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Document and Entity Information - USD ($) $ in Thousands	12 Months Ended
Document and Entity Information - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 05, 2020	Jun. 30, 2019
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2019
Document Fiscal Year Focus	2019
Entity Registrant Name	Galera Therapeutics, Inc.
Entity Central Index Key	0001563577
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Title of 12(b) Security	Common Stock, $0.001 par value per share
Trading Symbol	GRTX
Security Exchange Name	NASDAQ
Entity Shell Company	false
Entity Common Stock Shares Outstanding		24,820,070
Entity File Number	001-39114
Entity Incorporation State Country Code	DE
Entity Tax Identification Number	46-1454898
Entity Address, Address Line One	2 W. Liberty Blvd #100
Entity Address, City or Town	Malvern
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	19355
City Area Code	610
Local Phone Number	725-1500
Document Annual Report	true
Document Transition Report	false
Entity Voluntary Filers	No
Document Fiscal Period Focus	FY
Entity Ex Transition Period	true
Entity Public Float			$ 0
Entity Well-known Seasoned Issuer	No
Documents Incorporated by Reference	Portions of the registrant’s definitive Proxy Statement, relating to its 2020 Annual Meeting of Stockholders to be filed with the Securities and Exchange Commission are incorporated by reference into Part III of this Annual Report on Form 10-K.

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 18,356	$ 14,811
Short-term investments	93,934	66,706
Tax incentive receivable		870
Prepaid expenses and other current assets	5,280	1,465
Total current assets	117,570	83,852
Property and equipment, net	934	568
Acquired intangible asset	2,258	2,258
Goodwill	881	881
Right-of-use lease asset	815
Other assets	918	497
Total assets	123,376	88,056
Current liabilities:
Accounts payable	3,945	3,867
Accrued expenses	5,452	2,577
Lease liability	297
Total current liabilities	9,694	6,444
Royalty purchase liability	43,251	20,220
Deferred rent		12
Lease liability, net of current portion	534
Deferred tax liability	289	298
Total liabilities	53,768	26,974
Commitments (Note 8)
Redeemable convertible preferred stock, $0.001 par value: 96,385,795 shares authorized, issued and outstanding at December 31, 2018.		165,902
Stockholders’ equity (deficit):
Preferred stock, $0.001 par value: 10,000,000 shares authorized; no shares issued and outstanding.
Common stock, $0.001 par value: 200,000,000 shares authorized; 24,811,567 and 300,597 shares issued and outstanding at December 31, 2019 and 2018, respectively.	25
Additional paid-in capital	230,895
Accumulated other comprehensive income	38	3
Accumulated deficit	(161,350)	(104,823)
Total stockholders’ equity (deficit)	69,608	(104,820)
Total liabilities, redeemable convertible preferred stock and stockholders’ equity (deficit)	$ 123,376	88,056
Redeemable Convertible Preferred Stock
Current liabilities:
Redeemable convertible preferred stock, $0.001 par value: 96,385,795 shares authorized, issued and outstanding at December 31, 2018.		$ 165,902

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Statement Of Financial Position [Abstract]
Redeemable convertible preferred stock, par value		$ 0.001
Redeemable convertible preferred stock, shares authorized (shares)		96,385,795
Redeemable convertible preferred stock, shares issued (shares)		96,385,795
Redeemable convertible preferred stock, shares outstanding (shares)		96,385,795
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized (shares)	10,000,000	10,000,000
Preferred stock, shares issued (shares)	0	0
Preferred stock, shares outstanding (shares)	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized (shares)	200,000,000	200,000,000
Common stock, shares issued (shares)	24,811,567	300,597
Common stock, shares outstanding (shares)	24,811,567	300,597

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Operating expenses:
Research and development	$ 42,333	$ 18,663
General and administrative	8,358	5,592
Loss from operations	(50,691)	(24,255)
Other income (expenses):
Interest income	1,823	606
Interest expense	(3,031)	(220)
Foreign currency loss	(40)	(30)
Loss before income tax benefit	(51,939)	(23,899)
Income tax benefit	9	223
Net loss	(51,930)	(23,676)
Accretion of redeemable convertible preferred stock to redemption value	(7,176)	(5,910)
Net loss attributable to common stockholders	$ (59,106)	$ (29,586)
Net loss per share of common stock, basic and diluted	$ (16.31)	$ (98.42)
Weighted-average shares of common stock outstanding, basic and diluted	3,625,005	300,597

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (51,930)	$ (23,676)
Unrealized gain on short-term investments	35	6
Comprehensive loss	$ (51,895)	$ (23,670)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

CONSOLIDATED STATEMENTS OF CHANGES IN REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Total	Redeemable Convertible Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (loss)	Accumulated Deficit
Balance at Dec. 31, 2017	$ (76,105)				$ (3)	$ (76,102)
Balance (in shares) at Dec. 31, 2017		64,689,359
Balance at Dec. 31, 2017		$ 90,148
Balance (in shares) at Dec. 31, 2017			300,597
Sale of Series C redeemable convertible preferred stock, net of issuance costs of $0.3 million		$ 69,844
Sale of Series C redeemable convertible preferred stock,net of issuance costs, shares		31,696,436
Share-based compensation expense	865			$ 865
Accretion of redeemable convertible preferred stock to redemption value	(5,910)	$ 5,910		(865)		(5,045)
Unrealized gain on short-term investments	6				6
Net loss	(23,676)					(23,676)
Balance at Dec. 31, 2018	$ (104,820)				3	(104,823)
Balance (in shares) at Dec. 31, 2018	96,385,795	96,385,795
Balance at Dec. 31, 2018	$ 165,902	$ 165,902
Balance (in shares) at Dec. 31, 2018	300,597		300,597
Share-based compensation expense	$ 2,390			2,390
Accretion of redeemable convertible preferred stock to redemption value	(7,178)	7,178		(2,581)		(4,597)
Conversion of redeemable convertible preferred stock into common stock	173,080	$ (173,080)	$ 19	173,061
Conversion of redeemable convertible preferred stock into common stock, shares		(96,385,795)	19,061,502
Sale of common stock in initial public offering, net of issuance costs of $7.3 million	58,021		$ 6	58,015
Sale of common stock in initial public offering, net of issuance costs, shares			5,445,690
Exercise of stock options	$ 10			10
Exercise of stock options, shares	3,778		3,778
Unrealized gain on short-term investments	$ 35				35
Net loss	(51,930)					(51,930)
Balance at Dec. 31, 2019	$ 69,608		$ 25	$ 230,895	$ 38	$ (161,350)
Balance (in shares) at Dec. 31, 2019	24,811,567		24,811,567

CONSOLIDATED STATEMENTS OF CHANGES IN REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Statement Of Stockholders Equity [Abstract]
Sale of Series C redeemable convertible preferred stock, issuance costs		$ 0.3
Sale of common stock in initial public offering, issuance costs	$ 7.3

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended		14 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019
Operating activities:
Net loss	$ (51,930)	$ (23,676)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	267	127
Noncash interest expense	3,031	220
Share-based compensation expense	2,390	865
Reserve for tax incentive receivable	241
Deferred tax liability	(9)	(223)
Deferred rent	4	(2)
Changes in operating assets and liabilities:
Tax incentive receivable	629	(363)
Prepaid expenses and other current assets	(3,815)	(986)
Other assets	(421)	(255)
Accounts payable	77	1,587
Accrued expense	2,875	540
Cash used in operating activities	(46,661)	(22,166)
Investing activities:
Purchases of short-term investments	(123,192)	(71,190)
Proceeds from sales of short-term investments	96,000	12,501
Purchase of property and equipment	(633)	(347)
Cash used in investing activities	(27,825)	(59,036)
Financing activities:
Proceeds from royalty purchase agreement	20,000	20,000	$ 60,000
Proceeds from the sale of Series C redeemable convertible preferred stock, net of issuance costs		69,844
Proceeds from the sale of common stock in an initial public offering, net of issuance costs	58,021
Proceeds from exercise of stock options	10
Cash provided by financing activities	78,031	89,844
Net increase in cash and cash equivalents	3,545	8,642
Cash and cash equivalents at beginning of year	14,811	6,169
Cash and cash equivalents at end of year	18,356	14,811	$ 18,356
Supplemental schedule of non-cash financing activities:
Accretion of redeemable convertible preferred stock to redemption value	7,178	5,910
Conversion of redeemable convertible preferred stock into common stock	173,080
Purchase of property and equipment included in accounts payable and accrued expenses		$ 23
Initial recognition of operating lease right-of-use asset and operating lease liability	$ 1,084

Organization and Description of Business

12 Months Ended

Dec. 31, 2019

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Organization and Description of Business

1.	Organization and description of business

Galera Therapeutics, Inc. was incorporated as a Delaware corporation on November 19, 2012 (inception) and together with its subsidiaries (the Company, or Galera) is a clinical stage biopharmaceutical company focused on developing and commercializing a pipeline of novel, proprietary therapeutics that have the potential to transform radiotherapy in cancer. The Company’s lead product candidate, GC4419, is a potent and highly selective small molecule dismutase mimetic being developed for the reduction of severe oral mucositis (SOM). In February 2018, the U.S. Food and Drug Administration (FDA) granted Breakthrough Therapy Designation to GC4419 for the reduction of SOM induced by radiotherapy with or without systemic therapy. The Company is currently evaluating GC4419 in a Phase 3 registrational trial. The Company is also evaluating GC4419 in a Phase 2a trial for the reduction of the incidence of radiotherapy-induced esophagitis. In addition to developing GC4419 for the reduction of normal tissue toxicity from radiotherapy, the Company is developing its dismutase mimetics to increase the anti-cancer efficacy of higher daily doses of radiotherapy, including stereotactic body radiation therapy (SBRT). The Company’s second dismutase mimetic product candidate, intravenous GC4711, is being developed to increase the anti-cancer efficacy of SBRT, has successfully completed a Phase 1 trial and is currently being evaluated in a dose- and schedule-ranging Phase 1 trial in healthy volunteers. The Company plans to leverage its observations from the GC4419 SBRT pilot Phase 1b/2a trial in locally advanced pancreatic cancer (LAPC) to prepare a GC4711 SBRT combination Phase 1b/2a trial in non-small cell lung cancer (NSCLC).

