RAPT Therapeutics (RAPT) 10-Q 11 Aug 22 2022 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2022	Aug. 04, 2022
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q2
Trading Symbol	RAPT
Entity Registrant Name	RAPT Therapeutics, Inc.
Entity Central Index Key	0001673772
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity File Number	001-38997
Entity Tax Identification Number	47-3313701
Entity Address, Address Line One	561 Eccles Avenue
Entity Address, City or Town	South San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94080
City Area Code	650
Local Phone Number	489-9000
Entity Common Stock, Shares Outstanding		29,656,616
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common Stock $0.0001 par value per share
Security Exchange Name	NASDAQ
Entity Incorporation, State or Country Code	DE
Document Quarterly Report	true
Document Transition Report	false

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 57,203	$ 24,027
Marketable securities	150,138	165,627
Prepaid expenses and other current assets	2,588	3,319
Total current assets	209,929	192,973
Property and equipment, net	2,921	2,741
Operating lease right-of-use assets	6,055
Other assets	3,091	2,922
Total assets	221,996	198,636
Current liabilities:
Accounts payable	4,097	1,999
Accrued expenses	7,507	6,326
Deferred revenue, current		1,016
Operating lease liabilities, current	1,503
Other current liabilities	39	254
Total current liabilities	13,146	9,595
Deferred rent, net of current portion		2,150
Deferred revenue, non-current		511
Operating lease liabilities, non-current	6,717
Total liabilities	19,863	12,256
Commitments and contingencies
Stockholders' equity:
Preferred stock
Common stock	3	3
Additional paid-in capital	526,573	470,629
Accumulated other comprehensive loss	(745)	(206)
Accumulated deficit	(323,698)	(284,046)
Total stockholders' equity	202,133	186,380
Total liabilities and stockholders' equity	$ 221,996	$ 198,636

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Income Statement [Abstract]
Revenue	$ 886	$ 869	$ 1,527	$ 2,091
Operating expenses:
Research and development	14,359	13,190	31,029	26,961
General and administrative	5,436	3,760	10,184	7,772
Total operating expenses	19,795	16,950	41,213	34,733
Loss from operations	(18,909)	(16,081)	(39,686)	(32,642)
Other income (expense), net	(275)	(29)	34	18
Net loss	(19,184)	(16,110)	(39,652)	(32,624)
Other comprehensive income (loss):
Foreign currency translation gain	550	70	349	108
Unrealized loss on marketable securities	(178)	(18)	(888)	(68)
Total comprehensive loss	$ (18,812)	$ (16,058)	$ (40,191)	$ (32,584)
Net loss per share, basic	$ (0.62)	$ (0.63)	$ (1.31)	$ (1.29)
Net loss per share, diluted	$ (0.62)	$ (0.63)	$ (1.31)	$ (1.29)
Weighted average number of shares used in computing net loss per share, basic	31,140,323	25,589,947	30,356,515	25,217,542
Weighted average number of shares used in computing net loss per share, diluted	31,140,323	25,589,947	30,356,515	25,217,542

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) - USD ($) $ in Thousands	Total	At The Market	Public Offering	Common Stock	Common Stock At The Market	Common Stock Public Offering	Additional Paid-In Capital	Additional Paid-In Capital At The Market	Additional Paid-In Capital Public Offering	Accumulated Other Comprehensive Loss	Accumulated Deficit
Beginning balance at Dec. 31, 2020	$ 104,179			$ 2			$ 319,196			$ (177)	$ (214,842)
Beginning balance, shares at Dec. 31, 2020				24,773,361
Proceeds from issuance of common stock, net of issuance costs		$ 1,180						$ 1,180
Proceeds from issuance of common stock, net of issuance costs, shares					57,100
Proceeds from issuances of common stock under employee stock plans	121						121
Proceeds from issuances of common stock under employee stock plans, shares				31,620
Stock-based compensation	2,687						2,687
Foreign currency translation gain (loss)	38									38
Unrealized loss on marketable securities	(50)									(50)
Net loss	(16,514)										(16,514)
Ending balance at Mar. 31, 2021	91,641			$ 2			323,184			(189)	(231,356)
Ending balance, shares at Mar. 31, 2021				24,862,081
Beginning balance at Dec. 31, 2020	104,179			$ 2			319,196			(177)	(214,842)
Beginning balance, shares at Dec. 31, 2020				24,773,361
Foreign currency translation gain (loss)	108
Unrealized loss on marketable securities	(68)
Net loss	(32,624)
Ending balance at Jun. 30, 2021	217,579			$ 3			465,179			(137)	(247,466)
Ending balance, shares at Jun. 30, 2021				29,475,921
Beginning balance at Mar. 31, 2021	91,641			$ 2			323,184			(189)	(231,356)
Beginning balance, shares at Mar. 31, 2021				24,862,081
Proceeds from issuance of common stock, net of issuance costs		$ 3,510	$ 134,582			$ 1		$ 3,510	$ 134,581
Proceeds from issuance of common stock, net of issuance costs, shares					157,871	4,356,060
Proceeds from issuances of common stock under employee stock plans	1,016						1,016
Proceeds from issuances of common stock under employee stock plans, shares				99,909
Stock-based compensation	2,888						2,888
Foreign currency translation gain (loss)	70									70
Unrealized loss on marketable securities	(18)									(18)
Net loss	(16,110)										(16,110)
Ending balance at Jun. 30, 2021	217,579			$ 3			465,179			(137)	(247,466)
Ending balance, shares at Jun. 30, 2021				29,475,921
Beginning balance at Dec. 31, 2021	186,380			$ 3			470,629			(206)	(284,046)
Beginning balance, shares at Dec. 31, 2021				29,555,119
Proceeds from issuances of common stock under employee stock plans	132						132
Proceeds from issuances of common stock under employee stock plans, shares				37,640
Stock-based compensation	2,702						2,702
Foreign currency translation gain (loss)	(201)									(201)
Unrealized loss on marketable securities	(710)									(710)
Net loss	(20,468)										(20,468)
Ending balance at Mar. 31, 2022	167,835			$ 3			473,463			(1,117)	(304,514)
Ending balance, shares at Mar. 31, 2022				29,592,759
Beginning balance at Dec. 31, 2021	186,380			$ 3			470,629			(206)	(284,046)
Beginning balance, shares at Dec. 31, 2021				29,555,119
Foreign currency translation gain (loss)	349
Unrealized loss on marketable securities	(888)
Net loss	(39,652)
Ending balance at Jun. 30, 2022	202,133			$ 3			526,573			(745)	(323,698)
Ending balance, shares at Jun. 30, 2022				29,649,457
Beginning balance at Mar. 31, 2022	167,835			$ 3			473,463			(1,117)	(304,514)
Beginning balance, shares at Mar. 31, 2022				29,592,759
Proceeds from sale of pre-funded warrants in private placement, net of issuance costs	49,784						49,784
Proceeds from issuances of common stock under employee stock plans	654						654
Proceeds from issuances of common stock under employee stock plans, shares				56,698
Stock-based compensation	2,672						2,672
Foreign currency translation gain (loss)	550									550
Unrealized loss on marketable securities	(178)									(178)
Net loss	(19,184)										(19,184)
Ending balance at Jun. 30, 2022	$ 202,133			$ 3			$ 526,573			$ (745)	$ (323,698)
Ending balance, shares at Jun. 30, 2022				29,649,457

