RAPT Therapeutics (RAPT) 10-Q 9 May 24 2024 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2024	May 03, 2024
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2024
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q1
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		34,903,476
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	Mar. 31, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 45,317	$ 47,478
Marketable securities	96,262	111,384
Prepaid expenses and other current assets	6,781	2,920
Total current assets	148,360	161,782
Property and equipment, net	2,239	2,448
Operating lease right-of-use assets	4,772	5,228
Other assets	447	3,871
Total assets	155,818	173,329
Current liabilities:
Accounts payable	6,771	5,176
Accrued expenses	11,807	14,103
Operating lease liabilities, current	2,508	2,448
Other current liabilities	82	109
Total current liabilities	21,168	21,836
Operating lease liabilities, non-current	3,815	4,458
Total liabilities	24,983	26,294
Commitments and contingencies
Stockholders' equity:
Preferred stock
Common stock	3	3
Additional paid-in capital	646,045	631,611
Accumulated other comprehensive gain (loss)	(10)	103
Accumulated deficit	(515,203)	(484,682)
Total stockholders' equity	130,835	147,035
Total liabilities and stockholders' equity	$ 155,818	$ 173,329

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Operating expenses:
Research and development	$ 24,781	$ 25,574
General and administrative	7,737	5,988
Total operating expenses	32,518	31,562
Loss from operations	(32,518)	(31,562)
Other income, net	1,997	2,291
Net loss	(30,521)	(29,271)
Other comprehensive income (loss):
Unrealized gain (loss) on marketable securities	(113)	365
Total comprehensive loss	$ (30,634)	$ (28,906)
Net loss per share, basic	$ (0.79)	$ (0.76)
Net loss per share, diluted	$ (0.79)	$ (0.76)
Weighted average number of shares used in computing net loss per share, basic	38,625,365	38,280,539
Weighted average number of shares used in computing net loss per share, diluted	38,625,365	38,280,539

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) - USD ($) $ in Thousands	Total	At The Market	Common Stock	Common Stock At The Market	Additional Paid-In Capital	Additional Paid-In Capital At The Market	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning balance at Dec. 31, 2022	$ 245,166		$ 3		$ 613,073		$ (26)	$ (367,884)
Beginning balance, shares at Dec. 31, 2022			34,254,314
Issuances of common stock under employee stock plans	116				116
Issuances of common stock under employee stock plans, shares			35,417
Stock-based compensation	4,094				4,094
Unrealized gain (loss) on marketable securities	365						365
Net loss	(29,271)							(29,271)
Ending balance at Mar. 31, 2023	220,470		$ 3		617,283		339	(397,155)
Ending balance, shares at Mar. 31, 2023			34,289,731
Beginning balance at Dec. 31, 2023	147,035		$ 3		631,611		103	(484,682)
Beginning balance, shares at Dec. 31, 2023			34,398,312
Issuances of common stock under employee stock plans	67				67
Issuances of common stock under employee stock plans, shares			36,074
Issuance of common stock, net of issuance costs		$ 8,969				$ 8,969
Issuance of common stock, net of issuance costs, shares				365,316
Stock-based compensation	5,398				5,398
Unrealized gain (loss) on marketable securities	(113)						(113)
Net loss	(30,521)							(30,521)
Ending balance at Mar. 31, 2024	$ 130,835		$ 3		$ 646,045		$ (10)	$ (515,203)
Ending balance, shares at Mar. 31, 2024			34,799,702