Reverse stock split

The Company effected a one-for-5.056564 reverse stock split of its common stock on October 25, 2019. The reverse stock split combined each approximately five shares of the Company’s issued and outstanding common stock into one share of common stock and correspondingly adjusted the conversion price of its redeemable convertible preferred stock. No fractional shares were issued in connection with the reverse stock split. Any fractional share resulting from the reverse stock split was rounded down to the nearest whole share. All common stock, per share and related information presented in the consolidated financial statements and accompanying notes have been retroactively adjusted to reflect the reverse stock split.

Liquidity

The Company has incurred recurring losses and negative cash flows from operations since inception and has an accumulated deficit of $161.4 million as of December 31, 2019. The Company anticipates incurring additional losses until such time, if ever, that it can generate significant sales of its product candidates currently in development. The Company expects its existing cash, cash equivalents and short-term investments, together with the $20.0 million payment received from Clarus in February 2020 for the achievement of the third clinical milestone in the ROMAN trial and the $20.0 million payment from Clarus expected to be received upon the achievement of the remaining specified clinical milestone in our ROMAN trial, will enable the Company to fund its operating expenses and capital expenditure requirements into 2022, see Note 2 and Note 6.

On November 12, 2019, the Company completed an initial public offering (IPO) of its common stock, which resulted in the issuance and sale of 5,000,000 shares of its common stock at a public offering price of $12.00 per share, generating net proceeds of $53.0 million after deducting underwriting discounts and other offering costs. On December 9, 2019, in connection with the partial exercise of the over-allotment option granted to the underwriters of the Company's IPO, 445,690 additional shares of common stock were sold at the IPO price of $12.00 per share, generating net proceeds of approximately $5.0 million after deducting underwriting discounts and other offering costs. Upon the closing of the IPO, all outstanding shares of the Company’s Series A, Series B and Series C redeemable convertible preferred stock were automatically converted into 19,061,502 shares of the Company’s common stock.

Basis of Presentation and Significant Accounting Policies

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

Basis of Presentation and Significant Accounting Policies

2.	Basis of presentation and significant accounting policies

Basis of presentation and consolidation

The accompanying consolidated financial statements have been prepared in conformity with U.S. generally accepted accounting principles (U.S. GAAP). Any reference in these notes to applicable guidance is meant to refer to U.S. GAAP as found in the Accounting Standards Codification (ASC) and Accounting Standards Updates (ASU) of the Financial Accounting Standards Board (FASB).

The consolidated financial statements include the accounts of Galera Therapeutics, Inc. and its wholly owned subsidiaries, Galera Therapeutics Australia Pty Ltd (Galera Australia) and Galera Labs, LLC. All intercompany accounts and transactions have been eliminated in consolidation.

The Company has determined the functional currency of Galera Australia to be the U.S. dollar. The Company records remeasurement gains and losses on monetary assets and liabilities, such as tax incentive receivables and accounts payable, which are not denominated in U.S. dollars in the statements of operations.

The Company manages its operations as a single reportable segment for the purposes of assessing performance and making operating decisions.

Use of estimates

The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the consolidated financial statements and the reported amounts of expenses during the reporting period. Actual results could differ from those estimates.

Estimates and assumptions are periodically reviewed and the effects of revisions are reflected in the consolidated financial statements in the period they are determined to be necessary. Significant areas that require management’s estimates include the fair value of common stock prior to the IPO, share-based compensation assumptions, royalty purchase liability assumptions and accrued clinical trial expense.

Fair value of financial instruments

Management believes that the carrying amounts of the Company’s financial instruments, including accounts payable and accrued expenses, approximate fair value due to the short-term nature of those instruments. Short-term investments are recorded at their estimated fair value. The royalty purchase liability is accounted for as debt and interest is accreted over the expected repayment period which approximates fair value.

Concentration of credit risk

Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash and cash equivalents and short-term investments. 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 and cash equivalents.

Cash and cash equivalents

The Company considers all highly liquid investments that have maturities of three months or less when acquired to be cash equivalents. Cash and cash equivalents as of December 31, 2019 and 2018 consisted of bank deposits, U.S. Treasury obligations and a money market mutual fund invested in U.S. Treasury obligations.

Short-term investments

Short-term investments consist of debt securities with a maturity of greater than three months when acquired. The Company classifies its short-term investments at the time of purchase as available-for-sale securities, net of unrealized gains of $38,000 and $3,000 during the years ended December 31, 2019 and 2018, respectively. Available-for-sale securities are carried at fair value. Unrealized gains and losses on available-for-sale securities are reported in accumulated other comprehensive income (loss), a component of stockholders’ equity (deficit), until realized. Short-term investments at December 31, 2019 and 2018 consisted of U.S. Treasury obligations with fair values of $93.9 million and $66.7 million, respectively.

Tax incentive receivable

Galera Australia was eligible to participate in an Australian research and development tax incentive program under which the Company received a cash refund from the Australian Taxation Office (ATO) for a percentage of the research and development costs expended by Galera Australia in Australia. The cash refund is available to companies with an annual aggregate revenue of less than $20.0 million Australian dollars during the reimbursable period. The Company’s estimate of the amount of cash refund it expected to receive is included in tax incentive receivable in the accompanying consolidated balance sheet as of December 31, 2018 and such amount was recorded as reduction of research and development expense in the statements of operations for the year ended December 31, 2018.

Since November 2018, the Company has received $60.0 million in proceeds from its royalty purchase agreement (Note 6). Proceeds from the royalty purchase agreement are recognized as revenue for income tax reporting purposes in the United States. The Company requested a private ruling from the ATO regarding its eligibility to continue to participate in the research and development program. In December 2019, the ATO issued its Notice of Decision, concluding that those proceeds do constitute revenue, and that therefore Galera Australia was ineligible for the refund for the twelve-month period ended June 30, 2019 (Galera Australia’s fiscal year). Based on this private ruling, the Company believes that it will continue to be ineligible for the refund in Galera Australia’s fiscal year ended June 30, 2020, and accordingly has not recorded a receivable on the accompanying consolidated balance sheet as of December 31, 2019.

The Company had a tax incentive receivable of $870,000 at December 31, 2018, of which it collected $629,000 in March 2019 and wrote off the remaining $241,000 during the year ended December 31, 2019.

Property and equipment

Property and equipment are recorded at cost and depreciated using the straight-line method over their estimated useful lives ranging from three to five years. Leasehold improvements are amortized over the shorter of their economic lives or the remaining lease term. The costs of maintenance and repairs are expensed as incurred. Improvements and betterments that add new functionality or extend the useful life of the asset are capitalized.

Impairment of long-lived assets

Long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to estimated undiscounted future cash flows expected to be generated by the asset. If the carrying amount of an asset exceeds its estimated undiscounted future cash flows, then an impairment charge is recognized for the amount by which the carrying value of the asset exceeds the estimated fair value of the asset. As of December 31, 2019, the Company believes that no revision of the remaining useful lives or write-down of long-lived assets is required.

Goodwill and acquired intangible asset

In November 2012, the Company completed a Series A redeemable convertible preferred stock (Series A) financing with venture capital investors and simultaneously acquired Galera Therapeutics, LLC (LLC), a limited liability company incorporated in Missouri in 2009. LLC was renamed Galera Labs, LLC in January 2013 and operates as a wholly-owned subsidiary of the Company. The Company applied the purchase method of accounting under which the consideration given to the LLC members and noteholders was allocated to the fair value of the net assets assumed from the LLC at the date of the acquisition. The sole intangible asset acquired represented the fair value of in-process research and development (IPR&D) which has been recorded on the accompanying consolidated balance sheet as an indefinite life intangible asset. A deferred tax liability was recorded for the difference between the fair value of the acquired IPR&D and its tax basis of zero which was recognized as goodwill in applying the purchase method of accounting.

