the Company has experienced recurring net losses and negative cash flows from operating activities and expects to continue to incur losses into the foreseeable future. At June 30, 2019, the Company had an accumulated deficit of $56.5 million and had cash and cash equivalents of $28.5 million. The Company believes that its existing cash and cash equivalents will be sufficient to fund its operations into the second quarter of 2020. The Company will need to continue to raise a substantial amount of funds until it is able to generate revenues to fund its development activities and operations. The accompanying condensed consolidated financial statements have been prepared assuming that the Company will continue as a going concern, which contemplates the realization of assets and settlement of liabilities in the normal course of business. However, based on the Company’s current working capital, anticipated operating expenses and net losses and the uncertainties surrounding its ability to raise additional capital as needed, as discussed below, the Company believes that there is substantial doubt about its ability to continue as a going concern for one year after the date these condensed consolidated financial statements are issued.

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 June 30, 2019, and for the three and six months ended June 30, 2019 and 2018, have been prepared in accordance with the rules and regulations of the Securities and Exchange Commission (“SEC”) and with 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, 2018 filed with the SEC on Form S-4/A on May 6, 2019.

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 expenses and other 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 financial assets or liabilities, other than the preferred stock warrant liability described below, measured at fair value on a recurring basis. No transfers between levels have occurred during the periods presented.

Liabilities measured at fair value on a recurring basis are as follows (in thousands):

	Fair Value Measurements at Reporting Date Using
			Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
	Total		(Level 1)		(Level 2)		(Level 3)
At December 31, 2018
Preferred stock warrant liability	$	674	$	—	$	—	$	674

As of December 31, 2018, the preferred stock warrant liability was recorded at fair value utilizing the Black-Scholes option pricing model using significant unobservable inputs consistent with the inputs used for the Company’s stock-based compensation expense adjusted for the preferred stock warrants’ expected term and the fair value of the underlying preferred stock.

The Company calculated the final remeasurement of the preferred stock warrant liability on June 7, 2019, the Merger closing date, using the closing price of GTx’s common stock on that date to determine the fair value of the warrants, and recorded a $1.3 million change in the fair value of the preferred stock warrant liability for the three and six months ended June 30, 2019.

The assumptions used in the Black-Scholes option pricing model to determine the fair value of the preferred stock warrant liability as of December 31, 2018 were as follows:

		December 31,
		2018
Fair value of underlying preferred stock		$ 0.29
Risk-free interest rate		2.4% — 2.7%
Expected volatility		75.3% — 76.4%
Expected term (in years)		3.7 — 4.0
Expected dividend yield		—%

The following table provides a reconciliation of the preferred stock warrant liability measured at fair value using Level 3 significant unobservable inputs (in thousands):

	Preferred Stock Warrant Liability
Balance at December 31, 2018	$	674
Change in fair value		1,268
Reclassification of preferred stock warrant liability to equity		(1,942	)
Balance at June 30, 2019	$	—

Revenue Recognition

The Company currently generates revenue from a research subaward agreement from the California Institute for Regenerative Medicine (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 consideration is recorded as a grant receivable. At June 30, 2019, the Company had deferred grant revenue of $2.4 million and at December 31, 2018, the Company had a grant receivable of $0.1 million. The Company considers the grant receivable to be fully collectible; accordingly, no allowance for doubtful amounts has been established.

Stock-Based Compensation

Stock-based compensation expense represents the fair value of equity awards, on the grant date, recognized in the period using the Black- Scholes option pricing model. The Company recognizes expense for awards with graded vested schedules over the requisite service period of the awards (usually the vesting period) on a straight-line basis. For equity awards for which vesting is subject to performance-based milestones, the expense is recorded over the remaining service period after the point when the achievement of the milestone is probable or the performance condition has been achieved.

Income Taxes

The Company accounts for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements. Under this method, deferred tax assets and liabilities are determined on the basis of the differences between the financial statements and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date.

The Company recognizes net deferred tax assets to the extent that the Company believes these assets are more likely than not to be realized. In making such a determination, management considers all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies, and results of recent operations. If management determines that the Company would be able to realize its deferred tax assets in the future in excess of their net recorded amount, management would make an adjustment to the deferred tax asset valuation allowance, which would reduce the provision for income taxes.

Segment Reporting

Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision-maker in making decisions regarding resource allocation and assessing performance. The Company views its operations and manages its business in one operating segment in the United States.

Comprehensive Loss

Comprehensive loss is defined as a change in equity during a period from transactions and other events and circumstances from non-owner sources. Net loss and comprehensive loss were the same for all periods presented.

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 59,114 shares and 72,997 shares from the weighted-average number of common shares outstanding for the three and six months ended June 30, 2019, respectively, and has excluded weighted-average shares subject to repurchase of 180,724 shares and 194,545 shares from the weighted-average number of common shares outstanding for the three and six months ended June 30, 2018, respectively. Diluted net loss per share is computed by dividing the net loss by the weighted-average number of shares of common stock and dilutive common stock equivalents outstanding for the period determined using the treasury-stock and if-converted methods. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding as inclusion of the potentially dilutive securities would be antidilutive.

Potentially dilutive securities not included in the calculation of diluted net loss per share, because to do so would be anti-dilutive, are as follows (in common stock equivalent shares; in thousands):

	June 30,
	2019		2018
Redeemable convertible preferred stock		—		5,653
Warrants to purchase convertible preferred stock	—			372
Warrants to purchase common stock		842	—
Common stock options		810		152
Common stock subject to repurchase		45		165
		1,697		6,342

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”) 2018-13, Fair Value Measurement: Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement, which modifies the disclosure requirements for fair value measurements. The amendments relate to disclosures regarding unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements, and the narrative description of measurement uncertainty and are to be applied prospectively for only the most recent interim or annual period presented in the initial fiscal year of adoption. All other amendments should be applied retrospectively to all periods presented upon their effective date. The amendments are effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years, and early adoption is permitted. The Company is currently evaluating the timing and impact of the adoption of this guidance on the Company’s condensed consolidated financial statements.

