Dianthus Therapeutics (DNTH) 10-Q 8 Aug 24 2024 Q2 Quarterly report Financial data

Cover Page

Cover Page - shares	6 Months Ended
	Jun. 30, 2024	Aug. 06, 2024
Document Type	10-Q
Amendment Flag	false
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Jun. 30, 2024
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q2
Entity Registrant Name	Dianthus Therapeutics, Inc.
Trading Symbol	DNTH
Entity Central Index Key	0001690585
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	true
Entity Shell Company	false
Entity Tax Identification Number	81-0724163
Title of 12(b) Security	Common Stock
Entity Interactive Data Current	Yes
Security Exchange Name	NASDAQ
Entity Incorporation, State or Country Code	DE
Entity Address, Address Line One	7 Times Square, 43rd Floor
Entity Address, City or Town	New York
Entity Address, Postal Zip Code	10036
Entity Address, State or Province	NY
Securities Act File Number	001-38541
City Area Code	929
Local Phone Number	999-4055
Entity Common Stock, Shares Outstanding		29,354,320

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (unaudited) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 314,169	$ 132,325
Short-term investments	46,538	41,393
Receivable from related party	840	294
Unbilled receivable from related party	835	184
Prepaid expenses and other current assets	3,305	3,255
Total current assets	365,687	177,451
Property and equipment, net	189	185
Right-of-use operating lease assets	442	615
Other assets and restricted cash	2,641	1,154
Total assets	368,959	179,405
Current liabilities:
Accounts payable	3,695	2,610
Accrued expenses	5,857	6,504
Current portion of deferred revenue - related party	100	100
Current portion of operating lease liabilities	377	417
Total current liabilities	10,029	9,631
Deferred revenue - related party	682	736
Long-term operating lease liabilities	30	168
Total liabilities	10,741	10,535
Commitments and contingencies (Note 15)
Stockholders' equity/(deficit):
Preferred stock; $0.001 par value per share; authorized shares - 10,000,000 at June 30, 2024 and December 31, 2023; issued and outstanding - none at June 30, 2024 and December 31, 2023	0	0
Common stock; $0.001 par value per share; authorized shares - 150,000,000 at June 30, 2024 and December 31, 2023; issued and outstanding shares - 29,352,140 and 14,817,696 at June 30, 2024 and December 31, 2023, respectively	29	15
Additional paid-in capital	479,004	258,231
Accumulated deficit	(120,778)	(89,423)
Accumulated other comprehensive (loss)/income	(37)	47
Total stockholders' equity	358,218	168,870
Total liabilities and stockholders' equity	$ 368,959	$ 179,405

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (unaudited) (Parenthetical) - $ / shares	Jun. 30, 2024	Dec. 31, 2023	Sep. 11, 2023
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, Shares authorized	10,000,000	10,000,000
Preferred stock, Shares issued	0	0
Preferred stock, Shares outstanding	0	0
Common stock, Par value	$ 0.001	$ 0.001
Common stock, shares authorized	150,000,000	150,000,000
Common stock, Shares issued	29,352,140	14,817,696	11,021,248
Common stock, Shares outstanding	29,352,140	14,817,696

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Operating expenses:
Research and development	$ 18,070	$ 10,253	$ 31,148	$ 16,100
General and administrative	5,997	2,492	11,637	4,804
Total operating expenses	24,067	12,745	42,785	20,904
Loss from operations	(22,204)	(11,776)	(40,048)	(19,459)
Other income/(expense):
Interest income	4,708	687	8,930	1,293
Loss on currency exchange, net	(31)	(28)	(43)	(37)
Other expense	(80)	(23)	(194)	(26)
Total other income	4,597	636	8,693	1,230
Net loss	$ (17,607)	$ (11,140)	$ (31,355)	$ (18,229)
Net loss per share attributable to common stockholders, basic	$ (0.51)	$ (12.73)	$ (0.99)	$ (20.84)
Net loss per share attributable to common stockholders, diluted	$ (0.51)	$ (12.73)	$ (0.99)	$ (20.84)
Weighted-average number of shares of common stock outstanding including shares issuable under equity-classified pre-funded warrants, used in computing net loss per share of common stock, basic	34,227,038	874,900	31,794,881	874,805
Weighted-average number of shares of common stock outstanding including shares issuable under equity-classified pre-funded warrants, used in computing net loss per share of common stock, diluted	34,227,038	874,900	31,794,881	874,805
Comprehensive loss:
Net Income (Loss)	$ (17,607)	$ (11,140)	$ (31,355)	$ (18,229)
Other comprehensive (loss)/income:
Change in unrealized (losses)/gains related to available-for-sale debt securities	(10)	38	(84)	142
Total other comprehensive (loss)/income	(10)	38	(84)	142
Total comprehensive loss	(17,617)	(11,102)	(31,439)	(18,087)
Related Party [Member]
Revenues:
License revenue - related party	$ 1,863	$ 969	$ 2,737	$ 1,445

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Changes in Convertible Preferred Stock and Stockholders' Equity/(Deficit) - USD ($) $ in Thousands	Total	Common Stock [Member]	Preferred Stock [Member] Convertible Preferred Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning balance at Dec. 31, 2022	$ (44,368)	$ 0	$ 118,024	$ 1,661	$ (45,868)	$ (161)
Beginning balance, shares at Dec. 31, 2022		875,279	33,336,282
Stock-based compensation expense	533			533
Net Income (Loss)	(7,089)				(7,089)
Other comprehensive income loss	104					104
Ending balance at Mar. 31, 2023	(50,820)	$ 0	$ 118,024	2,194	(52,957)	(57)
Ending balance, shares at Mar. 31, 2023		875,279	33,336,282
Beginning balance at Dec. 31, 2022	(44,368)	$ 0	$ 118,024	1,661	(45,868)	(161)
Beginning balance, shares at Dec. 31, 2022		875,279	33,336,282
Net Income (Loss)	(18,229)
Ending balance at Jun. 30, 2023	(61,460)	$ 0	$ 118,024	2,656	(64,097)	(19)
Ending balance, shares at Jun. 30, 2023		875,279	33,336,282
Beginning balance at Mar. 31, 2023	(50,820)	$ 0	$ 118,024	2,194	(52,957)	(57)
Beginning balance, shares at Mar. 31, 2023		875,279	33,336,282
Stock-based compensation expense	462			462
Net Income (Loss)	(11,140)				(11,140)
Other comprehensive income loss	38					38
Ending balance at Jun. 30, 2023	(61,460)	$ 0	$ 118,024	2,656	(64,097)	(19)
Ending balance, shares at Jun. 30, 2023		875,279	33,336,282
Beginning balance at Dec. 31, 2023	168,870	$ 15	$ 0	258,231	(89,423)	47
Beginning balance, shares at Dec. 31, 2023		14,817,696	0
Issuance of common stock and pre-funded warrants in connection with the private placement, net of issuance costs	215,333	$ 14		215,319
Issuance of common stock and pre-funded warrants in connection with the private placement, net of issuance costs, shares		14,500,500
Exercise of stock options	271			271
Exercise of stock options, shares		30,430
Stock-based compensation expense	2,035			2,035
Net Income (Loss)	(13,748)				(13,748)
Other comprehensive income loss	(74)					(74)
Ending balance at Mar. 31, 2024	372,687	$ 29	$ 0	475,856	(103,171)	(27)
Ending balance, shares at Mar. 31, 2024		29,348,626	0
Beginning balance at Dec. 31, 2023	$ 168,870	$ 15	$ 0	258,231	(89,423)	47
Beginning balance, shares at Dec. 31, 2023		14,817,696	0
Exercise of stock options, shares	33,944
Net Income (Loss)	$ (31,355)
Ending balance at Jun. 30, 2024	358,218	$ 29	$ 0	479,004	(120,778)	(37)
Ending balance, shares at Jun. 30, 2024		29,352,140	0
Beginning balance at Mar. 31, 2024	372,687	$ 29	$ 0	475,856	(103,171)	(27)
Beginning balance, shares at Mar. 31, 2024		29,348,626	0
Exercise of stock options	47			47
Exercise of stock options, shares		3,514
Stock-based compensation expense	3,101			3,101
Net Income (Loss)	(17,607)				(17,607)
Other comprehensive income loss	(10)					(10)
Ending balance at Jun. 30, 2024	$ 358,218	$ 29	$ 0	$ 479,004	$ (120,778)	$ (37)
Ending balance, shares at Jun. 30, 2024		29,352,140	0

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Changes in Convertible Preferred Stock and Stockholders' Equity/(Deficit) (Parenthetical) $ in Thousands	3 Months Ended
	Mar. 31, 2024 USD ($)
Stock issuance cost	$ 14,665

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Cash flows from operating activities:
Net loss	$ (31,355)	$ (18,229)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense	45	28
Stock-based compensation expense	5,136	995
Accretion of discount on short-term investments	(940)	(566)
Amortization of right-of-use operating lease assets	173	137
Changes in operating assets and liabilities:
Receivable from related party	(546)	4,338
Unbilled receivable from related party	(651)	520
Prepaid expenses and other current assets	(50)	656
Deferred transaction costs	0	(1,163)
Other assets	(1,487)	12
Accounts payable, accrued expenses and operating lease liabilities	260	(1,715)
Deferred revenue - related party	(54)	(28)
Net cash used in operating activities	(29,469)	(15,015)
Cash flows from investing activities:
Capital expenditures	(49)	(35)
Purchases of short-term investments	(27,289)	(3,855)
Proceeds from maturities of short-term investments	23,000	43,885
Net cash (used in)/provided by investing activities	(4,338)	39,995
Cash flows from financing activities:
Proceeds from exercise of stock options	318	0
Proceeds from the private placement	229,998	0
Payment of issuance costs in connection with the private placement	(14,665)	0
Proceeds from issuance of promissory notes payable to related party	0	377
Repayment of promissory notes payable to related party	0	(377)
Net cash provided by financing activities	215,651	0
Increase in cash, cash equivalents and restricted cash	181,844	24,980
Cash, cash equivalents and restricted cash, beginning of period	132,391	15,425
Cash, cash equivalents and restricted cash, end of period	314,235	40,405
Supplemental Disclosure
Cash and cash equivalents	314,169	40,280
Restricted cash	66	125
Total cash, cash equivalents and restricted cash	$ 314,235	$ 40,405

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2024	Jun. 30, 2023
Pay vs Performance Disclosure
Net Income (Loss)	$ (17,607)	$ (13,748)	$ (11,140)	$ (7,089)	$ (31,355)	$ (18,229)

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Jun. 30, 2024
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Organization, Description of Bu