Intangible assets related to IPR&D are considered indefinite-lived intangible assets and, along with goodwill, are not amortized, but are assessed for impairment annually or more frequently if impairment indicators exist. For those compounds that reach commercialization, the IPR&D assets will be amortized over their estimated useful lives. If the associated research and development effort related to IPR&D is abandoned, the related assets will be written-off and the Company will record a noncash impairment loss on its consolidated statements of operations. For the years ended December 31, 2019 and 2018, the Company determined that there was no impairment to goodwill or IPR&D.

Royalty purchase liability

In November 2018, the Company entered into an Amended and Restated Purchase and Sale Agreement (Royalty Agreement), with Clarus IV Galera Royalty AIV, L.P., Clarus IV-A, L.P., Clarus IV-B, L.P., Clarus IV-C, L.P. and Clarus IV-D, L.P. (collectively, Clarus). Pursuant to the Royalty Agreement, the Company received a cash payment of $20.0 million in each of November 2018, April 2019 and February 2020 and is eligible to receive up to an additional $20.0 million from Clarus based upon the achievement of a specific clinical milestone in the ROMAN Trial. The proceeds received have been recorded as long-term debt obligations. Interest expense on such obligation is imputed by estimating risk adjusted future royalty payments over the term of the Royalty Agreement which takes into consideration the probability of obtaining FDA approval. Other significant assumptions include adjustments to estimated gross revenues to arrive at net product sales from which a royalty payment can be estimated. The non-cash interest expense recorded increases the balance of the royalty obligation. The royalty obligation will be reduced when royalty payments are made, if any.

However, actual royalty payments are highly uncertain and may change depending on a number of factors, including the Company’s ability to obtain FDA approval, successfully commercialize the Company’s product candidates and the timing of future royalty payments. The Company imputes interest expense on the royalty purchase obligations based on such factors at each reporting period. As these factors change, the Company will adjust its estimate of the imputed interest expense accordingly.

Leases

At lease commencement, the Company records a lease liability based on the present value of lease payments over the expected lease term including any options to extend the lease that the Company is reasonably certain to exercise. The Company calculates the present value of lease payments using an incremental borrowing rate as the Company’s leases do not provide an implicit interest rate. The Company’s incremental borrowing rate for a lease is the rate of interest it would have to pay on a collateralized basis to borrow an amount equal to the lease payments under similar terms. At the lease commencement date, the Company records a corresponding right-of-use lease asset based on the lease liability, adjusted for any lease incentives received and any initial direct costs paid to the lessor prior to the lease commencement date. The Company may enter into leases with an initial term of 12 months or less (Short-Term Leases). For Short-Term Leases, the Company records the rent expense on a straight-line basis and does not record the leases on the balance sheet. The Company had no Short-Term Leases as of December 31, 2019 and 2018.

After lease commencement, the Company measures its leases as follows: (i) the lease liability based on the present value of the remaining lease payments using the discount rate determined at lease commencement, and (ii) the right-of-use lease asset based on the remeasured lease liability, adjusted for any unamortized lease incentives received, any unamortized initial direct costs and the cumulative difference between rent expense and amounts paid under the lease agreement. Any lease incentives received and any initial direct costs are amortized on a straight-line basis over the expected lease term. Rent expense is recorded on a straight-line basis over the expected lease term.

Research and development expenses

Research and development costs are expensed as incurred and consist primarily of funds paid to third parties for the provision of services for product candidate development, clinical and preclinical development and related supply and manufacturing costs, and regulatory compliance costs. The Company accrues and expenses preclinical studies and clinical trial activities performed by third parties based upon estimates of the proportion of work completed over the term of the individual trial and patient enrollment rates in accordance with agreements with clinical research organizations and clinical trial sites. The Company determines the estimates by reviewing contracts, vendor agreements and purchase orders, and through discussions with internal clinical personnel and external service providers as to the progress or stage of completion of trials or services and the agreed-upon fee to be paid for such services. However, actual costs and timing of clinical trials are highly uncertain, subject to risks and may change depending upon a number of factors, including the Company’s clinical development plan.

Management makes estimates of the Company’s accrued expenses as of each balance sheet date in the Company’s consolidated financial statements based on facts and circumstances known to the Company at that time. If the actual timing of the performance of services or the level of effort varies from the estimate, the Company will adjust the accrual accordingly. Nonrefundable advance payments for goods and services, including fees for process development or manufacturing and distribution of clinical supplies that will be used in future research and development activities, are deferred and recognized as expense in the period that the related goods are consumed or services are performed.

Share-based compensation

The Company measures share-based awards at their grant-date fair value and records compensation expense on a straight-line basis over the vesting period of the awards.

Estimating the fair value of share-based awards requires the input of subjective assumptions, including the estimated fair value of the Company’s common stock prior to the IPO, and, for stock options, the expected life of the options and stock price volatility. The Company accounts for forfeitures of stock option awards as they occur. The Company uses the Black-Scholes option pricing model to value its stock option awards. The assumptions used in estimating the fair value of share-based awards represent management’s estimate and involve inherent uncertainties and the application of management’s judgment. As a result, if factors change and management uses different assumptions, share-based compensation expense could be materially different for future awards.

The expected life of the stock options is estimated using the “simplified method,” as the Company has no historical information from which to develop reasonable expectations about future exercise patterns and post-vesting employment termination behavior for its stock option grants. The simplified method is the midpoint between the vesting period and the contractual term of the option. For stock price volatility, the Company uses comparable public companies as a basis for its expected volatility to calculate the fair value of option grants. The risk-free rate is based on the U.S. Treasury yield curve commensurate with the expected life of the option.

Income taxes

The Company uses the asset and liability method of accounting for income taxes. Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases, and operating loss and credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. A valuation allowance is provided when it is more likely than not that some portion or all of a deferred tax asset will not be realized. The Company recognizes the benefit of an uncertain tax position that it has taken or expects to take on its income tax return if such a position is more likely than not to be sustained.

Accretion of redeemable convertible preferred stock

The Company’s redeemable convertible preferred stock is classified as temporary equity in the accompanying consolidated balance sheets, as of December 31, 2018. The carrying values of the redeemable convertible preferred stock were accreted to their respective redemption values for accruing dividends and issuance costs, using the effective interest method, from the date of issuance to the earliest date the holders can demand redemption. The redemption value was accreted through a charge to additional paid-in-capital, if available, or to accumulated deficit.

Net loss per share

Basic loss per share of common stock is computed by dividing net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding during each period. Diluted loss per share of common stock includes the effect, if any, from the potential exercise or conversion of securities, such as redeemable convertible preferred stock and stock options, which would result in the issuance of incremental shares of common stock. For diluted net loss per share, the weighted-average number of shares of common stock is the same for basic net loss per share due to the fact that when a net loss exists, dilutive securities are not included in the calculation as the impact is anti-dilutive.

The following potentially dilutive securities have been excluded from the computation of diluted weighted-average shares of common stock outstanding, as they would be anti-dilutive:

	December 31,
	2019		2018
Stock options		3,537,946		2,071,616
Redeemable convertible preferred stock		—		19,061,502
		3,537,946		21,133,118

Amounts in the above table reflect the common stock equivalents for the redeemable convertible preferred stock.

Recent accounting pronouncements

In February 2016, the FASB issued ASU No. 2016-02, Leases, which requires that lease arrangements longer than 12 months result in an entity recognizing an asset and liability on the balance sheet. Additionally, certain qualitative and quantitative disclosures will be required in the financial statements. The Company adopted ASU 2016-02 on January 1, 2019 (Note 7) using the modified retrospective transition approach and elected to apply the package of practical expedients.

In August 2016, the FASB issued ASU No. 2016-15, Classification of Certain Cash Receipts and Cash Payments (Topic 230), which provides specific guidance related to eight cash flow classification issues with the objective of reducing the existing diversity in practice for certain cash receipts and cash payments. The Company adopted this ASU on January 1, 2019 and it did not have a material impact on the Company’s consolidated financial statements.

In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement, which removes and modifies some existing disclosure requirements and adds others. This ASU is effective for all entities for fiscal years beginning after December 15, 2019, including interim periods therein. Early adoption is permitted for any eliminated or modified disclosures upon issuance of this ASU. The Company adopted this ASU on January 1, 2020 and it did not have a material impact on the Company’s consolidated financial statements.

Fair Value Measurements

12 Months Ended

Dec. 31, 2019

Fair Value Disclosures [Abstract]

Fair Value Measurements

3.	Fair value measurements

The Company utilizes valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs to the extent possible. The Company determines fair value based on assumptions that market participants would use in pricing an asset or liability in the principal or most advantageous market. When considering market participant assumptions in fair value measurements, the following fair value hierarchy distinguishes between observable and unobservable inputs, which are categorized in one of the following levels:

•

Level 1 Inputs: Unadjusted quoted prices in active markets for identical assets or liabilities accessible to the reporting entity at the measurement date.

•

Level 2 Inputs: Other than quoted prices included in Level 1 inputs that are observable for the asset or liability, either directly or indirectly, for substantially the full term of the asset or liability.