Recently Adopted Accounting Pronouncements

In February 2016, the FASB issued ASU 2016-02, Leases, which, for operating leases, requires a lessee to recognize a right-of-use asset and a lease liability, initially measured at the present value of the lease payments, in its balance sheet. The standard also requires a lessee to recognize a single lease cost, calculated so that the cost of the lease is allocated over the lease term, generally on a straight-line basis. The Company adopted this standard on January 1, 2019 using the modified retrospective approach. As the Company has elected the practical expedient for short-term leases, the adoption of this standard had no impact on the condensed consolidated financial statements on the date of adoption as the Company’s only lease was on a month-to-month basis for a contract period of less than one year and expired in May 2019. Subsequent to its adoption, the Company entered into a new office lease agreement and has applied the provisions of this guidance (See Note 3).

Balance Sheet Details

6 Months Ended

Jun. 30, 2019

Payables And Accruals [Abstract]

Balance Sheet Details

2.	Balance Sheet Details

Accrued liabilities consist of the following (in thousands):

	June 30,		December 31,
	2019		2018
Research and development	$	1,488	$	720
Legal fees		400		20
Unvested share liability		30		54
Compensation		472		85
Other		160		12
	$	2,550	$	891

Commitments, Contingencies and Related Party Transactions

6 Months Ended

Jun. 30, 2019

Commitments And Contingencies Disclosure [Abstract]

Commitments, Contingencies and Related Party Transactions

3.	Commitments, Contingencies and Related Party Transactions

Rent expense was $24,000 and $1,000 for the three months ended June 30, 2019 and 2018, respectively. Rent expense was $33,000 and $4,000 for the six months ended June 30, 2019 and 2018, respectively. Until May 31, 2019, the Company subleased its office space in San Diego, California on a month-to-month basis.

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 an operating lease right-of-use asset and an aggregate lease liability of $0.3 million as of June 30, 2019, in the accompanying condensed consolidated balance sheet. The weighted average remaining lease term was 1.75 years.

Maturities of lease liabilities due under this lease agreement as of June 30, 2019 are as follows (in thousands):

Maturity of lease liabilities	Operating Leases
2019 (6 months)	$	83
2020		166
2021		41
Total lease payments		290
Less imputed interest		(25	)
Total operating lease liabilities as of June 30, 2019		265
Less current portion of lease liability		(139	)
Lease liability	$	126

In June 2019, the Company engaged Newfront Insurance as its broker to obtain director and officer liability insurance for the Company effective as of the Merger. The son of Richard Vincent, the Company’s Chief Financial Officer, acted as the Company’s agent at Newfront Insurance. The Company paid a premium of approximately $1.0 million in June 2019, for which the son will derive a commission of approximately $87,000. See Notes 4 and 6.

Between April 10 and May 1, 2019, three putative class action lawsuits and one individual lawsuit were filed in the U.S. District Court for the District of Delaware: Wheby v. GTx, Inc. et al., Miller v. GTx, Inc. et al., Tabb v. GTx, Inc. et al., and Living Seas LLC v. GTx, Inc. et al. (collectively, the “Delaware Actions”) On April 11 and 23, 2019, two putative class actions were filed in the U.S. District Court for the Southern District of New York: Kopanic v. GTx, Inc. et al. and Cooper v. GTx, Inc. et al. (collectively, the “New York Actions” and, together with the Delaware Actions, the “Actions”). The Actions name as defendants us and our former board of directors, and, in the case of the Wheby and Miller actions, Private Oncternal and Merger Sub. The Actions allege that defendants violated Sections 14(a) and 20(a) of the Exchange Act, as well as Rule 14a-9 promulgated thereunder, in connection with our filing of the Registration Statement in connection with the Merger. Three of the Delaware Actions have now been voluntarily dismissed with prejudice: the Wheby action on June 12, 2019; the Miller action on July 15, 2019; and the Living Seas action on June 26, 2019. At June 30, 2019, the Company cannot predict the outcome of or estimate the possible loss or range of loss from any of these matters.

License, Collaboration and Research Subaward Agreements

6 Months Ended

Jun. 30, 2019

Organization Consolidation And Presentation Of Financial Statements [Abstract]

License, Collaboration and Research Subaward Agreements

4.	License, Collaboration and Research Subaward Agreements

Georgetown University (“Georgetown”)

In March 2014, the Company entered into an Exclusive License Agreement (the “Georgetown License Agreement”) with Georgetown, pursuant to which the Company: (i) licensed the exclusive worldwide right to patents and technologies for the development and commercialization of certain product candidates targeting EWS-FLI1 as an anti-tumor therapy for therapeutic, diagnostics, or research tool purposes, (ii) is solely responsible for all development and commercialization activities and costs, and (iii) is responsible for all costs related to the filing, prosecution and maintenance of the licensed patent rights.

Under the terms of the Georgetown License Agreement, commencing in 2015, the Company: (i) shall pay and has paid an annual license maintenance fee of $10,000 until the first commercial sale occurs, (ii) is required to make up to $0.2 million in aggregate milestone payments upon the achievement of certain regulatory milestones, and (iii) will be required to pay low single digit royalties based on annual net product sales. The Company accounted for the licensed technology as an asset acquisition because it did not meet the definition of a business. All milestone payments under the Georgetown License Agreement will be recognized as research and development expense upon completion of the required events, as the triggering events are not considered to be probable until they are achieved. As of June 30, 2019, the Company had not triggered or made any milestone payments under the Georgetown License Agreement.

The Georgetown License Agreement may be terminated by either party upon material breach or may be terminated by the Company as to one or more countries with 90 days written notice of termination. The term of the Georgetown License Agreement will continue until the expiration of the last valid claim within the patent rights covering the product. Georgetown may terminate the agreement in the event: (i) the Company fails to pay any amount and fails to cure such failure within 30 days after receipt of notice, (ii) the Company defaults in its obligation to obtain and maintain insurance and fails to remedy such breach within 60 days after receipt of notice, or (iii) the Company declares insolvency or bankruptcy. The Company may terminate the Georgetown License Agreement at any time upon at least 60 days’ written notice.

In 2017, the Company entered into a research agreement with Georgetown for up to $150,000. The Company recorded research and development expenses of $13,000 and $19,000 for the three months ended June 30, 2019 and 2018, and $32,000 for each of the six months ended June 30, 2019 and 2018.

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 recorded no research and development expense for the three and six months ended June 30, 2019 and 2018.