Organization, Description of Business and Liquidity	6 Months Ended
	Jun. 30, 2024
Organization, Description of Business and Liquidity	1. Organization, Description of Business and Liquidity Business Dianthus Therapeutics, Inc. (formerly Magenta Therapeutics, Inc.) (the “Company” or “Dianthus”) is a clinical-stage biotechnology company focused on developing next-generation complement therapeutics for patients with severe autoimmune and inflammatory diseases. The Company’s corporate headquarters are in New York, New York. Currently, the Company is devoting substantially all efforts and resources toward product research and development of its product candidates. The Company has incurred losses from operations and negative operating cash flows since its inception. There can be no assurance that its research and development programs will be successful, that products developed, if any, will obtain necessary regulatory approval, or that any approved product, if any, will be commercially viable. In addition, the Company operates in an environment of rapid technological change and is largely dependent on the services of its key employees, consultants, and advisors. Reverse Merger and Pre-Closing Financing On September 11, 2023, the Company completed its business combination with Dianthus Therapeutics OpCo, Inc. (formerly Dianthus Therapeutics, Inc.) (“Former Dianthus”) in accordance with the terms of the Agreement and Plan of Merger, dated as of May 2, 2023 (the “Merger Agreement”), by and among the Company, Dio Merger Sub, Inc., a Delaware corporation and a wholly owned subsidiary of the Company (“Merger Sub”), and Former Dianthus, pursuant to which, among other matters, Merger Sub merged with and into Former Dianthus, with Former Dianthus surviving as a wholly owned subsidiary of the Company (the “Reverse Merger”). In connection with the completion of the Reverse Merger, the Company changed its name from “Magenta Therapeutics, Inc.” to “Dianthus Therapeutics, Inc.,” and the business conducted by the Company became primarily the business conducted by Former Dianthus. Unless context otherwise requires, references herein to “Dianthus,” the “Company,” or the “combined company” refer to Dianthus Therapeutics, Inc. (formerly Magenta Therapeutics, Inc.) after completion of the Reverse Merger, the term “Former Dianthus” refers to Dianthus Therapeutics OpCo, Inc. (formerly Dianthus Therapeutics, Inc.), and the term “Magenta” refers to the Company prior to completion of the Reverse Merger. The Company was incorporated in June 2015 and Former Dianthus was incorporated in May 2019. Immediately prior to the effective time of the Reverse Merger, the Company effected a 1-for-16 reverse stock split of its common stock (the “Reverse Stock Split”). Unless noted otherwise, all references herein to share and per share amounts reflect the Reverse Stock Split. At the effective time of the Reverse Merger, the Company issued an aggregate of 11,021,248 shares of Company common stock to the Former Dianthus stockholders, based on the exchange ratio of approximately 0.2181 shares of Company common stock for each share of Former Dianthus common stock, including those shares of Former Dianthus common stock issued upon the conversion of Former Dianthus preferred stock and those shares of the Former Dianthus common stock issued in the pre-closing financing (as defined below), resulting in 14,817,696 shares of Company common stock being issued and outstanding following the effective time of the Reverse Merger. At the effective time of the Reverse Merger, the 2019 Stock Plan (as discussed in Note 12) was assumed by the Company, and each outstanding and unexercised option to purchase shares of Former Dianthus common stock immediately prior to the effective time of the Reverse Merger was assumed by the Company and converted into an option to purchase shares of Company common stock, with necessary adjustments to the number of shares and exercise price to reflect the exchange ratio, and each outstanding and unexercised warrant to purchase shares of Former Dianthus common stock immediately prior to the effective time of the Reverse Merger (including the Former Dianthus pre-funded warrants sold in the pre-closing financing) was converted into a warrant to purchase shares of Company common stock, with necessary adjustments to the number of shares and exercise price to reflect the exchange ratio. The Reverse Merger was accounted for as a reverse recapitalization in accordance with generally accepted accounting principles in the United States of America (“U.S. GAAP”). Under this method of accounting, Former Dianthus was deemed to be the accounting acquirer for financial reporting purposes. This determination was primarily based on the expectation that, immediately following the Reverse Merger: (i) Former Dianthus’ stockholders own a substantial majority of the voting rights in the combined company; (ii) Former Dianthus’ largest stockholders retain the largest interest in the combined company; (iii) Former Dianthus designated a majority (six of eight) of the initial members of the board of directors of the combined company; and (iv) Former Dianthus’ executive management team became the management team of the combined company. Accordingly, for accounting purposes: (i) the Reverse Merger was treated as the equivalent of Former Dianthus issuing stock to acquire the net assets of Magenta; (ii) the net assets of Magenta are recorded at their acquisition-date fair value in the unaudited condensed consolidated financial statements of Former Dianthus and (iii) the reported historical operating results of the combined company prior to the Reverse Merger are those of Former Dianthus. Additional information regarding the Reverse Merger is included in Note 3. Historical common stock figures of Former Dianthus have been retroactively restated based on the exchange ratio of approximately 0.2181 . On September 11, 2023, prior to the effective time of the Reverse Merger, the Company entered into a contingent value rights agreement (the “CVR Agreement”) with a rights agent, pursuant to which pre-Reverse Merger holders of Magenta common stock received one non-transferable contingent value right (each, a “CVR”) for each outstanding share of Magenta common stock held by such stockholder immediately prior to the effective time of the Reverse Merger on September 11, 2023. Subject to, and in accordance with, the terms and conditions of the CVR Agreement, each CVR represents the contractual right to receive a pro rata portion of the proceeds, if any, received by the Company as a result of (i) contingent payments made to the Company, such as milestone, royalty or earnout, when received under any pre-Reverse Merger disposition agreements related to Magenta’s pre-Reverse Merger assets and (ii) the Company’s sale of assets after the effective date of the Reverse Merger and prior to December 31, 2023, in each case, received within a three-year period following the closing of the Reverse Merger. As of June 30, 2024, no payments have been received under the CVR Agreement. Concurrently with the execution and delivery of the Merger Agreement, and in order to provide Former Dianthus with additional capital for its development programs, Former Dianthus entered into a subscription agreement, as amended (the “Subscription Agreement”), with certain investors named therein (the “Investors”), pursuant to which, subject to the terms and conditions of the Subscription Agreement, immediately prior to the effective time of the Reverse Merger, Former Dianthus issued and sold, and the Investors purchased, (i) 2,873,988 shares of Former Dianthus common stock and (ii) 210,320 pre-funded warrants, exercisable for 210,320 shares of Former Dianthus common stock, at a purchase price of approximately $ 23.34 per share or $ 23.34 per warrant, for an aggregate purchase price of approximately $ 72.0 million (the “pre-closing financing”). 2024 Private Placement On January 22, 2024, the Company entered into a securities purchase agreement for a private placement with certain institutional and accredited investors. At the closing of the private placement on January 24, 2024, the Company sold and issued 14,500,500 shares of common stock at a price per share of $ 12.00 , and pre-funded warrants to purchase 4,666,332 shares of common stock at a purchase price of $ 11.999 per pre-funded warrant, which represents the per share purchase price of the common stock less the $ 0.001 per share exercise price for each pre-funded warrant, for an aggregate purchase price of approximately $ 230 million. The pre-funded warrants are exercisable at any time after the date of issuance. A holder of pre-funded warrants may not exercise the warrant if the holder, together with its affiliates, would beneficially own more than 9.99 % of the number of shares of common stock outstanding immediately after giving effect to such exercise. A holder of pre-funded warrants may increase or decrease this percentage to a percentage not in excess of 19.99 % by providing at least 61 days’ prior notice to the Company. Risks and Uncertainties The Company is subject to risks and uncertainties common to early-stage companies in the biotechnology industry including, but not limited to, uncertainty of product development and commercialization, lack of marketing and sales history, development by its competitors of new technological innovations, dependence on its key personnel, market acceptance of products, product liability, protection of proprietary technology, ability to raise additional financing and compliance with government regulations. If the Company does not successfully commercialize any of its product candidates, it will be unable to generate recurring product revenue or achieve profitability. The Company’s lead product candidate that is in development and any future product candidates will require significant additional research and development efforts, including extensive preclinical and clinical testing and regulatory approval prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel and infrastructure, and extensive compliance-reporting capabilities. Even if its product development efforts are successful, it is uncertain when, if ever, the Company will generate revenue from product sales. Liquidity In accordance with Accounting Standards Update No. 2014-15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern (Subtopic 205-40), the Company has evaluated whether there are certain conditions and events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the accompanying unaudited condensed consolidated financial statements were issued (the “issuance date”): • Since its inception, the Company has funded its operations primarily with outside capital and has incurred significant recurring losses, including net losses of $ 31.4 million and $ 18.2 million for the six months ended June 30, 2024 and 2023, respectively. In addition, the Company had an accumulated deficit of $ 120.8 million as of June 30, 2024; • The Company expects to continue to incur significant recurring losses and rely on outside capital to fund its operations for the foreseeable future; and • As of the issuance date, the Company expects that its existing cash, cash equivalents and short-term investments on hand will be sufficient to fund its obligations as they become due for at least twelve months beyond the issuance date. The Company expects that its research and development and general and administrative costs will continue to increase significantly, including in connection with conducting clinical trials and manufacturing for its existing product candidate and any future product candidates to support commercialization and providing general and administrative support for its operations, including the costs associated with operating as a public company. In the event the Company is unable to secure additional outside capital, management will be required to seek other alternatives which may include, among others, a delay or termination of clinical trials or the development of its product candidates, temporary or permanent curtailment of the Company’s operations, a sale of assets, or other alternatives with strategic or financial partners. The accompanying unaudited condensed consolidated financial statements do not include any adjustments that might result from the outcome of these uncertainties. Accordingly, the unaudited condensed consolidated financial statements have been prepared on a basis that assumes the Company will continue as a going concern and which contemplates the realization of assets and satisfaction of liabilities and commitments in the ordinary course of business.

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2024
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying unaudited condensed consolidated financial statements as of June 30, 2024 and for the six months ended June 30, 2024 and 2023 have been prepared in conformity with 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 have been prepared on the same basis as the Company’s audited financial statements and 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. The results for the three and six months ended June 30, 2024 are not necessarily indicative of the results expected for the full fiscal year or any subsequent interim period. The unaudited condensed consolidated balance sheet as of 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 audited financial statements as of and for the year ended December 31, 2023, which are contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2023 filed with the Securities and Exchange Commission (“SEC”) on March 21, 2024. Any reference in these notes to applicable guidance is meant to refer to the authoritative U.S. GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Update (“ASU”) of the Financial Accounting Standards Board (“FASB”). Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. Actual results may differ materially from those estimates. Management considers many factors in selecting appropriate financial accounting policies and controls, and in developing the estimates and assumptions that are used in the preparation of these financial statements. Management must apply significant judgment in this process. In addition, other factors may affect estimates including the following: expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates, and whether historical trends are expected to be representative of future trends. The estimation process often may yield a range of potentially reasonable estimates of the ultimate future outcomes, and management must select an amount that falls within that range of reasonable estimates. Significant estimates are used in the following areas, among others: the recognition of research and development expense, stock-based compensation expense and revenue recognition. Cash and Cash Equivalents All short-term, highly liquid investments with original maturities of 90 days or less are considered to be cash and cash equivalents. The carrying amounts reported in the unaudited condensed consolidated balance sheets for cash and cash equivalents are valued at cost, which approximates fair value. Concentration of Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of cash, cash equivalents and short-term investments. The Company regularly maintains deposits in accredited financial institutions in excess of federally insured limits. The Company invests its excess cash primarily in money market funds, U.S. treasury securities and U.S. government agency securities in accordance with the Company’s investment policy. The Company’s investment policy defines allowable investments and establishes guidelines relating to credit quality, diversification, and maturities of its investments to preserve principal and maintain liquidity. The Company has not experienced any realized losses related to its cash, cash equivalents and short-term investments and management believes the Company is not exposed to significant risks of losses. As of June 30, 2024 and December 31, 2023 , the Company held cash deposits at Silicon Valley Bank (“SVB”) in excess of government insured limits. On March 10, 2023, SVB was closed by the California Department of Financial Protection and Innovation, and the Federal Deposit Insurance Corporation was appointed as receiver. No losses were incurred by the Company on deposits that were held at SVB. Management believes that the Company is not currently exposed to significant credit risk as the vast majority of the Company’s deposits were either owned directly by the Company and held in custody at a third-party financial institution or, subsequent to March 10, 2023, have been transferred to a third-party financial institution. The Company does not currently have any other significant relationships with SVB. Short-term Investments Short-term investments consist of investments in U.S. treasury and U.S. government agency securities. Management of the Company determines the appropriate classification of the securities at the time they are acquired and evaluates the appropriateness of such classifications at each balance sheet date. The Company classifies its short-term investments as available-for-sale pursuant to ASC 320, Investments – Debt and Equity Securities, and reports them at fair value in short-term investments with unrealized gains and losses reported as a component of accumulated other comprehensive income/(loss) on the unaudited condensed consolidated balance sheets. Realized gains and losses and declines in value judged to be other than temporary are included as a component of interest income based on the specific identification method. When the fair value is below the amortized cost of a marketable security, an estimate of expected credit losses is made in accordance with ASU No. 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments . The credit-related impairment amount is recognized in the unaudited condensed consolidated statements of operations and comprehensive loss. Credit losses are recognized through the use of an allowance for credit losses account in the unaudited condensed consolidated balance sheet and subsequent improvements in expected credit losses are recognized as a reversal of an amount in the allowance account. If the Company has the intent to sell the security or it is more likely than not that the Company will be required to sell the security prior to recovery of its amortized cost basis, then the allowance for the credit loss is written-off and the excess of the amortized cost basis of the asset over its fair value is recorded in the unaudited condensed consolidated statements of operations and comprehensive loss. There were no credit losses recorded during the six months ended June 30, 2024 or 2023. Additional information regarding short-term investments is included in Note 4. Receivable from Related Party and Unbilled Receivable from Related Party The receivable from related party and unbilled receivable from related party results from option and license agreements with Zenas BioPharma, Inc. (formerly Zenas BioPharma Limited) (“Zenas”), a related party. See Notes 13 and 16 for more information. The receivable represents amounts earned and billed to Zenas but not yet collected while unbilled receivable represents amounts earned but not yet billed to Zenas. The receivable and unbilled receivable are reported at net realizable value. The Company regularly evaluates the creditworthiness of Zenas and their financial condition and does not require collateral from Zenas. As of June 30, 2024 and December 31, 2023 , no allowance for doubtful accounts was recorded as all accounts were considered collectible. Property and Equipment Property and equipment are recorded at cost. Depreciation is provided using the straight-line method over estimated useful lives of three years for computer equipment and five years for furniture and fixtures. Expenditures for major renewals and betterments that extend the useful lives are capitalized. Expenditures for normal maintenance and repairs are expensed as incurred. The cost of assets sold or abandoned, and the related accumulated depreciation are eliminated from the accounts and any gains or losses are recognized in the accompanying unaudited condensed consolidated statements of operations and comprehensive loss of the respective period. Leases Operating leases are accounted for in accordance with ASU 2016-02, Leases , as amended (“ASC 842”). Right-of-use lease assets represent the right to use an underlying asset for the lease term and lease liabilities represent an obligation to make lease payments arising from the lease. The measurement of lease liabilities is based on the present value of future lease payments over the lease term. As the Company’s leases do not provide an implicit rate, management used the Company’s incremental borrowing rate based on the information available at the lease commencement date in determining the present value of future lease payments. The right-of-use asset is based on the measurement of the lease liability and includes any lease payments made prior to or on lease commencement and excludes lease incentives and initial direct costs incurred, as applicable. Rent expense for operating leases is recognized on a straight-line basis over the lease term. The Company does no t have any leases classified as finance leases. Management have elected the practical expedient to exclude short-term leases from right-of-use assets and lease liabilities. The Company’s leases do not have significant rent escalation, holidays, concessions, material residual value guarantees, material restrictive covenants or contingent rent provisions. The Company’s leases include both lease (e.g., fixed payments including rent, taxes, and insurance costs) and non-lease components (e.g., common-area or other maintenance costs), which are accounted for as a single lease component as management have elected the practical expedient to group lease and non-lease components for all leases. Additional information and disclosures required under ASC 842 are included in Note 9. Restricted Cash In accordance with ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash , restricted cash is included as a component of cash, cash equivalents and restricted cash in the accompanying unaudited condensed consolidated statements of cash flows. Restricted cash serves as collateral for a letter of credit securing office space. Restricted cash is recorded within other assets and restricted cash line item in the accompanying unaudited condensed consolidated balance sheets. Fair Value Measurements The Company calculates the fair value of assets and liabilities that qualify as financial instruments and includes additional information in the notes to the unaudited condensed consolidated financial statements when the fair value is different than the carrying value of these financial instruments. The Company is required to disclose information on all assets and liabilities reported at fair value that enables an assessment of the inputs used in determining the reported fair values. ASC Topic 820, Fair Value Measurements and Disclosures (“ASC 820”), defines fair value as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants at the measurement date. ASC 820 establishes a hierarchy of inputs used in measuring fair value that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that the observable inputs be used when available. Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect management’s assumptions about the inputs that market participants would use in pricing the asset or liability and are developed based on the best information available in the circumstances. The fair value hierarchy applies only to the valuation inputs used in determining the reported fair value of the investments and is not a measure of the investment credit quality. The three levels of the fair value hierarchy are described below: • Level 1 - Quoted prices in active markets for identical assets or liabilities. • Level 2 - Observable inputs other than quoted prices included in Level 1, such as quoted prices for similar assets and liabilities in active markets; quoted prices for identical or similar assets and liabilities in markets that are not active; or other inputs that are observable or can be corroborated by observable market data. • Level 3 - Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets and liabilities. This includes certain pricing models, discounted cash flow methodologies and similar valuation techniques that use significant unobservable inputs. To the extent that a valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by management in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. Management has segregated all financial assets and liabilities that are measured at fair value on a recurring basis into the most appropriate level within the fair value hierarchy based on the inputs used to determine the fair value at the measurement date in the table below. The Company’s valuation techniques for its Level 2 financial assets included using quoted prices for similar assets in active markets and quoted prices for similar assets in markets that are not active. The estimated fair value of receivable from related party, unbilled receivable from related party, accounts payable and accrued expenses approximate their carrying amounts due to the relatively short maturity of these instruments. Additional information regarding fair value measurements is included in Note 7. Classification of Convertible Preferred Stock Convertible preferred stock was recorded at its original issuance price, less direct and incremental offering costs, as stipulated by its terms. The Company had applied the guidance in ASC 480-10-S99, Distinguishing Liabilities from Equity-Overall-SEC Materials , and had therefore classified the convertible preferred stock outside of stockholders’ equity/(deficit). In September 2023, all outstanding shares of convertible preferred stock were converted into shares of common stock immediately prior to the effective time of the Reverse Merger. Additional information and disclosures are included in Note 11. Segment Information Operating segments are defined as components of an entity for which separate financial information is available and that is regularly reviewed by the Chief Operating Decision Maker (“CODM”) in deciding how to allocate resources and in assessing performance. The Company’s CODM is its Chief Executive Officer (“CEO”). The Company operates as a single operating segment and has one reportable segment. License Revenue – Related Party To date, the Company’s only revenue has been attributable to an upfront payment and cost reimbursements under the Company’s license agreement with Zenas. The Company has not generated any revenue from product sales and does not expect to generate any revenue from product sales for the foreseeable future. The Company recognizes revenue pursuant to ASC 606, Revenue from Contracts with Customers (“ASC 606”). ASC 606 applies to all contracts with customers, except for contracts that are within the scope of other standards. Under ASC 606, an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration that the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that an entity determines are within the scope of ASC 606, the entity performs the following five steps: (i) identify the contract with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when the performance obligation is satisfied. The Company evaluates the performance obligations promised in a contract that are based on goods and services that will be transferred to the customer and determines whether those obligations are both (i) capable of being distinct and (ii) distinct in the context of the contract. To the extent a contract includes multiple promised goods and services, the Company applies judgment to determine whether promised goods and services are both capable of being distinct and are distinct in the context of the contract. If these criteria are not met, the promised goods and services are accounted for as a combined performance obligation. Arrangements that include rights to additional goods or services that are exercisable at a customer’s discretion are generally considered options. The Company assesses if these options provide a material right to the customer and if so, they are considered performance obligations. The Company estimates the transaction price based on the amount expected to be received for transferring the promised goods or services in the contract. The consideration may include fixed consideration or variable consideration. At the inception of each arrangement that includes variable consideration, the Company evaluates the amount of potential transaction price and the likelihood that the transaction price will be received. Variable consideration is included in the transaction price if, in management’s judgment, it is probable that a significant future reversal of cumulative revenue under the contract will not occur. Any estimates, including the effect of the constraint on variable consideration, are evaluated at each reporting period for any changes. The Company then allocates the transaction price to each performance obligation and recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) control is transferred to the customer and the performance obligation is satisfied. Amounts received prior to satisfying the revenue recognition criteria are recorded as deferred revenue in the Company’s unaudited condensed consolidated balance sheets. If the related performance obligation is expected to be satisfied within the next twelve months this will be classified in current liabilities. Additional information and disclosures required under ASC 606 are included in Note 13. Research and Development Costs Research and development expenses are recorded as expense, as incurred. Research and development expenses consists of (i) costs to engage contractors who specialize in the development activities of the Company; (ii) external research and development costs incurred under arrangements with third parties, such as contract research organizations and consultants; and (iii) costs associated with preclinical activities and regulatory operations. The Company enters into consulting, research, and other agreements with commercial firms, researchers, and others for the provision of goods and services. Under such agreements, the Company may pay for services on a monthly, quarterly, project or other basis. Such arrangements are generally cancelable upon reasonable notice and payment of costs incurred. Costs are considered incurred based on an evaluation of the progress to completion of specific tasks under each contract using information and data provided by the service providers and vendors or our estimate of the level of service that has been performed at each reporting date, whereas payments are dictated by the terms of each agreement. As such, depending on the timing of payment relative to the receipt of goods or services, management may record either prepaid expenses or accrued services. These costs consist of direct and indirect costs associated with specific projects, as well as fees paid to various entities that perform certain research on behalf of the Company. Patent Costs Patent costs are expensed as incurred and recorded within general and administrative expenses. Income Taxes Income taxes are recorded in accordance with ASC 740, Income Taxes (“ASC 740”), which provides for deferred taxes using an asset and liability approach. The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements or tax returns. Deferred tax assets and liabilities are determined based on the difference between the financial statement and tax basis of assets and liabilities and for loss and credit carryforwards using enacted tax rates anticipated to be in effect for the year in which the differences are expected to reverse. Valuation allowances are provided, if, based upon the weight of available evidence, it is more likely than not that some or all the deferred tax assets will not be realized. The Company accounts for uncertain tax positions in accordance with the provisions of ASC 740. When uncertain tax positions exist, the Company recognizes the tax benefit of tax positions to the extent that the benefit will more likely than not be realized. The determination as to whether the tax benefit will more likely than not be realized is based upon the technical merits of the tax position, as well as consideration of the available facts and circumstances. As of June 30, 2024 and December 31, 2023 , the Company did no t have any material uncertain tax positions. The Company recognizes interest and penalties related to uncertain tax positions, if any exist, in income tax expense. Stock-Based Compensation The Company accounts for stock-based compensation awards in accordance with ASC Topic 718, Compensation – Stock Compensation (“ASC 718”). ASC 718 requires all stock-based payments, including grants of stock options and restricted stock, to be recognized in the unaudited condensed consolidated statements of operations and comprehensive loss based on their fair values. All of the stock-based awards are subject only to service-based vesting conditions. Management estimates the fair value of the stock option awards using the Black-Scholes option pricing model, which requires the input of assumptions, including (a) the fair value of the Company’s common stock, (b) the expected stock price volatility, (c) the calculation of expected term of the award, (d) the risk-free interest rate and (e) expected dividends. Management estimates the fair value of the restricted stock awards, if any, using the fair value of the Company’s common stock. Forfeitures are recognized as they are incurred. Prior to the Reverse Merger, management utilized valuation methodologies in accordance with the framework of the American Institute of Certified Public Accountants Technical Practice Aid, Valuation of Privately Held Company Equity Securities Issued as Compensation , to estimate the fair value of Former Dianthus common stock. Each valuation methodology included estimates and assumptions that required management’s judgment. These estimates and assumptions included objective and subjective factors, including external market conditions, the prices at which Former Dianthus sold shares of convertible preferred stock, the superior rights and preferences of the convertible preferred stock senior to Former Dianthus common stock at the time, and a probability analysis of various liquidity events, such as a public offering or sale of Former Dianthus, under differing scenarios. Changes to the key assumptions used in the valuations could have resulted in materially different fair values of Former Dianthus common stock at each valuation date. Following the Reverse Merger, the fair value of the Company’s common stock is based on the closing stock price on the date of grant as reported on the Nasdaq Capital Market. Prior to the Reverse Merger, due to a lack of company-specific historical and implied volatility data, management based its estimate of expected volatility on the historical volatility of a representative group of companies with similar characteristics to the Company, including stage of product development and life science industry focus. Management believes the group selected had sufficiently similar economic and industry characteristics and includes companies that are most representative of the Company. Following the Reverse Merger, expected volatility at the date of grant is estimated using a “look-back” period, which coincides with the expected term, of the Company's stock price as reported on the Nasdaq Capital Market. Management uses the simplified method, as prescribed by the SEC Staff Accounting Bulletin No. 107, Share-Based Payment , to calculate the expected term. The risk-free interest rate is based on observed interest rates appropriate for the term of the awards. The dividend yield assumption is based on history and expectation of paying no dividends. Compensation expense related to stock-based awards is calculated on a straight-line basis by recognizing the grant date fair value, over the associated service period of the award, which is generally the vesting term. Additional information regarding stock-based compensation is included in Note 12. Comprehensive Loss The only component of comprehensive loss other than net loss is change in unrealized gains/losses related to available-for-sale debt securities. Net Loss per Share Basic and diluted net loss per share attributable to common stockholders is computed by dividing net loss by the weighted-average number of common shares outstanding during the period. The weighted average number of common shares outstanding includes the weighted average effect of outstanding pre-funded warrants for the purchase of shares of common stock for which the remaining unfunded exercise price is $ 0.001 or less per share. Basic and diluted net loss per share attributable to common stockholders are calculated in conformity with the two-class method required for participating securities. Convertible preferred stock is a participating security in distributions of the Company. During the three and six months ended June 30, 2023, the net loss attributable to common stockholders was not allocated to the convertible preferred shares as the holders of convertible preferred shares did not have a contractual obligation to share in losses. Under the two-class method, basic net loss per share of common stock is computed by dividing net loss by the weighted-average number of shares of common stock outstanding during each period. During the three and six months ended June 30, 2023, the weighted-average number of shares of common stock outstanding used in the basic net loss per share calculation did not include unvested restricted common stock as these shares were considered contingently issuable shares until they vested. Diluted net loss per share of common stock includes the effect, if any, from the potential exercise or conversion of securities, such as convertible preferred stock, stock options and unvested restricted common stock, if any, which would result in the issuance of incremental shares of common stock. For diluted net loss per share, the weighted-average number of shares of common stock outstanding is the same for basic net loss per share due to the fact that when a net loss exists, dilutive securities are not included in the calculation as the impact is anti-dilutive. For all periods presented, basic and diluted net loss per share were the same, as any additional share equivalents would be anti-dilutive. Additional information is included in Note 14. Recently Issued Accounting Pronouncements In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures . ASU 2023-07 expands annual and interim disclosure requirements for reportable segments, primarily through enhanced disclosures about significant segment expenses. ASU 2023-07 is effective for fiscal years beginning after December 15, 2023, and for interim periods beginning after December 14, 2024, with early adoption permitted. The Company is currently evaluating the guidance and has not determined the impact this standard may have on the unaudited condensed consolidated financial statements. In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740), Improvements to Income Tax Disclosures , to enhance the transparency and decision usefulness of income tax disclosures. The enhancement will provide information to better assess how an entity’s operations and related tax risks and tax planning and operational opportunities affect its tax rate and prospects for future cash flows. Investors currently rely on the rate reconciliation table and other disclosures, including total income taxes paid, to evaluate income tax risks and opportunities. ASU No. 2023-09 is effective for fiscal years beginning after December 15, 2024 and early adoption is permitted. The Company is currently evaluating the impact ASU No. 2023-09 will have on the unaudited condensed consolidated financial statements and related disclosures.

