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 dedicated to developing potentially best in class therapies for patients living with severe autoimmune 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 common stock to the Former Dianthus stockholders, based on the exchange ratio of approximately 0.2181 shares of 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 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 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 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 would designate 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 would become 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 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 December 31, 2025, no receivables were recorded on the 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 $230.0 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 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. The Company sold 1,503,708 shares of its common stock under the ATM offering program during the year ended December 31, 2024, resulting in net proceeds of $39.2 million. No sales were made under the ATM offering program during the year ended December 31, 2025. As of the date of this filing, the Company has sold 2,626,834 shares of its common stock under the ATM offering program and has $100.1 million in remaining capacity under the ATM offering program.

On January 28, 2026, 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 $600.0 million. On January 30, 2026, the registration statement was declared effective by the SEC.

September 2025 Underwritten Public Offering

On September 9, 2025, the Company entered into an underwriting agreement with certain underwriters to issue and sell 7,627,879 shares of the Company’s common stock, including the full exercise by the underwriters of their option to purchase an additional 1,140,000 shares, at a public offering price of $33.00 per share and, in lieu of common stock to certain investors, pre-funded warrants to purchase 1,112,121 shares of the Company’s common stock at a public offering price of $32.999 per share, which represented the per share public offering price for the common stock less the $0.001 per share exercise price for each pre-funded warrant. The gross proceeds from the underwritten offering were $288.4 million, before underwriting discounts and commissions and estimated expenses of the offering. The underwritten offering closed on September 11, 2025.

The pre-funded warrants are exercisable at any time after the date of issuance. A holder of the pre-funded warrants may not exercise the warrant if the holder, together with its affiliates, would beneficially own more than 4.99%,9.99%, or 19.99%, as applicable to each holder, of the number of shares of common stock outstanding immediately after giving effect to such exercise. A holder of the 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.

The Company intends to use the net proceeds from this underwritten offering to advance the Company’s preclinical and clinical development activities, as well as for working capital and general corporate purposes. The Company may also use a portion of the proceeds to license, acquire or invest in new product candidates or for drug development activities related to such product candidates, complementary businesses, technology or assets.

The underwritten offering was made pursuant to a shelf registration statement, which became effective on October 9, 2024. A final prospectus supplement dated September 9, 2025 relating to and describing the terms of the underwritten offering was filed with the SEC on September 11, 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 current product candidates, as well as 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 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$162.3 million and $85.0 million for the years ended December 31, 2025 and 2024, respectively. In addition, the Company had an accumulated deficit of$336.7 million as of December 31, 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 candidates 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 consolidated financial statements do not include any adjustments that might result from the outcome of these uncertainties. Accordingly, the 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

Basis of Presentation

The financial statements have been prepared in conformity with U.S. GAAP. 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 revenues and 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 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 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 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.

Investments

The Company's investments consist of marketable securities classified as available-for-sale and reported at fair value on the consolidated balance sheets. 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. Investments in marketable securities with remaining maturities when purchased of greater than three months and less than one year are classified as current. Investments with a remaining maturity date greater than one year are classified as non-current. Unrealized gains and losses on available-for-sale securities are reported as a component of accumulated other comprehensive income/(loss) on the consolidated balance sheets. Interest earned on securities that are classified as available-for-sale are included in interest income. Realized gains and losses and declines in value judged to be other than temporary are included as a component of interest and investment income in the consolidated statements of operations and comprehensive loss, 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 consolidated statements of operations and comprehensive loss. Credit losses are recognized through the use of an allowance for credit losses account in the 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 consolidated statements of operations and comprehensive loss. There wereno credit losses recorded during the years ended December 31, 2025 or 2024.

Additional information regarding investments is included in Note 4.

Receivable from Former Related Party and Unbilled Receivable from Former Related Party

The receivable from former related party and the unbilled receivable from former related party results from the option and license agreements with Zenas BioPharma, Inc. (formerly Zenas BioPharma Limited) (“Zenas”). The Company previously considered Zenas to be a related party. See Notes 12 and 17 for more information. The receivable represents amounts earned and billed to Zenas but not yet collected as of period end while the unbilled receivable represents amounts earned but not yet billed to Zenas as of period end. The receivable and unbilled receivable are reported at net realizable value. The Company evaluated the creditworthiness of Zenas and their financial condition and did not require collateral from Zenas. No allowance for doubtful accounts is recorded as all accounts are considered collectible.

