Dianthus Therapeutics, Inc. /DE/

(in thousands, except share and per share data, unless otherwise stated)

1. Organization, Description of Business and Liquidity

Business

Dianthus Therapeutics, Inc. (the “Company” or “Dianthus”) is a clinical-stage biotechnology company focused on developing next-generation complement therapeutics for patients living 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 11) 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 would own a substantial majority of the voting rights in the combined company; (ii) Former Dianthus’ largest stockholders would 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 were 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. 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.

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, 2025, no receivables were recorded on the unaudited condensed consolidated balance sheet relating to such contingent payments.

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.

Shelf Registration Statement and ATM Offering Program

On October 1, 2024, the Company filed a registration statement with the Securities and Exchange Commission (the “SEC”) for the issuance of common stock, preferred stock, warrants, debt securities, rights and units up to an aggregate of $500.0 million. On October 9, 2024, the registration statement was declared effective by the SEC. The registration statement includes an at-the-market (“ATM”) offering program for the sale of up to $200.0 million of shares of the Company’s common stock. During the year ended December 31, 2024, the Company sold 1,503,708 shares of its common stock under the ATM offering program, resulting in net proceeds of $39.2 million. No sales were made under the ATM offering program during the three and six months ended June 30, 2025.

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”):

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Since its inception, the Company has funded its operations primarily with outside capital and has incurred significant recurring losses, including net losses of $61.1 million and $31.4 million for the six months ended June 30, 2025 and 2024, respectively. In addition, the Company had an accumulated deficit of$235.5 million as of June 30, 2025;

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The Company expects to continue to incur significant recurring losses and rely on outside capital to fund its operations for the foreseeable future; and

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As of the issuance date, the Company expects that its existing cash, cash equivalents and 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.

2. Summary of Significant Accounting Policies

The Company’s significant accounting policies are disclosed in the audited consolidated financial statements and the notes thereto in the Company’s Annual Report on Form 10-K for the year ended December 31, 2024, filed with the SEC on March 11, 2025. Except as reflected below, there were no changes to the Company’s significant accounting policies as described in the Annual Report on Form 10-K. Reflected in this note are updates to accounting policies, including the impact of the adoption of new policies.

Basis of Presentation

The accompanying unaudited condensed consolidated financial statements as of June 30, 2025 and for the three and six months ended June 30, 2025 and 2024 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, 2025 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, 2024 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, 2024, which are contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2024 filed with the SEC on March 11, 2025. 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 and revenue recognition.

Concentration of Credit Risk

Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of cash, cash equivalents and 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, U.S. government agency securities and corporate debt 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 significant realized losses related to its cash, cash equivalents and investments and management believes the Company is not exposed to significant risks of losses.

Recently Adopted Accounting Pronouncements

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 provides 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. On January 1, 2025, the Company adopted ASU 2023-09. The adoption of this standard did not have a material effect on the Company’s unaudited condensed consolidated financial position, results of operations, or cash flows.

Recently Issued Accounting Pronouncements

In November 2024, the FASB issued ASU 2024-03, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses. The amendments in ASU 2024-03 address investor requests for more detailed expense information and require additional disaggregated disclosures in the notes to financial statements for certain categories of expenses that are included on the face of the income statement. This guidance is effective for fiscal years beginning after December 15, 2026, and interim periods within fiscal years beginning after December 15, 2027, with early adoption permitted. The Company is currently evaluating this guidance to determine the impact it may have on the unaudited condensed consolidated financial statements.

In July 2025, the One Big Beautiful Bill Act (“OBBBA”) was enacted in the United States of America. The OBBBA includes significant provisions, including permanently repealing the requirement to capitalize domestic research and development expenditures for federal income tax purposes for taxable years beginning after December 31, 2024, and allowing for the accelerated deduction of any remaining unamortized domestic research and development expenditures. Foreign research and development expenditures are still required to be capitalized and amortized ratably over 15 years. The Company is currently evaluating this legislation to determine the potential impact it may have on the unaudited condensed consolidated financial statements.