Reverse Merger

Reverse Merger	6 Months Ended
	Jun. 30, 2024
Business Combination, Asset Acquisition, and Joint Venture Formation [Abstract]
Reverse Merger	3. Reverse Merger As described in Note 1, Merger Sub merged with and into Former Dianthus, with Former Dianthus surviving as a wholly owned subsidiary of the Company on September 11, 2023. The Reverse Merger was accounted for as a reverse asset acquisition accounted for as a reverse recapitalization in accordance with U.S. GAAP with Former Dianthus as the accounting acquirer of Magenta. At the effective time of the Reverse Merger, substantially all of the assets of Magenta consisted of cash and cash equivalents, marketable securities, as well as other nominal non-operating assets. Under such reverse recapitalization accounting, the assets and liabilities of Magenta were recorded at their fair value in Magenta’s financial statements at the effective time of the Reverse Merger, which approximated book value due to the short-term nature. No goodwill or intangible assets were recognized. As part of the recapitalization, the Company obtained the assets and liabilities listed below: Cash and cash equivalents $ 69,738 Other current assets 2,473 Accrued liabilities ( 616 ) Net assets acquired $ 71,595 With respect to the CVRs issued in connection with the Reverse Merger, the Company believes that the achievement of the milestones outlined in the CVR Agreement are highly susceptible to factors outside the Company's influence that are not expected to be resolved for a long period of time, if at all. In particular, these amounts are primarily influenced by the actions and judgments of third parties and the buyers of such assets and are based on the buyers of such assets progressing the in-process research and development assets into clinical trials, and in the case of one of the agreements, to a regulatory milestone. If the Company were to record a receivable for such contingent payments, it would also record a corresponding liability. As of June 30, 2024 , no receivables are recorded on the unaudited condensed consolidated balance sheet relating to such contingent payments.

Short-Term Investments

Short-Term Investments	6 Months Ended
	Jun. 30, 2024
Short-Term Investments [Abstract]
Short-Term Investments	4. Short-Term Investments The following table provides a summary of short-term investments: June 30, 2024 Amortized Gross Gross Fair Value Available-for-sale, short-term investments: U.S. treasury securities $ 45,574 $ — $ ( 35 ) $ 45,539 U.S. government agency securities 1,001 — ( 2 ) 999 Total available-for-sale, short-term investments $ 46,575 $ — $ ( 37 ) $ 46,538 December 31, 2023 Amortized Gross Gross Fair Value Available-for-sale, short-term investments: U.S. treasury securities $ 36,370 $ 48 $ — $ 36,418 U.S. government agency securities 4,976 — ( 1 ) 4,975 Total available-for-sale, short-term investments $ 41,346 $ 48 $ ( 1 ) $ 41,393

Prepaid Expenses and Other Curr

Prepaid Expenses and Other Current Assets	6 Months Ended
	Jun. 30, 2024
Prepaid Expense and Other Assets, Current [Abstract]
Prepaid Expenses and Other Current Assets	5. Prepaid Expenses and Other Current Assets The following table provides a summary of prepaid expenses and other current assets: June 30, December 31, Prepaid materials, supplies and research and development services $ 2,305 $ 2,155 Prepaid subscriptions, software and other administrative services 797 504 Prepaid insurance 203 596 Prepaid expenses and other current assets $ 3,305 $ 3,255

Property and Equipment

Property and Equipment	6 Months Ended
	Jun. 30, 2024
Property, Plant and Equipment [Abstract]
Property and Equipment	6. Property and Equipment The following table provides a summary of property and equipment: June 30, December 31, Computer equipment $ 281 $ 234 Furniture and fixtures 50 48 Subtotal 331 282 Less: accumulated depreciation ( 142 ) ( 97 ) Property and equipment, net $ 189 $ 185 Depreciation expense was $ 23 thousand and $ 45 thousand during the three and six months ended June 30, 2024 , respectively, and $ 15 thousand and $ 28 thousand during the three and six months ended June 30, 2023 , respectively.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	6 Months Ended
	Jun. 30, 2024
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	7. Fair Value of Financial Instruments The following table provides a summary of financial assets measured at fair value on a recurring basis: Fair Value at Description June 30, Level 1 Level 2 Level 3 Recurring Assets: Cash equivalents: Money market funds $ 313,103 $ 313,103 $ — $ — Short-term investments: U.S. treasury securities 45,539 45,539 — — U.S. government agency securities 999 — 999 — Total assets measured at fair value $ 359,641 $ 358,642 $ 999 $ — Fair Value at December 31, Description 2023 Level 1 Level 2 Level 3 Recurring Assets: Cash equivalents: Money market funds $ 131,193 $ 131,193 $ — $ — Short-term investments: U.S. treasury securities 36,418 36,418 — — U.S. government agency securities 4,975 — 4,975 — Total assets measured at fair value $ 172,586 $ 167,611 $ 4,975 $ — There were no transfers between levels for the six months ended June 30, 2024 or for the year ended December 31, 2023.

Accrued Expenses

Accrued Expenses	6 Months Ended
	Jun. 30, 2024
Accrued Expenses	8. Accrued Expenses The following table provides a summary of accrued expenses: June 30, December 31, Accrued external research and development $ 2,797 456 Accrued compensation 2,602 5,361 Accrued professional fees 211 422 Other accrued expenses 247 265 Accrued expenses $ 5,857 $ 6,504

Leases

Leases	6 Months Ended
	Jun. 30, 2024
Leases [Abstract]
Leases	9. Leases The Company leases space under operating leases for administrative offices in New York, New York, and Waltham, Massachusetts and wet laboratory space in Watertown, Massachusetts. The following table provides a summary of the components of lease costs and rent: Three Months Ended Six Months Ended 2024 2023 2024 2023 Operating lease cost $ 103 $ 88 $ 206 $ 175 Variable lease cost 7 6 15 13 Total operating lease costs $ 110 $ 94 $ 221 $ 188 The Company recorded operating lease costs of $ 0.1 million and $ 0.2 million during each of the three and six months ended June 30, 2024 and 2023 , respectively, within the general and administrative expenses line item in the unaudited condensed consolidated statements of operations and comprehensive loss. The Company recorded operating lease costs of $ 15 thousand and $ 30 thousand during the three and six months ended June 30, 2024 , respectively, and nil during the three and six months ended June 30, 2023 within the research and development expenses line item in the unaudited condensed consolidated statements of operations and comprehensive loss. Maturities of operating lease liabilities as of June 30, 2024, are as follows: 2024 (remaining 6 months) $ 212 2025 222 Total undiscounted operating lease payments 434 Less: imputed interest ( 27 ) Present value of operating lease liabilities $ 407 Balance sheet classification: Current portion of operating lease liabilities $ 377 Long-term operating lease liabilities 30 Total operating lease liabilities $ 407 The weighted-average remaining term of operating leases was 13 months and the weighted-average discount rate used to measure the present value of operating lease liabilities was 10.8 % as of June 30, 2024 .