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Operating activities
Net loss	$ (30,521)	$ (29,271)
Adjustments to reconcile net loss to net cash used in operating activities:
Accretion of discounts on marketable securities	(983)	(1,441)
Depreciation and amortization	314	299
Stock-based compensation expense	5,398	4,094
Non-cash operating lease expense	584	584
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(437)	490
Accounts payable, accrued expenses and other current liabilities	(728)	7,277
Operating lease liabilities	(711)	(634)
Net cash used in operating activities	(27,084)	(18,602)
Investing activities
Purchase of marketable securities	(16,814)	(37,878)
Proceeds from maturities of marketable securities	32,806	63,945
Purchase of property and equipment	(105)	(759)
Net cash provided by investing activities	15,887	25,308
Financing activities
Proceeds from issuance of common stock under employee stock plans	67	116
Net cash provided by financing activities	9,036	116
Net (decrease) increase in cash and cash equivalents	(2,161)	6,822
Cash and cash equivalents at beginning of period	47,478	38,946
Cash and cash equivalents at end of period	45,317	45,768
At The Market
Financing activities
Proceeds from equity offerings, net of issuance costs	$ 8,969	$ 0

Organization

Organization	3 Months Ended
	Mar. 31, 2024
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 therapeutics 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. Liquidity and Management Plans The accompanying condensed consolidated financial statements have been prepared assuming that the Company will continue as a going concern. Since inception, the Company has incurred net losses and negative cash flows from operations. During the quarter ended March 31, 2024, the Company incurred a net loss of $ 30.5 million and used $ 27.2 million of cash in operations and capital expenditures. At March 31, 2024, the Company had cash and cash equivalents and marketable securities of $ 141.6 million and working capital of $ 127.2 million. The Company plans to continue to incur substantial costs in order to conduct research and development activities, and additional capital will be needed to undertake these activities. The Company intends to raise such capital through the issuance of additional equity, borrowings or strategic alliances with other companies. However, if such arrangements are not available at adequate levels or on acceptable terms, the Company would be required to significantly reduce operating expenses and delay or reduce the scope of or eliminate some of its development programs. The Company believes that its current cash and cash equivalents and marketable securities will provide sufficient funds to enable it to meet its obligations for at least 12 months from the filing date of this Quarterly Report on Form 10-Q. The Company’s evaluation was based on the facts known as of the date of filing of this Quarterly Report on Form 10-Q, including the impacts of the clinical holds that the U.S. Food and Drug Administration (“FDA”) has placed on the Phase 2b trial of zelnecirnon in atopic dermatitis (“AD”) and the Phase 2a trial of zelnecirnon in asthma and the Company's decision to close and unblind both trials to support its discussions with the FDA .