Accounts Receivable

Accounts receivable relates to the license agreement with Tenacia Biotechnology (Hong Kong) Co., Limited (“Tenacia”). See Note 12 for more information. The receivable represents amounts earned and billed to Tenacia but not yet collected as of period end. The receivable are reported at net realizable value. The Company evaluated the creditworthiness of Tenacia and their financial condition and did not require collateral from Tenacia. No allowance for doubtful accounts is recorded as all accounts are 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 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 doesnot have any leases classified as finance leases. Management has 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 has 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 consolidated statements of cash flows. Restricted cash serves as collateral for a letter of credit securing office space. Restricted cash is recorded within the prepaid expenses and other current assets and the other assets and restricted cash line items in the accompanying 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 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:

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Level 1 - Quoted prices in active markets for identical assets or liabilities.

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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.

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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. 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 former related party, accounts receivable, 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.

License Revenues

To date, the Company’s only revenue has been attributable to upfront payments and cost reimbursements under the Company’s licensing agreements. 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) identifies the contract with a customer; (ii) identifies the performance obligations in the contract; (iii) determines the transaction price; (iv) allocates the transaction price to the performance obligations in the contract; and (v) recognizes 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 consolidated balance sheets. If the related performance obligation is expected to be satisfied within the next twelve months, the related deferred revenue is classified in current liabilities.

Additional information and disclosures required under ASC 606 are included in Note 12.

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, contract development and manufacturing organizations and consultants; and (iii) costs associated with preclinical and clinical 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 December 31, 2025 and 2024, the Company didnot have any material uncertain tax positions. The Company recognizes interest and penalties related to uncertain tax positions, if any exist, in income tax expense.

Additional information and disclosures required under ASC 740 are included in Note 13.

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 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.

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 11.

Comprehensive Loss

The only component of comprehensive loss other than net loss is change in unrealized gains related to marketable 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 shares of common stock outstanding during the period. The weighted average number of shares of common stock 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.

Diluted net loss per share of common stock includes the effect, if any, from the potential exercise or conversion of securities, such as stock options and warrants for the purchase of common stock, 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 15.

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 on a prospective basis. Refer to Note 13 to these consolidated financial statements for additional discussion.

Recently Issued Accounting Pronouncements

In November 2024, the FASB issued ASU No. 2024-03, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses. The amendments in ASU No. 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 the impact ASU No. 2024-03 may have on its consolidated financial statements and related disclosures.

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 andhas one reportable segment which focuses on developing next-generation therapies to transform the treatment of severe autoimmune 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 yet generated any revenue from product sales. 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 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 December 31, 2024, marketable securities within the corporate debt securities line item includes both commercial paper and corporate debt securities. Commercial paper held at December 31, 2024 was 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 $0.1 million for each of the years ended December 31, 2025 and 2024.

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 for the years ended December 31, 2025 or 2024. The weighted-average maturity of the securities held at December 31, 2025 was less than 12 months.

As of December 31, 2024, marketable securities within the corporate debt securities line item included both commercial paper and corporate debt securities. Commercial paper held at December 31, 2024 was 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 $0.3 million and $0.4 million for the years ended December 31, 2025 and 2024, respectively.

The Company recorded operating lease costs of $0.4 million within the general and administrative expenses line item in the consolidated statements of operations and comprehensive loss during each of the years ended December 31, 2025 and 2024. The Company recorded operating lease costs of $24 thousand and $58 thousand within the research and development expenses line item in the consolidated statements of operations and comprehensive loss during the years ended December 31, 2025 and 2024, respectively.

Maturities of operating lease liabilities as of December 31, 2025 are as follows:

The weighted-average remaining term of operating leases was 58 months and the weighted-average discount rate used to measure the present value of operating lease liabilities was 8.40% as of December 31, 2025.

10. Stockholders’ Equity

September 2025 Underwritten Public Offering

At the closing of an underwritten public offering on September 11, 2025, the Company issued and sold 7,627,879 shares of its common stock, including the full exercise by the underwriters of their option to purchase an additional 1,140,000 shares, and pre-funded warrants to purchase 1,112,121 shares of its common stock with a $0.001 per share exercise price. The gross proceeds from this underwritten public offering were $288.4 million, before underwriting discounts and commissions and estimated expenses related to this public offering.

The pre-funded warrants are exercisable at any time after the date of issuance and will not expire. As of December 31, 2025, there were 1,112,121 pre-funded warrants outstanding related to this underwritten public offering.