Agreements with the Regents of the University of California (the “Regents”)

In March 2016, and as amended and restated in August 2018 in connection with the spin-off transactions described below, the Company entered into a license agreement (as amended, the “Regents License Agreement”) for the development, manufacturing and distribution rights related to the development and commercialization of ROR1 related naked antibodies, antibody fragments or synthetic antibodies, and genetically engineered cellular therapy. The Regents License Agreement was amended on March 25, 2019 and May 15, 2019, to update the patents covered under the agreement. The Regents License Agreement provides for the following: (i) in May 2016, an upfront license fee of $0.5 million was paid and 107,108 shares of common stock were issued, (ii) $25,000 in annual license maintenance fees commencing in 2017, (iii) reimbursement of up to $30,000 in 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) no license maintenance fees as research and development expense for the three and six months ended June 30, 2019 and 2018, and (ii) $0.1 million and $23,000 in patent costs as general and administrative expense for the three months ended June 30, 2019 and 2018, respectively, and $0.2 million and $44,000 for the six months ended June 30, 2019 and 2018, respectively. As of June 30, 2019, 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, the Regents will have an aggregate budget of $3.6 million, with $125,000 payable quarterly. The Company recorded research and development expense under this Agreement of $0.1 million for each of the three months ended June 30, 2019 and 2018, and $0.3 million for each of the six months ended June 30, 2019 and 2018. Such costs are includable as part of the Company’s annual diligence obligations under the Regents License Agreement.

The Regents License Agreement will expire upon the later of the expiration date of the longest-lived patent rights or the 15th anniversary of the first commercial sale of a licensed product. The Regents may terminate the Regents License Agreement if: (i) a material breach by the Company is not cured within a reasonable time, (ii) the Company files a claim asserting the Regents licensed patent rights are invalid or unenforceable and (iii) the Company files for bankruptcy. The Company may terminate the agreement at any time upon at least 60 days’ written notice.

University of Tennessee Research Foundation (“UTRF”)

In July 2007, the Company and UTRF entered into a consolidated, amended and restated license agreement (the “SARM License Agreement”), pursuant to which the Company was granted exclusive worldwide rights in all existing selective androgen receptor modulator (“SARM”) technologies owned or controlled by UTRF, including all improvements thereto, and exclusive rights to future SARM technology that may be developed by certain scientists at the University of Tennessee or subsequently licensed to UTRF under certain existing inter-institutional agreements with The Ohio State University. Under the SARM License Agreement, the Company is obligated to pay UTRF annual license maintenance fees, low single-digit royalties on net sales of products and mid-single-digit royalties on sublicense revenues.

The Company and UTRF also entered into a license agreement (the “SARD License Agreement”) in March 2015 pursuant to which the Company was granted exclusive worldwide rights in all existing 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.

Velos Biopharma Holdings, LLC (“VBH”) and VelosBio, Inc. (“VelosBio”) Spin-off Transactions

In November 2017, the Company formed VBH and in December 2017, made an in-kind tax-free distribution of 100% of its interest in VBH to the Company’s stockholders, option holders and warrant holders of record. On February 6, 2018, the Company licensed and assigned its rights to two preclinical product candidates, previously under the Regents License Agreement, to VBH. In consideration for the license, the Company: (i) received a promissory note receivable from VBH of $0.1 million, with an annual interest rate of 2.64% and a due date of 10 years, and (ii) made a partial assignment of its March 2016 Regents License Agreement. Pursuant to the partial assignment, VBH assumed certain obligations related to the licensed Products under the Regents License Agreement as follows: (i) reimbursement of certain historical and future patent costs related to the Products, (ii) certain development and sales milestones for advancing licensed Products targets, (iii) low single-digit royalties, including potential future minimum annual royalties, on net sales of each licensed Product target are to be allocated between the Company and VBH, (iv) certain third party agreements and related obligations specifically related to the licensed Products, (v) minimum diligence requirements to advance licensed assets consisting of a minimum of $0.5 million in development spend annually through 2021, and (vi) Research Agreement obligations equal to $0.5 million annually commencing January 1, 2018. Due to the high uncertainty of the success of VBH ever repaying the note receivable and associated interest, the Company has provided a full valuation allowance for these amounts as of June 30, 2019.

In December 2017, VelosBio was incorporated with VBH being its sole stockholder. On February 6, 2018, VBH sublicensed and assigned its intellectual property rights to its two preclinical product candidates to VelosBio. In consideration for the license, VelosBio agreed to use commercially reasonable efforts to develop the licensed products as well as the following payment obligations: (i) the assumption of each of the VBH assumed obligations under the partial assignment between the Company and VBH as outlined above, and (ii) certain tiered development milestone and royalty payments to VBH. In August 2018, the Company entered into the amended and restated Regents License Agreement and VelosBio entered into their own license agreement directly with the Regents. There is no common control overlap between the companies.

Also on February 6, 2018, the Company and VelosBio entered into: (i) an asset purchase agreement whereby VelosBio purchased the Company’s right, title and interest in the Company’s nominal assets related to the two preclinical product candidates and assumed the Company’s $0.2 million convertible note payable and related $16,000 of accrued interest which has been recorded as other income, and (ii) a transition services agreement whereby the Company agreed to provide VelosBio with certain transition services, as follows: (a) access to certain common laboratory equipment at the Company’s lab facility, (b) certain named employees were to devote up to 80% of their time supporting VelosBio related activities, (c) cirmtuzumab manufacturing, process optimization and ancillary activities until VelosBio was able to establish their own, and (d) agreement to cost share the purchase of certain antibody materials with VelosBio. Such services were to be provided at cost or cost plus. During the three and six months ended June 30, 2018, the Company incurred $2.6 million and $2.7 million, respectively, of costs on behalf of VelosBio that were substantially reimbursed and recorded on a net basis within operating expenses in the accompanying condensed consolidated statements of operations. As of December 31, 2018, there were no ongoing rights or commitments under the asset purchase or transition services agreements.