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2024
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, 2023 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, 2023 filed on March 7, 2024 with the Securities and Exchange Commission (“SEC”). The accompanying condensed 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., which was established in 2018 and deregistered during the quarter ended June 30, 2023. All intercompany balances and transactions have been eliminated in consolidation. Stock-Based Compensation The Company determines employee, nonemployee and director stock-based compensation expense for all stock-based awards based on their grant date fair value using the Black-Scholes option-pricing model. For stock-based awards with service conditions only, stock-based compensation expense is recognized over the requisite service period using the straight-line method. Forfeitures are recognized as they occur. The fair value of restricted stock awards granted 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. 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 common 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 since the effect of potentially dilutive securities is anti-dilutive. Marketable Securities Marketable securities primarily consist of commercial paper, corporate debt securities 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). The 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. All of the Company's available-for-sale investments are subject to a periodic impairment review. For each available-for-sale investment whose fair value is below its amortized cost, the Company determines if the impairment is a result of a credit-related loss or other factors using both quantitative and qualitative 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. If the impairment is a result of a credit-related loss, the Company recognizes an allowance for credit losses. If the impairment is not a result of a credit loss, the Company recognizes the loss in other comprehensive loss. 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 (“FASB”) or other standard setting bodies and adopted by the Company as of the specified effective date. 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 November 2023, the FASB issued Accounting Standards Update (“ASU”) (No. 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures (“ASU No. 2023-07”), which provides updates to qualitative and quantitative reportable segment disclosure requirements, including enhanced disclosures about significant segment expenses and increased interim disclosure requirements, among others. ASU No. 2023-07 is effective for fiscal years beginning after December 15, 2023, and interim periods in fiscal years beginning after December 15, 2024. Early adoption is permitted, and the amendments should be applied retrospectively. The Company believes the adoption of this standard will not have a material impact on its consolidated financial statement disclosures. In December 2023, the FASB issued ASU No. 2023-09, Improvements to Income Tax Disclosures (“ASU No. 2023-09”), which requires disclosure of disaggregated income taxes paid, prescribes standard categories for the components of the effective tax rate reconciliation and modifies other income tax-related disclosures. ASU No. 2023-09 is effective for fiscal years beginning after December 15, 2024 and allows for adoption on a prospective basis, with a retrospective option. Early adoption is permitted. The Company is currently evaluating the impact of this standard on the income tax disclosures within the consolidated financial statements.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2024
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 (at least annually). Financial instruments include cash and cash equivalents, marketable securities, accounts payable and accrued expenses that 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 upon 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. 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 March 31, 2024 Fair Value Amortized Unrealized Unrealized Fair Financial assets: Money market funds Level 1 $ 10,337 $ — $ — $ 10,337 Corporate debt Level 2 18,795 15 ( 9 ) 18,801 Asset-backed securities Level 2 4,772 1 ( 2 ) 4,771 Commercial paper Level 2 55,661 2 ( 5 ) 55,658 U.S. government agency securities Level 2 52,024 17 ( 29 ) 52,012 Subtotal 141,589 35 ( 45 ) 141,579 Less: Cash equivalents ( 45,317 ) — — ( 45,317 ) Marketable securities $ 96,272 $ 35 $ ( 45 ) $ 96,262 As of December 31, 2023 Fair Value Amortized Unrealized Unrealized Fair Financial assets: Money market funds Level 1 $ 10,869 $ — $ — $ 10,869 Corporate debt Level 2 19,531 37 ( 9 ) 19,559 Asset-backed securities Level 2 5,242 7 ( 4 ) 5,245 Commercial paper Level 2 59,828 7 ( 8 ) 59,827 U.S. government agency securities Level 2 63,206 91 ( 18 ) 63,279 Subtotal 158,676 142 ( 39 ) 158,779 Less: Cash equivalents ( 47,395 ) — — ( 47,395 ) Marketable securities $ 111,281 $ 142 $ ( 39 ) $ 111,384 As of March 31, 2024, the unrealized losses on the Company’s securities that were in an unrealized loss position were caused by interest rate changes and were not attributable to credit losses. As of March 31, 2024, the Company held debt securities with an aggregate unrealized loss position of $ 45,000 that had an aggregate fair value of $ 44.3 million. 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 did no t record an allowance for credit losses or other impairment charges related to its marketable securities as of March 31, 2024. The following table presents the remaining contractual maturities of the Company’s marketable securities as of March 31, 2024 (in thousands): March 31, 2024 Maturing in one year or less $ 88,717 Maturing after one year through five years 7,545 Total $ 96,262

Property and Equipment

Property and Equipment	3 Months Ended
	Mar. 31, 2024
Property, Plant and Equipment [Abstract]
Property and Equipment	4. Property and Equipment Property and equipment consisted of the following (in thousands): March 31, December 31, 2024 2023 Laboratory equipment $ 7,484 $ 7,399 Leasehold improvements 3,295 3,295 Computer equipment 745 727 Furniture and fixtures 394 394 Total property and equipment 11,918 11,815 Less accumulated depreciation and amortization ( 9,679 ) ( 9,367 ) Property and equipment, net $ 2,239 $ 2,448 Depreciation and amortization expense was $ 0.3 million for each of the three months ended March 31, 2024 and 2023 .