•

Level 3 Inputs: Unobservable inputs for the asset or liability used to measure fair value to the extent that observable inputs are not available, thereby allowing for situations in which there is little, if any, market activity for the asset or liability at measurement date.

The following table presents the Company’s assets and liabilities that are measured at fair value on a recurring basis (amounts in thousands):

	December 31, 2019
	(Level 1)		(Level 2)		(Level 3)
Assets
Money market funds and U.S. Treasury obligations (included in cash equivalents)	$	17,447	$	—	$	—
Short-term investments	$	93,934	$	—	$	—

	December 31, 2018
	(Level 1)		(Level 2)		(Level 3)
Assets
Money market funds and U.S. Treasury obligations (included in cash equivalents)	$	13,770	$	—	$	—
Short-term investments	$	66,706	$	—	$	—

There were no changes in valuation techniques during the years ended December 31, 2019 and 2018. The Company’s short-term investment instruments are classified using Level 1 inputs within the fair value hierarchy because they are valued using quoted market prices, broker or dealer quotations, or alternative pricing sources with reasonable levels of price transparency.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Property and Equipment

12 Months Ended

Dec. 31, 2019

Property Plant And Equipment [Abstract]

Property and Equipment

4.	Property and equipment

Property and equipment consist of (amounts in thousands):

	December 31,
	2019			2018
Laboratory equipment	$	748		$	507
Computer hardware and software		218			109
Leasehold improvements		262			—
Furniture and fixtures		147			159
Property and equipment, gross		1,375			775
Less: Accumulated depreciation		(441	)		(207	)
Property and equipment, net	$	934		$	568

Depreciation expense was $0.3 million and $0.1 million for the years ended December 31, 2019 and 2018, respectively.

Accrued Expenses

12 Months Ended

Dec. 31, 2019

Payables And Accruals [Abstract]

Accrued Expenses

5.	Accrued expenses

Accrued expenses consist of (amounts in thousands):

	December 31,
	2019		2018
Compensation and related benefits	$	1,160	$	776
Research and development expenses		3,882		1,665
Professional fees		410		136
	$	5,452	$	2,577

Royalty Purchase Liability

12 Months Ended

Dec. 31, 2019

Royalty Purchase Liability [Abstract]

Royalty Purchase Liability

6.	Royalty purchase liability

Pursuant to the Royalty Agreement, Clarus agreed to pay up to $80.0 million (the Royalty Purchase Price) in four tranches of $20.0 million each upon the achievement of specific Phase 3 clinical trial patient enrollment milestones. The Company received the first tranche of the Royalty Purchase Price in November 2018. In April 2019, the Company received a $20.0 million payment in connection with the achievement of the second milestone under the Royalty Agreement. In February 2020, the Company received a $20.0 million payment in connection with the achievement of the third milestone under the Royalty Agreement.

The Company accounts for the Royalty Agreement as a debt instrument. The $40.0 million of proceeds from the first and second tranche under the Royalty Agreement have been recorded as a liability on the accompanying consolidated balance sheets. Interest expense is imputed based on the estimated royalty repayment period described below which results in a corresponding increase in the liability balance. The Company recognized $3.0 million and $0.2 million in noncash interest expense during the years ended December 31, 2019 and 2018, respectively. As of December 31, 2019, the effective interest rate was 8.7%.

Clarus is entitled to a mid single-digit percentage royalty based on the worldwide net sales of GC4419 and GC4711 (the Products). The royalty period will continue until the earlier of (i) the 12th anniversary of commercial launch of the Products, (ii) the expiration of the patents covering such Products, and (iii) the expiration of regulatory data protection or market exclusivity or similar regulatory protection afforded by the health authorities in such country, to the extent such protection or exclusivity effectively prevents generic versions of such Products from entering the market in such country.

If Clarus fails to fund the remaining $20.0 million Royalty Purchase Price within two days of the conditions to the payment of such tranche having been satisfied, the Company may terminate its obligation to accept such tranche and any additional remaining tranches. In such an event, the Company’s royalty obligations to Clarus shall be reduced to a low single-digit percentage.

The Royalty Agreement will remain in effect until the aggregate amount of the royalty payments paid to Clarus exceeds a fixed single-digit multiple of the actual amount of the Royalty Purchase Price received by the Company, unless earlier terminated pursuant to the mutual written agreement of the Company and Clarus.

Leases

12 Months Ended

Dec. 31, 2019

Leases [Abstract]

Leases

The Company has non-cancelable operating leases for office and laboratory space in Malvern, Pennsylvania and Creve Coeur, Missouri which, as of December 31, 2019, have remaining lease terms of approximately 3.2 and 1.1 years, respectively. The Company adopted ASC 842 on January 1, 2019 resulting in the recognition of a current operating lease liability of $0.3 million and a noncurrent operating lease liability of $0.8 million with a corresponding $1.1 million right-of-use (ROU) asset, which is based on the present value of the minimum rental payments of the lease. The discount rate used to account for the Company’s operating lease under ASC 842 is the Company’s estimated incremental borrowing rate of 5.3%.

Supplemental balance sheet information related to leases was as follows:

	December 31,
	2019
Operating Leases
Operating lease right-of-use assets	$	815

Other current liabilities		297
Operating lease liabilities		534
Total operating lease liabilities	$	831

The components of lease expense were as follows:

	Year ended December 31,
	2019
Operating lease costs
Operating lease rental expense	$	265
Interest on lease liabilities		50
Total operating lease liabilities	$	315

Supplemental cash flow information related to leases was as follows:

	Year ended December 31,
	2019
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from operating leases	$	437
Right-of-use assets obtained in exchange for lease obligation
Operating leases		1,084

Our operating lease liabilities as of December 31, 2019 will mature, as follows (amounts in thousands):

2020	$	332
2021		259
2022		260
2023		44
Total		895
Less: imputed interest		(64	)
	$	831

Commitments

12 Months Ended

Dec. 31, 2019

Commitments And Contingencies Disclosure [Abstract]

Commitments

8.Commitments

Executive employment agreements

The Company has entered into employment agreements with certain key executives, providing for compensation and severance in certain circumstances, as described in the respective agreements.

Legal matters

The Company is subject from time to time to various claims and legal actions arising during the ordinary course of its business. Management believes that there are currently no claims or legal actions that would reasonably be expected to have a material adverse effect on the Company’s results of operations, financial condition or cash flows.

Redeemable Convertible Preferred Stock

12 Months Ended

Dec. 31, 2019

Temporary Equity [Abstract]

Redeemable Convertible Preferred Stock

9.	Redeemable convertible preferred stock

The Company issued Series A redeemable convertible preferred stock (Series A), Series B redeemable convertible preferred stock (Series B), Series B-1 redeemable convertible preferred stock (Series B-1), Series B-2 redeemable convertible preferred stock (Series B-2), and Series C redeemable convertible preferred stock (Series C) (collectively, Preferred Stock).

As of December 31, 2018, the authorized, issued and outstanding shares of redeemable convertible preferred stock and their carrying amounts and liquidation values were as disclosed below (in thousands except share amounts):

	Shares Authorized		Shares Issued and Outstanding		Carrying Value		Liquidation Value
Series A		22,280,087		22,280,087	$	28,685	$	29,301
Series B		29,682,000		29,682,000		43,710		44,342
Series B-1		3,636,363		3,636,363		5,777		5,884
Series B-2		9,090,909		9,090,909		16,649		16,913
Series C		31,696,436		31,696,436		71,081		71,605
		96,385,795		96,385,795	$	165,902	$	168,045

Upon the closing of the IPO on November 12, 2019, all shares of Preferred Stock were automatically converted into an aggregate of 19,061,502 shares of common stock.

Share-based Compensation

12 Months Ended

Dec. 31, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Share-based Compensation

10.	Share-based compensation

In connection with the Company’s IPO, in November 2019, the Company’s board of directors adopted and the Company’s stockholders approved the Galera Therapeutics, Inc. 2019 Incentive Award Plan (the 2019 Plan), which became effective upon the effectiveness of the registration statement on Form S-1 for the IPO. Upon effectiveness of the 2019 Plan, the Company ceased granting new awards under the Prior Plan.

The 2019 Plan provides for the grant of incentive stock options, nonstatutory stock options, restricted stock awards, restricted stock units, stock appreciation rights and other stock-based awards. The number of shares of common stock initially available for issuance under the 2019 Plan is 1,948,970 shares of common stock plus the number of shares subject to awards outstanding under the Prior Plan that expire, terminate or are otherwise surrendered, cancelled, forfeited or repurchased by the Company on or after the effective date of the 2019 Plan. In addition, the number of shares of common stock available for issuance under the 2019 Plan is subject to an annual increase on the first day of each calendar year beginning on January 1, 2020 and ending on and including January 1, 2029 equal to the lesser of (i) 4% of the Company’s outstanding shares of common stock on the final day of the immediately preceding calendar year, and (ii) such smaller number of shares of common stock as determined by the Company’s board of directors. Pursuant to this provision, the Company added 992,463 shares to the total shares available for issuance under the 2019 Plan effective January 1, 2020. The maximum number of shares of common stock that may be issued under the 2019 Plan upon the exercise of incentive stock options is 14,130,029.