The California Institute for Regenerative Medicine (“CIRM”) Award

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”) to advance the Company’s Phase 1/2 clinical trial evaluating cirmtuzumab in combination with ibrutinib for the treatment of patients with B-cell lymphoid malignancies, including chronic lymphocytic leukemia and mantle cell lymphoma. The Company: (i) is conducting this study in collaboration with UC San Diego, (ii) estimates it will receive $16.1 million in development milestones under research subaward agreements throughout the award project period, estimated to be from October 1, 2017 to March 31, 2022, (iii) is committed to certain co-funding requirements, (iv) received subaward payments of $2.4 million and $0 in three months ended June 30, 2019 and 2018, respectively, and $3.7 million and $0.5 million the for six months ended June 30, 2019 and 2018, respectively, and (v) is required to provide UC San Diego progress and financial update reports throughout the award period. The subaward does not bear a royalty payment commitment, nor is the subaward otherwise refundable. For the three months ended June 30, 2019 and 2018, the Company recorded revenue of $0.7 million and $1.5 million, respectively, and recorded revenue of $1.1 million and $1.7 million for the six months ended June 30, 2019 and 2018, respectively. Related qualifying subaward costs for the three months ended June 30, 2019 and 2018 was $1.2 million and $2.8 million, respectively, and $2.1 million and $3.1 million for the six months ended June 30, 2019 and 2018, respectively. As of June 30, 2019, the Company believes it has met its obligations under the CIRM award and UC San Diego subawards.

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. The Company and Pharmacyclics amended the Clinical Trial and Supply Agreement in August 2019. Such agreement does not bear any upfront costs, inventory purchase costs, milestone or royalty payment commitments or other financial obligations.

License and Development Agreement with Shanghai Pharmaceutical (USA) Inc. (“SPH USA”), a Related Party

In November 2018, the Company entered into a License and Development Agreement (“LDA”) with SPH USA for: (i) the territory of the People’s Republic of China, Hong Kong, Macau, and Taiwan (“Greater China”), and (ii) rights to manufacture, develop, market, distribute and sell all of the Company’s product candidates under the Georgetown License Agreement and the Regents License Agreement (exclusive to Greater China only). Under the LDA, SPH USA is solely responsible for: (a) all preclinical and clinical development activities required in order to obtain regulatory approval in Greater China for such product candidates, (b) any third-party license milestone or royalty payments owed under the Georgetown License Agreement and the Regents License Agreement, and (c) paying the Company a low single digit royalty on net sales in the territory.

The LDA will expire upon the expiration of the last royalty term for the last licensed product. The LDA may be terminated by: (i) SPH USA on a country by country or product by product basis with 180 days written notice, (ii) either party upon material breach that is not cured within 90 days, and (iii) either party in the event the other party declares insolvency or bankruptcy.

Merger

6 Months Ended

Jun. 30, 2019

Merger [Abstract]

Merger

The Merger, which closed on June 7, 2019, was accounted for as a reverse asset acquisition pursuant to Topic 805, Business Combinations, 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 was recorded as in-process research and development (“IPR&D”) expenses in the Company’s condensed consolidated statement of operations for the three and six months ended June 30, 2019.

Pursuant to the Merger Agreement, on June 7, 2019, the Company, a representative of holders of the contingent value rights (“CVRs”), and Computershare, Inc. as rights agent entered into a Contingent Value Rights Agreement (the “CVR Agreement”). Pursuant to the CVR Agreement, the Company’s stockholders of record as of immediately prior to the Merger received one CVR for each share of the Company’s common stock held immediately prior to the Merger. CVR holders are entitled to receive 75% of the aggregate amount of any net proceeds received by the combined company during the 15-year period after the closing of the Merger from the grant, sale or transfer of rights to the Company’s SARD or SARM technology that occurs during the 10-year period after the closing (or in the 11th year if based on a term sheet approved during the initial 10-year period) and, if applicable, to receive royalties on the sale of any SARD or SARM products by the combined company during the 15-year period after the closing. The CVR Agreement will continue in effect until the payment of all amounts payable thereunder. As of the June 7, 2019 closing date and June 30, 2019, no milestones had been accrued as there were no potential milestones yet considered probable.

The total purchase price paid in the Merger has been allocated to the net assets acquired and liabilities assumed based on their fair values as of the completion of the Merger. The following summarizes the purchase price paid in the Merger (in thousands, except share and per share amounts):

Number of shares of the combined organization owned by the Company’s pre-Merger stockholders		3,458,170
Multiplied by the fair value per share of GTx common stock (1)	$	8.40
Fair value of consideration issued to effect the Merger	$	29,049
Transaction costs		2,154
Purchase price	$	31,203

(1)	Based on the last reported sale price of the Company’s common stock on the Nasdaq Capital Market on June 7, 2019, the closing date of the Merger, and gives effect to the Reverse Stock Split.

The allocation of the purchase price is as follows:

Cash acquired	$	18,292
Net liabilities assumed		(5,177	)
IPR&D (2)		18,088
Purchase price	$	31,203

(2) Represents the research and development projects of GTx which were in-process, but not yet completed, and which the Company plans to advance. This consists primarily of GTx’s preclinical SARD technology. Current accounting standards require that the fair value of IPR&D projects acquired in an asset acquisition with no alternative future use be allocated a portion of the consideration transferred and charged to expense on the acquisition date. The acquired assets did not have outputs or employees.

Stockholders' Equity (Deficit)

6 Months Ended

Jun. 30, 2019

Equity [Abstract]

Stockholders' Equity (Deficit)

6. Stockholders’ Equity (Deficit)

Amended and Restated Articles of Incorporation

On June 7, 2019, the Company’s certificate of incorporation was amended and restated to authorize 60,000,000 shares of common stock and 5,000,000 shares of undesignated preferred stock, each with a par value of $0.001 per share.

Convertible Preferred Stock

In connection with the Merger, all of the outstanding shares of Private Oncternal’s convertible preferred stock were converted into 8,148,268 shares of the Company’s common stock. As of December 31, 2018, Private Oncternal’s convertible preferred stock is classified as temporary equity on the accompanying condensed consolidated balance sheets in accordance with authoritative guidance for the classification and measurement of potentially redeemable securities whose redemption is based upon certain change in control events outside of Private Oncternal’s control, including liquidation, sale or transfer of control of Private Oncternal. Private Oncternal did not adjust the carrying values of the convertible preferred stock to the liquidation preferences of such shares because the occurrence of any such change of control event was not deemed probable.

Sales of Convertible Preferred Stock

In September, November and December 2017, Private Oncternal issued an aggregate of 1,662,494 shares of Series B-2 preferred stock at a per share purchase price of $6.13, raising net cash proceeds of $8.9 million, of which $1.1 million was collected in February 2018 and, as such, was recorded as a stock subscription receivable within mezzanine equity at December 31, 2017.