Accrued Expenses

Accrued Expenses	3 Months Ended
	Mar. 31, 2024
Payables and Accruals [Abstract]
Accrued Expenses	5. Accrued Expenses Accrued expenses consisted of the following (in thousands): March 31, December 31, 2024 2023 Accrued research and development expenses $ 7,141 $ 7,281 Accrued compensation 3,932 6,303 Accrued professional and consulting services 531 341 Other 203 178 Total accrued expenses $ 11,807 $ 14,103

Common Stock

Common Stock	3 Months Ended
	Mar. 31, 2024
Equity [Abstract]
Common Stock	6. Common Stock As of March 31, 2024, the Company had reserved the following shares of common stock for future issuance: Options issued and outstanding under the 2019 Equity Incentive Plan and 5,484,490 Shares available for future grants under the 2019 Equity Incentive Plan 3,009,835 Pre-funded warrants issued and outstanding 4,000,000 Shares reserved under the 2019 Employee Stock Purchase Plan 650,858 Total 13,145,183 On August 11, 2023, the Company filed a shelf registration statement on Form S-3 with the SEC, which was declared effective on August 17, 2023, related to the sale and issuance of up to $ 450 million of the Company’s securities, including up to $ 150 million of shares of common stock that may be offered and sold from time to time in one or more “at-the-market” offerings pursuant to a Controlled Equity Offering SM Sales Agreement (the “ATM Sales Agreement”) with Cantor Fitzgerald & Co. (“Cantor”) and Leerink Partners LLC. The ATM Sales Agreement replaced the Controlled Equity Offering SM Sales Agreement dated November 4, 2020 by and among the Company, Cantor and Stifel, Nicolaus & Company, Incorporated (the “Prior ATM Sales Agreement”). During the three months ended March 31, 2024 , the Company sold 365,316 shares of common stock in “at-the-market” offerings pursuant to the ATM Sales Agreement for net proceeds of $ 9.0 million, after deducting commissions and other offering related costs. No shares were sold under the Prior ATM Sales Agreement during the three months ended March 31, 2023. As of March 31, 2024 , $ 140.6 million remained available under the ATM Sales Agreement.

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2024
Share-Based Payment Arrangement [Abstract]
Stock-based Compensation	7. Stock-Based Compensatio n Stock option activity under the 2019 Equity Incentive Plan (the “2019 Plan”) is set forth below for the three months ended March 31, 2024: Weighted Average Average Remaining Aggregate Number of Exercise Contractual Intrinsic Shares Price Per Term Value Outstanding Share (Years) (in thousands) Balances at December 31, 2023 4,099,947 $ 21.00 7.6 $ 23,206 Stock options granted 1,426,119 24.41 Stock options exercised ( 14,374 ) 4.67 Stock options forfeited ( 27,202 ) 23.25 Balances at March 31, 2024 5,484,490 $ 21.92 8.0 $ 1,289 As of March 31, 2024 , 3,009,835 shares remained available for issuance under the 2019 Plan. Restricted stock unit (“RSU”) activity under the 2019 Plan is set forth below for the three months ended March 31, 2024: Weighted Average Number of Grant Date Shares Fair Value Outstanding Per Share Balances at December 31, 2023 13,500 $ 44.66 RSUs granted — — RSUs vested and settled ( 13,500 ) 44.66 RSUs forfeited — — Balances at March 31, 2024 — $ — 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 2024 2023 Research and development $ 2,637 $ 1,960 General and administrative 2,761 2,134 Total stock-based compensation expense $ 5,398 $ 4,094 As of March 31, 2024 , unrecognized stock-based compensation expense related to outstanding unvested stock options and RSUs that are expected to vest was $ 51.6 million. This unrecognized stock-based compensation expense is expected to be recognized over 3.1 years. The Company recorded stock-based compensation expense related to the 2019 ESPP of $ 0.3 million for each of the three months ended March 31, 2024 and 2023 .