In November 2019, the Company’s board of directors adopted and the Company’s stockholders approved the Galera Therapeutics, Inc. 2019 Employee Stock Purchase Plan (the ESPP). The ESPP allows employees to buy Company stock through after-tax payroll deductions at a discount from market value. The number of shares of common stock initially available for issuance under the ESPP is 243,621 shares of common stock plus an annual increase on the first day of each calendar year beginning on January 1, 2020 and ending on and including January 1, 2029 equal to the lesser of (i) 1% of the Company’s outstanding shares of common stock on the final day of the immediately preceding calendar year and (ii) such smaller number of shares of common stock as determined by the Company’s board of directors, provided that not more than 3,288,886 shares of common stock may be issued under the ESPP. Pursuant to this provision, the Company added 248,115 shares to the total shares available for issuance under the ESPP effective January 1, 2020.

In November 2012, the Company adopted the Equity Incentive Plan (the Prior Plan). The total number of shares authorized under the Prior Plan as of December 31, 2019 was 3,038,259, all of which were subject to outstanding awards. No further grants will be made under the Prior Plan; however, the Prior Plan continues to govern awards that are outstanding under it.

Share-based compensation expense was as follows for the years ended December 31, 2019 and 2018 (in thousands):

	Year ended December 31,
	2019		2018
Research and development	$	1,163	$	434
General and administrative		1,227		431
	$	2,390	$	865

The following table summarizes the activity related to stock option grants for the years ended December 31, 2019 and 2018:

	Shares			Weighted average exercise price per share		Weighted- average remaining contractual life (years)
Outstanding at January 1, 2018		2,025,376		$	2.12
Granted		68,982			4.39
Forfeited		(22,742	)		4.40
Outstanding at December 31, 2018		2,071,616		$	2.17
Granted		1,646,054			8.88
Exercised		(3,778	)		2.60
Forfeited		(175,946	)		4.50
Outstanding at December 31, 2019		3,537,946		$	5.17		7.3
Vested and exercisable at December 31, 2019		2,014,887		$	2.63		5.9
Vested and expected to vest at December 31, 2019		3,537,946		$	5.17		7.3

As of December 31, 2019, the unrecognized compensation cost was $9.2 million and will be recognized over an estimated weighted-average remaining amortization period of 3.3 years. The aggregate intrinsic value of options outstanding and options exercisable as of December 31, 2019 was $28.3 million and $21.2 million, respectively. Options granted during the years ended December 31, 2019 and 2018 had weighted-average grant-date fair values of $6.66 and $3.49 per share, respectively.

The fair value of options is estimated using the Black-Scholes option pricing model, which takes into account inputs such as the exercise price, the estimated fair value of the underlying common stock at the grant date, expected term, expected stock price volatility, risk-free interest rate and dividend yield. The fair value of stock options during the years ended December 31, 2019 and 2018 was determined using the methods and assumptions discussed below.

•

The expected term of employee stock options with service-based vesting is determined using the “simplified” method, as prescribed in SEC’s Staff Accounting Bulletin (SAB) No. 107, whereby the expected life equals the arithmetic average of the vesting term and the original contractual term of the option due to the Company’s lack of sufficient historical data. The expected term of nonemployee options is equal to the contractual term.

•

The expected stock price volatility is based on historical volatilities of comparable public entities within the Company’s industry which were commensurate with the expected term assumption as described in SAB No. 107.

•

The risk-free interest rate is based on the interest rate payable on U.S. Treasury securities in effect at the time of grant for a period that is commensurate with the expected term.

•

The expected dividend yield is 0% because the Company has not historically paid, and does not expect for the foreseeable future to pay, a dividend on its common stock.

•

Prior to the Company’s IPO, its board of directors had periodically estimated the fair value of the Company’s common stock considering, among other things, contemporaneous valuations of its common stock prepared by an unrelated third-party valuation firm in accordance with the guidance provided by the American Institute of Certified Public Accountants 2013 Practice Aid, Valuation of Privately-Held-Company Equity Securities Issued as Compensation. Since the closing of the IPO, the Company’s board of directors has determined the per share value of the Company’s common stock based on the closing price as reported by the NASDAQ Global Market on the date of the grant.

The grant date fair value of each option grant was estimated throughout the year using the Black-Scholes option-pricing model using the following weighted-average assumptions:

	Year ended December 31,
	2019			2018
Expected term (in years)		6.2			7.8
Expected stock price volatility		89.7	%		88.0	%
Risk-free interest rate		2.26	%		2.79	%
Expected dividend yield		0	%		0	%

Income Taxes

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Income Taxes

11. Income Taxes

The Company’s loss before income taxes for the years ended December 31, 2019 and 2018 is as follows (in thousands):

	Year ended December 31,
	2019			2018
Domestic	$	(49,918	)	$	(22,779	)
Foreign		(2,021	)		(1,120	)
	$	(51,939	)	$	(23,899	)

The Company’s tax provision (benefit) for the years ended December 31, 2019 and 2018 is summarized as follows (in thousands):

	Year ended December 31,
	2019			2018
Current
Federal	$	—		$	—
State		—			—
Foreign		—			—
		—			—
Deferred:
Federal		194			(379	)
State		(203	)		156
Foreign		—			—
		(9	)		(223	)
Total income tax benefit	$	(9	)	$	(223	)

A reconciliation of the federal income tax rate to the Company’s effective tax rate is as follows:

	Year ended December 31,
	2019				2018
Rate reconciliation:
Federal tax benefit at statutory rate		21.0		%		21.0		%
State tax, net of federal benefit		4.3				0.7
Net operating loss carryforwards		(0.2	)			10.6
Change in tax rate		(0.6	)			(0.4	)
Sale of royalty interest		(8.1	)			(17.6	)
Difference in foreign rate		0.4				0.4
Research & development		4.3				3.3
Change in valuation allowance		(19.5	)			(16.2	)
Share-based compensation		(0.4	)			(0.6	)
Other		(1.2	)			(0.3	)
Total provision		—		%		0.9		%

The tax effects of temporary differences that give rise to significant portions of the deferred tax assets and liabilities were as follows (in thousands):

	December 31,
	2019			2018
Deferred tax assets
Net operating loss carryforwards	$	27,470		$	19,733
Share-based compensation		511			118
Research & development credits		5,073			2,317
Accrued expenses and other		—			119
Gross deferred tax assets		33,054			22,287
Valuation allowance		(32,062	)		(21,908	)
Net deferred tax asset		992			379
Deferred tax liabilities
Accrued expenses and other		(613	)		—
Acquired in-process research and development		(668	)		(677	)
Net deferred tax liabilities	$	(289	)	$	(298	)

In assessing the need for a valuation allowance, the Company may utilize indefinite-lived deferred tax liabilities from an intangible asset as a future source of income. The Company’s acquired IPR&D intangible asset can be utilized as a source of income arising from the future reversal of temporary differences that can be offset against post 2017 indefinite-lived net operating losses (NOLs). Therefore, the Company is permitted to offset the indefinite-lived deferred tax liability up to the 80 percent limitation for NOLs generated subsequent to January 1, 2018. The valuation allowance increased by $10.2 million and $3.9 million for the years ended December 31, 2019 and 2018, respectively.

The following table summarizes carryforwards of federal, state and foreign NOLs and tax credits as of December 31, 2019 and 2018, respectively (in thousands):

	December 31,
	2019		2018
Combined NOL Carryforwards:
Federal	$	91,472	$	64,520
State		113,587		81,807
Foreign		1,175		812

The NOL carryforwards begin expiring in 2032 for federal income tax purposes, and in 2032 for state purposes. Utilization of the NOLs and general business tax credits carryforwards may be subject to a substantial limitation under Sections 382 and 383 of the Internal Revenue Code of 1986 as amended, if changes in ownership of the company have occurred previously or occur in the future. As of December 31, 2019, the Company also has federal and state research and development tax credit carryforwards of $5.1 million that will begin to expire in 2032, unless previously utilized.

The NOL and tax credit carryforwards are subject to review and possible adjustment by the Internal Revenue Service and state tax authorities. NOL and tax credit carryforwards may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant shareholders over a three-year period in excess of 50 percent, as defined under Sections 382 and 383 of the Internal Revenue Code, respectively, as well as similar state provisions. This could limit the amount of tax attributes that can be utilized annually to offset future taxable income or tax liabilities. Subsequent ownership changes may further affect the limitation in future years. The Company has not done an analysis to determine whether or not ownership changes have occurred since inception. Certain state NOLs may also be limited, including Pennsylvania, which limits NOL utilization as a percentage of apportioned taxable income.

The Company will recognize interest and penalties related to uncertain tax positions as income tax expense. As of December 31, 2019, the Company had no accrued interest and penalties related to uncertain tax positions and no amounts have been recognized in the Company’s statements of operations. Due to NOL and tax credit carryforwards that remain unutilized, income tax returns from 2016 through 2018 remain subject to examination by the taxing jurisdictions. The NOLs remain subject to review until utilized.