Common Stock

Common Stock	6 Months Ended
	Jun. 30, 2024
Equity [Abstract]
Common Stock	10. Common Stock At the closing of the private placement on January 24, 2024, the Company issued 14,500,500 shares of common stock and pre-funded warrants to purchase 4,666,332 shares of common stock with a $ 0.001 per share exercise price. The pre-funded warrants are exercisable at any time after the date of issuance and will not expire. As of June 30, 2024 , there were 4,666,332 pre-funded warrants outstanding related to this private placement. At the effective time of the Reverse Merger on September 11, 2023, the Company issued an aggregate of 11,021,248 shares of Company common stock to the Former Dianthus stockholders, based on the exchange ratio of approximately 0.2181 shares of Company common stock for each share of Former Dianthus common stock, including those shares of Former Dianthus common stock issued upon the conversion of Former Dianthus preferred stock and those shares of the Former Dianthus common stock issued in the pre-closing financing. In conjunction with the pre-closing financing, the Company also issued pre-funded warrants to purchase 210,320 shares of common stock with a $ 0.001 per share exercise price. The pre-funded warrants are exercisable at any time after the date of issuance and will not expire. As of June 30, 2024 , there were 210,320 pre-funded warrants outstanding related to this financing. As of June 30, 2024 and December 31, 2023 , the Company was authorized to issue up to 150,000,000 shares of $ 0.001 par value of Company common stock. As of June 30, 2024 and December 31, 2023 , the Company had issued and outstanding shares of common stock of 29,352,140 and 14,817,696 , respectively. Each share of Company common stock entitles the holder to one vote on all matters submitted to a vote of the Company’s stockholders. Common stockholders are entitled to receive dividends, as may be declared by the Company’s board of directors, if any. No dividends have been declared or paid by the Company through June 30, 2024. The Company had the following shares of Company common stock reserved for future issuance as of June 30, 2024 and December 31, 2023: As of As of Issuance of common stock upon exercise of stock options 4,420,676 1,749,475 Equity awards available for grant under stock award plans 2,045,704 879,461 Shares available for issuance under the Employee Stock Purchase Plan 99,578 37,078 Issuance of common stock upon exercise of warrants 4,881,329 214,997 Total common stock reserved for future issuance 11,447,287 2,881,011

Preferred Stock and Convertible

Preferred Stock and Convertible Preferred Stock	6 Months Ended
	Jun. 30, 2024
Stockholders' Equity Note [Abstract]
Preferred Stock and Convertible Preferred Stock	11. Preferred Stock and Convertible Preferred Stock Preferred Stock As of June 30, 2024 , the Company was authorized to issue up to 10,000,000 shares of preferred stock at a par value of $ 0.001 . As of June 30, 2024 , no shares of preferred stock were issued and outstanding. Convertible Preferred Stock On September 11, 2023, the Company completed the Reverse Merger with Former Dianthus in accordance with the Merger Agreement. Under the terms of the Merger Agreement, immediately prior to the effective time of the Reverse Merger, each share of Former Dianthus convertible preferred stock was converted into a share of Former Dianthus common stock. At closing of the Reverse Merger, the Company issued an aggregate of 7,269,183 shares of its common stock to Former Dianthus convertible preferred stockholders, based on the exchange ratio of approximately 0.2181 shares of Company common stock for each share of Former Dianthus common stock outstanding immediately prior to the Reverse Merger.

Stock-Based Compensation

Stock-Based Compensation	6 Months Ended
	Jun. 30, 2024
Share-Based Payment Arrangement [Abstract]
Stock-Based Compensation	12. Stock-Based Compensation 2018 Stock Option and Incentive Plan The Company grants stock-based awards under the Amended and Restated Dianthus Therapeutics, Inc. Stock Option and Incentive Plan (the “2018 Incentive Plan”), which originally became effective on June 19, 2018 as the Magenta Therapeutics, Inc. 2018 Stock Option and Incentive Plan and was amended and restated in September 2023 and renamed the Amended and Restated Dianthus Therapeutics, Inc. Stock Option and Incentive Plan. The 2018 Incentive Plan provides for the grant of incentive stock options, nonqualified stock options, stock appreciation rights, restricted stock awards, restricted stock units, unrestricted stock awards, cash-based awards, and dividend equivalent rights. In connection with the Reverse Merger, the 2018 Incentive Plan also provided for the assumption of shares remaining available for delivery under the 2019 Stock Plan (as defined below), and such shares will be available for the granting of awards under the 2018 Incentive Plan in accordance with applicable stock exchange requirements. The Company also has outstanding stock options under the Magenta Therapeutics, Inc. 2016 Stock Option and Grant Plan, as amended (the “2016 Plan”), but is no longer granting awards under the 2016 Plan. The 2018 Incentive Plan provides that the number of shares reserved and available for issuance under the 2018 Incentive Plan will automatically increase each January 1 by 4 % of the outstanding number of shares of the Company’s common stock on the immediately preceding December 31 (the “Evergreen Provision”) or such lesser number of shares as determined by the Company’s board of directors or compensation committee of the board of directors. The number of shares reserved for issuance under the 2018 Incentive Plan increased by 592,707 on January 1, 2024. Shares of common stock underlying any awards under the 2018 Incentive Plan, the 2019 Stock Plan and the 2016 Plan that are forfeited, cancelled, held back upon exercise or settlement of an award to satisfy the exercise price or tax withholding, reacquired by the Company prior to vesting, satisfied without any issuance of stock, expire or are otherwise terminated (other than by exercise) will be available for future awards under the 2018 Incentive Plan. On May 23, 2024, the Company's stockholders approved an amendment and restatement of the 2018 Incentive Plan (the “2018 Amended Plan”) to: • provide for an increase in the number of shares of common stock reserved for issuance thereunder by 2,931,820 shares; • increase the Evergreen Provision (as described above) from 4 % to 5 % of issued and outstanding shares of common stock on December 31 of the preceding calendar year; and • extend the expiration date until March 14, 2034. As of June 30, 2024 , 1,953,704 shares of the Company’s common stock were available for grant under the 2018 Amended Plan. The 2018 Amended Plan is administered by either the board of directors or the compensation committee of the board of directors. The exercise prices, vesting and other restrictions are determined at the discretion of the administrator, except that the term of stock options and stock appreciation rights may not be greater than ten years (or five years for certain incentive stock options). Awards typically vest over 12 months to four years . The exercise price for stock options granted may not be less than the fair value of common stock as of the date of grant (or 110 % of the fair value of common stock for certain incentive stock options). The fair value of common stock is based on quoted market prices. 2019 Stock Plan In July 2019, Former Dianthus’ Board of Directors adopted, and the Former Dianthus’ stockholders approved, the Dianthus Therapeutics, Inc. 2019 Stock Plan (the “2019 Stock Plan”). In connection with the Reverse Merger, the Company assumed options to purchase shares of Former Dianthus’s common stock that were outstanding under the 2019 Stock Plan immediately prior to the Reverse Merger and such options were converted into options to purchase 1,273,454 shares of Company’s common stock (the “Assumed Options”). No further awards will be made under the 2019 Stock Plan; however, the Assumed Options will remain outstanding under the 2019 Stock Plan in accordance with their terms, as adjusted to reflect the Reverse Merger. 2019 Employee Stock Purchase Plan Employees may elect to participate in the Dianthus Therapeutics, Inc. 2019 Employee Stock Purchase Plan, as amended (the “ESPP”). The purchase price of common stock under the ESPP is equal to 85 % of the lower of the fair market value of the common stock on the offering date or the exercise date. The six-month offering periods previously began in December and June of each year. During the six months ended June 30, 2024 and 2023 , there were no shares of common stock purchased under the ESPP. As of June 30, 2024 , 99,578 shares remained available for issuance under the ESPP. The ESPP provides that the number of shares reserved and available for issuance under the ESPP will automatically increase each January 1 through January 1, 2029, by the lesser of (i) 1 % of the number of shares issued and outstanding on the immediately preceding December 31, (ii) 62,500 shares and (iii) such number of shares as determined by the Company’s board of directors or its appointed administrator. The number of shares reserved for issuance under the ESPP increased by 62,500 on January 1, 2024. Stock Option Inducement Grant and Inducement Plan In December 2023, the Company’s board of directors granted an option to purchase 96,000 shares of common stock to a new hire as an inducement grant. In February 2024, the Company’s board of directors approved the Dianthus Therapeutics, Inc. Equity Inducement Plan (the “Inducement Plan”), which provides for up to 300,000 shares of common stock for inducement awards. As of June 30, 2024 , there were 92,000 shares available to be granted under the Inducement Plan. Stock Options The following table summarizes stock option activity for the six months ended June 30, 2024: Number of Weighted Weighted Aggregate (in years) Balance at January 1, 2024 1,749,475 $ 10.61 8.4 $ 3,181 Options granted, fair value of $ 15.72 per share 2,788,000 20.30 16,048 Options exercised ( 33,944 ) 9.14 504 Options forfeited ( 82,855 ) 15.52 926 Balance at June 30, 2024 4,420,676 $ 16.64 9.1 $ 42,783 Exercisable options at June 30, 2024 1,026,134 $ 12.26 8.2 $ 15,433 Unvested options at June 30, 2024 3,394,542 $ 17.97 9.4 $ 27,350 The aggregate intrinsic value of options is calculated as the difference between the exercise price of the options and the fair value of the common stock for those options that had exercise prices lower than the fair value of the common stock. The weighted average grant-date fair value per share of stock options granted during the six months ended June 30, 2024 was $ 15.72 per share. The table below summarizes the assumptions used to determine the grant-date fair value of stock options issued, presented on a weighted average basis during the three and six months ended June 30, 2024 and 2023. Three Months Ended Six Months Ended 2024 2023 2024 2023 Risk-free interest rate 4.5 % 4.1 % 4.3 % 3.8 % Expected term (in years) 6.0 6.1 6.0 6.1 Expected volatility 92.3 % 86.4 % 92.7 % 85.0 % Expected dividend yield 0.0 % 0.0 % 0.0 % 0.0 % Stock Warrants In April 2021, Former Dianthus issued 4,677 warrants for the purchase of common stock at an exercise price of $ 1.65 per share. The warrants vested on July 30, 2023 and had a grant date fair value of $ 1.16 per warrant. As of June 30, 2024 , the warrants have a weighted average remaining contractual term of 6.8 years. Stock-based Compensation Expense The following table provides a summary of stock-based compensation expense: Three Months Ended Six Months Ended 2024 2023 2024 2023 Research and development $ 1,350 $ 141 $ 2,189 $ 332 General and administrative 1,751 321 2,947 663 Total stock-based compensation expense $ 3,101 $ 462 $ 5,136 $ 995 As of June 30, 2024 , there was $ 45.5 million of total unrecognized compensation cost related to granted stock options. The Company expects to recognize that cost over a remaining weighted-average period of 3.4 years.

License Revenue - Related Party

License Revenue - Related Party	6 Months Ended
	Jun. 30, 2024
Related Party Transactions [Abstract]
License Revenue - Related Party	13. License Revenue – Related Party In September 2020, the Company entered into an Option Agreement with Zenas (“Zenas Option”), a related party (See Note 16). Through the Zenas Option, the Company provided Zenas an option to enter into an exclusive license agreement for the development and commercialization of products arising from its research of monoclonal antibody antagonists targeting certain specific complement proteins. In September 2021, the Company notified Zenas that it had elected the first antibody sequence as a clinical candidate. In October 2021, Zenas notified the Company that it was exercising its option for such clinical candidate. The Zenas Option provided that upon the exercise of the option, the Company would negotiate in good faith a license agreement with Zenas pursuant to which it would grant Zenas the exclusive license with respect to the antibody sequences for the Zenas territory, which includes People’s Republic of China, including Hong Kong, Macau, and Taiwan. In accordance with Zenas Option, within 60 days following the execution of a license agreement, Zenas agreed to pay the Company a one-time payment of $ 1.0 million for the exercise of the corresponding option. In addition, in connection with the exercise of the Zenas Option, Zenas was required to reimburse the Company for a portion of chemistry, manufacturing, and controls-related (“CMC”) costs and expenses from the date of delivery of its option exercise notice through the execution of a license agreement. In June 2022, the Company and Zenas executed the license agreement (“Zenas License”). The Zenas Option and Zenas License are collectively referred to as the “Zenas Agreements.” The Zenas License provides Zenas with a license in the People’s Republic of China, including Hong Kong, Macau, and Taiwan, for the development and commercialization of sequences and products under the first antibody sequence. The Company is also obligated to perform certain research and development and CMC services and will also participate in a joint steering committee (“JSC”). Under the Zenas License, Zenas also has the right to exercise an option with respect to a second antibody sequence. If Zenas exercises the option and pays the Company the option exercise fee related to the second antibody sequence, the Company will grant Zenas an exclusive license to the sequences and products under this second antibody sequence. Since the Zenas Agreements were negotiated with a single commercial objective, they are treated as a combined contract for accounting purposes. The Company assessed the Zenas Agreements in accordance with ASC 606 and concluded that it represents a contract with a customer and is within the scope of ASC 606. The Company determined that there is one combined performance obligation that consists of the license and data transfer, the research and development and CMC services and the participation in the JSC. The Company determined that Zenas’ right to exercise an option with respect to a second antibody sequence does not represent a material right. The consideration under the Zenas Agreements includes the following payments by Zenas to the Company: (i) a $ 1.0 million upfront payment upon execution of the Zenas License; (ii) an approximate $ 1.1 million payment representing reimbursement for a portion of development costs previously incurred by the Company; (iii) reimbursement of a portion of all CMC-related costs and expenses for the first antibody sequence through the manufacture of the first two batches of drug product; (iv) reimbursement of a portion of all non-CMC-related costs and expenses for the development of the first antibody sequence through the first regulatory approval; (v) development milestones totaling up to $ 11.0 million; and (vi) royalties on net sales ranging from the mid-single digits to the low teen percentages. The Company determined that the combined performance obligation is satisfied over time; therefore, the Company will recognize the transaction price from the license agreement over the Company’s estimated period to complete its activities. The Company concluded that it will utilize a cost-based input method to measure its progress toward completion of its performance obligation and to calculate the corresponding amount of revenue to recognize each period. The Company believes this is the best measure of progress because other measures do not reflect how the Company transfers its performance obligation to Zenas. In applying the cost-based input method of revenue recognition, the Company uses actual costs incurred relative to budgeted costs expected to be incurred for the combined performance obligation. These costs consist primarily of third-party contract costs. Revenue will be recognized based on the level of costs incurred relative to the total budgeted costs for the combined performance obligation. A cost-based input method of revenue recognition requires management to make estimates of costs to complete the Company’s performance obligation. In making such estimates, judgment is required to evaluate assumptions related to cost estimates. The Company also determined that the milestone payments of $ 11.0 million are variable consideration under ASC 606 which need to be added to the transaction price when it is probable that a significant revenue reversal will not occur. Based on the nature of the milestones, such as the regulatory approvals which are generally not within the Company’s control, the Company will not consider achievement of this milestone to be probable until the uncertainty associated with such milestone has been resolved. When it is probable that a significant reversal of revenue will not occur, the milestone payment will be added to the transaction price for which the Company recognizes revenue. As of June 30, 2024, no milestones had been achieved. There is a sales or usage-based royalty exception within ASC 606 that applies when a license of intellectual property is the predominant item to which the royalty relates. In accordance with this royalty exception, the Company will recognize royalty 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). As of June 30, 2024 , no royalty revenue had been recognized. The Company recognized related party license revenue totaling $ 1.9 million and $ 1.0 million for the three months ended June 30, 2024 and 2023 , respectively, and $ 2.7 million and $ 1.5 million for the six months ended June 30, 2024 and 2023, respectively, associated with the Zenas Agreements. As of June 30, 2024 , the Company recorded a related party receivable of $ 0.8 million, unbilled related party receivable of $ 0.8 million, current deferred related party revenue of $ 0.1 million and noncurrent deferred related party revenue of $ 0.7 million on its unaudited condensed consolidated balance sheet. As of December 31, 2023 , the Company recorded a related party receivable of $ 0.3 million, unbilled related party receivable of $ 0.2 million, current deferred related party revenue of $ 0.1 million and noncurrent deferred related party revenue of $ 0.7 million on its unaudited condensed consolidated balance sheet.