Net Loss Per Share

Net Loss Per Share	3 Months Ended
	Mar. 31, 2024
Earnings Per Share [Abstract]
Net Loss Per Share	8. 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 months ended March 31, 2024 and 2023 (in thousands, except share and per share data): Three Months Ended 2024 2023 Numerator: Net loss $ ( 30,521 ) $ ( 29,271 ) Denominator: Weighted-average shares used to compute net loss per share, basic and diluted 38,625,365 38,280,539 Net loss per share, basic and diluted $ ( 0.79 ) $ ( 0.76 ) For the three months ended March 31, 2024 and 2023 , 4,000,000 pre-funded warrants to purchase the Company’s shares of common stock, issued in the May 2022 private placement financing, were included on a weighted average basis in the basic and diluted net loss per share calculation. As of March 31, 2024, all the pre-funded warrants issued in the private placement financing were outstanding. Potential dilutive securities that were not included in the diluted per share calculations because they would be anti-dilutive were as follows: As of March 31, 2024 2023 Stock options issued and outstanding under the 2019 Plan and 2015 Stock Plan 5,484,490 3,786,831 Estimated shares issuable under the 2019 ESPP 61,848 46,101 RSUs subject to future vesting — 13,500 Total 5,546,338 3,846,432

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2024
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, 2023 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, 2023 filed on March 7, 2024 with the Securities and Exchange Commission (“SEC”). The accompanying condensed 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., which was established in 2018 and deregistered during the quarter ended June 30, 2023. All intercompany balances and transactions have been eliminated in consolidation.
Stock-Based Compensation	Stock-Based Compensation The Company determines employee, nonemployee and director stock-based compensation expense for all stock-based awards based on their grant date fair value using the Black-Scholes option-pricing model. For stock-based awards with service conditions only, stock-based compensation expense is recognized over the requisite service period using the straight-line method. Forfeitures are recognized as they occur. The fair value of restricted stock awards granted 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.
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 common 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 since the effect of potentially dilutive securities is anti-dilutive.
Marketable Securities	Marketable Securities Marketable securities primarily consist of commercial paper, corporate debt securities 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). The 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. All of the Company's available-for-sale investments are subject to a periodic impairment review. For each available-for-sale investment whose fair value is below its amortized cost, the Company determines if the impairment is a result of a credit-related loss or other factors using both quantitative and qualitative 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. If the impairment is a result of a credit-related loss, the Company recognizes an allowance for credit losses. If the impairment is not a result of a credit loss, the Company recognizes the loss in other comprehensive loss.
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 (“FASB”) or other standard setting bodies and adopted by the Company as of the specified effective date. 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 November 2023, the FASB issued Accounting Standards Update (“ASU”) (No. 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures (“ASU No. 2023-07”), which provides updates to qualitative and quantitative reportable segment disclosure requirements, including enhanced disclosures about significant segment expenses and increased interim disclosure requirements, among others. ASU No. 2023-07 is effective for fiscal years beginning after December 15, 2023, and interim periods in fiscal years beginning after December 15, 2024. Early adoption is permitted, and the amendments should be applied retrospectively. The Company believes the adoption of this standard will not have a material impact on its consolidated financial statement disclosures. In December 2023, the FASB issued ASU No. 2023-09, Improvements to Income Tax Disclosures (“ASU No. 2023-09”), which requires disclosure of disaggregated income taxes paid, prescribes standard categories for the components of the effective tax rate reconciliation and modifies other income tax-related disclosures. ASU No. 2023-09 is effective for fiscal years beginning after December 15, 2024 and allows for adoption on a prospective basis, with a retrospective option. Early adoption is permitted. The Company is currently evaluating the impact of this standard on the income tax disclosures within the consolidated financial statements.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2024
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 March 31, 2024 Fair Value Amortized Unrealized Unrealized Fair Financial assets: Money market funds Level 1 $ 10,337 $ — $ — $ 10,337 Corporate debt Level 2 18,795 15 ( 9 ) 18,801 Asset-backed securities Level 2 4,772 1 ( 2 ) 4,771 Commercial paper Level 2 55,661 2 ( 5 ) 55,658 U.S. government agency securities Level 2 52,024 17 ( 29 ) 52,012 Subtotal 141,589 35 ( 45 ) 141,579 Less: Cash equivalents ( 45,317 ) — — ( 45,317 ) Marketable securities $ 96,272 $ 35 $ ( 45 ) $ 96,262 As of December 31, 2023 Fair Value Amortized Unrealized Unrealized Fair Financial assets: Money market funds Level 1 $ 10,869 $ — $ — $ 10,869 Corporate debt Level 2 19,531 37 ( 9 ) 19,559 Asset-backed securities Level 2 5,242 7 ( 4 ) 5,245 Commercial paper Level 2 59,828 7 ( 8 ) 59,827 U.S. government agency securities Level 2 63,206 91 ( 18 ) 63,279 Subtotal 158,676 142 ( 39 ) 158,779 Less: Cash equivalents ( 47,395 ) — — ( 47,395 ) Marketable securities $ 111,281 $ 142 $ ( 39 ) $ 111,384
Schedule of Remaining Contractual Maturities of Marketable Securities	The following table presents the remaining contractual maturities of the Company’s marketable securities as of March 31, 2024 (in thousands): March 31, 2024 Maturing in one year or less $ 88,717 Maturing after one year through five years 7,545 Total $ 96,262