In December 2017, the Tax Cuts and Jobs Act (2017 Tax Act) was enacted. The 2017 Tax Act includes a number of changes to existing U.S. tax laws that impact the Company, most notably a reduction of the U.S. corporate income tax rate from 34 percent to 21 percent for the tax years beginning after December 31, 2017. The accounting for the income tax effect of the 2017 Tax Act was complete as of December 31, 2018.

Related Party Transactions

12 Months Ended

Dec. 31, 2019

Related Party Transactions

12.	Related party transactions

IntellectMap provides advisory services to the Company. The chief executive officer of IntellectMap is the brother of the Company’s chief executive officer. Fees incurred by us with respect to IntellectMap during the years ended December 31, 2019 and 2018 were $0.3 million and $0.2 million, respectively.

Basis of Presentation and Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

Liquidity

Basis of Presentation and Consolidation

Basis of presentation and consolidation

The Company manages its operations as a single reportable segment for the purposes of assessing performance and making operating decisions.

Use of Estimates

Use of estimates

Fair Value of Financial Instruments

Fair value of financial instruments

Concentration of Credit Risk

Concentration of credit risk

Cash and Cash Equivalents

Cash and cash equivalents

Short-Term Investments

Short-term investments

Tax Incentive Receivable

Tax incentive receivable

The Company had a tax incentive receivable of $870,000 at December 31, 2018, of which it collected $629,000 in March 2019 and wrote off the remaining $241,000 during the year ended December 31, 2019.

Property and Equipment

Property and equipment

Impairment of Long-Lived Assets

Impairment of long-lived assets

Goodwill and Acquired Intangible Asset

Goodwill and acquired intangible asset

Royalty Purchase Liability

Royalty purchase liability

Leases

Research and Development Expenses

Research and development expenses

Share-Based Compensation

Share-based compensation

The Company measures share-based awards at their grant-date fair value and records compensation expense on a straight-line basis over the vesting period of the awards.

Income Taxes

Income taxes

Accretion of Redeemable Convertible Preferred Stock

Accretion of redeemable convertible preferred stock

Net Loss Per Share

Net loss per share

The following potentially dilutive securities have been excluded from the computation of diluted weighted-average shares of common stock outstanding, as they would be anti-dilutive:

	December 31,
	2019		2018
Stock options		3,537,946		2,071,616
Redeemable convertible preferred stock		—		19,061,502
		3,537,946		21,133,118

Amounts in the above table reflect the common stock equivalents for the redeemable convertible preferred stock.

Recent Accounting Pronouncements

Recent accounting pronouncements

Basis of Presentation and Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

Dilutive Securities Excluded from Computation of Diluted Weighted Average Shares of Common Stock Outstanding

The following potentially dilutive securities have been excluded from the computation of diluted weighted-average shares of common stock outstanding, as they would be anti-dilutive:

	December 31,
	2019		2018
Stock options		3,537,946		2,071,616
Redeemable convertible preferred stock		—		19,061,502
		3,537,946		21,133,118

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2019

Fair Value Disclosures [Abstract]

Summary of Assets and Liabilities Measured at Fair Value on Recurring Basis

The following table presents the Company’s assets and liabilities that are measured at fair value on a recurring basis (amounts in thousands):

	December 31, 2019
	(Level 1)		(Level 2)		(Level 3)
Assets
Money market funds and U.S. Treasury obligations (included in cash equivalents)	$	17,447	$	—	$	—
Short-term investments	$	93,934	$	—	$	—

	December 31, 2018
	(Level 1)		(Level 2)		(Level 3)
Assets
Money market funds and U.S. Treasury obligations (included in cash equivalents)	$	13,770	$	—	$	—
Short-term investments	$	66,706	$	—	$	—

Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2019

Property Plant And Equipment [Abstract]

Schedule of Property Plant and Equipment

Property and equipment consist of (amounts in thousands):

	December 31,
	2019			2018
Laboratory equipment	$	748		$	507
Computer hardware and software		218			109
Leasehold improvements		262			—
Furniture and fixtures		147			159
Property and equipment, gross		1,375			775
Less: Accumulated depreciation		(441	)		(207	)
Property and equipment, net	$	934		$	568

Accrued Expenses (Tables)

12 Months Ended

Dec. 31, 2019

Payables And Accruals [Abstract]

Schedule of Accrued Expenses

Accrued expenses consist of (amounts in thousands):

	December 31,
	2019		2018
Compensation and related benefits	$	1,160	$	776
Research and development expenses		3,882		1,665
Professional fees		410		136
	$	5,452	$	2,577

Leases (Tables)

12 Months Ended

Dec. 31, 2019

Leases [Abstract]

Summary of Supplemental Balance Sheet Information Related to Leases

Supplemental balance sheet information related to leases was as follows:

	December 31,
	2019
Operating Leases
Operating lease right-of-use assets	$	815

Other current liabilities		297
Operating lease liabilities		534
Total operating lease liabilities	$	831

Summary of Components of Lease Expense

The components of lease expense were as follows:

	Year ended December 31,
	2019
Operating lease costs
Operating lease rental expense	$	265
Interest on lease liabilities		50
Total operating lease liabilities	$	315

Summary of Supplemental Cash Flow Information Related to Leases

Supplemental cash flow information related to leases was as follows:

	Year ended December 31,
	2019
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from operating leases	$	437
Right-of-use assets obtained in exchange for lease obligation
Operating leases		1,084

Summary of Operating Leases Liabilities Maturities

Our operating lease liabilities as of December 31, 2019 will mature, as follows (amounts in thousands):

2020	$	332
2021		259
2022		260
2023		44
Total		895
Less: imputed interest		(64	)
	$	831

Redeemable Convertible Preferred Stock (Tables)

12 Months Ended

Dec. 31, 2019

Temporary Equity [Abstract]

Schedule of Redeemable Convertible Preferred Stock

	Shares Authorized		Shares Issued and Outstanding		Carrying Value		Liquidation Value
Series A		22,280,087		22,280,087	$	28,685	$	29,301
Series B		29,682,000		29,682,000		43,710		44,342
Series B-1		3,636,363		3,636,363		5,777		5,884
Series B-2		9,090,909		9,090,909		16,649		16,913
Series C		31,696,436		31,696,436		71,081		71,605
		96,385,795		96,385,795	$	165,902	$	168,045

Share-based Compensation (Tables)

12 Months Ended

Dec. 31, 2019

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Share-based Compensation Expense

Share-based compensation expense was as follows for the years ended December 31, 2019 and 2018 (in thousands):

	Year ended December 31,
	2019		2018
Research and development	$	1,163	$	434
General and administrative		1,227		431
	$	2,390	$	865

Summary of Activity Related to Stock Option Grants

The following table summarizes the activity related to stock option grants for the years ended December 31, 2019 and 2018:

	Shares			Weighted average exercise price per share		Weighted- average remaining contractual life (years)
Outstanding at January 1, 2018		2,025,376		$	2.12
Granted		68,982			4.39
Forfeited		(22,742	)		4.40
Outstanding at December 31, 2018		2,071,616		$	2.17
Granted		1,646,054			8.88
Exercised		(3,778	)		2.60
Forfeited		(175,946	)		4.50
Outstanding at December 31, 2019		3,537,946		$	5.17		7.3
Vested and exercisable at December 31, 2019		2,014,887		$	2.63		5.9
Vested and expected to vest at December 31, 2019		3,537,946		$	5.17		7.3

Summary of Fair Value of Each Option Grant Estimated Throughout Year Using Black-Scholes Option-pricing Model

The grant date fair value of each option grant was estimated throughout the year using the Black-Scholes option-pricing model using the following weighted-average assumptions:

	Year ended December 31,
	2019			2018
Expected term (in years)		6.2			7.8
Expected stock price volatility		89.7	%		88.0	%
Risk-free interest rate		2.26	%		2.79	%
Expected dividend yield		0	%		0	%

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2019

Income Tax Disclosure [Abstract]

Summary of Company's Loss Before Income Taxes

The Company’s loss before income taxes for the years ended December 31, 2019 and 2018 is as follows (in thousands):

	Year ended December 31,
	2019			2018
Domestic	$	(49,918	)	$	(22,779	)
Foreign		(2,021	)		(1,120	)
	$	(51,939	)	$	(23,899	)

Summary of Company's Tax Provision (Benefit)

The Company’s tax provision (benefit) for the years ended December 31, 2019 and 2018 is summarized as follows (in thousands):

	Year ended December 31,
	2019			2018
Current
Federal	$	—		$	—
State		—			—
Foreign		—			—
		—			—
Deferred:
Federal		194			(379	)
State		(203	)		156
Foreign		—			—
		(9	)		(223	)
Total income tax benefit	$	(9	)	$	(223	)

Summary of Effective Tax Rate of Reconciliation of Federal Income Tax Rate

A reconciliation of the federal income tax rate to the Company’s effective tax rate is as follows:

	Year ended December 31,
	2019				2018
Rate reconciliation:
Federal tax benefit at statutory rate		21.0		%		21.0		%
State tax, net of federal benefit		4.3				0.7
Net operating loss carryforwards		(0.2	)			10.6
Change in tax rate		(0.6	)			(0.4	)
Sale of royalty interest		(8.1	)			(17.6	)
Difference in foreign rate		0.4				0.4
Research & development		4.3				3.3
Change in valuation allowance		(19.5	)			(16.2	)
Share-based compensation		(0.4	)			(0.6	)
Other		(1.2	)			(0.3	)
Total provision		—		%		0.9		%

Schedule of Significant Portions of Deferred Tax Assets and Liabilities

The tax effects of temporary differences that give rise to significant portions of the deferred tax assets and liabilities were as follows (in thousands):

	December 31,
	2019			2018
Deferred tax assets
Net operating loss carryforwards	$	27,470		$	19,733
Share-based compensation		511			118
Research & development credits		5,073			2,317
Accrued expenses and other		—			119
Gross deferred tax assets		33,054			22,287
Valuation allowance		(32,062	)		(21,908	)
Net deferred tax asset		992			379
Deferred tax liabilities
Accrued expenses and other		(613	)		—
Acquired in-process research and development		(668	)		(677	)
Net deferred tax liabilities	$	(289	)	$	(298	)

Summary of Carryforwards of Federal, State and Foreign NOLs and Tax Credits

The following table summarizes carryforwards of federal, state and foreign NOLs and tax credits as of December 31, 2019 and 2018, respectively (in thousands):

	December 31,
	2019		2018
Combined NOL Carryforwards:
Federal	$	91,472	$	64,520
State		113,587		81,807
Foreign		1,175		812

Organization and description of business - Additional Information (Details) $ / shares in Units, $ in Thousands			1 Months Ended	12 Months Ended		14 Months Ended
	Dec. 09, 2019 USD ($) $ / shares shares	Nov. 12, 2019 USD ($) $ / shares shares	Feb. 29, 2020 USD ($)	Dec. 31, 2019 USD ($) shares	Dec. 31, 2018 USD ($) shares	Dec. 31, 2019 USD ($) shares
Organization And Description Of Business [Line Items]
Date of incorporation				Nov. 19, 2012
Reverse stock split description				The Company effected a one-for-5.056564 reverse stock split of its common stock on October 25, 2019. The reverse stock split combined each approximately five shares of the Company’s issued and outstanding common stock into one share of common stock and correspondingly adjusted the conversion price of its redeemable convertible preferred stock
Reverse stock split ratio				0.197762749566702
Proceeds from royalty purchase agreement \| $				$ 20,000	$ 20,000	$ 60,000
Accumulated deficit \| $				$ (161,350)	$ (104,823)	$ (161,350)
Common stock, shares issued (shares) \| shares				24,811,567	300,597	24,811,567
Shares issued upon conversion \| shares		19,061,502
Redeemable Convertible Preferred Stock
Organization And Description Of Business [Line Items]
Shares issued upon conversion \| shares		19,061,502
IPO
Organization And Description Of Business [Line Items]
Common stock, shares issued (shares) \| shares		5,000,000
Public offering price \| $ / shares		$ 12.00
Net proceeds from stock offering \| $		$ 53,000
Over-allotment option
Organization And Description Of Business [Line Items]
Common stock, shares issued (shares) \| shares	445,690
Public offering price \| $ / shares	$ 12.00
Net proceeds from stock offering \| $	$ 5,000
Subsequent Event
Organization And Description Of Business [Line Items]
Proceeds from royalty purchase agreement \| $			$ 20,000

Basis of Presentation and Significant Accounting Policies - Additional Information (Details)	1 Months Ended				12 Months Ended			14 Months Ended
	Feb. 29, 2020 USD ($)	Apr. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Nov. 30, 2018 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2018 AUD ($)	Dec. 31, 2019 USD ($)
Accounting Policies [Line Items]
Proceeds from royalty purchase agreement					$ 20,000,000	$ 20,000,000		$ 60,000,000
Tax incentive receivable						870,000
Tax incentive receivable collected			$ 629,000
Tax incentive receivable wrote off					$ 241,000
Property, plant and equipment, depreciation methods					straight-line method
Impairment to goodwill					$ 0	0
Subsequent Event
Accounting Policies [Line Items]
Proceeds from royalty purchase agreement	$ 20,000,000
Royalty Agreements
Accounting Policies [Line Items]
Proceeds from royalty purchase agreement		$ 20,000,000		$ 20,000,000	$ 40,000,000
Royalty Agreements \| Subsequent Event
Accounting Policies [Line Items]
Proceeds from royalty purchase agreement	$ 20,000,000
Minimum
Accounting Policies [Line Items]
Property, plant and equipment, estimated useful lives					3 years
Maximum
Accounting Policies [Line Items]
Property, plant and equipment, estimated useful lives					5 years
Maximum \| Royalty Agreements
Accounting Policies [Line Items]
Additional royalty purchase agreement					$ 20,000,000
Research and Development Expense
Accounting Policies [Line Items]
Maximum annual aggregate revenue for eligible to get refund							$ 20,000,000
US Treasury Securities
Accounting Policies [Line Items]
Short-term investments fair value					93,900,000	66,700,000		$ 93,900,000
Unrealized gain on short-term investments					$ 38,000	$ 3,000

Basis of Presentation and Significant Accounting Policies - Dilutive Securities Excluded from Computation of Diluted Weighted Average Shares of Common Stock Outstanding (Details) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities excluded from computation of earnings per share	3,537,946	21,133,118
Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities excluded from computation of earnings per share	3,537,946	2,071,616
Redeemable Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities excluded from computation of earnings per share		19,061,502

Fair Value Measurements - Summary of Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Level 1 \| Money Market Funds and U.S. Treasury Obligations
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents, at fair value	$ 17,447	$ 13,770
Level 1 \| Short- Term Investments
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments	93,934	66,706
Level 2 \| Money Market Funds and U.S. Treasury Obligations
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents, at fair value	0	0
Level 2 \| Short- Term Investments
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments	0	0
Level 3 \| Money Market Funds and U.S. Treasury Obligations
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents, at fair value	0	0
Level 3 \| Short- Term Investments
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments	$ 0	$ 0

Fair Value Measurements - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Changes in valuation techniques	$ 0	$ 0

Property and Equipment - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 1,375	$ 775
Less: Accumulated depreciation	(441)	(207)
Property and equipment, net	934	568
Laboratory Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	748	507
Computer Hardware and Software
Property Plant And Equipment [Line Items]
Property and equipment, gross	218	109
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	262
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 147	$ 159

Property and Equipment - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Property Plant And Equipment [Abstract]
Depreciation	$ 267	$ 127

Accrued Expenses - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Payables And Accruals [Abstract]
Compensation and related benefits	$ 1,160	$ 776
Research and development expenses	3,882	1,665
Professional fees	410	136
Accrued expenses	$ 5,452	$ 2,577

Royalty Purchase Liability - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended			12 Months Ended		14 Months Ended
	Feb. 29, 2020	Apr. 30, 2019	Nov. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019
Royalty Purchase Liability [Line Items]
Total agreed amount of royalty purchase price				$ 43,251	$ 20,220	$ 43,251
Royalty purchase price				20,000	20,000	$ 60,000
Noncash interest expense				3,031	220
Subsequent Event
Royalty Purchase Liability [Line Items]
Royalty purchase price	$ 20,000
Royalty Agreements
Royalty Purchase Liability [Line Items]
Total agreed amount of royalty purchase price			$ 80,000
Royalty purchase price		$ 20,000	20,000	40,000
Noncash interest expense				$ 3,000	$ 200
Effective interest rate				8.70%		8.70%
Outstanding amount of royalty agreement				$ 20,000		$ 20,000
Period of notice for termination of royalty agreement				2 days
Royalty Agreements \| Subsequent Event
Royalty Purchase Liability [Line Items]
Royalty purchase price	20,000
Royalty Agreements \| First Tranche
Royalty Purchase Liability [Line Items]
Royalty purchase price			$ 20,000
Royalty Agreements \| Second Tranche
Royalty Purchase Liability [Line Items]
Royalty purchase price		$ 20,000
Royalty Agreements \| Third Tranche \| Subsequent Event
Royalty Purchase Liability [Line Items]
Royalty purchase price	$ 20,000

Leases - Additional Information (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Lessee Lease Description [Line Items]
Operating lease liability, non current	$ 534
Operating lease, right-of-use asset	815
ASC 842
Lessee Lease Description [Line Items]
Operating lease liability, current	300
Operating lease liability, non current	800
Operating lease, right-of-use asset	$ 1,100
Operating lease, discount rate	5.30%
ASC 842 \| Office
Lessee Lease Description [Line Items]
Non-cancelable operating lease, term	3 years 2 months 12 days
ASC 842 \| Laboratory Space
Lessee Lease Description [Line Items]
Non-cancelable operating lease, term	1 year 1 month 6 days