Net Loss Per Share

Net Loss Per Share	6 Months Ended
	Jun. 30, 2024
Earnings Per Share [Abstract]
Earnings Per Share [Text Block]	14. Net Loss Per Share Basic and diluted net loss per share of common stock is calculated as follows: Three Months Ended Six Months Ended 2024 2023 2024 2023 Numerator: Net loss $ ( 17,607 ) $ ( 11,140 ) $ ( 31,355 ) $ ( 18,229 ) Denominator: Weighted-average shares of common stock outstanding 34,227,038 875,279 31,794,881 875,279 Less: weighted-average unvested restricted shares of common stock — ( 379 ) — ( 474 ) Weighted-average shares used to compute net loss 34,227,038 874,900 31,794,881 874,805 Net loss per share attributable to common stockholders, $ ( 0.51 ) $ ( 12.73 ) $ ( 0.99 ) $ ( 20.84 ) Pre-funded warrants totaling 4,876,652 shares have been included in the computation of basic and diluted net loss per share of common stock for the three and six months ended June 30, 2024 as the pre-funded warrants are issuable for nominal consideration pursuant to their terms. The Company’s potential dilutive securities, which include convertible preferred stock, stock options, unvested restricted shares of common stock, and warrants for the purchase of common stock, have been excluded from the computation of diluted net loss per share as the effect would be antidilutive. Therefore, the weighted-average number of shares of common stock outstanding used to calculate both basic and diluted net loss per share is the same. The following potential dilutive securities, presented on an as converted basis, were excluded from the calculation of net loss per share due to their anti-dilutive effect: Three Months Ended Six Months Ended 2024 2023 2024 2023 Convertible preferred stock (as converted) — 7,269,183 — 7,269,183 Stock options outstanding 4,420,676 1,494,028 4,420,676 1,494,028 Unvested restricted shares of common stock — 254 — 254 Warrants for the purchase of common stock 4,677 4,677 4,677 4,677 Total 4,425,353 8,768,142 4,425,353 8,768,142

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2024
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	15. Commitments and Contingencies Alloy Therapeutics, LLC In August 2019, the Company entered into a license agreement with Alloy Therapeutics, LLC (“Alloy”). The license agreement was amended in October 2022. The license agreement with Alloy grants to the Company the following: • A worldwide, non-exclusive license to use the Alloy technology solely to generate Alloy antibodies and platform assisted antibodies for internal, non-clinical research purposes, and • With respect to Alloy antibodies and platform assisted antibodies that are selected by the Company for inclusion into a partnered antibody program, a worldwide, assignable license to make, have made, use, offer for sale, sell, import, develop, manufacture, and commercialize products comprising partnered antibody programs selected from Alloy antibodies and platform assisted antibodies in any field of use. The Company pays annual license fees and annual partnered antibody program fees totaling $ 0.1 million to Alloy. The Company is also obligated to pay a $ 0.1 million fee to Alloy if the Company sublicenses a product developed with Alloy antibodies or platform assisted antibodies. Upon the achievement, with the first selected antibody for products developed with Alloy, of (i) certain development milestones and (ii) certain commercial milestones, the Company is obligated to make additional payments to Alloy of up to $ 1.8 million and $ 11.0 million, respectively. Upon the achievement, with the second selected antibody for products developed with Alloy, of (i) certain development milestones and (ii) certain commercial milestones, the Company is obligated to make additional payments to Alloy of up to $ 3.1 million and $ 15.0 million, respectively. The Company recorded $ 0.6 million during each of the three and six months ended June 30, 2024 and $ 50 thousand during each of the three and six months ended June 30, 2023 for amounts owed under the Alloy license agreement within the research and development expenses line item in the unaudited condensed consolidated statements of operations and comprehensive loss. OmniAb, Inc. In September 2022, the Company entered into a commercial platform license agreement and services agreement with two subsidiaries of Ligand Pharmaceuticals Incorporated (“Ligand”). In November 2022, Ligand spun-off these subsidiaries into a separate legal entity, OmniAb, Inc. (“OmniAb”). The platform license agreement and services agreement with OmniAb grants to the Company the following: • A worldwide, non-exclusive, non-sublicensable license under the OmniAb technology to use chicken animals (solely at OmniAb’s facilities and through OmniAb personnel) for generation of OmniAb antibodies for research purposes. • A worldwide, non-exclusive license under the OmniAb technology to use rodent animals (solely at approved contract research organization (“CRO”) facilities and through approved CRO personnel) for generation of OmniAb antibodies for research purposes. Such license is non-sublicensable except to an approved CRO. Upon the achievement of certain development milestones, the Company is obligated to make additional payments to OmniAb of up to $ 12.2 million. Upon the achievement of certain commercial milestones, the Company is obligated to make royalty payments in the low to mid-single digit percentages. The Company did no t record any amounts owed under the Ligand license agreement during the six months ended June 30, 2024 . The Company recorded $ 50 thousand and $ 0.2 million during the three and six months ended June 30, 2023, respectively, for amounts owed under the Ligand license agreement within research and development expenses line item in the unaudited condensed consolidated statements of operations and comprehensive loss. IONTAS Limited In July 2020, the Company entered into a collaborative research agreement with IONTAS Limited (“IONTAS”) to perform certain milestone-based research and development activities for the Company under its first development program. This agreement was amended in January 2023 to extend their services to additional development programs. IONTAS provides dedicated resources to perform the research and development activities and receives compensation for those resources as well as success-based milestone payments. Upon the achievement, with the first development program with IONTAS, of (i) certain development milestones and (ii) certain commercial milestones, the Company is obligated to make additional payments to IONTAS of up to £ 3.1 million (approximately $ 3.9 million based on the June 30, 2024 exchange rate) and £ 2.3 million (approximately $ 2.9 million based on the June 30, 2024 exchange rate), respectively. Upon the achievement, with the second development program with IONTAS, of certain development milestones, the Company is obligated to make additional payments to IONTAS of up to £ 2.5 million (approximately $ 3.2 million based on the June 30, 2024 exchange rate). The Company recorded $ 0.6 million and $ 1.0 million during the three and six months ended June 30, 2024 , respectively, and $ 0.8 million and $ 1.4 million during the three and six months ended June 30, 2023, respectively, for amounts owed under the IONTAS collaborative research license agreement within the research and development expenses line item in the unaudited condensed consolidated statements of operations and comprehensive loss. Indemnification Agreements In the ordinary course of business, the Company may provide indemnification of varying scope and terms to employees, consultants, vendors, business partners and other parties with respect to certain matters including, but not limited to, losses arising out of breach of such agreements or from intellectual property infringement claims made by third parties. To date, the Company has not incurred any material costs as a result of such indemnification agreements. The Company is not aware of any indemnification arrangements that could have a material effect on its financial position, results of operations or cash flows, and has not accrued any liabilities related to such obligations in its unaudited condensed consolidated financial statements as of June 30, 2024 and December 31, 2023. Litigation From time to time, the Company may be exposed to litigation relating to potential products and operations. The Company is not currently engaged in any legal proceedings that are expected, individually or in the aggregate, to have a material adverse effect on its financial condition, results of operations or cash flows. Other As of June 30, 2024 and December 31, 2023 , the Company had standing agreements with consultants, contractors or service providers whose terms do not yield material long-term commitments.