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Operating activities
Net loss	$ (39,652)	$ (32,624)
Adjustments to reconcile net loss to net cash used in operating activities:
Amortization of premium on marketable securities	507	430
Depreciation and amortization	535	536
Stock-based compensation expense	5,374	5,575
Gain on foreign currency translation	349	108
Non-cash operating lease expense	854	0
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	562	(563)
Accounts payable, accrued expenses and other current liabilities	3,300	471
Deferred revenue	(1,527)	(1,709)
Deferred rent	0	(50)
Operating lease liabilities	(1,075)	0
Net cash used in operating activities	(30,773)	(27,826)
Investing activities
Purchase of marketable securities	(72,241)	(118,705)
Proceeds from maturities of marketable securities	86,335	67,715
Purchase of property and equipment	(715)	(291)
Net cash provided by (used in) investing activities	13,379	(51,281)
Financing activities
Proceeds from equity offerings, net of issuance costs	49,784	134,582
Proceeds from issuance of common stock under employee stock plans	786	1,137
Net cash provided by financing activities	50,570	140,409
Net increase inn cash and cash equivalents	33,176	61,302
Cash and cash equivalents at beginning of period	24,027	24,918
Cash and cash equivalents at end of period	57,203	86,220
Supplemental disclosures of non-cash investing and financing information
Right-of-use asset obtained in exchange for lease obligation	(6,585)	0
Issuance costs related to public offering included in accrued expenses		403
At The Market
Financing activities
Proceeds from equity offerings, net of issuance costs	$ 0	$ 4,690

Organization

Organization	6 Months Ended
	Jun. 30, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	1. Organization Description of the Business RAPT Therapeutics, Inc. (“RAPT” or the “Company”) is a clinical-stage, immunology-based biopharmaceutical company focused on discovering, developing and commercializing oral small molecule therapies for patients with significant unmet needs in inflammatory diseases and oncology. Utilizing its proprietary drug discovery and development engine, the Company develops highly selective small molecules that are designed to modulate the critical immune responses underlying these diseases. The Company is located in South San Francisco, California. Equity Financing In May 2022, the Company completed the sale of pre-funded warrants to purchase 4,000,000 shares of its common stock at a price of $ 12.4999 per pre-funded warrant, which sale was done as a private investment in public equity ("PIPE") financing. Net proceeds received from the PIPE financing were approximately $ 49.8 million, after deducting $ 0.2 million of offering expenses. As of June 30, 2022 , all of the pre-funded warrants issued in the PIPE financing were outstanding (see Note 8).

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2022
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) for interim financial information and pursuant to Article 10 of Regulation S‑X of the Securities Act of 1933, as amended (the “Securities Act”). Accordingly, they do not include all of the information and notes required by U.S. GAAP for complete financial statements. These unaudited condensed consolidated financial statements include only normal and recurring adjustments that the Company believes are necessary to fairly state the Company’s financial position and the results of its operations and cash flows. Interim-period results are not necessarily indicative of results of operations or cash flows for a full year or any subsequent interim period. The condensed consolidated balance sheet at December 31, 2021 has been derived from the audited financial statements at that date but does not include all disclosures required by U.S. GAAP for complete financial statements. Because all of the disclosures required by U.S. GAAP for complete financial statements are not included herein, these unaudited condensed consolidated financial statements and the notes accompanying them should be read in conjunction with the Company’s audited consolidated financial statements included in its Annual Report on Form 10-K for the year ended December 31, 2021 filed on March 10, 2022 with the SEC. The accompanying consolidated financial statements have been prepared in accordance with U.S. GAAP and include the consolidated accounts of the Company and its wholly-owned subsidiary, RAPT Therapeutics Australia Pty Ltd. All intercompany balances and transactions have been eliminated in consolidation. Revenue License and collaborative agreement revenue consists of license, milestone and royalty payments generated through agreements with strategic partners for the development and commercialization of certain product candidates. The terms of an agreement may include a non-refundable upfront fee, payments based upon achievement of milestones and royalties on net product sales. If a portion of the nonrefundable upfront fee or other payments received is allocated to continuing performance obligations under the terms of an agreement, such portion is recorded as deferred revenue and recognized as revenue when or as the underlying performance obligation is satisfied. The Company recognizes revenue when it transfers promised goods or services to customers or counterparties in an amount that reflects the consideration to which the Company expects to be entitled in exchange for those goods or services. In determining the appropriate amount of revenue to be recognized, the Company performs the following steps: (i) identification of the promised goods or services in the agreement; (ii) determination of whether the promised goods or services are performance obligations, including whether they are distinct in the context of the agreement; (iii) measurement of the transaction price, including any constraint on variable consideration; (iv) allocation of the transaction price to performance obligations based on estimated selling prices; and (v) recognition of revenue when or as the Company satisfies each performance obligation. Licenses: If a license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in an agreement, the Company will recognize revenue from the nonrefundable, upfront fee allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. If a license is bundled with other performance obligations, the Company utilizes judgment to assess the nature of the combined performance obligations to determine whether the combined performance obligations are satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Milestone payments: If an agreement includes event-based or milestone payments, the Company evaluates whether the events or milestones are considered likely to be achieved and estimates the amount to be included in the transaction price using the most likely amount method. If it is unlikely that a significant revenue reversal would occur, the value of the associated event-based or milestone payments is included in the transaction price. Event-based or milestone payments that are not within the control of the Company are not included in the transaction price until they become likely to be achieved. Royalties: If an agreement includes sales-based royalties and the license is deemed to be the predominant item to which the royalties relate, the Company will recognize revenue at the later of (i) when the related sales occur or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied or partially satisfied. Stock-Based Compensation The Company measures stock-based compensation expense for all employee and non-employee stock-based awards based on their grant date fair value using the Black-Scholes option-pricing model. Subsequent to the adoption of ASU 2018-07, Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting , stock-based compensation expense for non-employee stock-based awards is also measured based on the grant date fair value with the estimated fair value expensed over the period for which the non-employee is required to provide service in exchange for the award. For stock-based awards with service conditions only, stock-based compensation expense is recognized over the requisite service period using the straight-line method. For awards with performance conditions, the Company evaluates the probability of achieving performance conditions at each reporting date. The Company recognizes stock-based compensation expense using an accelerated attribution method when it is deemed probable that the performance condition will be met. Forfeitures are recognized as they occur. The fair value of restricted stock awards granted after the Company’s initial public offering (“IPO”) is determined based on the stock price on the date of grant. The estimated fair value is amortized as compensation expense over the service period of the award. Stock-based compensation expense related to the Company’s employee stock purchase plan is recognized based on the fair value of each award estimated on the first day of the offering period using the Black‑Scholes option-pricing model and recorded as expense over the service period using the straight‑line method. 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 during the period, without consideration of potential dilutive securities. Diluted net loss per share is computed by dividing the net loss by the sum of the weighted average number of common shares outstanding during the period plus the number of potential dilutive securities outstanding during the period calculated in accordance with the treasury stock method. Diluted net loss per share is the same as basic net loss per share for all periods presented since the effect of including potential dilutive securities is anti-dilutive. Marketable Securities Marketable securities primarily consist of commercial paper, corporate bonds and U.S. government agency securities. The Company has classified its marketable securities as available-for-sale and may sell these securities prior to their stated maturities. The Company views these marketable securities as available to support current operations and classifies marketable securities with maturities beyond 12 months as current assets. The Company’s marketable securities are carried at estimated fair value, which is derived from independent pricing sources based on quoted prices in active markets for similar securities. Unrealized gains and losses are reported as a component of accumulated other comprehensive income (loss), net of tax. The amortized cost of marketable securities is adjusted for amortization of premiums and accretion of discounts to maturity, which is included in other income, net on the condensed consolidated statements of operations. Leases At inception of a contract, the Company determines whether an arrangement is or contains a lease. For all leases, the Company determines the classification as either operating leases or financing leases. Operating leases are included in operating lease right-of-use (“ROU”) assets and operating lease liabilities in the Company’s Condensed Consolidated Balance Sheets. Lease recognition occurs at the commencement date and lease liability amounts are based on the present value of lease payments over the lease term. The lease term may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. The Company uses an implicit rate when readily available, or its incremental borrowing rate based on the information available at lease commencement date, in determining the present value of lease payments. ROU assets represent our right to use underlying assets for the lease term and operating lease liabilities represent our obligation to make lease payments under the lease. ROU assets also include any lease payments made prior to the commencement date and exclude lease incentives received. Operating lease expense is recognized on a straight-line basis over the lease term. Lease agreements with both lease and nonlease components are generally accounted for together as a single lease component . Recent Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (the “FASB”) or other standard setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed, the impact of recently issued standards that are not yet effective will not have a material impact on the Company’s condensed consolidated financial statements upon adoption. Under the Jumpstart Our Business Startups Act of 2012, as amended (the “JOBS Act”), the Company meets the definition of an emerging growth company and has elected the extended transition period for complying with new or revised accounting standards pursuant to Section 107(b) of the JOBS Act. In June 2016, the FASB issued Accounting Standard Update (“ASU”) No. 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments . ASU 2016-13 amended the guidance on reporting credit losses for assets held at amortized cost basis and available-for-sale debt securities. For available-for-sale debt securities, credit losses will be presented as an allowance rather than as a write-down. In April 2019, the FASB issued ASU No. 2019-04, Codification Improvements to Topic 326, Financial Instruments—Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments , to increase awareness of the amendments and to expedite improvements to Topic 326. In May 2019, the FASB issued ASU No. 2019-05, Financial Instruments—Credit Losses, Topic 326 , which provided companies an option to irrevocably elect the fair value option for certain financial assets previously measured at amortized cost basis. These ASUs do not change the core principle of the guidance in ASU 2016-13; instead, these amendments are intended to clarify and improve operability of certain topics. In November 2019, the FASB issued ASU No. 2019-10, Financial Instruments—Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842): Effective Dates and ASU No. 2019-11, Codification Improvements to Topic 326, Financial Instruments—Credit Losses , which defer the effective date of the new credit loss standard. ASU 2016-13 and its related amendments are effective for the Company’s fiscal year beginning after December 15, 2022 and early adoption is permitted. The Company is currently assessing when it will adopt ASU 2016-13 and the impact that adoption will have on its condensed consolidated financial statements and related disclosures. In August 2020, the FASB issued ASU 2020-06, Debt - Debt with Conversion and other Options (Subtopic 470-20) and Derivatives and Hedging: Contracts in Entity’s Own Equity (Subtopic 815-40) (“ASU 2020-06”). ASU 2020-06 simplifies the complexity associated with applying GAAP for certain financial instruments with characteristics of liabilities and equity by removing certain accounting models that separate the embedded conversion features from the host contract for convertible instruments. The standard also enhances the consistency of earnings-per-share calculations by requiring that an entity use the if-converted method and that the effect of potential share settlement be included in diluted earnings-per-share calculations. ASU 2020-06 became effective for fiscal years and interim periods within those fiscal years beginning after December 15, 2021. The Company is currently assessing when it will adopt ASU 2020-06 and the impact that adoption will have on its condensed consolidated financial statements and related disclosures .