Property and Equipment (Tables)

Property and Equipment (Tables)	3 Months Ended
	Mar. 31, 2024
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment	Property and equipment consisted of the following (in thousands): March 31, December 31, 2024 2023 Laboratory equipment $ 7,484 $ 7,399 Leasehold improvements 3,295 3,295 Computer equipment 745 727 Furniture and fixtures 394 394 Total property and equipment 11,918 11,815 Less accumulated depreciation and amortization ( 9,679 ) ( 9,367 ) Property and equipment, net $ 2,239 $ 2,448

Accrued Expenses (Tables)

Accrued Expenses (Tables)	3 Months Ended
	Mar. 31, 2024
Payables and Accruals [Abstract]
Schedule of Accrued Expenses	Accrued expenses consisted of the following (in thousands): March 31, December 31, 2024 2023 Accrued research and development expenses $ 7,141 $ 7,281 Accrued compensation 3,932 6,303 Accrued professional and consulting services 531 341 Other 203 178 Total accrued expenses $ 11,807 $ 14,103

Common Stock (Tables)

Common Stock (Tables)	3 Months Ended
	Mar. 31, 2024
Equity [Abstract]
Summary of Reserved Shares of Common Stock for Future Issuance	As of March 31, 2024, the Company had reserved the following shares of common stock for future issuance: Options issued and outstanding under the 2019 Equity Incentive Plan and 5,484,490 Shares available for future grants under the 2019 Equity Incentive Plan 3,009,835 Pre-funded warrants issued and outstanding 4,000,000 Shares reserved under the 2019 Employee Stock Purchase Plan 650,858 Total 13,145,183

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2024
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 three months ended March 31, 2024: Weighted Average Average Remaining Aggregate Number of Exercise Contractual Intrinsic Shares Price Per Term Value Outstanding Share (Years) (in thousands) Balances at December 31, 2023 4,099,947 $ 21.00 7.6 $ 23,206 Stock options granted 1,426,119 24.41 Stock options exercised ( 14,374 ) 4.67 Stock options forfeited ( 27,202 ) 23.25 Balances at March 31, 2024 5,484,490 $ 21.92 8.0 $ 1,289
Summary of RSU Activity	Restricted stock unit (“RSU”) activity under the 2019 Plan is set forth below for the three months ended March 31, 2024: Weighted Average Number of Grant Date Shares Fair Value Outstanding Per Share Balances at December 31, 2023 13,500 $ 44.66 RSUs granted — — RSUs vested and settled ( 13,500 ) 44.66 RSUs forfeited — — Balances at March 31, 2024 — $ —
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 2024 2023 Research and development $ 2,637 $ 1,960 General and administrative 2,761 2,134 Total stock-based compensation expense $ 5,398 $ 4,094