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. The Company sold 1,503,708 shares of its common stock under the ATM offering program during the year ended December 31, 2024, resulting in net proceeds of $39.2 million. No sales were made under the ATM offering program during the year ended December 31, 2025. As of the date of this filing, the Company has sold 2,626,834 shares of its common stock under the ATM offering program and has $100.1 million in remaining capacity under the ATM offering program.

On January 28, 2026, 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 $600.0 million. On January 30, 2026, the registration statement was declared effective by the SEC.

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 December 31, 2025, there were 832,333 pre-funded warrants outstanding related to this private placement.

Preferred Stock

As of December 31, 2025, the Company was authorized to issue up to 10,000,000 shares of preferred stock at a par value of $0.001. As of December 31, 2025, no shares of preferred stock were issued and outstanding.

Common Stock

As of December 31, 2025, the Company was authorized to issue up to 150,000,000 shares of common stock at a par value of $0.001. As of December 31, 2025, the Company had issued and outstanding 43,223,090 shares of common stock.

Each share of 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 December 31, 2025.

The Company had the following shares of common stock reserved for future issuance:

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:

•

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 below) 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.

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 December 31, 2025,1,174,479 shares of 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 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 (i) the offering date or (ii) the exercise date. The six-month offering periods begin in January and July of each year. During the year ended December 31, 2025, the Company issued 18,801 shares of common stock pursuant to the ESPP, respectively. As of December 31, 2025,143,277 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. In December 2025, the Company’s board of directors approved an amendment to the Inducement Plan (the “Amended Inducement Plan”), which increased the number of shares of common stock available for inducement awards to 900,000. As of December 31, 2025,714,000 shares of common stock were available for grant under the Amended Inducement Plan.

Stock Options

The following table summarizes stock option activity for the year ended December 31, 2025:

The aggregate intrinsic valueof 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) December 31, 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 year ended December 31, 2025 was $18.27 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:

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 December 31, 2025, the warrants have a weighted average remaining contractual term of 5.3 years.

Stock-based Compensation Expense

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

As of December 31, 2025, there was $59.0 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 2.7 years.

12. License Revenues

In September 2020, the Company entered into an Option Agreement (the “Zenas Option”) with Zenas, formerly considered a related party (See Note 17). 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, 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 Greater Chinaand 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 each 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 recognizes revenue. No milestones were achieved under the Zenas Agreements prior to novation. During the year ended December 31, 2025, $6.0 million ofmilestones were achieved under the Tenacia Agreements and added to the transaction price. No milestones were achieved under the Tenacia Agreements during the year ended December 31, 2024.

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 and $5.9 million during the years ended December 31, 2025 and 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 consolidated balance sheet.

The Company recognized license revenue totaling $2.0 million and $0.3 million during the years ended December 31, 2025 and 2024, respectively, associated with the Tenacia Agreements. As of December 31, 2025, the Company recorded accounts receivable of $52 thousand, an unbilled receivable of $50 thousand within prepaid expenses and other current assets, current deferred revenue of $1.2 million and noncurrent deferred revenue of $5.8 million on its consolidated balance sheet.

13. Income Taxes

For the years ended December 31, 2025 and 2024, the Company recordedno current or deferred income tax expenses or benefits as it has incurred losses since inception and has provided a full valuation allowance against its deferred tax assets.

As further described in Note 2, the Company elected to prospectively adopt the guidance in ASU 2023-09. The following table is a reconciliation of the Company’s effective income tax rate to the statutory federal income tax rate for the year ended December 31, 2025 in accordance with the guidance in ASU 2023-09:

The following table is a reconciliation of the Company’s effective income tax rate to the statutory federal income tax rate for the year ended December 31, 2024 in accordance with the guidance prior to the adoption of ASU 2023-09:

The following table provides a summary of net deferred tax assets:

As of December 31, 2025, the Company had federal net operating loss carryforwards of approximately $475.9 million, of which $458.3 million can be carried forward indefinitely. As of December 31, 2025, the Company had state tax net operating loss carryforwards of approximately $419.0 million, which will begin to expire in 2038. As of December 31, 2025, the Company had federal, state, and foreign tax credit carryforwards of approximately $26.4 million, $4.3 million andnil, respectively. All tax credits have a limited carryforward period and will begin to expire in 2038.