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2022
Fair Value Disclosures [Abstract]
Fair Value Measurements	3. Fair Value Measurements Fair value accounting is applied for all financial assets and liabilities that are recognized or disclosed at fair value in the financial statements on a recurring basis. Financial instruments such as cash and cash equivalents, accounts payable and accrued liabilities approximate fair value due to their relatively short maturities. Assets and liabilities recorded at fair value on a recurring basis in the balance sheet are categorized based on the level of judgment associated with the inputs used to measure their fair values. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The authoritative guidance on fair value measurements establishes a three-tier fair value hierarchy for disclosure of fair value measurements as follows: Level 1—Inputs are unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date; Level 2—Inputs are observable, unadjusted quoted prices in active markets for similar assets or liabilities, unadjusted quoted prices for identical or similar assets or liabilities in markets that are not active or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities; and Level 3—Unobservable inputs that are significant to the measurement of the fair value of the assets or liabilities that are supported by little or no market data. To date, the Company has not recorded any impairment charges on marketable securities due to other-than-temporary declines in market value. In determining whether a decline is other than temporary, the Company considers various factors, including the length of time and extent to which the market value has been less than amortized cost, the financial condition and near-term prospects of the issuer and the Company’s intent and ability to retain its investment in the issuer for a period of time sufficient to allow for any anticipated recovery in market value. The Company estimates the fair values of investments in corporate debt securities, commercial paper and U.S. government agency securities using valuations obtained from third-party pricing services. The pricing services utilize industry standard valuation models, including both income and market-based approaches, for which all significant inputs are observable, either directly or indirectly, to estimate fair value. These inputs include reported trades of and broker/dealer quotes on the same or similar securities, issuer credit spreads, benchmark securities, prepayment/default projections based on historical data and other observable inputs. Cash equivalents and marketable securities, all of which are classified as available-for-sale securities and measured at fair value on a recurring basis, consisted of the following (in thousands): As of June 30, 2022 Fair Value Amortized Unrealized Unrealized Fair Financial assets: Money market funds—classified Level 1 $ 55,827 $ — $ — $ 55,827 Corporate debt Level 2 65,084 6 ( 578 ) 64,512 Commercial paper Level 2 38,963 — — 38,963 U.S. government agency securities Level 2 47,214 — ( 551 ) 46,663 Total $ 207,088 $ 6 $ ( 1,129 ) $ 205,965 As of December 31, 2021 Fair Value Amortized Unrealized Unrealized Fair Financial assets: Money market funds—classified Level 1 $ 22,658 $ — $ — $ 22,658 Corporate debt Level 2 52,704 — ( 139 ) 52,565 Asset-backed securities Level 2 23,882 — ( 21 ) 23,861 Commercial paper Level 2 59,532 — — 59,532 U.S. government agency securities Level 2 29,744 — ( 75 ) 29,669 Total $ 188,520 $ — $ ( 235 ) $ 188,285 The Company does not intend to sell the securities that are in an unrealized loss position and the Company believes it is more likely than not that the investments will be held until recovery of the amortized cost bases. The Company has determined that the gross unrealized losses on marketable securities as of June 30, 2022 were temporary in nature. The following table presents the remaining contractual maturities of the Company’s marketable securities as of June 30, 2022 (in thousands): June 30, 2022 Due in less than one year $ 205,965 Due in more than one year — Total $ 205,965

Property and Equipment

Property and Equipment	6 Months Ended
	Jun. 30, 2022
Property, Plant and Equipment [Abstract]
Property and Equipment	4. Property and Equipment Property and equipment consisted of the following (in thousands): June 30, December 31, 2022 2021 Laboratory equipment $ 6,573 $ 6,291 Leasehold improvements 3,295 3,295 Computer equipment 464 482 Furniture and fixtures 394 357 Total property and equipment 10,726 10,425 Less accumulated depreciation and amortization ( 7,805 ) ( 7,684 ) Property and equipment, net $ 2,921 $ 2,741 Depreciation and amortization expense was $ 0.2 million and $ 0.2 million for the three months ended June 30, 2022 and 2021 , and $ 0.5 million and $ 0.5 million for the six months ended June 30, 2022 and 2021 , respectively.