3. Segment Reporting

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 (the “CODM”) in deciding how to allocate resources and in assessing the Company’s performance. The Company operates as asingle operating segment and hasone reportable segment which focuses on developing next-generation complement therapeutics for patients living with severe autoimmune and inflammatory diseases.

The Company’s CODM is its Chief Executive Officer. The CODM manages the Company’s operations on a consolidated basis as one operating segment for the purposes of evaluating financial performance and allocating resources.

The Company has not generated any revenue from product sales yet. The CODM assesses the financial performance of the segment and decides how to allocate resources based on net loss on a consolidated basis. The measure of segment assets is reported on the unaudited condensed consolidated balance sheets as total consolidated assets.

The CODM uses net loss predominantly in the annual operating budget and in the strategic planning and forecasting process. Such profit or loss measure is used to monitor budget versus actual results on an ongoing basis by the CODM and determines how resources are allocated to the various activities of the Company. The CODM also uses net loss to evaluate the Company’s performance and considers net loss when determining management’s incentive compensation.

All of the Company’s tangible assets are held in the United States. The Company views its operations and manages its business in one operating segment, operating exclusively in the United States.

The table below provides a summary of the segment profit or loss, including significant segment expenses:

4. Cash Equivalents and Marketable Securities

The Company’s investments consist of marketable securities classified as available-for-sale. The following tables provide a summary of the estimated fair value of the Company’s cash equivalents and marketable securities:

As of June 30, 2025 and December 31, 2024, marketable securities within the corporate debt securities line item includes both commercial paper and corporate debt securities. Commercial paper held at both June 30, 2025 and December 31, 2024 were classified as short-term securities.

Interest and Investment Income

The following table provides a summary of the components of interest and investment income:

5. Prepaid Expenses and Other Current Assets

The following table provides a summary of prepaid expenses and other current assets:

6. Property and Equipment

The following table provides a summary of property and equipment:

Depreciation expense was $30 thousand and $57 thousand for the three and six months ended June 30, 2025, respectively, and $23 thousand and $45 thousand for the three and six months ended June 30, 2024, respectively.

7. Fair Value of Financial Instruments

The following table provides a summary of financial assets measured at fair value on a recurring basis:

There wereno transfers between levels during the six months ended June 30, 2025 or for the year ended December 31, 2024. The weighted-average maturity of the securities held at June 30, 2025 was less than 12 months.

As of June 30, 2025 and December 31, 2024, marketable securities within the corporate debt securities line item includes both commercial paper and corporate debt securities. Commercial paper held at both June 30, 2025 and December 31, 2024 were classified as short-term securities and classified within Level 2 of the fair value hierarchy.

8. Accrued Expenses

The following table provides a summary of accrued expenses:

9. Leases

The Company leases space under operating leases for administrative offices in New York, New York, and Waltham, Massachusetts. The Company previously leased wet laboratory space in Watertown, Massachusetts, but this lease terminated in March 2025.

The following table provides a summary of the components of lease costs and rent:

Cash paid for amounts included in the measurement of operating lease liabilities was $0.1 million and $0.2 million for each of the three and six months ended June 30, 2025 and 2024, respectively.

The Company recorded operating lease costs of $0.1 million and $0.2 million during each of thethree and six months ended June 30, 2025 and 2024, 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 ofnil and $24 thousand during thethree and six months ended June 30, 2025, respectively, and $15 thousand and $30 thousand during the three and six months ended June 30, 2024, respectively, 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, 2025, are as follows:

The weighted-average remaining term of operating leases was 65 months, and the weighted-average discount rate used to measure the present value of operating lease liabilities was 8.4% as of June 30, 2025.

10. Stockholders' Equity

Shelf Registration Statement and ATM Offering Program

On October 1, 2024, the Company filed a registration statement with the SEC for the issuance of common stock, preferred stock, warrants, debt securities, rights and units up to an aggregate of $500.0 million. On October 9, 2024, the registration statement was declared effective by the SEC. The registration statement includes an ATM offering program for the sale of up to $200.0 million of shares of the Company’s common stock. During the year ended December 31, 2024, the Company sold 1,503,708 shares of its common stock under the ATM offering program, resulting in net proceeds of $39.2 million. No sales were made under the ATM offering program during the three and six months ended June 30, 2025. As of June 30, 2025, the Company had $160.8 million of remaining capacity under the ATM offering program.