Leases - Summary of Balance Sheet Information Related to Leases (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Leases [Abstract]
Operating lease right-of-use assets	$ 815
Other current liabilities	297
Operating lease liability, non current	534
Total operating lease liabilities	$ 831

Leases - Summary of Components of Lease Expense (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)
Leases [Abstract]
Operating lease rental expense	$ 265
Interest on lease liabilities	50
Total operating lease liabilities	$ 315

Leases - Summary of Supplemental Cash Flow Information Related to Lease (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)
Leases [Abstract]
Operating cash flows from operating leases	$ 437
Right-of-use assets obtained in exchange for lease obligation
Operating leases	$ 1,084

Leases - Summary of Operating Leases Liabilities Maturities (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Leases [Abstract]
2020	$ 332
2021	259
2022	260
2023	44
Total	895
Less: imputed interest	(64)
Operating lease liabilities	$ 831

Commitments - Additional Information (Details)	Dec. 31, 2019 Claim
Commitments And Contingencies Disclosure [Abstract]
Number of pending claims or legal actions	0

Redeemable Convertible Preferred Stock - Schedule of Redeemable Convertible Preferred Stock (Details) $ in Thousands	Dec. 31, 2018 USD ($) shares
Temporary Equity [Line Items]
Shares Authorized	96,385,795
Shares Issued	96,385,795
Shares Outstanding	96,385,795
Carrying Value \| $	$ 165,902
Liquidation Value \| $	$ 168,045
Series A
Temporary Equity [Line Items]
Shares Authorized	22,280,087
Shares Issued	22,280,087
Shares Outstanding	22,280,087
Carrying Value \| $	$ 28,685
Liquidation Value \| $	$ 29,301
Series B
Temporary Equity [Line Items]
Shares Authorized	29,682,000
Shares Issued	29,682,000
Shares Outstanding	29,682,000
Carrying Value \| $	$ 43,710
Liquidation Value \| $	$ 44,342
Series B-1
Temporary Equity [Line Items]
Shares Authorized	3,636,363
Shares Issued	3,636,363
Shares Outstanding	3,636,363
Carrying Value \| $	$ 5,777
Liquidation Value \| $	$ 5,884
Series B-2
Temporary Equity [Line Items]
Shares Authorized	9,090,909
Shares Issued	9,090,909
Shares Outstanding	9,090,909
Carrying Value \| $	$ 16,649
Liquidation Value \| $	$ 16,913
Series C
Temporary Equity [Line Items]
Shares Authorized	31,696,436
Shares Issued	31,696,436
Shares Outstanding	31,696,436
Carrying Value \| $	$ 71,081
Liquidation Value \| $	$ 71,605

Redeemable Convertible Preferred Stock - Additional Information (Details)	Nov. 12, 2019 shares
Temporary Equity Disclosure [Abstract]
Shares issued upon conversion	19,061,502

Share-based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	12 Months Ended
	Nov. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation cost		$ 9.2
Estimated recognition weighted-average amortization period		3 years 3 months 18 days
Aggregate intrinsic value of options outstanding		$ 28.3
Aggregate intrinsic value of options exercisable		$ 21.2
Weighted-average grant-date fair values of options granted		$ 6.66	$ 3.49
Expected dividend yield		0.00%	0.00%
2019 Incentive Award Plan \| Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares of common stock initially available for issuance	1,948,970
Percentage of shares of common stock outstanding	4.00%
Number of additional shares available for issuance	992,463
2019 Incentive Award Plan \| Common Stock \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares issued under the plan	14,130,029
2019 Employee Stock Purchase Plan \| Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of shares of common stock outstanding	1.00%
Number of additional shares available for issuance	248,115
Number of shares available for issuance	243,621
2019 Employee Stock Purchase Plan \| Common Stock \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares issued under the plan	3,288,886
2012 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for issuance		0
Number of shares authorized		3,038,259

Share-based Compensation - Summary of Share-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total share-based compensation expense	$ 2,390	$ 865
Research and Development Expense
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total share-based compensation expense	1,163	434
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total share-based compensation expense	$ 1,227	$ 431

Share-based Compensation - Summary of Activity Related to Stock Option Grants (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Shares, Outstanding beginning balance	2,071,616	2,025,376
Shares, Granted	1,646,054	68,982
Shares, Exercised	(3,778)
Shares, Forfeited	(175,946)	(22,742)
Shares, Outstanding ending balance	3,537,946	2,071,616
Shares, Vested and exercisable	2,014,887
Shares, Vested and expected to vest	3,537,946
Weighted average exercise price per share, Outstanding beginning balance	$ 2.17	$ 2.12
Weighted average exercise price per share, Granted	8.88	4.39
Weighted average exercise price per share, Exercised	2.60
Weighted average exercise price per share, Forfeited	4.50	4.40
Weighted average exercise price per share, Outstanding ending balance	5.17	$ 2.17
Weighted average exercise price per share, Vested and exercisable	2.63
Weighted average exercise price per share, Vested and expected to vest	$ 5.17
Weighted average remaining contractual life, Outstanding	7 years 3 months 18 days
Weighted average remaining contractual life, Vested and exercisable	5 years 10 months 24 days
Weighted average remaining contractual life, Vested and expected to vest	7 years 3 months 18 days

Share-based Compensation - Summary of Fair Value of Each Option Grant Estimated Throughout Year Using Black-Scholes Option-pricing Model (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions And Methodology [Abstract]
Expected term (in years)	6 years 2 months 12 days	7 years 9 months 18 days
Expected stock price volatility	89.70%	88.00%
Risk-free interest rate	2.26%	2.79%
Expected dividend yield	0.00%	0.00%

Income Taxes - Summary of Company's Loss Before Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Domestic	$ (49,918)	$ (22,779)
Foreign	(2,021)	(1,120)
Loss before income tax benefit	$ (51,939)	$ (23,899)

Income Taxes - Summary of Company's Tax Provision (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Current - Federal	$ 0	$ 0
Current - State	0	0
Current - Foreign	0	0
Current - Total	0	0
Deferred - Federal	194	(379)
Deferred - State	(203)	156
Deferred - Foreign	0	0
Deferred - Total	(9)	(223)
Total income tax benefit	$ (9)	$ (223)

Income Taxes - Summary of Effective Tax Rate of Reconciliation of Federal Income Tax Rate (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Federal tax benefit at statutory rate	21.00%	21.00%
State tax, net of federal benefit	4.30%	0.70%
Net operating loss carryforwards	(0.20%)	10.60%
Change in tax rate	(0.60%)	(0.40%)
Sale of royalty interest	(8.10%)	(17.60%)
Difference in foreign rate	0.40%	0.40%
Research & development	4.30%	3.30%
Change in valuation allowance	(19.50%)	(16.20%)
Share-based compensation	(0.40%)	(0.60%)
Other	(1.20%)	(0.30%)
Total provision		0.90%

Income Taxes - Schedule of Significant Portions of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets
Net operating loss carryforwards	$ 27,470	$ 19,733
Share-based compensation	511	118
Research & development credits	5,073	2,317
Accrued expenses and other		119
Gross deferred tax assets	33,054	22,287
Valuation allowance	(32,062)	(21,908)
Net deferred tax asset	992	379
Deferred tax liabilities
Accrued expenses and other	(613)
Acquired in-process research and development	(668)	(677)
Net deferred tax liabilities	$ (289)	$ (298)

Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Line Items]
Percentage of maximum offset indefinite lived deferred tax liability for net operating loss	80.00%
Income tax benefit	$ (9)	$ (223)
Income tax benefit	3 years
Tax credit carryforward, amount	50.00%
Accrued interest and penalties	$ 0
Tax Cuts and Jobs Act, Accounting Complete [true false]	true
Tax Cuts and Jobs Act, Accounting Complete, Date	Dec. 31, 2018
Federal
Income Tax Disclosure [Line Items]
Net operating loss carryforwards expiration date	Dec. 31, 2032
State
Income Tax Disclosure [Line Items]
Net operating loss carryforwards expiration date		Dec. 31, 2032
Research and Development \| Federal
Income Tax Disclosure [Line Items]
Tax credit carryforward, amount	$ 5,100
Tax credit carryforward expire date	Dec. 31, 2032
Research and Development \| State
Income Tax Disclosure [Line Items]
Tax credit carryforward, amount		$ 5,100
Tax credit carryforward expire date		Dec. 31, 2032
Valuation Allowance, Operating Loss Carryforward
Income Tax Disclosure [Line Items]
Increase in valuation allowance	$ 10,200	$ 3,900

Income Taxes - Summary of Carryforwards of Federal, State and Foreign NOLs and Tax Credits (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Federal
Operating Loss Carryforwards [Line Items]
Combined NOL Carryforwards	$ 91,472	$ 64,520
State
Operating Loss Carryforwards [Line Items]
Combined NOL Carryforwards	113,587	81,807
Foreign
Operating Loss Carryforwards [Line Items]
Combined NOL Carryforwards	$ 1,175	$ 812

Related Party Transactions (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
IntellectMap
Related Party Transaction [Line Items]
Advisory services fees	$ 0.3	$ 0.2