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	3 Months Ended
	Mar. 31, 2024
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 months ended March 31, 2024 and 2023 (in thousands, except share and per share data): Three Months Ended 2024 2023 Numerator: Net loss $ ( 30,521 ) $ ( 29,271 ) Denominator: Weighted-average shares used to compute net loss per share, basic and diluted 38,625,365 38,280,539 Net loss per share, basic and diluted $ ( 0.79 ) $ ( 0.76 )
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 March 31, 2024 2023 Stock options issued and outstanding under the 2019 Plan and 2015 Stock Plan 5,484,490 3,786,831 Estimated shares issuable under the 2019 ESPP 61,848 46,101 RSUs subject to future vesting — 13,500 Total 5,546,338 3,846,432

Organization - Additional Infor

Organization - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Net loss	$ 30,521	$ 29,271
Cash used in operations and capital expenditures	27,200
Cash and cash equivalents and marketable securities	141,600
Working capital	$ 127,200

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	Mar. 31, 2024	Dec. 31, 2023
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 141,589	$ 158,676
Unrealized Gains	35	142
Unrealized Losses	(45)	(39)
Fair Value	141,579	158,779
Less: Cash equivalents	(45,317)	(47,395)
Marketable securities, Amortized Cost	96,272	111,281
Marketable securities, Unrealized Gains	35	142
Marketable securities, Unrealized Losses	(45)	(39)
Marketable securities, Fair Value	96,262	111,384
Level 1 | Money Market Funds
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	10,337	10,869
Fair Value	10,337	10,869
Level 2 | Corporate Debt
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	18,795	19,531
Unrealized Gains	15	37
Unrealized Losses	(9)	(9)
Fair Value	18,801	19,559
Level 2 | Asset-backed Securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	4,772	5,242
Unrealized Gains	1	7
Unrealized Losses	(2)	(4)
Fair Value	4,771	5,245
Level 2 | Commercial Paper
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	55,661	59,828
Unrealized Gains	2	7
Unrealized Losses	(5)	(8)
Fair Value	55,658	59,827
Level 2 | U.S. Government Agency Securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	52,024	63,206
Unrealized Gains	17	91
Unrealized Losses	(29)	(18)
Fair Value	$ 52,012	$ 63,279

Fair Value Measurements - Sch_2

Fair Value Measurements - Schedule of Remaining Contractual Maturities of Marketable Securities (Details) $ in Thousands	Mar. 31, 2024 USD ($)
Investments, Debt and Equity Securities [Abstract]
Maturing in one year or less	$ 88,717
Maturing after one year through five years	7,545
Total	$ 96,262

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details)	Mar. 31, 2024 USD ($)
Fair Value Disclosures [Abstract]
Debt securities unrealized loss	$ 45,000
Aggregate fair value	44,300,000
Allowance for credit losses or other impairment charges related to marketable securities	$ 0

Property and Equipment - Schedu

Property and Equipment - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Property Plant And Equipment [Line Items]
Total property and equipment	$ 11,918	$ 11,815
Less accumulated depreciation and amortization	(9,679)	(9,367)
Property and equipment, net	2,239	2,448
Laboratory Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	7,484	7,399
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	745	727
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Total property and equipment	$ 394	$ 394

Property and Equipment - Additi

Property and Equipment - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Property, Plant and Equipment [Abstract]
Depreciation and amortization expense	$ 314	$ 299

Accrued Expenses - Schedule of

Accrued Expenses - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Payables and Accruals [Abstract]
Accrued research and development expenses	$ 7,141	$ 7,281
Accrued compensation	3,932	6,303
Accrued professional and consulting services	531	341
Other	203	178
Total accrued expenses	$ 11,807	$ 14,103

Common Stock - Summary of Reser

Common Stock - Summary of Reserved Shares of Common Stock for Future Issuance (Detail)	Mar. 31, 2024 shares
Class Of Stock [Line Items]
Total shares reserved	13,145,183
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	5,484,490
2019 Equity Incentive Plan | Shares Available for Future Grants
Class Of Stock [Line Items]
Total shares reserved	3,009,835
2019 Employee Stock Purchase Plan
Class Of Stock [Line Items]
Total shares reserved	650,858