In November 2018, contemporaneous with entering into the LDA, Private Oncternal issued 2,495,114 shares of Series C preferred stock to SPH USA, at a per share purchase price of $6.81, raising net cash proceeds of $16.8 million. Private Oncternal concluded that the shares were issued at fair value and therefore no value was ascribed to the LDA.

Common Stock Warrants

In September, November and December 2017, as adjusted for the Exchange Ratio, Private Oncternal issued 371,624 Series B-2 warrants, 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.

On September 29, 2017, the Company completed a private placement transaction that included warrants to purchase an aggregate of 469,996 shares of the Company’s common stock at an exercise price of $63.14 per share. The five-year warrants expire on September 29, 2022.

The Company assessed whether the above warrants require accounting as derivatives after the Merger closing. The Company determined that the warrants were indexed to the Company's own stock. As such, the Company has concluded the warrants meet the scope exception for determining whether the instruments require accounting as warrant liabilities. As of June 30, 2019, none of the warrants have been exercised.

Common Stock and Unvested Share Liability

The Company has issued restricted common stock subject to vesting and repurchase by the Company. For employee and non-employee awards, the issuance date fair value is recognized over the requisite service period of the award (usually the vesting period) on a straight-line basis. In addition, the Company has outstanding unvested shares related to the early exercise of stock options. The Company has the right, but not the obligation, to repurchase any unvested shares at the original purchase price upon any voluntary or involuntary termination. The consideration received in exchange for unvested shares is recorded as an unvested share liability on the accompanying consolidated balance sheets and is reclassified into common stock and additional paid-in capital as the shares vest. At June 30, 2019 and December 31, 2018, the unvested share liability was $30,000 and $54,000, respectively.

A summary of the Company’s unvested shares is as follows (in thousands):

	Number of
	Shares
Balance at December 31, 2018		100
Vested shares		(55	)
Balance at June 30, 2019		45

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) any shares of common stock which were subject to awards under the GTx 2013 Equity Incentive Plan (the “2013 Plan”) as of June 7, 2019 which became available for issuance under the 2019 Plan in a number not to exceed 278,343 shares, 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.

As of June 30, 2019, there were 322,775 outstanding and fully vested options under the 2013 Plan with a weighted average exercise price of $76.58 per share.

In July 2015, Private Oncternal adopted the 2015 Plan which provided for the issuance of up to 631,120 shares of common stock for incentive stock options, non-statutory stock options, restricted stock awards, restricted stock unit awards and other stock awards to its employees, members of its board of directors and consultants. In general, the options issued under the 2015 Plan expire ten years from the date of grant and vest over a four-year period. Certain grants vest based on the achievement of development or regulatory milestones. No further awards will be made under the 2015 Plan, which was terminated in June 2019.

The 2015 Plan allows for the early exercise of all stock option grants if authorized by the board of directors at the time of grant. The Company has the option to repurchase any unvested shares at the original purchase price upon any voluntary or involuntary termination.

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, 2018		504,019		$	0.81
Granted		10,000		$	7.92
Cancelled		(25,226	)	$	0.81
Exercised		(1,834	)	$	0.81
Balance at June 30, 2019		486,959		$	0.81

The aggregate intrinsic value of stock options exercised during the six months ended June 30, 2019 and 2018 and year ended December 31, 2018 was not material. 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						Six Months Ended
	June 30,						June 30,
	2019			2018			2019			2018
Risk-free interest rate		2.1	%		—	%		2.1	%		—	%
Expected volatility		82	%		—	%		82	%		—	%
Expected term (in years)		10			—	%		10			—	%
Expected dividend yield		—	%		—	%		—	%		—	%

Expected volatility. Prior to the Merger, Private Oncternal did not have a trading history for its common stock. Accordingly, the expected volatility assumption is based on volatilities of a peer group of similar companies whose share prices are publicly available. The peer group was developed based on companies in the life sciences industry. The Company will continue to apply this process until a sufficient amount of historical information regarding the volatility of its own stock price becomes available.

Expected term. The expected term represents the period of time that options are expected to be outstanding. Because Private Oncternal did not have historical exercise behavior, it determined the expected life assumption using the simplified method for employees, which is an average of the contractual term of the option and its vesting period. The expected term for nonemployee options is generally the remaining contractual term.

Risk-free interest rate. The risk-free interest rate is based on the implied yield on the U.S. Treasury securities with a maturity date similar to the expected term of the associated stock option award.

Expected dividend yield. The Company bases the expected dividend yield assumption on the fact that it has never paid cash dividends and has no present intention to pay cash dividends and, therefore, used an expected dividend yield of zero.

Stock-based compensation expense recognized for all equity awards has been reported in the statements of operations as follows (in thousands):

	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2019		2018		2019		2018
Research and development	$	41	$	15	$	67	$	31
General and administrative		22		26		35		53
	$	63	$	41	$	102	$	84

As of the latest balance sheet presented, the total compensation cost related to nonvested awards not yet recognized and the weighted-average period over which it is expected to be recognized was $90,000 and 2.9 years, respectively.

Common Stock Reserved for Future Issuance

Common stock reserved for future issuance is as follows (in thousands):

	June 30, 2019
Common stock warrants		842
Common stock options issued and outstanding		810
Common stock available for issuance under the 2019 Plan		1,671
		3,323

Description of Business, Basis of Presentation and Summary of Significant Accounting Policies (Policies)

6 Months Ended

Jun. 30, 2019

Accounting Policies [Abstract]

Merger

Reverse Stock Split and Exchange Ratio

Principles of Consolidation

Liquidity and Going Concern

Unaudited Interim Financial Information

Use of Estimates

Cash and Cash Equivalents

Concentration of Credit Risk

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

Preferred Stock Warrant Liability

Fair Value Measurements

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.