In assessing the realizability of the net deferred tax assets, management considers all relevant positive and negative evidence in determining whether it is more likely than not that some portion or all the deferred income tax assets will not be realized. The realization of the gross deferred tax assets is dependent on several factors, including the generation of sufficient taxable income prior to the expiration of the net operating loss carryforwards. Management believes that it is more likely than not that the Company’s deferred income tax assets will not be realized. As a result of the analysis, the Company determined that a full valuation allowance against the deferred tax assets, net, was required.

Changes in the valuation allowance for deferred tax assets during the years ended December 31, 2025 and 2024 related primarily to the increase in net operating loss carryforwards, capitalized research and development expenses and research tax credit carryforwards. During the years ended December 31, 2025 and 2024, capitalized research and development expenses increased pursuant to Section 174 of the Internal Revenue Code of 1986, as amended (the “Code”). The changes in the valuation allowance for the years ended December 31, 2025 and 2024 were as follows:

The Company is subject to tax and will continue to file federal income tax returns in the United States as well as in certain state and local jurisdictions. The Company is subject to tax examinations for tax years ended December 31, 2022 and forward in all applicable income tax jurisdictions. Tax audits and examinations can involve complex issues, interpretations and judgments. The resolution of matters may span multiple years particularly if subject to litigation or negotiation. In addition, the utilization of tax carryforwards, from periods prior to those previously mentioned may also be audited by the taxing authorities once utilized.

Net operating loss carryforwards are subject to review and possible adjustment by the Internal Revenue Service (the “IRS”) and may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant shareholders over a three-year period in excess of 50% as defined under Sections 382 and 383 in the Code, which could limit the amount of tax attributes that can be utilized annually to offset future taxable income or tax liabilities. The amount of the annual limitation is determined based on the Company’s value immediately prior to the ownership change. Subsequent ownership changes may further affect the limitation in future years.

The Company hasnot recorded any liabilities for unrecognized tax benefits as of December 31, 2025 or 2024. The Company will recognize interest and penalties related to uncertain tax positions, if any, in income tax expense. As of December 31, 2025 and 2024, the Company hadno accrued interest or penalties related to uncertain tax positions.

The Company has madeno income tax payments and receivedno income tax refunds during the year. All payments made to taxing authorities were for non-income based tax liabilities and are outside the scope of ASC 740.

On July 4, 2025, the One Big Beautiful Bill Act (“OBBBA”) was enacted. The OBBBA includes several significant tax provisions, such as the permanent extension of certain expiring provisions of the Tax Cuts and Jobs Act, modifications to the international tax framework and the restoration of certain business provisions. The legislation has multiple effective dates, with certain provisions effective in 2025 and others implemented through 2027. On August 28, 2025, the IRS released procedural guidance (Rev. Proc. 2025-28) for implementing Section 174A and related elections for domestic research or experimental (“R&E”)expenditures. Transition rules provide taxpayers with options to account for any remaining unamortized domestic R&E expenditures paid or incurred in taxable years beginning after December 31, 2021, and before January 1, 2025. Taxpayers may continue to amortize such unamortized amounts over the remaining five-year period; alternatively, they may elect to deduct any remaining unamortized domestic R&E expenditures either entirely in the first tax year beginning after December 31, 2024, or ratably over two taxable years (e.g., 2025 or ratably in 2025 and 2026). The Company has elected to continue to capitalize all domestic R&E expenditures and will continue to amortize previously capitalized and unamortized domestic R&E expenditures over the remaining five-year period. As of December 31, 2024, the Company had approximately $131.0 million of remaining unamortized domestic R&E expenditures, representing approximately $32.4 million of its gross deferred tax assets. As of December 31, 2025, the Company had approximately $191.0 million of remaining unamortized domestic R&E expenditures, representing approximately $50.4 million of its gross deferred tax assets.

14. Employee Benefit Plan

The Company maintains a defined contribution benefit plan under section 401(k) of the Code covering substantially all qualified employees of the Company (the “401(k) Plan”). Eligible employees are able to contribute 100% of their eligible compensation up to the maximum amount allowed under the Code. The Company matches 100% of each eligible employee’s contributions up to 4% of total eligible compensation. Contributions are allocated to each participant’s individual account and are then invested in selected investment alternatives according to the participant’s directions. The 401(k) Plan currently does not offer the ability to invest in the Company’s securities. Employees are immediately and fully vested in their contributions. The Company recorded expense of $1.0 million and $0.5 million representing employer contributions under the 401(k) Plan during the years ended December 31, 2025 and 2024, respectively.