Private Placement Offering

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, 2025, there were 3,665,999 pre-funded warrants outstanding related to this private placement.

Preferred Stock

As of June 30, 2025, the Company was authorized to issue up to 10,000,000 shares of the Company’s preferred stock at a par value of $0.001. As of June 30, 2025, no shares of Company preferred stock were issued and outstanding.

Common Stock

As of June 30, 2025, 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, 2025, the Company had issued and outstanding shares of Company common stock of 32,176,482.

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, 2025.

The Company had the following shares of Company common stock reserved for future issuance as of June 30, 2025 and December 31, 2024:

11. Stock-Based Compensation

2018 Stock Option and Incentive Plan

The Company grants stock-based awards under the Second Amended and Restated Dianthus Therapeutics, Inc. Stock Option and 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 “Prior 2018 Incentive Plan”).

On May 23, 2024, the Company’s stockholders approved an amendment and restatement of the Prior 2018 Incentive Plan, and it was renamed the Second Amended and Restated Dianthus Therapeutics, Inc. Stock Option and Incentive Plan (the “2018 Amended Plan”) to:

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provide for an increase in the number of shares of common stock reserved for issuance thereunder by 2,931,820 shares;

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increase the Evergreen Provision (as described below) from 4% to 5% of issued and outstanding shares of common stock on December 31 of the preceding calendar year; and

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extend the expiration date until March 14, 2034.

The 2018 Amended 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. 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 thanten years(orfive years for certain incentive stock options). Awards typically vest over 12 months tofour 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.

The 2018 Amended Plan also provides for the assumption of shares remaining available for delivery under the 2019 Stock Plan (as defined below) pursuant to the terms of the Reverse Merger, and such shares will be available for the granting of awards under the 2018 Amended 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 Amended Plan provides that the number of shares reserved and available for issuance under the 2018 Amended Plan will automatically increase each January 1 by 5% 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.

Pursuant to the Evergreen Provision, the number of shares reserved for issuance under the 2018 Amended Plan increased by 1,555,767 on January 1, 2025. Shares of common stock underlying any awards under the 2018 Amended 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 Amended Plan.

As of June 30, 2025,1,511,541 shares of the Company’s common stock were available for grant under the 2018 Amended Plan.

2019 Stock Plan

In July 2019, Former Dianthus’s board of directors adopted, and the Former Dianthus’s 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 Company common stock under the ESPP is equal to 85% of the lower of the fair market value of the common stock on (i) the offering date or (ii) the exercise date. The six-month offering periods previously began in December and June of each year. During the six months ended June 30, 2025, the Company issued 6,938 shares of common stock pursuant to the ESPP. As of June 30, 2025,155,140 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, 2025.

Inducement Plan

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, 2025, there were 108,042 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, 2025:

The aggregate intrinsic value of options granted, options exercised and options forfeited represents the difference between (i) the exercise price of the option and (ii) the closing market price of the Company’s common stock on (x) June 30, 2025, (y) the date of exercise, or (z) the date of forfeiture, respectively.

The weighted average grant-date fair value per share of stock options granted during the six months ended June 30, 2025 was $16.27 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, 2025 and 2024:

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, 2025, the warrants have a weighted average remaining contractual term of 5.8 years.

Stock-based Compensation Expense

The following table provides a summary of stock-based compensation expense:

As of June 30, 2025, there was $60.4 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 2.9 years.

12. License Revenues

Zenas BioPharma, Inc.

In September 2020, the Company entered into an Option Agreement (the “Zenas Option”) with Zenas BioPharma, Inc. (formerly Zenas BioPharma Limited) (“Zenas”), formerly considered a related party (See Note 15). 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 October 2021, Zenas exercised its option for such clinical candidate under the Zenas Option. Zenas paid 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 CMC costs and expenses from the date of delivery of its option exercise notice through the execution of a license agreement.