Liabilities measured at fair value on a recurring basis are as follows (in thousands):

	Fair Value Measurements at Reporting Date Using
			Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
	Total		(Level 1)		(Level 2)		(Level 3)
At December 31, 2018
Preferred stock warrant liability	$	674	$	—	$	—	$	674

The assumptions used in the Black-Scholes option pricing model to determine the fair value of the preferred stock warrant liability as of December 31, 2018 were as follows:

		December 31,
		2018
Fair value of underlying preferred stock		$ 0.29
Risk-free interest rate		2.4% — 2.7%
Expected volatility		75.3% — 76.4%
Expected term (in years)		3.7 — 4.0
Expected dividend yield		—%

The following table provides a reconciliation of the preferred stock warrant liability measured at fair value using Level 3 significant unobservable inputs (in thousands):

	Preferred Stock Warrant Liability
Balance at December 31, 2018	$	674
Change in fair value		1,268
Reclassification of preferred stock warrant liability to equity		(1,942	)
Balance at June 30, 2019	$	—

Revenue Recognition

Stock-Based Compensation

	June 30,
	2019		2018
Redeemable convertible preferred stock		—		5,653
Warrants to purchase convertible preferred stock	—			372
Warrants to purchase common stock		842	—
Common stock options		810		152
Common stock subject to repurchase		45		165
		1,697		6,342

Recently Accounting Pronouncements

Recently Issued Accounting Pronouncements

Recently Adopted Accounting Pronouncements

Description of Business, Basis of Presentation and Summary of Significant Accounting Policies (Tables)

6 Months Ended

Jun. 30, 2019

Schedule of Liabilities Measured at Fair Value on Recurring Basis

Liabilities measured at fair value on a recurring basis are as follows (in thousands):

	Fair Value Measurements at Reporting Date Using
			Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
	Total		(Level 1)		(Level 2)		(Level 3)
At December 31, 2018
Preferred stock warrant liability	$	674	$	—	$	—	$	674

Schedule of Reconciliation of Warrant Liability Measured at Fair Value Using Level 3 Significant Unobservable Inputs

The following table provides a reconciliation of the preferred stock warrant liability measured at fair value using Level 3 significant unobservable inputs (in thousands):

	Preferred Stock Warrant Liability
Balance at December 31, 2018	$	674
Change in fair value		1,268
Reclassification of preferred stock warrant liability to equity		(1,942	)
Balance at June 30, 2019	$	—

Schedule of Potentially Dilutive Securities Excluded from Calculation of Diluted Net Loss per Share Would Be Anti-dilutive

	June 30,
	2019		2018
Redeemable convertible preferred stock		—		5,653
Warrants to purchase convertible preferred stock	—			372
Warrants to purchase common stock		842	—
Common stock options		810		152
Common stock subject to repurchase		45		165
		1,697		6,342

Preferred Stock Warrants

Schedule of Assumptions Used to Determine Fair Value

The assumptions used in the Black-Scholes option pricing model to determine the fair value of the preferred stock warrant liability as of December 31, 2018 were as follows:

		December 31,
		2018
Fair value of underlying preferred stock		$ 0.29
Risk-free interest rate		2.4% — 2.7%
Expected volatility		75.3% — 76.4%
Expected term (in years)		3.7 — 4.0
Expected dividend yield		—%

Balance Sheet Details (Tables)

6 Months Ended

Jun. 30, 2019

Payables And Accruals [Abstract]

Summary of Accrued Liabilities

Accrued liabilities consist of the following (in thousands):

	June 30,		December 31,
	2019		2018
Research and development	$	1,488	$	720
Legal fees		400		20
Unvested share liability		30		54
Compensation		472		85
Other		160		12
	$	2,550	$	891

Commitments, Contingencies and Related Party Transactions (Tables)

6 Months Ended

Jun. 30, 2019

Commitments And Contingencies Disclosure [Abstract]

Summary of Maturities of Lease Liabilities

Maturities of lease liabilities due under this lease agreement as of June 30, 2019 are as follows (in thousands):

Maturity of lease liabilities	Operating Leases
2019 (6 months)	$	83
2020		166
2021		41
Total lease payments		290
Less imputed interest		(25	)
Total operating lease liabilities as of June 30, 2019		265
Less current portion of lease liability		(139	)
Lease liability	$	126

Merger - (Tables)

6 Months Ended

Jun. 30, 2019

Merger [Abstract]

Summary of Purchase Price Paid in Merger

The following summarizes the purchase price paid in the Merger (in thousands, except share and per share amounts):

Number of shares of the combined organization owned by the Company’s pre-Merger stockholders		3,458,170
Multiplied by the fair value per share of GTx common stock (1)	$	8.40
Fair value of consideration issued to effect the Merger	$	29,049
Transaction costs		2,154
Purchase price	$	31,203

(1)	Based on the last reported sale price of the Company’s common stock on the Nasdaq Capital Market on June 7, 2019, the closing date of the Merger, and gives effect to the Reverse Stock Split.

Summary of Allocation of Purchase Price

The allocation of the purchase price is as follows:

Cash acquired	$	18,292
Net liabilities assumed		(5,177	)
IPR&D (2)		18,088
Purchase price	$	31,203

Stockholders' Equity (Deficit) (Tables)

6 Months Ended

Jun. 30, 2019

Summary of Unvested Shares

A summary of the Company’s unvested shares is as follows (in thousands):

	Number of
	Shares
Balance at December 31, 2018		100
Vested shares		(55	)
Balance at June 30, 2019		45

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, 2018		504,019		$	0.81
Granted		10,000		$	7.92
Cancelled		(25,226	)	$	0.81
Exercised		(1,834	)	$	0.81
Balance at June 30, 2019		486,959		$	0.81

Summary of Share-Based Compensation Expense

Stock-based compensation expense recognized for all equity awards has been reported in the statements of operations as follows (in thousands):

	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2019		2018		2019		2018
Research and development	$	41	$	15	$	67	$	31
General and administrative		22		26		35		53
	$	63	$	41	$	102	$	84

Common Stock Reserved for Future Issuance

Common stock reserved for future issuance is as follows (in thousands):

	June 30, 2019
Common stock warrants		842
Common stock options issued and outstanding		810
Common stock available for issuance under the 2019 Plan		1,671
		3,323

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,
	2019			2018			2019			2018
Risk-free interest rate		2.1	%		—	%		2.1	%		—	%
Expected volatility		82	%		—	%		82	%		—	%
Expected term (in years)		10			—	%		10			—	%
Expected dividend yield		—	%		—	%		—	%		—	%

- Definition

Tabular disclosure of an entity's stock, including par or stated value per share, number and dollar amount of share subscriptions, shares authorized, shares issued, shares outstanding, number and dollar amount of shares held in an employee trust, dividend per share, total dividends, share conversion features, par value plus additional paid in capital, the value of treasury stock and other information necessary to a fair presentation, and EPS information. Stock by class includes common, convertible, and preferred stocks which are not redeemable or redeemable solely at the option of the issuer. Includes preferred stock with redemption features that are solely within the control of the issuer and mandatorily redeemable stock if redemption is required to occur only upon liquidation or termination of the reporting entity. If more than one issue is outstanding, state the title of each issue and the corresponding dollar amount; dollar amount of any shares subscribed but unissued and the deduction of subscriptions receivable there from; number of shares authorized, issued, and outstanding.