Common Stock - Additional Infor

Common Stock - Additional Information (Details) - USD ($) $ in Thousands		3 Months Ended
	Aug. 17, 2023	Mar. 31, 2024	Mar. 31, 2023
Class Of Stock [Line Items]
Total shares reserved		13,145,183
ATM Sales Agreement
Class Of Stock [Line Items]
Shares issued during period value		$ 8,969
Net proceeds received after deducting underwriting discounts and other offering related costs		8,969	$ 0
Common stock remained available value		$ 140,600
ATM Sales Agreement | Common Stock
Class Of Stock [Line Items]
Shares issued during period		365,316
Sales Agreement | ATM Sales Agreement
Class Of Stock [Line Items]
Shares issued during period		365,316	0
Net proceeds received after deducting underwriting discounts and other offering related costs		$ 9,000
Maximum | ATM Sales Agreement
Class Of Stock [Line Items]
Shares issued during period value	$ 450,000
Maximum | Sales Agreement | ATM Sales Agreement | Common Stock
Class Of Stock [Line Items]
Shares issued during period value	$ 150,000

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	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares Outstanding, Beginning Balance	4,099,947
Number of Shares Outstanding, Stock options granted	1,426,119
Number of Shares Outstanding, Stock options exercised	(14,374)
Number of Shares Outstanding, Stock options forfeited	(27,202)
Number of Shares Outstanding, Ending Balance	5,484,490	4,099,947
Weighted Average Exercise Price Per Share, Beginning Balance	$ 21
Weighted Average Exercise Price Per Share, Stock options granted	24.41
Weighted Average Exercise Price Per Share, Stock options exercised	4.67
Weighted Average Exercise Price Per Share, Stock options forfeited	23.25
Weighted Average Exercise Price Per Share, Ending Balance	$ 21.92	$ 21
Average Remaining Contractual Term (Years), Balance	8 years	7 years 7 months 6 days
Aggregate Intrinsic Value	$ 1,289	$ 23,206

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
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	$ 51,600
Unrecognized stock-based compensation cost, expected period to be recognized	3 years 1 month 6 days
Stock-based compensation expense	$ 5,398	$ 4,094
2019 ESPP
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 300	$ 300
2019 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares remained available for issuance	3,009,835

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of RSU Activity (Details) - 2019 Plan - Restricted Stock Unit ("RSU")	3 Months Ended
	Mar. 31, 2024 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares Outstanding, Beginning Balance | shares	13,500
Number of Shares Outstanding, RSUs vested and settled | shares	(13,500)
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

Stock-Based Compensation - Su_3

Stock-Based Compensation - Summary of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 5,398	$ 4,094
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	2,637	1,960
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 2,761	$ 2,134

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
	Mar. 31, 2024	Mar. 31, 2023
Numerator:
Net loss	$ (30,521)	$ (29,271)
Denominator:
Weighted-average shares used to compute net loss per share, basic	38,625,365	38,280,539
Weighted-average shares used to compute net loss per share, diluted	38,625,365	38,280,539
Net loss per share, basic	$ (0.79)	$ (0.76)
Net loss per share, diluted	$ (0.79)	$ (0.76)

Net Loss Per Share - Additional

Net Loss Per Share - Additional Information (Details) - shares	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Earnings Per Share [Abstract]
Pre-funded warrants to purchase common stock	4,000,000	4,000,000

Net Loss Per Share - Potential

Net Loss Per Share - Potential Dilutive Securities not Included in Diluted per Share Calculations (Details) - shares	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive securities	5,546,338	3,846,432
Stock Options Issued and Outstanding Under 2019 Plan and 2015 Stock Plan
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive securities	5,484,490	3,786,831
Estimated Shares Issuable Under the 2019 ESPP
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive securities	61,848	46,101
RSUs Subject to Future Vesting
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive securities		13,500