In June 2022, pursuant to the Zenas Option, the Company negotiated in good faith a license agreement with Zenas (the “Zenas License Agreement” and, together with the Zenas Option, the “Zenas Agreements”). The Zenas License Agreement provided Zenas with a license in the People’s Republic of China, including Hong Kong, Macau, and Taiwan (“Greater China”) for the development and commercialization of sequences and products under the first antibody sequence. The Company was also obligated to perform certain research and development and CMC services and participated in a joint steering committee (“JSC”).

The consideration under the Zenas Agreements included the following payments by Zenas to the Company: (i) a $1.0 million upfront payment upon the exercise of the corresponding option under the Zenas Option; (ii) an approximately $1.1 million reimbursement payment 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.

Tenacia Biotechnology (Hong Kong) Co., Limited

On October 21, 2024, Zenas assigned the Zenas Agreements to its affiliated entity, Zenas BioPharma (HK) Limited (“Zenas HK”). After the assignment, the Company entered into a novation agreement (the “Novation Agreement”) with Zenas HK and Tenacia Biotechnology (Hong Kong) Co., Limited (“Tenacia”) and an amendment to the Zenas License Agreement, now with Tenacia (as amended, the “Tenacia License Agreement”), pursuant to which Tenacia replaced Zenas HK as a party to the Zenas Agreements, and certain economic terms under the Zenas License Agreement with respect to cost sharing and development milestones were amended.

Except as otherwise noted below, the terms of the Zenas License Agreement were unchanged when novated by the Novation Agreement and amended by the Tenacia License Agreement.

The consideration under the Tenacia License Agreement, which replaced the consideration of the Zenas License Agreement, related to the first antibody sequence includes the following payments by Tenacia to the Company: (i) a $2.5 million upfront payment, which was paid to the Company in October 2024 upon execution of the Tenacia License Agreement; (ii) reimbursement of a portion of certain clinical costs; (iii) development milestones totaling up to $15.0 million; and (iv) royalties on net sales ranging from the mid-single digits to the low teen percentages. Tenacia is also responsible for paying local development costs in the Greater China and a portion of the central development costs based on the number of patients enrolled from China in our global Phase 3 studies.

Under the Zenas Agreements, Zenas also had the right to exercise an option with respect to a second antibody sequence, which is now held by Tenacia (the “Tenacia Option” and, together with the Tenacia License Agreement, the “Tenacia Agreements”). Pursuant to the Tenacia Option, if Tenacia exercises the option and pays the Company the option exercise fee related to the second antibody sequence, the Company will grant Tenacia an exclusive license to the sequences and products under this second antibody sequence.

Accounting for the Zenas and Tenacia Agreements

Since the Zenas Agreements were negotiated with a single commercial objective, it was treated as a combined contract for accounting purposes. The Company assessed the Zenas Agreements in accordance with ASC 606, Revenue from Contracts with Customers (“ASC 606”), and concluded that it represented a contract with a customer and was within the scope of ASC 606. The Company determined that there was one combined performance obligation that consisted 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 did not represent a material right.

The Company determined that the combined performance obligation would be satisfied over time; therefore, the Company recognized the transaction price from the license agreement over the Company’s estimated period to complete its activities. The Company concluded that it would utilize a cost-based input method to measure its progress toward the completion of its performance obligation and to calculate the corresponding amount of revenue to recognize each period. The Company believed that this was the best measure of progress because other measures did not reflect how the Company transferred its performance obligation to Zenas. In applying the cost-based input method of revenue recognition, the Company used actual costs incurred relative to budgeted costs expected to be incurred for the combined performance obligation. These costs consisted primarily of third-party contract costs. Revenue was 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 required management to make estimates of costs to complete the Company’s performance obligation. In making such estimates, judgment was required to evaluate assumptions related to cost estimates.

The Company assessed the Tenacia Agreements in accordance with ASC 606 and applied the same considerations above to the Tenacia Agreements. With the exception of the cost sharing and development milestones noted below, the key terms of the Zenas License Agreement were unchanged when novated by the Novation Agreement and amended by the Tenacia License Agreement. Therefore, the Company determined that the accounting considerations and resulting conclusions noted above related to the Zenas Agreements also apply to the Tenacia Agreements.