Accrued Expenses

Accrued Expenses	6 Months Ended
	Jun. 30, 2022
Payables and Accruals [Abstract]
Accrued Expenses	5. Accrued Expenses Accrued expenses consisted of the following (in thousands): June 30, December 31, 2022 2021 Accrued research and development expenses $ 3,978 $ 2,205 Accrued compensation 2,877 3,652 Accrued professional and consulting services 525 415 Other 127 54 Total accrued expenses $ 7,507 $ 6,326

Leases

Leases	6 Months Ended
	Jun. 30, 2022
Leases [Abstract]
Leases	6. Leases The Company adopted ASU No. 2016-02, Leases (Topic 842) on January 1, 2022 using the modified retrospective approach. The Company elected to apply the modified retrospective approach that allowed it to continue applying the guidance in effect, at the time of adoption, in the comparative periods presented in the Condensed Consolidated Balance Sheets and recognize a cumulative-effect adjustment to the opening balance of accumulated deficit on the date of adoption. The Company also elected the package of practical expedients, which permits it not to reassess under the new standard the prior conclusions about lease identification, lease classification and initial direct costs. Lastly, the Company elected the short-term lease practical expedients allowed under the standard and the practical expedient to use hindsight in determining the lease term for all its leases. As a result of applying the modified retrospective approach to adopt the lease guidance, the following adjustments were made to accounts on the Condensed Consolidated Balance Sheet as of January 1, 2022 (in thousands): Balance Sheet December 31, 2021 Effect of January 1, Assets Operating lease right-of-use assets $ — $ 6,585 $ 6,585 Total assets $ — $ 6,585 $ 6,585 Liabilities Operating lease liabilities, current $ — $ 1,471 $ 1,471 Deferred rent (1) 2,386 ( 2,386 ) — Operating lease liabilities, non-current — 7,500 7,500 Total Lease Liabilities $ 2,386 $ 6,585 $ 8,971 (1) Included in other liabilities and deferred rent, net of current portion on the balance sheet. In May 2015, the Company entered into an operating lease for 30,376 square feet of laboratory and office facilities in South San Francisco, California, which was to expire in May 2022 . In April 2018, the Company amended the lease agreement to include an additional 6,378 square feet of laboratory and office space increasing the total leased premises to 36,754 square feet. The lease amendment extended the lease term to November 2026 and contained scheduled rent increases over the lease term and an option for the Company to extend the lease for an additional five-year term. The Company does not have any financing lease agreements as of June 30, 2022. The following table summarizes maturities of operating lease liabilities as of June 30, 2022 (in thousands): 2022 (remaining six months) $ 1,022 2023 2,109 2024 2,183 2025 2,259 2026 2,137 Thereafter — Total future undiscounted lease payments 9,710 Less: Imputed interest ( 1,490 ) Total Lease Liabilities $ 8,220 The following table summarizes the balance sheet classification of operating leases at June 30, 2022 (in thousands): Operating leases Operating lease right-of-use assets $ 6,055 Operating lease liabilities, current 1,503 Operating lease liabilities, non-current 6,717 Total operating lease liabilities $ 8,220 For the three and six months ended June 30, 2022 , the Company incurred $ 0.4 million and $ 0.9 million, respectively, of lease expense included in operating expenses in the condensed consolidated statement of operations in relation to the operating lease. Variable lease expense was insignificant for the three and six months ended June 30, 2022 , respectively. Rent expense was $ 0.4 million and $ 0.9 million during the three and six months ended June 30, 2022, respectively. Cash paid for amounts included in the measurement of operating lease liabilities for the six months ended June 30, 2022 was $ 1.1 mill ion and was included in net cash used in operating activities in the Company’s condensed consolidated statements of cash flows. As of June 30, 2022 , the weighted-average remaining lease term and discount rate for the Company’s operating leases was 4.42 years and 8 %, respectively.

Collaboration Agreements

Collaboration Agreements	6 Months Ended
	Jun. 30, 2022
Collaboration Agreements [Abstract]
Collaboration Agreements	7. Collaboration Agreements Collaboration and License Agreement with Hanmi In December 2019, the Company entered into a Collaboration and License Agreement (the “Hanmi Agreement”) with Hanmi Pharmaceutical Ltd. (“Hanmi”), pursuant to which the Company granted Hanmi an exclusive license to develop, manufacture and commercialize FLX475 and related compounds and products with respect to human cancers in the Republic of Korea, the Republic of China (Taiwan) and the People’s Republic of China, including the special administrative regions of Macau and Hong Kong (the “Hanmi Territory”), and certain sublicense rights. In consideration of the rights granted under the Hanmi Agreement, the Company was entitled to $ 10.0 million in an upfront payment of $ 4.0 million and a near-term milestone payment of $ 6.0 million. The milestone payment was received in April 2020. Additionally, the Company will be eligible to receive contingent payments of up to $ 108.0 million upon the achievement of specified milestones, as well as double-digit royalties on future net sales of FLX475 in the Hanmi Territory. The transaction price as of June 30, 2022 was $ 10.4 million, consisting of the upfront fee of $ 4.0 million, the near-term milestone payment of $ 6.0 million and $ 0.4 million related to the supply of FLX475 to Hanmi. The Company recognizes revenue for the performance obligation by applying the cost-based input method over the estimated service period. The Company determined that this method most faithfully depicts the transfer of its performance obligations to Hanmi as it reflects the progress made towards providing Hanmi with the necessary know-how to continue developing FLX475 in the Hanmi Territory. The Company recognized $ 0.9 million and $ 1.5 million for the three and six months ended June 30, 2022 , respectively, and $ 0.9 million and $ 2.1 million for the three and six months ended June 30, 2021, respectively, as revenue pursuant to the Hanmi Agreement. As of June 30, 2022 there was no remaining deferred revenue related to the Hanmi Agreement, as the performance obligation of providing Hanmi with the necessary know-how to develop FLX475 in the Hanmi Territory was substantially complete as of that date. As of December 31, 2021 , deferred revenue related to the Hanmi Agreement was $ 1.5 million.

Common Stock

Common Stock	6 Months Ended
	Jun. 30, 2022
Equity [Abstract]
Common Stock	8. Common Stock As of June 30, 2022, the Company had reserved the following shares of common stock for future issuance: Options issued and outstanding under the 2019 Equity Incentive Plan and 2,907,596 Restricted stock units issued and outstanding under the 2019 Equity 27,000 Options available for future grants under the 2019 Equity Incentive Plan 2,942,751 Pre-funded warrants issued and outstanding 4,000,000 Shares reserved under the 2019 Employee Stock Purchase Plan 518,870 Total 10,396,217 As of June 30, 2022 , there was up to $ 90.9 million available for future issuance of shares of common stock under the Controlled Equity Offering SM Sales Agreement with Cantor Fitzgerald & Co. and Stifel, Nicolaus & Company, Incorporated (the “ATM Sales Agreement”). In May 2022, through the PIPE financing, the Company issued pre-funded warrants to purchase an aggregate of 4,000,000 shares of the Company’s common stock. Each pre-funded warrant has an exercise price of $ 0.0001 per share. The purchase price per pre-funded warrant was $ 12.4999 (representing the $ 12.50 per share closing price of the common stock on May 24, 2022, less the exercise price of $ 0.0001 per pre-funded warrant). The PIPE financing resulted in net proceeds of $ 49.8 million, after deducting $ 0.2 million of offering expenses. As of June 30, 2022, all the pre-funded warrants issued in the PIPE financing were outstanding. The pre-funded warrants issued provide that the holder will not have the right to exercise any portion of the pre-funded warrants if such holder, together with its affiliates, would beneficially own in excess of 9.99 % of the number of shares of the Company's common stock outstanding immediately after giving effect to such exercise (the “Beneficial Ownership Limitation”); provided, however, that the holder may increase or decrease the Beneficial Ownership Limitation by giving 61 days’ notice to the Company, but not to any percentage in excess of 19.99 %. The pre-funded warrants were classified as a component of permanent equity in the Company's condensed consolidated balance sheet as they are freestanding financial instruments that are immediately exercisable, do not embody an obligation for the Company to repurchase its shares and permit the holders to receive a fixed number of shares of common stock upon exercise.