15. Net Loss Per Share

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

Pre-funded warrants have been included in the computation of basic and diluted net loss per share of common stock as the pre-funded warrants are issuable for nominal consideration pursuant to their terms. There were outstanding pre-funded warrants of 1,944,454 and 4,666,332 as of December 31, 2025 and 2024, respectively. The outstanding pre-funded warrants increased the weighted-average number of shares of common stock outstanding by 3,302,164 shares and 4,546,993 shares for the year ended December 31, 2025 and 2024, respectively.

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:

16. Commitments and Contingencies

License Agreement with Nanjing Leads Biolabs Co. Ltd.

On October 16, 2025, the Company entered into a License and Collaboration Agreement (the “Leads License Agreement”) with Nanjing Leads Biolabs Co. Ltd. (“Leads”), pursuant to which Leads granted the Company a royalty-bearing, exclusive license outside of Greater China to develop, manufacture, commercialize, or otherwise exploit DNTH212, a bifunctional fusion protein being developed in China by Leads as LBL-047. The Company also obtained certain non-exclusive rights to perform development and manufacturing activities in Greater China to support DNTH212 outside of Greater China. DNTH212 is an investigational, extended half-life bifunctional fusion protein targeting plasmacytoid dendritic cell BDCA2 to reduce Type 1 interferon production, while simultaneously inhibiting BAFF/APRIL to suppress B cell function. On December 23, 2025, Leads and the Company jointly announced the initiation of a Phase 1 clinical trial for LBL-047 (DNTH212).

Under the terms of the Leads License Agreement, the Company will pay Leads up to $38.0 million, comprised of $30.0 million in upfront and near-term milestone payments plus an additional $8.0 million milestone, payable in cash or the Company’s common stock at the Company’s election, upon the initiation of a Dianthus-led Phase 1 study, for exclusive rights to develop and commercialize DNTH212 globally outside of Greater China. Leads will also be eligible to receive up to $962.0 million in development and regulatory approval milestones across three key geographies and sales-based milestones across five indications, as well as tiered royalties from mid-single digits up to a low double-digit on ex-Greater China net sales.

The Leads License Agreement will remain in effect on a country-by-country and product-by-product basis until expiration of the applicable royalty term, unless earlier terminated. Each party has customary termination rights, including for uncured material breach, insolvency, patent challenge, or, in the case of the Company, for convenience.

The Company recorded $30.0 million for amounts owed under the Leads License Agreement, including upfront and near-term milestone payments, within the research and development expenses line item in the consolidated statements of operations and comprehensive loss during the year ended December 31, 2025. During the three months ended December 31, 2025, the Company paid Leads $25.0 million in upfront and near-term milestone payments. In addition, the Company recorded $5.0 million of milestone payments within the accounts payable line item on its consolidated balance sheet as of December 31, 2025.

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 payments to IONTAS of up to £3.1 million (approximately $4.2 million based on the December 31, 2025 exchange rate) and £2.3 million (approximately $3.1 million based on the December 31, 2025 exchange rate), respectively. Upon the achievement, with the second development program with IONTAS, of certain development milestones, the Company is obligated to make payments to IONTAS of up to £2.5 million (approximately $3.4 million based on the December 31, 2025 exchange rate). The Company recorded $1.7 million and $2.0 million for amounts owed under the IONTAS collaborative research license agreement, including milestone payments, within the research and development expenses line item in the consolidated statements of operations and comprehensive loss during the years ended December 31, 2025 and 2024, respectively.

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 antibowedies 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 products developed with Alloy, of (i) certain development milestones and (ii) certain commercial milestones, the Company is obligated to make payments to Alloy of up to $1.8 million and $11.0 million, respectively. The Company recorded $1.1 million and $0.6 million for amounts owed under the Alloy license agreement, including milestone payments, within the research and development expenses line item in the consolidated statements of operations and comprehensive loss during the years ended December 31, 2025 and 2024, respectively.

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 consolidated financial statements as of December 31, 2025 or 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 December 31, 2025, the Companyhad 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.

17. Related Party Transactions

The Company previously considered Zenas to be a related party because the sole member of Tellus BioVentures LLC (“Tellus”), who is 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 consolidated statements of operations and comprehensive loss. As of December 31, 2025 and 2024, the fair value of the investment in Zenas was $0.7 million and $0.1 million, respectively, which was included within other assets and restricted cash on the Company’s consolidated balance sheet.