The Company also determined that the milestone payments of $15.0 million (previously $11.0 million under the Zenas License Agreement) 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. Should it be probable that a significant reversal of revenue will not occur, the milestone payment will be added to the transaction price for which the Company recognized revenue. No milestones were achieved under the Zenas Agreements prior to novation. During the six months ended June 30, 2025, the Company recognized revenue of $1.0 million related to milestones achieved under the Tenacia Agreements, which is included within the license revenue line item in the Company’s unaudited condensed consolidated statements of operations and comprehensive loss.

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). The Company hasnot recorded any royalty revenue to date.

The Company recognized related party license revenue totalingnil during each of the three and six months ended June 30, 2025, and $1.9 million and $2.7 million during the three and six months ended June 30, 2024, respectively, associated with the Zenas Agreements. As of December 31, 2024, the Company recorded a related party receivable of$0.8 million on its unaudited condensed consolidated balance sheet.

During the three and six months ended June 30, 2025, the Company recognized license revenue totaling $0.2 million and $1.4 million, respectively, associated with the Tenacia License Agreement. As of June 30, 2025, the Company recorded a receivable of $39 thousand, an unbilled receivable of $0.1 million within prepaid expenses and other current assets, current deferred revenue of $0.5 million and noncurrent deferred revenue of $1.8 million on its unaudited condensed consolidated balance sheet. As of December 31, 2024, the Company recorded an unbilled receivable of $0.2 million within prepaid expenses and other current assets, current deferred revenue of $0.5 million and noncurrent deferred revenue of $1.9 million on its unaudited condensed consolidated balance sheet.

13. Net Loss Per Share

Basic and diluted net loss per share of common stock is calculated as follows:

Pre-funded warrants totaling 3,665,999 shares have been included in the computation of basic and diluted net loss per share of common stockfor the three and six months ended June 30, 2025 as the pre-funded warrants are issuable for nominal consideration pursuant to their terms. 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 stock options 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:

14. 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:

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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

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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 $0.1 million during each of the three and six months ended June 30, 2025 and $0.6 million during each of the three and six months ended June 30, 2024 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.

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 $4.3 million based on the June 30, 2025 exchange rate) and £2.3 million (approximately $3.2 million based on the June 30, 2025 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 $3.4 million based on the June 30, 2025 exchange rate). The Company recorded $0.2 million and $0.4 million during the three and six months ended June 30, 2025, respectively, and $0.6 million and $1.0 million during the three and six months ended June 30, 2024, 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, 2025 and December 31, 2024.

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, 2025 and December 31, 2024, the Company had standing agreements with consultants, contractors or service providers that generally can be terminated by the Company with 30 to 60 days written notice, unless otherwise indicated.

15. Related Party Transactions

Zenas BioPharma, Inc.

The Company previously considered Zenas to be a related party because the sole member of Tellus BioVentures LLC (“Tellus”), who was a significant shareholder in the Company and was a member of the board of directors of the Company until May 2025, is a significant shareholder in Zenas and serves as Chief Executive Officer and Chairman of the board of directors of Zenas. As of May 2025, the Company no longer considers Zenas to be a related party. See Note 12 for more information.

In September 2020, Zenas issued 156,848 common shares to the Company in exchange for the Zenas Option. Previously, the Company used the measurement alternative as the measurement attribute for accounting for the Zenas common stock which did 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 was not readily determinable nor was there a reliable source for observable transactions from which the Company could determine a fair value. On September 12, 2024, Zenas announced the pricing of its initial public offering (the “Zenas IPO”) of $17.00 per share, which also included a 1-for-8.6831 reverse stock split of its capital stock. Upon the Zenas IPO, the fair value of the Zenas common stock was deemed readily determinable. The Company reassesses the fair value of the investment at the end of each reporting period, with any adjustments to the fair value recorded as unrealized gains or losses within other income (loss) in the unaudited condensed consolidated statements of operations and comprehensive loss. As of June 30, 2025 and December 31, 2024, the fair value of the investment in Zenas was $0.2 million and $0.1 million, respectively, which was included within other assets and restricted cash on the Company’s unaudited condensed consolidated balance sheet.