Stock-based Compensation

Stock-based Compensation	6 Months Ended
	Jun. 30, 2022
Share-Based Payment Arrangement [Abstract]
Stock-based Compensation	9. Stock-based Compensatio n Stock option activity under the 2019 Equity Incentive Plan (the “2019 Plan”) is set forth below for the six months ended June 30, 2022: Weighted Average Average Remaining Aggregate Number of Exercise Contractual Intrinsic Shares Price Per Term Value Outstanding Share (Years) (in thousands) Balances at December 31, 2021 2,024,681 $ 18.33 8.0 $ 38,417 Stock options authorized — Stock options granted 1,005,432 19.39 Stock options exercised ( 44,910 ) 8.24 Stock options forfeited ( 77,607 ) 24.96 Balances at June 30, 2022 2,907,596 $ 18.67 8.3 $ 8,158 As of June 30, 2022 , 2,942,751 shares remained available for issuance under the 2019 Plan. Restricted stock unit (“RSU”) activity under the 2019 Plan is set forth below for the six months ended June 30, 2022: Weighted Average Number of Grant Date Shares Fair Value Outstanding Per Share Balances at December 31, 2021 40,500 $ 44.66 RSUs granted — — RSUs vested and settled ( 13,500 ) 44.66 RSUs forfeited — — Balances at June 30, 2022 27,000 $ 44.66 Stock-based compensation expense Total stock-based compensation expense recognized for options and RSUs granted to both employees and non-employees and for the 2019 Employee Stock Purchase Plan (the “2019 ESPP”) was as follows (in thousands): For the Three Months Ended June 30, For the Six Months Ended June 30, 2022 2021 2022 2021 Research and development $ 1,269 $ 1,627 $ 2,448 $ 3,101 General and administrative 1,403 1,261 2,926 2,474 Total stock-based compensation expense $ 2,672 $ 2,888 $ 5,374 $ 5,575 As of June 30, 2022 , unrecognized stock-based compensation expense related to outstanding unvested stock options and RSUs that are expected to vest was $ 24.2 million. This unrecognized stock-based compensation expense is expected to be recognized over 2.8 years. The Company recorded stock-based compensation expense related to the 2019 ESPP of $ 0.2 million and $ 0.3 million for the three and six months ended June 30, 2022 , respectively, and $ 1.0 million and $ 1.8 million for the three and six months ended June 30, 2021 , respectively.

Net Loss Per Share

Net Loss Per Share	6 Months Ended
	Jun. 30, 2022
Earnings Per Share [Abstract]
Net Loss Per Share	10. Net Loss Per Share Net loss per share The following table sets forth the computation of the basic and diluted net loss per share for the three and six months ended June 30, 2022 and 2021 (in thousands, except share and per share data): Three Months Ended Six Months Ended 2022 2021 2022 2021 Numerator: Net loss $ ( 19,184 ) $ ( 16,110 ) $ ( 39,652 ) $ ( 32,624 ) Denominator: Weighted-average shares used to compute net loss per 31,140,323 25,589,947 30,356,515 25,217,542 Net loss per share, basic and diluted $ ( 0.62 ) $ ( 0.63 ) $ ( 1.31 ) $ ( 1.29 ) As of June 30, 2022, 4,000,000 pre-funded warrants to purchase the Company's shares of common stock, issued in the May 2022 PIPE financing (see Note 8), were included in the basic and diluted net loss per share calculation. Potential dilutive securities that were not included in the diluted per share calculations because they would be anti-dilutive were as follows: As of June 30, 2022 2021 Stock options issued and outstanding under the 2019 2,907,596 1,984,626 Estimated shares issuable under the 2019 ESPP 7,946 9,965 RSUs subject to future vesting 27,000 40,500 Total 2,942,542 2,035,091

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2022
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) for interim financial information and pursuant to Article 10 of Regulation S‑X of the Securities Act of 1933, as amended (the “Securities Act”). Accordingly, they do not include all of the information and notes required by U.S. GAAP for complete financial statements. These unaudited condensed consolidated financial statements include only normal and recurring adjustments that the Company believes are necessary to fairly state the Company’s financial position and the results of its operations and cash flows. Interim-period results are not necessarily indicative of results of operations or cash flows for a full year or any subsequent interim period. The condensed consolidated balance sheet at December 31, 2021 has been derived from the audited financial statements at that date but does not include all disclosures required by U.S. GAAP for complete financial statements. Because all of the disclosures required by U.S. GAAP for complete financial statements are not included herein, these unaudited condensed consolidated financial statements and the notes accompanying them should be read in conjunction with the Company’s audited consolidated financial statements included in its Annual Report on Form 10-K for the year ended December 31, 2021 filed on March 10, 2022 with the SEC. The accompanying consolidated financial statements have been prepared in accordance with U.S. GAAP and include the consolidated accounts of the Company and its wholly-owned subsidiary, RAPT Therapeutics Australia Pty Ltd. All intercompany balances and transactions have been eliminated in consolidation.
Revenue	Revenue License and collaborative agreement revenue consists of license, milestone and royalty payments generated through agreements with strategic partners for the development and commercialization of certain product candidates. The terms of an agreement may include a non-refundable upfront fee, payments based upon achievement of milestones and royalties on net product sales. If a portion of the nonrefundable upfront fee or other payments received is allocated to continuing performance obligations under the terms of an agreement, such portion is recorded as deferred revenue and recognized as revenue when or as the underlying performance obligation is satisfied. The Company recognizes revenue when it transfers promised goods or services to customers or counterparties in an amount that reflects the consideration to which the Company expects to be entitled in exchange for those goods or services. In determining the appropriate amount of revenue to be recognized, the Company performs the following steps: (i) identification of the promised goods or services in the agreement; (ii) determination of whether the promised goods or services are performance obligations, including whether they are distinct in the context of the agreement; (iii) measurement of the transaction price, including any constraint on variable consideration; (iv) allocation of the transaction price to performance obligations based on estimated selling prices; and (v) recognition of revenue when or as the Company satisfies each performance obligation. Licenses: If a license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in an agreement, the Company will recognize revenue from the nonrefundable, upfront fee allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. If a license is bundled with other performance obligations, the Company utilizes judgment to assess the nature of the combined performance obligations to determine whether the combined performance obligations are satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Milestone payments: If an agreement includes event-based or milestone payments, the Company evaluates whether the events or milestones are considered likely to be achieved and estimates the amount to be included in the transaction price using the most likely amount method. If it is unlikely that a significant revenue reversal would occur, the value of the associated event-based or milestone payments is included in the transaction price. Event-based or milestone payments that are not within the control of the Company are not included in the transaction price until they become likely to be achieved. Royalties: If an agreement includes sales-based royalties and the license is deemed to be the predominant item to which the royalties relate, the Company will recognize revenue at the later of (i) when the related sales occur or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied or partially satisfied.
Stock-Based Compensation	Stock-Based Compensation The Company measures stock-based compensation expense for all employee and non-employee stock-based awards based on their grant date fair value using the Black-Scholes option-pricing model. Subsequent to the adoption of ASU 2018-07, Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting , stock-based compensation expense for non-employee stock-based awards is also measured based on the grant date fair value with the estimated fair value expensed over the period for which the non-employee is required to provide service in exchange for the award. For stock-based awards with service conditions only, stock-based compensation expense is recognized over the requisite service period using the straight-line method. For awards with performance conditions, the Company evaluates the probability of achieving performance conditions at each reporting date. The Company recognizes stock-based compensation expense using an accelerated attribution method when it is deemed probable that the performance condition will be met. Forfeitures are recognized as they occur. The fair value of restricted stock awards granted after the Company’s initial public offering (“IPO”) is determined based on the stock price on the date of grant. The estimated fair value is amortized as compensation expense over the service period of the award. Stock-based compensation expense related to the Company’s employee stock purchase plan is recognized based on the fair value of each award estimated on the first day of the offering period using the Black‑Scholes option-pricing model and recorded as expense over the service period using the straight‑line method.
Net Loss Per Share	Net Loss Per Share Basic net loss per share is computed by dividing the net loss by the weighted average number of common shares outstanding during the period, without consideration of potential dilutive securities. Diluted net loss per share is computed by dividing the net loss by the sum of the weighted average number of common shares outstanding during the period plus the number of potential dilutive securities outstanding during the period calculated in accordance with the treasury stock method. Diluted net loss per share is the same as basic net loss per share for all periods presented since the effect of including potential dilutive securities is anti-dilutive.
Marketable Securities	Marketable Securities Marketable securities primarily consist of commercial paper, corporate bonds and U.S. government agency securities. The Company has classified its marketable securities as available-for-sale and may sell these securities prior to their stated maturities. The Company views these marketable securities as available to support current operations and classifies marketable securities with maturities beyond 12 months as current assets. The Company’s marketable securities are carried at estimated fair value, which is derived from independent pricing sources based on quoted prices in active markets for similar securities. Unrealized gains and losses are reported as a component of accumulated other comprehensive income (loss), net of tax. The amortized cost of marketable securities is adjusted for amortization of premiums and accretion of discounts to maturity, which is included in other income, net on the condensed consolidated statements of operations.
Leases	Leases At inception of a contract, the Company determines whether an arrangement is or contains a lease. For all leases, the Company determines the classification as either operating leases or financing leases. Operating leases are included in operating lease right-of-use (“ROU”) assets and operating lease liabilities in the Company’s Condensed Consolidated Balance Sheets. Lease recognition occurs at the commencement date and lease liability amounts are based on the present value of lease payments over the lease term. The lease term may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. The Company uses an implicit rate when readily available, or its incremental borrowing rate based on the information available at lease commencement date, in determining the present value of lease payments. ROU assets represent our right to use underlying assets for the lease term and operating lease liabilities represent our obligation to make lease payments under the lease. ROU assets also include any lease payments made prior to the commencement date and exclude lease incentives received. Operating lease expense is recognized on a straight-line basis over the lease term. Lease agreements with both lease and nonlease components are generally accounted for together as a single lease component .
Recent Accounting Pronouncements	Recent Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (the “FASB”) or other standard setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed, the impact of recently issued standards that are not yet effective will not have a material impact on the Company’s condensed consolidated financial statements upon adoption. Under the Jumpstart Our Business Startups Act of 2012, as amended (the “JOBS Act”), the Company meets the definition of an emerging growth company and has elected the extended transition period for complying with new or revised accounting standards pursuant to Section 107(b) of the JOBS Act. In June 2016, the FASB issued Accounting Standard Update (“ASU”) No. 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments . ASU 2016-13 amended the guidance on reporting credit losses for assets held at amortized cost basis and available-for-sale debt securities. For available-for-sale debt securities, credit losses will be presented as an allowance rather than as a write-down. In April 2019, the FASB issued ASU No. 2019-04, Codification Improvements to Topic 326, Financial Instruments—Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments , to increase awareness of the amendments and to expedite improvements to Topic 326. In May 2019, the FASB issued ASU No. 2019-05, Financial Instruments—Credit Losses, Topic 326 , which provided companies an option to irrevocably elect the fair value option for certain financial assets previously measured at amortized cost basis. These ASUs do not change the core principle of the guidance in ASU 2016-13; instead, these amendments are intended to clarify and improve operability of certain topics. In November 2019, the FASB issued ASU No. 2019-10, Financial Instruments—Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842): Effective Dates and ASU No. 2019-11, Codification Improvements to Topic 326, Financial Instruments—Credit Losses , which defer the effective date of the new credit loss standard. ASU 2016-13 and its related amendments are effective for the Company’s fiscal year beginning after December 15, 2022 and early adoption is permitted. The Company is currently assessing when it will adopt ASU 2016-13 and the impact that adoption will have on its condensed consolidated financial statements and related disclosures. In August 2020, the FASB issued ASU 2020-06, Debt - Debt with Conversion and other Options (Subtopic 470-20) and Derivatives and Hedging: Contracts in Entity’s Own Equity (Subtopic 815-40) (“ASU 2020-06”). ASU 2020-06 simplifies the complexity associated with applying GAAP for certain financial instruments with characteristics of liabilities and equity by removing certain accounting models that separate the embedded conversion features from the host contract for convertible instruments. The standard also enhances the consistency of earnings-per-share calculations by requiring that an entity use the if-converted method and that the effect of potential share settlement be included in diluted earnings-per-share calculations. ASU 2020-06 became effective for fiscal years and interim periods within those fiscal years beginning after December 15, 2021. The Company is currently assessing when it will adopt ASU 2020-06 and the impact that adoption will have on its condensed consolidated financial statements and related disclosures .