Related Party Transactions

Related Party Transactions	6 Months Ended
	Jun. 30, 2024
Related Party Transactions [Abstract]
Related Party Transactions	16. Related Party Transactions Zenas BioPharma Limited The Company is a party to option and license agreements with Zenas, a related party. The Company considers Zenas to be a related party because (i) Tellus BioVentures LLC (“Tellus”), whose sole member is a significant shareholder in the Company and has a seat on the Board of Directors of the Company, is also a significant shareholder in Zenas and serves as Chief Executive Officer and Chairman of the Board of Directors of Zenas and (ii) Fairmount Healthcare Fund LP and Fairmount Healthcare Fund II LP (together, the “Fairmount Funds”), who are significant shareholders in the Company and have a seat on the Board of Directors of the Company, are also significant shareholders in Zenas and have a seat on the Board of Directors of Zenas. As of June 30, 2024 , Tellus and affiliated entities owned approximately 5 %, and the Fairmount Funds and affiliated entities owned approximately 9 % of the Company’s outstanding shares. See Note 13 for more information. In connection with these agreements, the Company recognized $ 1.9 million and $ 1.0 million for the three months ended June 30, 2024 and 2023 , respectively, and $ 2.7 million and $ 1.5 million for the six months ended June 30, 2024 and 2023, respectively, within the license revenue – related party line item in the unaudited condensed consolidated statements of operations and comprehensive loss. As of June 30, 2024 , the Company recorded a related party receivable of $ 0.8 million, unbilled related party receivable of $ 0.8 million, current deferred related party revenue of $ 0.1 million and noncurrent deferred related party revenue of $ 0.7 million on its unaudited condensed consolidated balance sheet. As of December 31, 2023 , the Company recorded a related party receivable of $ 0.3 million, unbilled related party receivable of $ 0.2 million, current deferred related party revenue of $ 0.1 million and noncurrent deferred related party revenue of $ 0.7 million on its unaudited condensed consolidated balance sheet. In 2020, Zenas issued 156,848 shares of common stock to the Company in exchange for the Zenas Option. The Company determined that the fair value on the date of issuance was not material to its unaudited condensed consolidated financial statements. The Company used the measurement alternative as the measurement attribute for accounting for the Zenas common stock which does not require it to assess the fair value of the common stock at each reporting period as the fair value of the Zenas common stock is not readily determinable nor is there a reliable source for observable transactions from which the Company could determine a fair value. In addition, the Company does not have ready access to significant events occurring at Zenas. If the Company does identify observable price changes in orderly transactions for the identical or similar shares of common stock of Zenas, the Company will measure the shares of common stock at fair value as of the date that the observable transaction occurred. Fairmount Funds On March 13, 2023, the Fairmount Funds issued promissory notes in the aggregate principal amount of $ 0.4 million to Former Dianthus at an interest rate of 4.5 % per annum. On March 15, 2023, Former Dianthus repaid principal and interest in the amount of $ 0.4 million to the Fairmount Funds in satisfaction of its obligations under the promissory notes.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2024
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements as of June 30, 2024 and for the six months ended June 30, 2024 and 2023 have been prepared in conformity with 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 have been prepared on the same basis as the Company’s audited financial statements and 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. The results for the three and six months ended June 30, 2024 are not necessarily indicative of the results expected for the full fiscal year or any subsequent interim period. The unaudited condensed consolidated balance sheet as of 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 audited financial statements as of and for the year ended December 31, 2023, which are contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2023 filed with the Securities and Exchange Commission (“SEC”) on March 21, 2024. Any reference in these notes to applicable guidance is meant to refer to the authoritative U.S. GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Update (“ASU”) of the Financial Accounting Standards Board (“FASB”).
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. Actual results may differ materially from those estimates. Management considers many factors in selecting appropriate financial accounting policies and controls, and in developing the estimates and assumptions that are used in the preparation of these financial statements. Management must apply significant judgment in this process. In addition, other factors may affect estimates including the following: expected business and operational changes, sensitivity and volatility associated with the assumptions used in developing estimates, and whether historical trends are expected to be representative of future trends. The estimation process often may yield a range of potentially reasonable estimates of the ultimate future outcomes, and management must select an amount that falls within that range of reasonable estimates. Significant estimates are used in the following areas, among others: the recognition of research and development expense, stock-based compensation expense and revenue recognition.
Cash and Cash Equivalents	Cash and Cash Equivalents All short-term, highly liquid investments with original maturities of 90 days or less are considered to be cash and cash equivalents. The carrying amounts reported in the unaudited condensed consolidated balance sheets for cash and cash equivalents are valued at cost, which approximates fair value.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of cash, cash equivalents and short-term investments. The Company regularly maintains deposits in accredited financial institutions in excess of federally insured limits. The Company invests its excess cash primarily in money market funds, U.S. treasury securities and U.S. government agency securities in accordance with the Company’s investment policy. The Company’s investment policy defines allowable investments and establishes guidelines relating to credit quality, diversification, and maturities of its investments to preserve principal and maintain liquidity. The Company has not experienced any realized losses related to its cash, cash equivalents and short-term investments and management believes the Company is not exposed to significant risks of losses. As of June 30, 2024 and December 31, 2023 , the Company held cash deposits at Silicon Valley Bank (“SVB”) in excess of government insured limits. On March 10, 2023, SVB was closed by the California Department of Financial Protection and Innovation, and the Federal Deposit Insurance Corporation was appointed as receiver. No losses were incurred by the Company on deposits that were held at SVB. Management believes that the Company is not currently exposed to significant credit risk as the vast majority of the Company’s deposits were either owned directly by the Company and held in custody at a third-party financial institution or, subsequent to March 10, 2023, have been transferred to a third-party financial institution. The Company does not currently have any other significant relationships with SVB.
Short-term Investments	Short-term Investments Short-term investments consist of investments in U.S. treasury and U.S. government agency securities. Management of the Company determines the appropriate classification of the securities at the time they are acquired and evaluates the appropriateness of such classifications at each balance sheet date. The Company classifies its short-term investments as available-for-sale pursuant to ASC 320, Investments – Debt and Equity Securities, and reports them at fair value in short-term investments with unrealized gains and losses reported as a component of accumulated other comprehensive income/(loss) on the unaudited condensed consolidated balance sheets. Realized gains and losses and declines in value judged to be other than temporary are included as a component of interest income based on the specific identification method. When the fair value is below the amortized cost of a marketable security, an estimate of expected credit losses is made in accordance with ASU No. 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments . The credit-related impairment amount is recognized in the unaudited condensed consolidated statements of operations and comprehensive loss. Credit losses are recognized through the use of an allowance for credit losses account in the unaudited condensed consolidated balance sheet and subsequent improvements in expected credit losses are recognized as a reversal of an amount in the allowance account. If the Company has the intent to sell the security or it is more likely than not that the Company will be required to sell the security prior to recovery of its amortized cost basis, then the allowance for the credit loss is written-off and the excess of the amortized cost basis of the asset over its fair value is recorded in the unaudited condensed consolidated statements of operations and comprehensive loss. There were no credit losses recorded during the six months ended June 30, 2024 or 2023. Additional information regarding short-term investments is included in Note 4.
Receivable from Related Party and Unbilled Receivable from Related Party	Receivable from Related Party and Unbilled Receivable from Related Party The receivable from related party and unbilled receivable from related party results from option and license agreements with Zenas BioPharma, Inc. (formerly Zenas BioPharma Limited) (“Zenas”), a related party. See Notes 13 and 16 for more information. The receivable represents amounts earned and billed to Zenas but not yet collected while unbilled receivable represents amounts earned but not yet billed to Zenas. The receivable and unbilled receivable are reported at net realizable value. The Company regularly evaluates the creditworthiness of Zenas and their financial condition and does not require collateral from Zenas. As of June 30, 2024 and December 31, 2023 , no allowance for doubtful accounts was recorded as all accounts were considered collectible.
Property and Equipment	Property and Equipment Property and equipment are recorded at cost. Depreciation is provided using the straight-line method over estimated useful lives of three years for computer equipment and five years for furniture and fixtures. Expenditures for major renewals and betterments that extend the useful lives are capitalized. Expenditures for normal maintenance and repairs are expensed as incurred. The cost of assets sold or abandoned, and the related accumulated depreciation are eliminated from the accounts and any gains or losses are recognized in the accompanying unaudited condensed consolidated statements of operations and comprehensive loss of the respective period.
Leases	Leases Operating leases are accounted for in accordance with ASU 2016-02, Leases , as amended (“ASC 842”). Right-of-use lease assets represent the right to use an underlying asset for the lease term and lease liabilities represent an obligation to make lease payments arising from the lease. The measurement of lease liabilities is based on the present value of future lease payments over the lease term. As the Company’s leases do not provide an implicit rate, management used the Company’s incremental borrowing rate based on the information available at the lease commencement date in determining the present value of future lease payments. The right-of-use asset is based on the measurement of the lease liability and includes any lease payments made prior to or on lease commencement and excludes lease incentives and initial direct costs incurred, as applicable. Rent expense for operating leases is recognized on a straight-line basis over the lease term. The Company does no t have any leases classified as finance leases. Management have elected the practical expedient to exclude short-term leases from right-of-use assets and lease liabilities. The Company’s leases do not have significant rent escalation, holidays, concessions, material residual value guarantees, material restrictive covenants or contingent rent provisions. The Company’s leases include both lease (e.g., fixed payments including rent, taxes, and insurance costs) and non-lease components (e.g., common-area or other maintenance costs), which are accounted for as a single lease component as management have elected the practical expedient to group lease and non-lease components for all leases. Additional information and disclosures required under ASC 842 are included in Note 9.
Restricted Cash	Restricted Cash In accordance with ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash , restricted cash is included as a component of cash, cash equivalents and restricted cash in the accompanying unaudited condensed consolidated statements of cash flows. Restricted cash serves as collateral for a letter of credit securing office space. Restricted cash is recorded within other assets and restricted cash line item in the accompanying unaudited condensed consolidated balance sheets.
Fair Value Measurements	Fair Value Measurements The Company calculates the fair value of assets and liabilities that qualify as financial instruments and includes additional information in the notes to the unaudited condensed consolidated financial statements when the fair value is different than the carrying value of these financial instruments. The Company is required to disclose information on all assets and liabilities reported at fair value that enables an assessment of the inputs used in determining the reported fair values. ASC Topic 820, Fair Value Measurements and Disclosures (“ASC 820”), defines fair value as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants at the measurement date. ASC 820 establishes a hierarchy of inputs used in measuring fair value that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that the observable inputs be used when available. Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect management’s assumptions about the inputs that market participants would use in pricing the asset or liability and are developed based on the best information available in the circumstances. The fair value hierarchy applies only to the valuation inputs used in determining the reported fair value of the investments and is not a measure of the investment credit quality. The three levels of the fair value hierarchy are described below: • Level 1 - Quoted prices in active markets for identical assets or liabilities. • Level 2 - Observable inputs other than quoted prices included in Level 1, such as quoted prices for similar assets and liabilities in active markets; quoted prices for identical or similar assets and liabilities in markets that are not active; or other inputs that are observable or can be corroborated by observable market data. • Level 3 - Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets and liabilities. This includes certain pricing models, discounted cash flow methodologies and similar valuation techniques that use significant unobservable inputs. To the extent that a valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by management in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. Management has segregated all financial assets and liabilities that are measured at fair value on a recurring basis into the most appropriate level within the fair value hierarchy based on the inputs used to determine the fair value at the measurement date in the table below. The Company’s valuation techniques for its Level 2 financial assets included using quoted prices for similar assets in active markets and quoted prices for similar assets in markets that are not active. The estimated fair value of receivable from related party, unbilled receivable from related party, accounts payable and accrued expenses approximate their carrying amounts due to the relatively short maturity of these instruments. Additional information regarding fair value measurements is included in Note 7.
Classification of Convertible Preferred Stock	Classification of Convertible Preferred Stock Convertible preferred stock was recorded at its original issuance price, less direct and incremental offering costs, as stipulated by its terms. The Company had applied the guidance in ASC 480-10-S99, Distinguishing Liabilities from Equity-Overall-SEC Materials , and had therefore classified the convertible preferred stock outside of stockholders’ equity/(deficit). In September 2023, all outstanding shares of convertible preferred stock were converted into shares of common stock immediately prior to the effective time of the Reverse Merger. Additional information and disclosures are included in Note 11.
Segment Information	Segment Information Operating segments are defined as components of an entity for which separate financial information is available and that is regularly reviewed by the Chief Operating Decision Maker (“CODM”) in deciding how to allocate resources and in assessing performance. The Company’s CODM is its Chief Executive Officer (“CEO”). The Company operates as a single operating segment and has one reportable segment.
License Revenue - Related Party	License Revenue – Related Party To date, the Company’s only revenue has been attributable to an upfront payment and cost reimbursements under the Company’s license agreement with Zenas. The Company has not generated any revenue from product sales and does not expect to generate any revenue from product sales for the foreseeable future. The Company recognizes revenue pursuant to ASC 606, Revenue from Contracts with Customers (“ASC 606”). ASC 606 applies to all contracts with customers, except for contracts that are within the scope of other standards. Under ASC 606, an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration that the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that an entity determines are within the scope of ASC 606, the entity performs the following five steps: (i) identify the contract with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when the performance obligation is satisfied. The Company evaluates the performance obligations promised in a contract that are based on goods and services that will be transferred to the customer and determines whether those obligations are both (i) capable of being distinct and (ii) distinct in the context of the contract. To the extent a contract includes multiple promised goods and services, the Company applies judgment to determine whether promised goods and services are both capable of being distinct and are distinct in the context of the contract. If these criteria are not met, the promised goods and services are accounted for as a combined performance obligation. Arrangements that include rights to additional goods or services that are exercisable at a customer’s discretion are generally considered options. The Company assesses if these options provide a material right to the customer and if so, they are considered performance obligations. The Company estimates the transaction price based on the amount expected to be received for transferring the promised goods or services in the contract. The consideration may include fixed consideration or variable consideration. At the inception of each arrangement that includes variable consideration, the Company evaluates the amount of potential transaction price and the likelihood that the transaction price will be received. Variable consideration is included in the transaction price if, in management’s judgment, it is probable that a significant future reversal of cumulative revenue under the contract will not occur. Any estimates, including the effect of the constraint on variable consideration, are evaluated at each reporting period for any changes. The Company then allocates the transaction price to each performance obligation and recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) control is transferred to the customer and the performance obligation is satisfied. Amounts received prior to satisfying the revenue recognition criteria are recorded as deferred revenue in the Company’s unaudited condensed consolidated balance sheets. If the related performance obligation is expected to be satisfied within the next twelve months this will be classified in current liabilities. Additional information and disclosures required under ASC 606 are included in Note 13.
Research and Development Costs	Research and Development Costs Research and development expenses are recorded as expense, as incurred. Research and development expenses consists of (i) costs to engage contractors who specialize in the development activities of the Company; (ii) external research and development costs incurred under arrangements with third parties, such as contract research organizations and consultants; and (iii) costs associated with preclinical activities and regulatory operations. The Company enters into consulting, research, and other agreements with commercial firms, researchers, and others for the provision of goods and services. Under such agreements, the Company may pay for services on a monthly, quarterly, project or other basis. Such arrangements are generally cancelable upon reasonable notice and payment of costs incurred. Costs are considered incurred based on an evaluation of the progress to completion of specific tasks under each contract using information and data provided by the service providers and vendors or our estimate of the level of service that has been performed at each reporting date, whereas payments are dictated by the terms of each agreement. As such, depending on the timing of payment relative to the receipt of goods or services, management may record either prepaid expenses or accrued services. These costs consist of direct and indirect costs associated with specific projects, as well as fees paid to various entities that perform certain research on behalf of the Company.
Patent Costs	Patent Costs Patent costs are expensed as incurred and recorded within general and administrative expenses.
Income Taxes	Income Taxes Income taxes are recorded in accordance with ASC 740, Income Taxes (“ASC 740”), which provides for deferred taxes using an asset and liability approach. The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements or tax returns. Deferred tax assets and liabilities are determined based on the difference between the financial statement and tax basis of assets and liabilities and for loss and credit carryforwards using enacted tax rates anticipated to be in effect for the year in which the differences are expected to reverse. Valuation allowances are provided, if, based upon the weight of available evidence, it is more likely than not that some or all the deferred tax assets will not be realized. The Company accounts for uncertain tax positions in accordance with the provisions of ASC 740. When uncertain tax positions exist, the Company recognizes the tax benefit of tax positions to the extent that the benefit will more likely than not be realized. The determination as to whether the tax benefit will more likely than not be realized is based upon the technical merits of the tax position, as well as consideration of the available facts and circumstances. As of June 30, 2024 and December 31, 2023 , the Company did no t have any material uncertain tax positions. The Company recognizes interest and penalties related to uncertain tax positions, if any exist, in income tax expense.
Stock-Based Compensation	Stock-Based Compensation The Company accounts for stock-based compensation awards in accordance with ASC Topic 718, Compensation – Stock Compensation (“ASC 718”). ASC 718 requires all stock-based payments, including grants of stock options and restricted stock, to be recognized in the unaudited condensed consolidated statements of operations and comprehensive loss based on their fair values. All of the stock-based awards are subject only to service-based vesting conditions. Management estimates the fair value of the stock option awards using the Black-Scholes option pricing model, which requires the input of assumptions, including (a) the fair value of the Company’s common stock, (b) the expected stock price volatility, (c) the calculation of expected term of the award, (d) the risk-free interest rate and (e) expected dividends. Management estimates the fair value of the restricted stock awards, if any, using the fair value of the Company’s common stock. Forfeitures are recognized as they are incurred. Prior to the Reverse Merger, management utilized valuation methodologies in accordance with the framework of the American Institute of Certified Public Accountants Technical Practice Aid, Valuation of Privately Held Company Equity Securities Issued as Compensation , to estimate the fair value of Former Dianthus common stock. Each valuation methodology included estimates and assumptions that required management’s judgment. These estimates and assumptions included objective and subjective factors, including external market conditions, the prices at which Former Dianthus sold shares of convertible preferred stock, the superior rights and preferences of the convertible preferred stock senior to Former Dianthus common stock at the time, and a probability analysis of various liquidity events, such as a public offering or sale of Former Dianthus, under differing scenarios. Changes to the key assumptions used in the valuations could have resulted in materially different fair values of Former Dianthus common stock at each valuation date. Following the Reverse Merger, the fair value of the Company’s common stock is based on the closing stock price on the date of grant as reported on the Nasdaq Capital Market. Prior to the Reverse Merger, due to a lack of company-specific historical and implied volatility data, management based its estimate of expected volatility on the historical volatility of a representative group of companies with similar characteristics to the Company, including stage of product development and life science industry focus. Management believes the group selected had sufficiently similar economic and industry characteristics and includes companies that are most representative of the Company. Following the Reverse Merger, expected volatility at the date of grant is estimated using a “look-back” period, which coincides with the expected term, of the Company's stock price as reported on the Nasdaq Capital Market. Management uses the simplified method, as prescribed by the SEC Staff Accounting Bulletin No. 107, Share-Based Payment , to calculate the expected term. The risk-free interest rate is based on observed interest rates appropriate for the term of the awards. The dividend yield assumption is based on history and expectation of paying no dividends. Compensation expense related to stock-based awards is calculated on a straight-line basis by recognizing the grant date fair value, over the associated service period of the award, which is generally the vesting term. Additional information regarding stock-based compensation is included in Note 12.
Comprehensive Loss	Comprehensive Loss The only component of comprehensive loss other than net loss is change in unrealized gains/losses related to available-for-sale debt securities.
Net Loss per Share	Net Loss per Share Basic and diluted net loss per share attributable to common stockholders is computed by dividing net loss by the weighted-average number of common shares outstanding during the period. The weighted average number of common shares outstanding includes the weighted average effect of outstanding pre-funded warrants for the purchase of shares of common stock for which the remaining unfunded exercise price is $ 0.001 or less per share. Basic and diluted net loss per share attributable to common stockholders are calculated in conformity with the two-class method required for participating securities. Convertible preferred stock is a participating security in distributions of the Company. During the three and six months ended June 30, 2023, the net loss attributable to common stockholders was not allocated to the convertible preferred shares as the holders of convertible preferred shares did not have a contractual obligation to share in losses. Under the two-class method, basic net loss per share of common stock is computed by dividing net loss by the weighted-average number of shares of common stock outstanding during each period. During the three and six months ended June 30, 2023, the weighted-average number of shares of common stock outstanding used in the basic net loss per share calculation did not include unvested restricted common stock as these shares were considered contingently issuable shares until they vested. Diluted net loss per share of common stock includes the effect, if any, from the potential exercise or conversion of securities, such as convertible preferred stock, stock options and unvested restricted common stock, if any, which would result in the issuance of incremental shares of common stock. For diluted net loss per share, the weighted-average number of shares of common stock outstanding is the same for basic net loss per share due to the fact that when a net loss exists, dilutive securities are not included in the calculation as the impact is anti-dilutive. For all periods presented, basic and diluted net loss per share were the same, as any additional share equivalents would be anti-dilutive. Additional information is included in Note 14.
Recently Adopted Accounting Pronouncements	Recently Issued Accounting Pronouncements In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures . ASU 2023-07 expands annual and interim disclosure requirements for reportable segments, primarily through enhanced disclosures about significant segment expenses. ASU 2023-07 is effective for fiscal years beginning after December 15, 2023, and for interim periods beginning after December 14, 2024, with early adoption permitted. The Company is currently evaluating the guidance and has not determined the impact this standard may have on the unaudited condensed consolidated financial statements. In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740), Improvements to Income Tax Disclosures , to enhance the transparency and decision usefulness of income tax disclosures. The enhancement will provide information to better assess how an entity’s operations and related tax risks and tax planning and operational opportunities affect its tax rate and prospects for future cash flows. Investors currently rely on the rate reconciliation table and other disclosures, including total income taxes paid, to evaluate income tax risks and opportunities. ASU No. 2023-09 is effective for fiscal years beginning after December 15, 2024 and early adoption is permitted. The Company is currently evaluating the impact ASU No. 2023-09 will have on the unaudited condensed consolidated financial statements and related disclosures.