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+ Details

Description of Business, Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Details)			3 Months Ended		6 Months Ended
	Jun. 07, 2019	Mar. 06, 2019	Jun. 30, 2019 USD ($) shares	Jun. 30, 2018 shares	Jun. 30, 2019 USD ($) segment shares	Jun. 30, 2018 shares	Dec. 31, 2018 USD ($)
Description Of Business Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Accumulated deficit			$ (56,524,000)		$ (56,524,000)		$ (31,384,000)
Cash and cash equivalents			28,516,000		28,516,000		20,645,000
Preferred stock warrant liability			1,300,000		1,300,000		674,000
Deferred grant revenue			2,387,000		2,387,000
Grants receivable							$ 100,000
Allowance for doubtful accounts			$ 0		$ 0
Number of operating segments \| segment					1
Weighted-average shares subject to repurchase \| shares			59,114	180,724	72,997	194,545
Merger Agreement
Description Of Business Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Reverse stock split of common stock	7
Merger Agreement \| Combined organization’s
Description Of Business Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Common stock and preferred stock exchange ratio		0.073386
Ownership percentage of stockholders upon closing of merger		77.50%

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

Description of Business, Basis of Presentation and Summary of Significant Accounting Policies - Schedule of Reconciliation of Warrant Liability Measured at Fair Value Using Level 3 Significant Unobservable Inputs (Details) - Level 3 - Preferred Stock Warrants $ in Thousands	6 Months Ended
	Jun. 30, 2019 USD ($)
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 674
Change in fair value	1,268
Reclassification of preferred stock warrant liability to equity	$ (1,942)

Description of Business, 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, 2019	Jun. 30, 2018
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities	1,697	6,342
Redeemable Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities		5,653
Warrants to Purchase Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities		372
Warrants to purchase common stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities	842
Common Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities	810	152
Common Stock Subject to Repurchase
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities	45	165

Balance Sheet Details - Accrued Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Payables And Accruals [Abstract]
Research and development	$ 1,488	$ 720
Legal fees	400	20
Unvested share liability	30	54
Compensation	472	85
Other	160	12
Total accrued liabilities	$ 2,550	$ 891

Commitments, Contingencies and Related Party Transactions - Additional Information (Details)	1 Months Ended		3 Months Ended		6 Months Ended
	Jun. 30, 2019 USD ($)	May 31, 2019 USD ($) ft²	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)
Commitments And Contingencies [Line Items]
Operating lease liability	$ 265,000		$ 265,000		$ 265,000
Chief Financial Officer
Commitments And Contingencies [Line Items]
Insurance premium	1,000,000
Insurance commissions	$ 87,000
San Diego, California \| Office Space
Commitments And Contingencies [Line Items]
Rent expense			$ 24,000	$ 1,000	$ 33,000	$ 4,000
Rentable area \| ft²		4,677
Lease expiration date		Mar. 31, 2021
Annual base rent		$ 166,000,000
Lease discount rate	10.00%		10.00%		10.00%
Operating lease liability	$ 300,000		$ 300,000		$ 300,000
Weighted average remaining lease term	1 year 9 months		1 year 9 months		1 year 9 months

Commitments, Contingencies and Related Party Transactions - Summary of Maturities of Lease Liabilities (Details) $ in Thousands	Jun. 30, 2019 USD ($)
Operating Lease Liabilities Payments Due [Abstract]
2019 (6 months)	$ 83
2020	166
2021	41
Total lease payments	290
Less imputed interest	(25)
Operating lease liability	265
Less current portion of lease liability	(139)
Lease liability	$ 126

License, Collaboration and Research Subaward Agreements - Additional Information (Details)		1 Months Ended		3 Months Ended		6 Months Ended		12 Months Ended
	Feb. 06, 2018 USD ($) Product	Aug. 31, 2017 USD ($)	May 31, 2016 USD ($) shares	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Dec. 31, 2018	Dec. 31, 2017 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Patent costs as general and administrative expense				$ 1,619,000	$ 555,000	$ 2,551,000	$ 1,136,000
Loss from operations				(21,620,000)	(2,541,000)	(23,978,000)	(4,223,000)
Grant revenue				674,000	1,527,000	1,144,000	1,715,000
Velos Biopharma Holdings, LLC
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of preclinical product candidates licensed and assigned \| Product	2
University of California San Diego School of Medicine \| The California Institute for Regenerative Medicine ("CIRM") Award
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Grants awarded to researchers		$ 18,300,000
Development milestones to be received under research subaward agreements throughout award project period		$ 16,100,000
Subaward payments received				2,400,000	0	3,700,000	500,000
Grant revenue				700,000	1,500,000	1,100,000	1,700,000
Related qualifying subaward costs				1,200,000	2,800,000	2,100,000	3,100,000
Exclusive License Agreement \| Georgetown University
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Annual license maintenance fee to be paid and payment made										$ 10,000
Potential milestone payments				0		$ 0
Written notice of termination, period						90 days
Days after receipt of notice, to pay failure amount						30 days
Days after receipt of notice for default in payment						60 days
Minimum period in days of written notice to terminate license agreement						60 days
Research and development expense				13,000	19,000	$ 32,000	32,000
Exclusive License Agreement \| Maximum \| Georgetown University
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Potential milestone payments										$ 200,000
Collaborative agreement research funding amount									$ 150,000
Collaboration Agreement \| MD Anderson Cancer Center
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research and development expense				0	0	$ 0	0
Potential regulatory milestone payments											$ 1,000,000
Regents License Agreement \| Velos Biopharma Holdings, LLC \| Spin-off Transactions
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Percentage of tax free interest distribution									100.00%
Number of preclinical product candidates licensed and assigned \| Product	2
Promissory note receivable	$ 100,000
Annual interest rate	2.64%
Promissory note maturity period	10 years
Payment required to advance licensed assets	$ 500,000
Research agreement obligation	$ 500,000
Regents License Agreement \| Regents of the University of California
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Written notice of termination, period						60 days
Research and development expense				0	0	$ 0	0
Upfront license fees paid			$ 500,000
Common stock, shares, issued \| shares			107,108
Annual license maintenance fees									$ 25,000
Worldwide sales milestones based on achievement of tiered revenue levels			$ 75,000,000
Patent costs as general and administrative expense				100,000	23,000	200,000	44,000
Regents License Agreement \| Maximum \| Regents of the University of California
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Potential regulatory milestone payments			12,500,000
Reimbursement of annual patent costs			30,000
Regents License Agreement \| 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
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
Asset Purchase Agreement \| Velos Biopharma Holdings, LLC
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of preclinical product candidates licensed and assigned \| Product	2
Convertible note payable	$ 200,000
Accrued interest of convertible note payable	$ 16,000
Percentage of devoting business activities								80.00%
Loss from operations					$ 2,600,000		$ 2,700,000