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2022
Fair Value Disclosures [Abstract]
Schedule of Cash Equivalents and Marketable Securities Classified as Available-for-Sale Securities Measured at Fair Value on Recurring Basis	Cash equivalents and marketable securities, all of which are classified as available-for-sale securities and measured at fair value on a recurring basis, consisted of the following (in thousands): As of June 30, 2022 Fair Value Amortized Unrealized Unrealized Fair Financial assets: Money market funds—classified Level 1 $ 55,827 $ — $ — $ 55,827 Corporate debt Level 2 65,084 6 ( 578 ) 64,512 Commercial paper Level 2 38,963 — — 38,963 U.S. government agency securities Level 2 47,214 — ( 551 ) 46,663 Total $ 207,088 $ 6 $ ( 1,129 ) $ 205,965 As of December 31, 2021 Fair Value Amortized Unrealized Unrealized Fair Financial assets: Money market funds—classified Level 1 $ 22,658 $ — $ — $ 22,658 Corporate debt Level 2 52,704 — ( 139 ) 52,565 Asset-backed securities Level 2 23,882 — ( 21 ) 23,861 Commercial paper Level 2 59,532 — — 59,532 U.S. government agency securities Level 2 29,744 — ( 75 ) 29,669 Total $ 188,520 $ — $ ( 235 ) $ 188,285
Schedule of Remaining Contractual Maturities of Marketable Securities	The following table presents the remaining contractual maturities of the Company’s marketable securities as of June 30, 2022 (in thousands): June 30, 2022 Due in less than one year $ 205,965 Due in more than one year — Total $ 205,965

Property and Equipment (Tables)

Property and Equipment (Tables)	6 Months Ended
	Jun. 30, 2022
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment	Property and equipment consisted of the following (in thousands): June 30, December 31, 2022 2021 Laboratory equipment $ 6,573 $ 6,291 Leasehold improvements 3,295 3,295 Computer equipment 464 482 Furniture and fixtures 394 357 Total property and equipment 10,726 10,425 Less accumulated depreciation and amortization ( 7,805 ) ( 7,684 ) Property and equipment, net $ 2,921 $ 2,741

Accrued Expenses (Tables)

Accrued Expenses (Tables)	6 Months Ended
	Jun. 30, 2022
Payables and Accruals [Abstract]
Schedule of Accrued Expenses	Accrued expenses consisted of the following (in thousands): June 30, December 31, 2022 2021 Accrued research and development expenses $ 3,978 $ 2,205 Accrued compensation 2,877 3,652 Accrued professional and consulting services 525 415 Other 127 54 Total accrued expenses $ 7,507 $ 6,326

Leases (Tables)

Leases (Tables)	6 Months Ended
	Jun. 30, 2022
Leases [Abstract]
Summary of Balance Sheets Adjustments Related to Lease Accounting Standard Update	As a result of applying the modified retrospective approach to adopt the lease guidance, the following adjustments were made to accounts on the Condensed Consolidated Balance Sheet as of January 1, 2022 (in thousands): Balance Sheet December 31, 2021 Effect of January 1, Assets Operating lease right-of-use assets $ — $ 6,585 $ 6,585 Total assets $ — $ 6,585 $ 6,585 Liabilities Operating lease liabilities, current $ — $ 1,471 $ 1,471 Deferred rent (1) 2,386 ( 2,386 ) — Operating lease liabilities, non-current — 7,500 7,500 Total Lease Liabilities $ 2,386 $ 6,585 $ 8,971 (1) Included in other liabilities and deferred rent, net of current portion on the balance sheet.
Summary of Maturities of Lease Liabilities	The following table summarizes maturities of operating lease liabilities as of June 30, 2022 (in thousands): 2022 (remaining six months) $ 1,022 2023 2,109 2024 2,183 2025 2,259 2026 2,137 Thereafter — Total future undiscounted lease payments 9,710 Less: Imputed interest ( 1,490 ) Total Lease Liabilities $ 8,220
Summary of Balance Sheet Classification of Leases	The following table summarizes the balance sheet classification of operating leases at June 30, 2022 (in thousands): Operating leases Operating lease right-of-use assets $ 6,055 Operating lease liabilities, current 1,503 Operating lease liabilities, non-current 6,717 Total operating lease liabilities $ 8,220