Reverse Merger (Tables)

Reverse Merger (Tables)	6 Months Ended
	Jun. 30, 2024
Business Combination, Asset Acquisition, and Joint Venture Formation [Abstract]
Schedule of Company Obtained Assets and Liabilities	As part of the recapitalization, the Company obtained the assets and liabilities listed below: Cash and cash equivalents $ 69,738 Other current assets 2,473 Accrued liabilities ( 616 ) Net assets acquired $ 71,595

Short-Term Investments (Tables)

Short-Term Investments (Tables)	6 Months Ended
	Jun. 30, 2024
Short-Term Investments [Abstract]
Schedule of short-term investments	The following table provides a summary of short-term investments: June 30, 2024 Amortized Gross Gross Fair Value Available-for-sale, short-term investments: U.S. treasury securities $ 45,574 $ — $ ( 35 ) $ 45,539 U.S. government agency securities 1,001 — ( 2 ) 999 Total available-for-sale, short-term investments $ 46,575 $ — $ ( 37 ) $ 46,538 December 31, 2023 Amortized Gross Gross Fair Value Available-for-sale, short-term investments: U.S. treasury securities $ 36,370 $ 48 $ — $ 36,418 U.S. government agency securities 4,976 — ( 1 ) 4,975 Total available-for-sale, short-term investments $ 41,346 $ 48 $ ( 1 ) $ 41,393

Prepaid Expenses and Other Cu_2

Prepaid Expenses and Other Current Assets (Tables)	6 Months Ended
	Jun. 30, 2024
Prepaid Expense and Other Assets, Current [Abstract]
Summary of Prepaid Expenses and Other Current Assets	The following table provides a summary of prepaid expenses and other current assets: June 30, December 31, Prepaid materials, supplies and research and development services $ 2,305 $ 2,155 Prepaid subscriptions, software and other administrative services 797 504 Prepaid insurance 203 596 Prepaid expenses and other current assets $ 3,305 $ 3,255

Property and Equipment (Tables)

Property and Equipment (Tables)	6 Months Ended
	Jun. 30, 2024
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment, Net	The following table provides a summary of property and equipment: June 30, December 31, Computer equipment $ 281 $ 234 Furniture and fixtures 50 48 Subtotal 331 282 Less: accumulated depreciation ( 142 ) ( 97 ) Property and equipment, net $ 189 $ 185

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	6 Months Ended
	Jun. 30, 2024
Fair Value Disclosures [Abstract]
Schedule of Financial Assets Measured at Fair Value on Recurring Basis	The following table provides a summary of financial assets measured at fair value on a recurring basis: Fair Value at Description June 30, Level 1 Level 2 Level 3 Recurring Assets: Cash equivalents: Money market funds $ 313,103 $ 313,103 $ — $ — Short-term investments: U.S. treasury securities 45,539 45,539 — — U.S. government agency securities 999 — 999 — Total assets measured at fair value $ 359,641 $ 358,642 $ 999 $ — Fair Value at December 31, Description 2023 Level 1 Level 2 Level 3 Recurring Assets: Cash equivalents: Money market funds $ 131,193 $ 131,193 $ — $ — Short-term investments: U.S. treasury securities 36,418 36,418 — — U.S. government agency securities 4,975 — 4,975 — Total assets measured at fair value $ 172,586 $ 167,611 $ 4,975 $ —

Accrued Expenses (Tables)

Accrued Expenses (Tables)	6 Months Ended
	Jun. 30, 2024
Schedule of Accrued Expenses	The following table provides a summary of accrued expenses: June 30, December 31, Accrued external research and development $ 2,797 456 Accrued compensation 2,602 5,361 Accrued professional fees 211 422 Other accrued expenses 247 265 Accrued expenses $ 5,857 $ 6,504

Leases (Tables)

Leases (Tables)	6 Months Ended
	Jun. 30, 2024
Leases [Abstract]
Summary of the Components of Lease Costs and Rent	The following table provides a summary of the components of lease costs and rent: Three Months Ended Six Months Ended 2024 2023 2024 2023 Operating lease cost $ 103 $ 88 $ 206 $ 175 Variable lease cost 7 6 15 13 Total operating lease costs $ 110 $ 94 $ 221 $ 188
Schedule of Maturities of Operating Lease Liabilities	Maturities of operating lease liabilities as of June 30, 2024, are as follows: 2024 (remaining 6 months) $ 212 2025 222 Total undiscounted operating lease payments 434 Less: imputed interest ( 27 ) Present value of operating lease liabilities $ 407 Balance sheet classification: Current portion of operating lease liabilities $ 377 Long-term operating lease liabilities 30 Total operating lease liabilities $ 407

Common Stock (Tables)

Common Stock (Tables)	6 Months Ended
	Jun. 30, 2024
Equity [Abstract]
Schedule of Common Stock Shares Reserved for Future Issuance	The Company had the following shares of Company common stock reserved for future issuance as of June 30, 2024 and December 31, 2023: As of As of Issuance of common stock upon exercise of stock options 4,420,676 1,749,475 Equity awards available for grant under stock award plans 2,045,704 879,461 Shares available for issuance under the Employee Stock Purchase Plan 99,578 37,078 Issuance of common stock upon exercise of warrants 4,881,329 214,997 Total common stock reserved for future issuance 11,447,287 2,881,011

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2024
Share-Based Payment Arrangement [Abstract]
Schedule of Stock Option Activity	The following table summarizes stock option activity for the six months ended June 30, 2024: Number of Weighted Weighted Aggregate (in years) Balance at January 1, 2024 1,749,475 $ 10.61 8.4 $ 3,181 Options granted, fair value of $ 15.72 per share 2,788,000 20.30 16,048 Options exercised ( 33,944 ) 9.14 504 Options forfeited ( 82,855 ) 15.52 926 Balance at June 30, 2024 4,420,676 $ 16.64 9.1 $ 42,783 Exercisable options at June 30, 2024 1,026,134 $ 12.26 8.2 $ 15,433 Unvested options at June 30, 2024 3,394,542 $ 17.97 9.4 $ 27,350
Schedule of Grant-Date Fair Value of Stock Options Issued, Presented on a Weighted Average Basis	The table below summarizes the assumptions used to determine the grant-date fair value of stock options issued, presented on a weighted average basis during the three and six months ended June 30, 2024 and 2023. Three Months Ended Six Months Ended 2024 2023 2024 2023 Risk-free interest rate 4.5 % 4.1 % 4.3 % 3.8 % Expected term (in years) 6.0 6.1 6.0 6.1 Expected volatility 92.3 % 86.4 % 92.7 % 85.0 % Expected dividend yield 0.0 % 0.0 % 0.0 % 0.0 %
Schedule of Stock Based Compensation Expense	The following table provides a summary of stock-based compensation expense: Three Months Ended Six Months Ended 2024 2023 2024 2023 Research and development $ 1,350 $ 141 $ 2,189 $ 332 General and administrative 1,751 321 2,947 663 Total stock-based compensation expense $ 3,101 $ 462 $ 5,136 $ 995

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	6 Months Ended
	Jun. 30, 2024
Earnings Per Share [Abstract]
Schedule of Basic and diluted net loss per share of common stock	Basic and diluted net loss per share of common stock is calculated as follows: Three Months Ended Six Months Ended 2024 2023 2024 2023 Numerator: Net loss $ ( 17,607 ) $ ( 11,140 ) $ ( 31,355 ) $ ( 18,229 ) Denominator: Weighted-average shares of common stock outstanding 34,227,038 875,279 31,794,881 875,279 Less: weighted-average unvested restricted shares of common stock — ( 379 ) — ( 474 ) Weighted-average shares used to compute net loss 34,227,038 874,900 31,794,881 874,805 Net loss per share attributable to common stockholders, $ ( 0.51 ) $ ( 12.73 ) $ ( 0.99 ) $ ( 20.84 )
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The following potential dilutive securities, presented on an as converted basis, were excluded from the calculation of net loss per share due to their anti-dilutive effect: Three Months Ended Six Months Ended 2024 2023 2024 2023 Convertible preferred stock (as converted) — 7,269,183 — 7,269,183 Stock options outstanding 4,420,676 1,494,028 4,420,676 1,494,028 Unvested restricted shares of common stock — 254 — 254 Warrants for the purchase of common stock 4,677 4,677 4,677 4,677 Total 4,425,353 8,768,142 4,425,353 8,768,142

Organization, Description of _2

Organization, Description of Business and Liquidity - Additional Information (Detail) $ / shares in Units, $ in Thousands			3 Months Ended				6 Months Ended
	Jan. 24, 2024 $ / shares shares	Jan. 22, 2024 USD ($) $ / shares shares	Jun. 30, 2024 USD ($) $ / shares shares	Mar. 31, 2024 USD ($) shares	Jun. 30, 2023 USD ($) shares	Mar. 31, 2023 USD ($) shares	Jun. 30, 2024 USD ($) $ / shares shares	Jun. 30, 2023 USD ($) shares	Dec. 31, 2023 USD ($) shares	Sep. 11, 2023 $ / shares shares	Dec. 31, 2022 shares
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Reverse stock split description							Immediately prior to the effective time of the Reverse Merger, the Company effected a 1-for-16 reverse stock split of its common stock (the “Reverse Stock Split”). Unless noted otherwise, all references herein to share and per share amounts reflect the Reverse Stock Split.
Net Income (Loss) | $			$ (17,607)	$ (13,748)	$ (11,140)	$ (7,089)	$ (31,355)	$ (18,229)
Accumulated deficit | $			$ (120,778)				$ (120,778)		$ (89,423)
Common stock, Shares issued			29,352,140				29,352,140		14,817,696	11,021,248
Exchange ratio of reverse merger			0.2181				0.2181			0.2181
Shares of common stock issued in pre-closing financing							2,873,988
Shares pre-funded warrants to purchase							210,320
Pre-Funded Warrants Exercisable			210,320				210,320
Prefunded warrants price per share | $ / shares			$ 23.34				$ 23.34
common stock price per share | $ / shares			23.34				23.34
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares			$ 0.001				$ 0.001
Proceeds from pre-closing financing | $			$ 72,000				$ 72,000
Prefunded Warrants [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights										210,320
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares										$ 0.001
2024 Private Placement [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Stock issued, price per shares | $ / shares		$ 12
Sold and issued of shares	14,500,500	14,500,500
2024 Private Placement [Member] | Prefunded Warrants [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Stock issued, price per shares | $ / shares		$ 11.999
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	4,666,332	4,666,332
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares	$ 0.001	$ 0.001
Aggregate purchase price of pre-funded warrant | $		$ 230,000
Class of warrant or right maximum beneficial ownership percent		9.99%
Pre-funded warrants increase or decrease percentage		19.99%
Common Stock [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Common stock, Shares issued			29,352,140				29,352,140		14,817,696	14,817,696
Common stock, Shares outstanding			29,352,140	29,348,626	875,279	875,279	29,352,140	875,279	14,817,696	14,817,696	875,279

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Summary Of Significant Accounting Policies [Line Items]
Credit losses recorded	$ 0	$ 0
Allowance for doubtful accounts	0		$ 0
Financial lease liability	$ 0
Exercise price (in USD per share)	$ 0.001
Unrecognized tax benefits	$ 0		$ 0

Reverse Merger - Schedule of Co

Reverse Merger - Schedule of Company Obtained Assets and Liabilities (Detail) $ in Thousands	Sep. 11, 2023 USD ($)
Business Acquisition [Line Items]
Cash and cash equivalents	$ 69,738
Other current assets	2,473
Accrued liabilities	(616)
Net assets acquired	$ 71,595

Short-Term Investments - Schedu

Short-Term Investments - Schedule of Short-term Investments (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	$ 46,575	$ 41,346
Gross Unrealized Gain	0	48
Gross Unrealized Loss	(37)	(1)
Fair Value	46,538	41,393
U.S. Treasury Securities
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	45,574	36,370
Gross Unrealized Gain	0	48
Gross Unrealized Loss	(35)	0
Fair Value	45,539	36,418
U.S. Government Agency Securities
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost	1,001	4,976
Gross Unrealized Gain	0	0
Gross Unrealized Loss	(2)	(1)
Fair Value	$ 999	$ 4,975

Prepaid Expenses and Other Cu_3

Prepaid Expenses and Other Current Assets - Summary of Prepaid Expenses and Other Current Assets (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Prepaid Expense and Other Assets, Current [Abstract]
Prepaid materials, supplies and research and development services	$ 2,305	$ 2,155
Prepaid subscriptions, software and other administrative services	797	504
Prepaid Insurance	203	596
Prepaid expenses and other current assets	$ 3,305	$ 3,255

Property and Equipment - Schedu

Property and Equipment - Schedule of Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 331	$ 282
Less: accumulated depreciation	(142)	(97)
Property, Plant and Equipment, Net, Total	189	185
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	281	234
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 50	$ 48

Property and Equipment - Additi

Property and Equipment - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 23	$ 15	$ 45	$ 28

Fair Value of Financial Instr_3

Fair Value of Financial Instruments - Schedule of Financial Assets Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	$ 46,538	$ 41,393
Fair Value on Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	359,641	172,586
Level 1 | Fair Value on Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	358,642	167,611
Level 2 | Fair Value on Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value	999	4,975
Money Market Funds | Fair Value on Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	313,103	131,193
Money Market Funds | Level 1 | Fair Value on Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	313,103	131,193
U.S. Treasury Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	45,539	36,418
U.S. Treasury Securities | Fair Value on Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	45,539	36,418
U.S. Treasury Securities | Level 1 | Fair Value on Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	45,539	36,418
U.S. Government Agency Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	999	4,975
U.S. Government Agency Securities | Fair Value on Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	999	4,975
U.S. Government Agency Securities | Level 2 | Fair Value on Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term investments	$ 999	$ 4,975

Fair Value of Financial Instr_4

Fair Value of Financial Instruments - Additional Information (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2024	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Fair Value on Recurring Basis Level 1	$ 0	$ 0
Fair Value on Recurring Basis Level 2	0	0
Fair Value on Recurring Basis Level 3	$ 0	$ 0

Accrued Expenses - Schedule of

Accrued Expenses - Schedule of Accrued Expenses (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Payables and Accruals [Abstract]
Accrued external research and development	$ 2,797	$ 456
Accrued compensation	2,602	5,361
Accrued professional fees	211	422
Other accrued expenses	247	265
Accrued expenses	$ 5,857	$ 6,504

Leases - Additional Information

Leases - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Leases [Line Items]
Operating lease description			The Company leases space under operating leases for administrative offices in New York, New York, and Waltham, Massachusetts and wet laboratory space in Watertown, Massachusetts.
Operating lease costs	$ 110	$ 94	$ 221	$ 188
Weighted-Average remaining lease term	13 months		13 months
Weighted-average discount rate - operating lease	10.80%		10.80%
General and Administrative Expenses [Member]
Leases [Line Items]
Operating lease costs	$ 100	100	$ 200	200
Research and Development Expense [Member]
Leases [Line Items]
Operating lease costs	$ 15	$ 0	$ 30	$ 0

Leases - Summary of the Compone

Leases - Summary of the Components of Lease Costs and Rent (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Lease, Cost [Abstract]
Operating lease cost	$ 103	$ 88	$ 206	$ 175
Variable lease cost	7	6	15	13
Total operating lease costs	$ 110	$ 94	$ 221	$ 188

Leases - Schedule of Maturities

Leases - Schedule of Maturities of Operating Lease Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Leases [Abstract]
2024 (remaining 6 months)	$ 212
2025	222
Total undiscounted operating lease payments	434
Less: imputed interest	(27)
Present value of operating lease liabilities	407
Current portion of operating lease liabilities	377	$ 417
Long-term operating lease liabilities	30	$ 168
Operating Lease, Liability	$ 407