Merger - Additional Information (Details) - CVR Agreement	Jun. 07, 2019 CVR
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Contingent value right per common stock	1
Percentage of net proceeds entitled to be received per CVR	75.00%
Period from closing during which payment of percentage of net proceeds would be payable under the CVR	15 years
Period from closing during which the grant, sale or transfer of rights to the Company's SARD or SARM technology could trigger a payment under the CVR Agreement	10 years

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

Merger - Summary of Allocation of Purchase Price (Details) - USD ($) $ in Thousands		3 Months Ended	6 Months Ended
	Jun. 07, 2019	Jun. 30, 2019	Jun. 30, 2019
Merger [Abstract]
Cash acquired	$ 18,292		$ 18,292
Net liabilities assumed	(5,177)
In-process research and development	18,088	$ 18,088	$ 18,088
Purchase price	$ 31,203

Stockholders' Equity (Deficit) - Sales of Convertible Preferred Stock (Details) - USD ($)	1 Months Ended	4 Months Ended	6 Months Ended
	Nov. 30, 2018	Dec. 31, 2017	Jun. 30, 2018	Jun. 30, 2019	Jun. 07, 2019	Dec. 31, 2018	Feb. 28, 2018
Class Of Stock [Line Items]
Preferred stock, shares issued				0		0
Preferred stock, par value				$ 0.001	$ 0.001	$ 0.001
Net cash proceeds from issuance of preferred stock			$ 1,100,000
Series B-2 Convertible Preferred Stock \| Private Oncternal
Class Of Stock [Line Items]
Preferred stock, shares issued		1,662,494
Preferred stock, par value		$ 6.13
Net cash proceeds from issuance of preferred stock		$ 8,900,000
Preferred stock, value collected							$ 1,100,000
Series C Convertible Preferred Stock \| Private Oncternal
Class Of Stock [Line Items]
Preferred stock, shares issued	2,495,114
Preferred stock, par value	$ 6.81
Net cash proceeds from issuance of preferred stock	$ 16,800,000
Preferred stock, value collected	$ 0

Stockholders' Equity (Deficit) - Common Stock Warrants (Details) - Common Stock Warrants - $ / shares		1 Months Ended	6 Months Ended
	Sep. 29, 2017	Sep. 30, 2017	Jun. 30, 2019
Class Of Stock [Line Items]
Warrants issued		371,624
Warrants exercise price per share	$ 63.14	$ 6.13
Warrants issued expiration period			The warrants expire on various dates in September, November and December 2022.
Number of common stock warrants exercised			0
Private Placement, September 2017
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

Stockholders' Equity (Deficit) - Equity Incentive Plans (Details) - $ / shares		1 Months Ended
	Jun. 07, 2019	Jul. 31, 2015	Jun. 30, 2019
Class Of Stock [Line Items]
Number of common stock shares provided for issuance of stock awards to its employees			3,323,000
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	278,343
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			1,671,000
2013 plan
Class Of Stock [Line Items]
Number of options outstanding and fully vested			322,775
Weighted average exercise price of options outstanding and fully vested			$ 76.58
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

Stockholders' Equity (Deficit) - Summary of Stock Option Activity (Details) - 2019 Incentive Award Plan and 2015 Equity Incentive Plan	6 Months Ended
	Jun. 30, 2019 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of options, beginning balance \| shares	504,019
Number of options, granted \| shares	10,000
Number of options, cancelled \| shares	(25,226)
Number of options, exercised \| shares	(1,834)
Number of options, ending balance \| shares	486,959
Weighted average exercise price, beginning balance \| $ / shares	$ 0.81
Weighted average exercise price, granted \| $ / shares	7.92
Weighted average exercise price, cancelled \| $ / shares	0.81
Weighted average exercise price, exercised \| $ / shares	0.81
Weighted average exercise price, ending balance \| $ / shares	$ 0.81

Stockholders' Equity (Deficit) - Schedule of Assumptions Used to Estimate Fair Value of Stock Option Grants (Details)	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Risk-free interest rate	2.10%	2.10%
Expected volatility	82.00%	82.00%
Expected term (in years)	10 years	10 years

Stockholders' Equity (Deficit) - Share-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 63	$ 41	$ 102	$ 84
Research and development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	41	15	67	31
General and administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 22	$ 26	$ 35	$ 53

Stockholders' Equity (Deficit) - Summary of Unvested Shares (Details)	6 Months Ended
	Jun. 30, 2019 shares
Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Number Of Shares Roll Forward
Number of shares unvested, beginning balance	100,000
Number of shares, vested shares	(55,000)
Number of shares unvested, ending balance	45,000

Stockholders' Equity (Deficit) - Stock-Based Compensation Expense (Details)	6 Months Ended
	Jun. 30, 2019 USD ($)
Equity [Abstract]
Compensation cost related to nonvested awards not yet recognized	$ 90,000
Remaining weighted-average period	2 years 10 months 24 days

Description of Business, Basis of Presentation and Summary of Significant Accounting Policies - Schedule of Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Preferred stock warrant liability	$ 1,300	$ 674
Fair Value, Measurements, Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Preferred stock warrant liability		674
Level 3 \| Fair Value, Measurements, Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Preferred stock warrant liability		$ 674

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

Stockholders' Equity (Deficit) - Common Stock and Unvested Share Liability (Details) - USD ($)	Jun. 30, 2019	Dec. 31, 2018
Equity [Abstract]
Unvested share liability	$ 30,000	$ 54,000