Common Stock (Tables)

Common Stock (Tables)	6 Months Ended
	Jun. 30, 2022
Equity [Abstract]
Summary of Reserved Shares of Common Stock for Future Issuance	As of June 30, 2022, the Company had reserved the following shares of common stock for future issuance: Options issued and outstanding under the 2019 Equity Incentive Plan and 2,907,596 Restricted stock units issued and outstanding under the 2019 Equity 27,000 Options available for future grants under the 2019 Equity Incentive Plan 2,942,751 Pre-funded warrants issued and outstanding 4,000,000 Shares reserved under the 2019 Employee Stock Purchase Plan 518,870 Total 10,396,217

Stock-based Compensation (Table

Stock-based Compensation (Tables)	6 Months Ended
	Jun. 30, 2022
Share-Based Payment Arrangement [Abstract]
Summary of Stock Option Activity	Stock option activity under the 2019 Equity Incentive Plan (the “2019 Plan”) is set forth below for the six months ended June 30, 2022: Weighted Average Average Remaining Aggregate Number of Exercise Contractual Intrinsic Shares Price Per Term Value Outstanding Share (Years) (in thousands) Balances at December 31, 2021 2,024,681 $ 18.33 8.0 $ 38,417 Stock options authorized — Stock options granted 1,005,432 19.39 Stock options exercised ( 44,910 ) 8.24 Stock options forfeited ( 77,607 ) 24.96 Balances at June 30, 2022 2,907,596 $ 18.67 8.3 $ 8,158
Summary of RSU Activity	Restricted stock unit (“RSU”) activity under the 2019 Plan is set forth below for the six months ended June 30, 2022: Weighted Average Number of Grant Date Shares Fair Value Outstanding Per Share Balances at December 31, 2021 40,500 $ 44.66 RSUs granted — — RSUs vested and settled ( 13,500 ) 44.66 RSUs forfeited — — Balances at June 30, 2022 27,000 $ 44.66
Summary of Stock-based Compensation Expense	Total stock-based compensation expense recognized for options and RSUs granted to both employees and non-employees and for the 2019 Employee Stock Purchase Plan (the “2019 ESPP”) was as follows (in thousands): For the Three Months Ended June 30, For the Six Months Ended June 30, 2022 2021 2022 2021 Research and development $ 1,269 $ 1,627 $ 2,448 $ 3,101 General and administrative 1,403 1,261 2,926 2,474 Total stock-based compensation expense $ 2,672 $ 2,888 $ 5,374 $ 5,575

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	6 Months Ended
	Jun. 30, 2022
Earnings Per Share [Abstract]
Computation of Basic and Diluted Net Loss per Share	The following table sets forth the computation of the basic and diluted net loss per share for the three and six months ended June 30, 2022 and 2021 (in thousands, except share and per share data): Three Months Ended Six Months Ended 2022 2021 2022 2021 Numerator: Net loss $ ( 19,184 ) $ ( 16,110 ) $ ( 39,652 ) $ ( 32,624 ) Denominator: Weighted-average shares used to compute net loss per 31,140,323 25,589,947 30,356,515 25,217,542 Net loss per share, basic and diluted $ ( 0.62 ) $ ( 0.63 ) $ ( 1.31 ) $ ( 1.29 )
Potential Dilutive Securities not Included in Diluted per Share Calculations	Potential dilutive securities that were not included in the diluted per share calculations because they would be anti-dilutive were as follows: As of June 30, 2022 2021 Stock options issued and outstanding under the 2019 2,907,596 1,984,626 Estimated shares issuable under the 2019 ESPP 7,946 9,965 RSUs subject to future vesting 27,000 40,500 Total 2,942,542 2,035,091

Organization (Details)

Organization (Details) - Pre-funded Warrants $ / shares in Units, $ in Millions	1 Months Ended
	May 31, 2022 USD ($) $ / shares shares
Class of Stock [Line Items]
Pre-funded warrants to purchase | shares	4,000,000
Purchase price per warrant | $ / shares	$ 12.4999
Net proceeds from financing	$ 49.8
Offering expenses	$ 0.2

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Cash Equivalents and Marketable Securities Classified as Available-for-Sale Securities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 207,088	$ 188,520
Unrealized Gains	6
Unrealized Losses	(1,129)	(235)
Fair Value	205,965	188,285
Level 1 | Money Market Funds | Cash Equivalents
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	55,827	22,658
Fair Value	55,827	22,658
Level 2 | Corporate Debt
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	65,084	52,704
Unrealized Gains	6
Unrealized Losses	(578)	(139)
Fair Value	64,512	52,565
Level 2 | Asset-backed Securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost		23,882
Unrealized Losses		(21)
Fair Value		23,861
Level 2 | Commercial Paper
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	38,963	59,532
Fair Value	38,963	59,532
Level 2 | U.S. Government Agency Securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	47,214	29,744
Unrealized Losses	(551)	(75)
Fair Value	$ 46,663	$ 29,669

Fair Value Measurements - Sch_2

Fair Value Measurements - Schedule of Remaining Contractual Maturities of Marketable Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Due in less than one year	$ 205,965
Total	$ 205,965	$ 188,285

Property and Equipment - Schedu

Property and Equipment - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Property Plant And Equipment [Line Items]
Total property and equipment	$ 10,726	$ 10,425
Less accumulated depreciation and amortization	(7,805)	(7,684)
Property and equipment, net	2,921	2,741
Laboratory Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	6,573	6,291
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total property and equipment	3,295	3,295
Computer Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	464	482
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Total property and equipment	$ 394	$ 357

Property and Equipment - Additi

Property and Equipment - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Property, Plant and Equipment [Abstract]
Depreciation and amortization expense	$ 200	$ 200	$ 535	$ 536

Accrued Expenses - Schedule of

Accrued Expenses - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Payables and Accruals [Abstract]
Accrued research and development expenses	$ 3,978	$ 2,205
Accrued compensation	2,877	3,652
Accrued professional and consulting services	525	415
Other	127	54
Total accrued expenses	$ 7,507	$ 6,326

Leases - Summary of Balance She

Leases - Summary of Balance Sheets Adjustments Related to Lease Accounting Standard Update (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Jan. 01, 2022	Dec. 31, 2021
Lessee Lease Description [Line Items]
Operating lease right-of-use assets	$ 6,055
Total assets	221,996		$ 198,636
Operating lease liabilities, current	1,503
Operating lease liabilities, non-current	6,717
Total liabilities	$ 19,863		12,256
ASC 842
Lessee Lease Description [Line Items]
Operating lease right-of-use assets		$ 6,585
Total assets		6,585
Operating lease liabilities, current		1,471
Operating lease liabilities, non-current		7,500
Total liabilities		8,971
ASC 842 | Previously Reported
Lessee Lease Description [Line Items]
Deferred rent (1)			2,386
Total liabilities			$ 2,386
ASC 842 | Effect of adoption of ASC 842
Lessee Lease Description [Line Items]
Operating lease right-of-use assets		6,585
Total assets		6,585
Operating lease liabilities, current		1,471
Deferred rent (1)		(2,386)
Operating lease liabilities, non-current		7,500
Total liabilities		$ 6,585