Common Stock - Additional Infor

Common Stock - Additional Information (Details)			6 Months Ended
	Jan. 24, 2024 $ / shares shares	Jan. 22, 2024 $ / shares shares	Jun. 30, 2024 $ / shares shares	Dec. 31, 2023 $ / shares shares	Sep. 11, 2023 $ / shares shares
Exercise price (in USD per share) | $ / shares			$ 0.001
Shares pre-funded warrants to purchase			210,320
Common stock, shares authorized			150,000,000	150,000,000
Common stock, Shares issued			29,352,140	14,817,696	11,021,248
Common stock, Shares outstanding			29,352,140	14,817,696
Exchange ratio of reverse merger			0.2181		0.2181
Common stock, Par value | $ / shares			$ 0.001	$ 0.001
Common Stock, Dividends, Per Share, Declared | $ / shares			$ 0
Prefunded Warrants [Member]
Pre-funded warrants to purchase					210,320
Pre-funded warrants outstanding			4,876,652
Exercise price (in USD per share) | $ / shares					$ 0.001
2024 Private Placement [Member]
Sold and issued of shares	14,500,500	14,500,500
2024 Private Placement [Member] | Prefunded Warrants [Member]
Pre-funded warrants to purchase	4,666,332	4,666,332
Pre-funded warrants outstanding			4,666,332
Exercise price (in USD per share) | $ / shares	$ 0.001	$ 0.001
Reverse Merger [Member] | Prefunded Warrants [Member]
Pre-funded warrants outstanding			210,320
Common Stock
Common stock, shares authorized			150,000,000	150,000,000
Common stock, Shares issued			29,352,140	14,817,696	14,817,696
Common stock, Shares outstanding			29,352,140	14,817,696
Common stock, Par value | $ / shares			$ 0.001	$ 0.001

Common Stock - Schedule of Comm

Common Stock - Schedule of Common Stock Reserved For Future Issuance (Details) - shares	Jun. 30, 2024	Dec. 31, 2023
Equity [Abstract]
Issuance of common stock upon exercise of stock options	4,420,676	1,749,475
Equity awards available for grant under stock award plans	2,045,704	879,461
Shares available for issuance under the Employee Stock Purchase Plan	99,578	37,078
Issuance of common stock upon exercise of warrants	4,881,329	214,997
Total common stock reserved for future issuance	11,447,287	2,881,011

Preferred Stock and Convertib_2

Preferred Stock and Convertible Preferred Stock - Additional Information (Details)	Sep. 11, 2023 shares	Jun. 30, 2024 $ / shares shares	Dec. 31, 2023 $ / shares shares
Class of Stock [Line Items]
Preferred stock, Shares authorized		10,000,000	10,000,000
Preferred stock, par value | $ / shares		$ 0.001	$ 0.001
Preferred stock, Shares issued		0	0
Preferred stock, Shares outstanding		0	0
Convertible preferred stock, Terms of conversion	Under the terms of the Merger Agreement, immediately prior to the effective time of the Reverse Merger, each share of Former Dianthus convertible preferred stock was converted into a share of Former Dianthus common stock.
Shares issued upon conversion of convertible preferred stock	7,269,183
Exchange ratio of reverse merger	0.2181	0.2181

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions			1 Months Ended	6 Months Ended		12 Months Ended
	May 23, 2024	Jan. 01, 2024	Apr. 30, 2021	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023	Feb. 29, 2024	Jul. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average fair value of stock options granted				$ 15.72
Number of Shares, Options vested and expected to vest as of September 30, 2023				1,026,134
Number of Shares, Granted				2,788,000
Warrant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock exercise price			$ 1.65
Vesting period				6 years 9 months 18 days
Warrants issued			4,677
Warrant per grant date fair value			$ 1.16
2018 Stock Option and Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, terms of award				The 2018 Incentive Plan provides for the grant of incentive stock options, nonqualified stock options, stock appreciation rights, restricted stock awards, restricted stock units, unrestricted stock awards, cash-based awards, and dividend equivalent rights. In connection with the Reverse Merger, the 2018 Incentive Plan also provided for the assumption of shares remaining available for delivery under the 2019 Stock Plan (as defined below), and such shares will be available for the granting of awards under the 2018 Incentive Plan in accordance with applicable stock exchange requirements. The Company also has outstanding stock options under the Magenta Therapeutics, Inc. 2016 Stock Option and Grant Plan, as amended (the “2016 Plan”), but is no longer granting awards under the 2016 Plan.
Total unrecognized stock-based compensation expense related to unvested share-based awards				$ 45.5
Period for recognition of unrecognized expense				3 years 4 months 24 days
Number of shares reserved and available for issuance increment percentage				4%
Additional number of shares reserved and available for issuance		592,707
2018 Amended Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for issuance				1,953,704
Percentage of purchase price of common stock under the ESPP				110%
Number of shares reserved and available for issuance increment percentage	5%
Additional number of shares reserved and available for issuance	2,931,820
2018 Amended Plan [Member] | Restricted Stock [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period				12 months
2018 Amended Plan [Member] | Restricted Stock [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period				4 years
2018 Amended Plan [Member] | Stock Options and Stock Appreciation Rights [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term of award				10 years
2018 Amended Plan [Member] | Certain Incentive Stock Options [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term of award				5 years
2019 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, terms of award				The ESPP provides that the number of shares reserved and available for issuance under the ESPP will automatically increase each January 1 through January 1, 2029, by the lesser of (i) 1% of the number of shares issued and outstanding on the immediately preceding December 31, (ii) 62,500 shares and (iii) such number of shares as determined by the Company’s board of directors or its appointed administrator. The number of shares reserved for issuance under the ESPP increased by 62,500 on January 1, 2024.
Shares available for issuance				99,578
Percentage of purchase price of common stock under the ESPP				85%
Common stock purchased				0	0
Additional number of shares reserved and available for issuance		62,500
2019 Employee Stock Purchase Plan [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares reserved and available for issuance increment percentage				1%
Additional number of shares reserved and available for issuance				62,500
2019 Stock Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Options vested and expected to vest as of September 30, 2023								1,273,454
Inducement Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted				92,000		96,000
Inducement Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares for issuance under the Plan (shares)							300,000

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Stock Option Activity (Detail) $ / shares in Units, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2024 USD ($) $ / shares shares	Dec. 31, 2023 USD ($) $ / shares shares
Share-Based Payment Arrangement [Abstract]
Number of Shares, Beginning Balance | shares	1,749,475
Number of Shares, Granted | shares	2,788,000
Number of Shares, Exercised | shares	(33,944)
Number of Shares, Forfeited | shares	(82,855)
Number of Shares, Ending Balance | shares	4,420,676	1,749,475
Number of Shares, Options exercisable as of March 31, 2024 | shares	1,026,134
Number of Shares, Options vested and expected to vest as of March 31, 2024 | shares	3,394,542
Weighted-Average Exercise Price, Outstanding, Beginning balance | $ / shares	$ 10.61
Weighted-Average Exercise Price, Granted | $ / shares	20.3
Weighted-Average Exercise Price, Exercised | $ / shares	9.14
Weighted-Average Exercise Price, Forfeited | $ / shares	15.52
Weighted-Average Exercise Price, Outstanding, Ending balance | $ / shares	16.64	$ 10.61
Weighted-Average Exercise Price, Options exercisable as of March 31, 2024 | $ / shares	12.26
Weighted-Average Exercise Price, Options vested and expected to vest as of March 31, 2024 | $ / shares	$ 17.97
Weighted Average Remaining Contractual Term	9 years 1 month 6 days	8 years 4 months 24 days
Weighted Average Remaining Contractual Term, Options exercisable as of March 31, 2024	8 years 2 months 12 days
Weighted Average Remaining Contractual Term, Options vested and expected to vest as of March 31, 2024	9 years 4 months 24 days
Aggregate Intrinsic Value, Beginning Balance | $	$ 3,181
Aggregate Intrinsic Value, Granted | $	16,048
Aggregate Intrinsic Value, Exercised | $	504
Aggregate Intrinsic Value, Forfeited | $	926
Aggregate Intrinsic Value, Ending Balance | $	42,783	$ 3,181
Aggregate Intrinsic Value, Options exercisable as of March 31, 2024 | $	15,433
Aggregate Intrinsic Value, Options vested and expected to vest as of March 31, 2024 | $	$ 27,350

Stock-Based Compensation - Sc_2

Stock-Based Compensation - Schedule of Stock Option Activity (Parenthetical) (Detail)	6 Months Ended
	Jun. 30, 2024 $ / shares
Share-Based Payment Arrangement [Abstract]
Weighted average fair value of stock options granted	$ 15.72

Stock-Based Compensation - Sc_3

Stock-Based Compensation - Schedule of Grant-date Fair Value of Stock Options Issued, Presented on a Weighted Average Basis (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Share-Based Payment Arrangement [Abstract]
Risk-free interest rate	4.50%	4.10%	4.30%	3.80%
Expected term	6 years	6 years 1 month 6 days	6 years	6 years 1 month 6 days
Expected volatility	92.30%	86.40%	92.70%	85%
Expected dividend yield	0%	0%	0%	0%

Stock-Based Compensation - Sc_4

Stock-Based Compensation - Schedule of Stock Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock based compensation expense	$ 3,101	$ 462	$ 5,136	$ 995
Stock-based Compensation Expense | Research and Development Expenses [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock based compensation expense	1,350	141	2,189	332
Stock-based Compensation Expense | General and Administrative Expenses [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock based compensation expense	$ 1,751	$ 321	$ 2,947	$ 663

License Revenue - Related Par_2

License Revenue - Related Party - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2023	Sep. 30, 2021
Related Party Transaction [Line Items]
Deferred revenue current	$ 100		$ 100			$ 100
Deferred revenue noncurrent	682		682			736
Zenas BioPharma Limited [Member]
Related Party Transaction [Line Items]
Reimbursement of development costs					$ 1,100
License revenue - related party	1,900	$ 1,000	2,700	$ 1,500
Related party receivable	800		800			300
Unbilled receivable from related party	800		800			200
Deferred revenue current	100		100			100
Deferred revenue noncurrent	$ 700		700			$ 700
Zenas BioPharma Limited [Member] | Milestone [Member]
Related Party Transaction [Line Items]
Development milestones					11,000
Zenas BioPharma Limited [Member] | Royalty [Member]
Related Party Transaction [Line Items]
License revenue - related party			$ 0
Zenas BioPharma Limited [Member] | Upfront Payment [Member]
Related Party Transaction [Line Items]
Upfront payments					$ 1,000		$ 1,000

Net Loss Per Share - Schedule o

Net Loss Per Share - Schedule of Basic and diluted net loss per share of common stock (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2024	Jun. 30, 2023
Earnings Per Share [Abstract]
Net Income (Loss)	$ (17,607)	$ (13,748)	$ (11,140)	$ (7,089)	$ (31,355)	$ (18,229)
Weighted-average shares of common stock outstanding including shares issuable under equity-classified pre-funded warrants	34,227,038		875,279		31,794,881	875,279
Less: weighted-average unvested restricted shares of common stock	0		(379)		0	(474)
Weighted Average Number of Shares Outstanding, Basic	34,227,038		874,900		31,794,881	874,805
Weighted Average Number of Shares Outstanding, Diluted	34,227,038		874,900		31,794,881	874,805
Net loss per share attributable to common stockholders, basic	$ (0.51)		$ (12.73)		$ (0.99)	$ (20.84)
Net loss per share attributable to common stockholders, diluted	$ (0.51)		$ (12.73)		$ (0.99)	$ (20.84)

Net Loss Per Share - Additional

Net Loss Per Share - Additional Information (Details)	Jun. 30, 2024 shares
Prefunded Warrants [Member]
Class of Warrant or Right [Line Items]
Total pre-funded warrants amount	4,876,652

Net Loss Per Share - Schedule_2

Net Loss Per Share - Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share (Detail) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	4,425,353	8,768,142	4,425,353	8,768,142
Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0	7,269,183	0	7,269,183
Employee Stock Option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	4,420,676	1,494,028	4,420,676	1,494,028
Restricted Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0	254	0	254
Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	4,677	4,677	4,677	4,677

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) $ in Thousands, £ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2024 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2024 GBP (£)
Other Commitments [Line Items]
Research and development expense	$ 18,070	$ 10,253	$ 31,148	$ 16,100
Alloy Therapeutics Llc [Member]
Other Commitments [Line Items]
Payment of annual license fees and program fees			100
Research and development expense	600	50	600	50
Alloy Therapeutics Llc [Member] | Development Milestone [Member] | First Selected Antibody [Member] | Maximum [Member]
Other Commitments [Line Items]
Potential milestone payments due	1,800		1,800
Alloy Therapeutics Llc [Member] | Development Milestone [Member] | Second Selected Antibody [Member] | Maximum [Member]
Other Commitments [Line Items]
Potential milestone payments due	3,100		3,100
Alloy Therapeutics Llc [Member] | Commercial Milestone [Member] | First Selected Antibody [Member] | Maximum [Member]
Other Commitments [Line Items]
Potential milestone payments due	11,000		11,000
Alloy Therapeutics Llc [Member] | Commercial Milestone [Member] | Second Selected Antibody [Member] | Maximum [Member]
Other Commitments [Line Items]
Potential milestone payments due	15,000		15,000
Ligand Pharmaceuticals Incorporated [Member]
Other Commitments [Line Items]
Research and development expense		50	0	200
IONTAS Limited [Member]
Other Commitments [Line Items]
Research and development expense	600	$ 800	1,000	$ 1,400
IONTAS Limited [Member] | Development Milestone [Member] | First Development Program [Member]
Other Commitments [Line Items]
Potential milestone payments due	3,900		3,900		£ 3.1
IONTAS Limited [Member] | Development Milestone [Member] | Second Development Program [Member]
Other Commitments [Line Items]
Potential milestone payments due	3,200		3,200		2.5
IONTAS Limited [Member] | Commercial Milestone [Member] | First Development Program [Member]
Other Commitments [Line Items]
Potential milestone payments due	2,900		2,900		£ 2.3
OmniAb Inc [Member] | Development Milestone [Member]
Other Commitments [Line Items]
Potential milestone payments due	$ 12,200		$ 12,200

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended		6 Months Ended
	Mar. 15, 2023	Mar. 13, 2023	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023	Sep. 11, 2023	Dec. 31, 2020
Related Party Transaction [Line Items]
Common stock, Shares issued			29,352,140		29,352,140		14,817,696	11,021,248
Common stock, Par value			$ 0.001		$ 0.001		$ 0.001
Unbilled receivable from related party			$ 835		$ 835		$ 184
Deferred revenue current			100		100		100
Deferred revenue noncurrent			682		682		736
Aggregate principal amount					0	$ 377
Principal and interest repaid					0	377
Zenas BioPharma Limited [Member]
Related Party Transaction [Line Items]
Common stock, Shares issued									156,848
Related party receivable			800		800		300
Unbilled receivable from related party			800		800		200
Deferred revenue current			100		100		100
Deferred revenue noncurrent			$ 700		$ 700		$ 700
Zenas BioPharma Limited [Member] | Dianthus [Member]
Related Party Transaction [Line Items]
Aggregate principal amount		$ 400
Interest rate		4.50%
Zenas BioPharma Limited [Member] | Tellus Bioventures Llc [Member]
Related Party Transaction [Line Items]
Percentage of outstanding shares			5%		5%
Zenas BioPharma Limited [Member] | Fairmount Funds [Member]
Related Party Transaction [Line Items]
Percentage of outstanding shares			9%		9%
Principal and interest repaid	$ 400
License Revenue [Member] | Zenas BioPharma Limited [Member]
Related Party Transaction [Line Items]
Revenues			$ 1,900	$ 1,000	$ 2,700	$ 1,500