Leases - Additional Information

Leases - Additional Information (Details) $ in Millions	1 Months Ended		3 Months Ended	6 Months Ended
	Apr. 30, 2018 ft²	May 31, 2015 ft²	Jun. 30, 2022 USD ($)	Jun. 30, 2022 USD ($)
Lessee Lease Description [Line Items]
Lease expiration period		2022-05
Additional laboratory and office facilities under lease	6,378
Increased of leased premises	36,754
Lessee operating lease extended lease term	2026-11
Lease existence of option to extend		true
Lessee operating lease option to extend		5 years
Lease expense | $			$ 0.4	$ 0.9
Cash paid for operating lease liabilities | $				$ 1.1
Operating lease, weighted average remaining lease term			4 years 5 months 1 day	4 years 5 months 1 day
Operating lease, weighted average discount rate, percent			8%	8%
South San Francisco and California
Lessee Lease Description [Line Items]
Laboratory and office facilities under lease		30,376

Leases - Summary of Maturities

Leases - Summary of Maturities of Lease Liabilities (Details) $ in Thousands	Jun. 30, 2022 USD ($)
Leases [Abstract]
2022 (remaining six months)	$ 1,022
2023	2,109
2024	2,183
2025	2,259
2026	2,137
Total future undiscounted lease payments	9,710
Less: Imputed interest	(1,490)
Total Lease Liabilities	$ 8,220

Leases - Summary of Balance S_2

Leases - Summary of Balance Sheet Classification of Leases (Details) $ in Thousands	Jun. 30, 2022 USD ($)
Leases [Abstract]
Operating lease right-of-use assets	$ 6,055
Operating lease liabilities, current	1,503
Operating lease liabilities, non-current	6,717
Total operating lease liabilities	$ 8,220

Collaboration Agreements - Addi

Collaboration Agreements - Additional Information (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021	Apr. 30, 2020	Dec. 31, 2019
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue recognized	$ 886,000	$ 869,000	$ 1,527,000	$ 2,091,000
Collaboration and License Agreement | Hanmi Pharmaceutical Co., LTD
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront and near-term milestone payment	10,400,000		10,400,000				$ 10,000,000
Upfront fee	4,000,000		4,000,000				4,000,000
Milestone payment	6,000,000		6,000,000			$ 6,000,000
Milestone payment related to supply	400,000		400,000
Revenue recognized	900,000	$ 900,000	1,500,000	$ 2,100,000
Deferred revenue	$ 0		$ 0		$ 1,500,000
Collaboration and License Agreement | Hanmi Pharmaceutical Co., LTD | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Contingent payments upon achievement of specified milestones							$ 108,000,000

Common Stock - Summary of Reser

Common Stock - Summary of Reserved Shares of Common Stock for Future Issuance (Detail)	Jun. 30, 2022 shares
Class Of Stock [Line Items]
Total shares reserved	10,396,217
Pre-funded warrants issued and outstanding
Class Of Stock [Line Items]
Total shares reserved	4,000,000
2019 Equity Incentive Plan and 2015 Stock Plan | Options Issued and Outstanding
Class Of Stock [Line Items]
Total shares reserved	2,907,596
2019 Equity Incentive Plan | Restricted Stock Units Issued and Outstanding
Class Of Stock [Line Items]
Total shares reserved	27,000
2019 Equity Incentive Plan | Options Available for Future Grants
Class Of Stock [Line Items]
Total shares reserved	2,942,751
2019 Employee Stock Purchase Plan
Class Of Stock [Line Items]
Total shares reserved	518,870

Common Stock - Additional Infor

Common Stock - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended
	May 31, 2022	Jun. 30, 2022	May 24, 2022
Class Of Stock [Line Items]
Beneficial ownership limitation, minimum percentage of shares outstanding	9.99%
Beneficial ownership limitation, maximum percentage of shares outstanding	19.99%
Common Stock
Class Of Stock [Line Items]
Closing price per share			$ 12.50
Pre-funded Warrants
Class Of Stock [Line Items]
Number of warrants to purchase	4,000,000
Exercise price per warrant share	$ 0.0001
Purchase price per warrant	$ 12.4999
Net proceeds from issuance of pre-funded warrants	$ 49.8
Offering expenses	$ 0.2
ATM Sales Agreement
Class Of Stock [Line Items]
Common stock available for future issuance value		$ 90.9

Stock-based Compensation - Summ

Stock-based Compensation - Summary of Stock Option Activity (Details) - 2019 Plan - Share-based Payment Arrangement, Option - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2022	Dec. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares Outstanding, Beginning Balance	2,024,681
Number of Shares Outstanding, Stock options granted	1,005,432
Number of Shares Outstanding, Stock options exercised	(44,910)
Number of Shares Outstanding, Stock options forfeited	(77,607)
Number of Shares Outstanding, Ending Balance	2,907,596	2,024,681
Weighted Average Exercise Price Per Share, Beginning Balance	$ 18.33
Weighted Average Exercise Price Per Share, Stock options granted	19.39
Weighted Average Exercise Price Per Share, Stock options exercised	8.24
Weighted Average Exercise Price Per Share, Stock options forfeited	24.96
Weighted Average Exercise Price Per Share, Ending Balance	$ 18.67	$ 18.33
Average Remaining Contractual Term (Years), Balance	8 years 3 months 18 days	8 years
Aggregate Intrinsic Value	$ 8,158	$ 38,417

Stock-based Compensation - Addi

Stock-based Compensation - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized stock-based compensation cost related to outstanding unvested stock options that are expected to vest	$ 24,200		$ 24,200
Unrecognized stock-based compensation cost, expected period to be recognized			2 years 9 months 18 days
Stock-based compensation expense	2,672	$ 2,888	$ 5,374	$ 5,575
2019 ESPP
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 200	$ 1,000	$ 300	$ 1,800
2019 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares remained available for issuance	2,942,751		2,942,751

Stock-based Compensation - Su_2

Stock-based Compensation - Summary of RSU Activity (Details) - 2019 Plan - Restricted Stock Unit ("RSU")	6 Months Ended
	Jun. 30, 2022 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares Outstanding, Beginning Balance | shares	40,500
Number of Shares Outstanding, RSUs vested and settled | shares	(13,500)
Number of Shares Outstanding, Ending Balance | shares	27,000
Weighted Average Grant Date Fair Value Per Share, Beginning Balance | $ / shares	$ 44.66
Weighted Average Grant Date Fair Value Per Share, RSUs vested and settled | $ / shares	44.66
Weighted Average Grant Date Fair Value Per Share, Ending Balance | $ / shares	$ 44.66

Stock-based Compensation - Su_3

Stock-based Compensation - Summary of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 2,672	$ 2,888	$ 5,374	$ 5,575
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	1,269	1,627	2,448	3,101
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 1,403	$ 1,261	$ 2,926	$ 2,474

Net Loss Per Share - Computatio

Net Loss Per Share - Computation of Basic and Diluted Net Loss per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2022	Jun. 30, 2021
Numerator:
Net loss	$ (19,184)	$ (20,468)	$ (16,110)	$ (16,514)	$ (39,652)	$ (32,624)
Denominator:
Weighted-average shares used to compute net loss per share, basic	31,140,323		25,589,947		30,356,515	25,217,542
Weighted-average shares used to compute net loss per share, diluted	31,140,323		25,589,947		30,356,515	25,217,542
Net loss per share, basic	$ (0.62)		$ (0.63)		$ (1.31)	$ (1.29)
Net loss per share, diluted	$ (0.62)		$ (0.63)		$ (1.31)	$ (1.29)

Net Loss Per Share - Additional

Net Loss Per Share - Additional Information (Details)	6 Months Ended
	Jun. 30, 2022 shares
Earnings Per Share [Abstract]
Pre-funded warrants to purchase common stock	4,000,000

Net Loss Per Share - Potential

Net Loss Per Share - Potential Dilutive Securities not Included in Diluted per Share Calculations (Details) - shares	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive securities	2,942,542	2,035,091
Stock Options Issued And Outstanding Equity Incentive Plan And Under 2019 Equity Incentive Plan And 2015 Stock Plan
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive securities	2,907,596	1,984,626
Estimated Shares Issuable Under Employee Stock Purchase Plan
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive securities	7,946	9,965
RSUs Subject to Future Vesting
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive securities	27,000	40,500