Zenas BioPharma, Inc. 10-Q

Item 1. Financial Statements Zenas BioPharma, Inc. Condensed Consolidated Balance Sheets (Unaudited) (in thousands, except share and per share amounts) ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, ​ December 31, ​ ​ ​ ​ 2026 ​ ​ ​ 2025 Assets ​ ​ ​ ​ ​ ​ ​ ​ Current assets: ​ ​ ​ ​ ​ ​ Cash and cash equivalents ​ $ 500,224 ​ $ 110,641 Short-term investments ​ ​ 216,981 ​ ​ 232,551 Prepaid expenses and other current assets ​ ​ 12,959 ​ ​ 7,979 Total current assets ​ ​ 730,164 ​ ​ 351,171 Property and equipment, net ​ ​ 28 ​ ​ 34 Operating lease right-of-use assets, net ​ ​ 1,090 ​ ​ 1,354 Long-term investments ​ ​ 1,340 ​ ​ 17,272 Other non-current assets ​ ​ 15,060 ​ ​ 13,809 Total assets ​ $ 747,682 ​ $ 383,640 Liabilities and Stockholders’ Equity ​ ​ ​ ​ ​ ​ Current liabilities: ​ ​ ​ ​ ​ ​ Accounts payable ​ $ 8,944 ​ $ 7,111 Accrued expenses ​ ​ 51,180 ​ ​ 54,423 Operating lease liabilities, current ​ ​ 1,037 ​ ​ 1,115 Total current liabilities ​ ​ 61,161 ​ ​ 62,649 Long-term liabilities: ​ ​ ​ ​ ​ ​ Royalty obligation ​ ​ 84,900 ​ ​ 78,636 Senior secured term loan, net ​ ​ 72,084 ​ ​ — Convertible senior notes, net ​ ​ 193,631 ​ ​ — Operating lease liabilities, less current portion ​ ​ 77 ​ ​ 211 Total long-term liabilities ​ ​ 350,692 ​ ​ 78,847 Total liabilities ​ ​ 411,853 ​ ​ 141,496 Commitments and contingencies (Note 13) ​ ​ ​ ​ ​ ​ Stockholders’ equity: ​ ​ ​ ​ ​ ​ Preferred stock, par value $ 0.0001 per share; 25,000,000 shares authorized and no shares issued and outstanding as of March 31, 2026 and December 31, 2025 ​ ​ — ​ ​ — Common stock, par value $ 0.0001 per share; 175,000,000 shares authorized at March 31, 2026 and December 31, 2025, respectively; 62,383,377 and 54,485,518 shares issued and outstanding as of March 31, 2026 and December 31, 2025, respectively ​ ​ 6 ​ ​ 5 Additional paid-in capital ​ ​ 1,182,315 ​ ​ 1,007,331 Accumulated other comprehensive loss ​ ​ ( 377 ) ​ ​ ( 64 ) Accumulated deficit ​ ​ ( 846,115 ) ​ ​ ( 765,128 ) Total stockholders’ equity ​ ​ 335,829 ​ ​ 242,144 Total liabilities and stockholders’ equity ​ $ 747,682 ​ $ 383,640 ​ The accompanying notes are an integral part of these condensed consolidated financial statements. ​ 6 Table of Contents Zenas BioPharma, Inc. Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) (in thousands, except share and per share amounts) ​ ​ ​ ​ ​ ​ ​ ​ For the three months ended March 31, ​ ​ 2026 ​ ​ 2025 Revenue: ​ ​ ​ ​ ​ License and collaboration revenue $ — ​ $ 10,000 Total revenue ​ — ​ ​ 10,000 Operating expenses: ​ ​ ​ ​ ​ Research and development ​ 60,439 ​ ​ 34,915 General and administrative ​ 16,911 ​ ​ 12,415 Total operating expenses ​ 77,350 ​ ​ 47,330 Loss from operations ​ ( 77,350 ) ​ ​ ( 37,330 ) Other income (expense), net: ​ ​ ​ ​ ​ Interest expense on royalty obligation ​ ( 6,263 ) ​ ​ — Interest expense on senior secured term loan ​ ( 368 ) ​ ​ — Interest income ​ 3,018 ​ ​ 3,394 Other (expense) income, net ​ ( 24 ) ​ ​ 158 Total other income (expense), net ​ ( 3,637 ) ​ ​ 3,552 Loss before income taxes ​ ( 80,987 ) ​ ​ ( 33,778 ) Income tax provision (benefit) ​ — ​ ​ ( 205 ) Net loss $ ( 80,987 ) ​ $ ( 33,573 ) Net loss per share - basic and diluted $ ( 1.46 ) ​ $ ( 0.80 ) Weighted-average common stock outstanding - basic and diluted ​ 55,624,631 ​ ​ 41,800,802 Comprehensive loss: ​ ​ ​ ​ ​ Net loss $ ( 80,987 ) ​ $ ( 33,573 ) Other comprehensive income (loss): ​ ​ ​ ​ ​ Unrealized (loss) gain on investments ​ ( 341 ) ​ ​ 12 Foreign currency translation adjustment ​ 28 ​ ​ ( 65 ) Comprehensive loss $ ( 81,300 ) ​ $ ( 33,626 ) ​ The accompanying notes are an integral part of these condensed consolidated financial statements. ​ ​ 7 Table of Contents Zenas BioPharma, Inc. Condensed Consolidated Statements of Stockholders’ Equity (Unaudited) (in thousands, except share data) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Common Stock ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Shares ​ ​ ​ Amount ​ ​ ​ Additional Paid-in Capital ​ ​ ​ Accumulated Other Comprehensive Loss ​ ​ ​ Accumulated Deficit ​ ​ ​ Total Stockholders' Equity Balance as of December 31, 2025 ​ 54,485,518 ​ $ 5 ​ $ 1,007,331 ​ $ ( 64 ) ​ $ ( 765,128 ) ​ $ 242,144 Exercises of common stock options ​ 25,767 ​ ​ — ​ ​ 367 ​ ​ — ​ ​ — ​ ​ 367 Stock-based compensation expense ​ — ​ ​ — ​ ​ 9,195 ​ ​ — ​ ​ — ​ ​ 9,195 Purchases of common stock under the Employee Stock Purchase Plan ​ 44,369 ​ ​ — ​ ​ 592 ​ ​ — ​ ​ — ​ ​ 592 Issuance of common stock from ATM offering, net of underwriting commissions and other offering costs ​ 2,827,723 ​ ​ — ​ ​ 71,186 ​ ​ — ​ ​ — ​ ​ 71,186 Issuance of common stock from equity offering, net of underwriting commissions and other offering costs ​ 5,000,000 ​ ​ 1 ​ ​ 93,644 ​ ​ — ​ ​ — ​ ​ 93,645 Unrealized loss on investments ​ — ​ ​ — ​ ​ — ​ ​ ( 341 ) ​ ​ — ​ ​ ( 341 ) Foreign currency translation adjustment ​ — ​ ​ — ​ ​ — ​ ​ 28 ​ ​ — ​ ​ 28 Net loss ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ ( 80,987 ) ​ ​ ( 80,987 ) Balance as of March 31, 2026 ​ 62,383,377 ​ $ 6 ​ $ 1,182,315 ​ $ ( 377 ) ​ $ ( 846,115 ) ​ $ 335,829 ​ The accompanying notes are an integral part of these condensed consolidated financial statements. ​ ​ 8 Table of Contents Zenas BioPharma, Inc. Condensed Consolidated Statements of Stockholders’ Equity (Unaudited) (in thousands, except share data) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Common Stock ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Shares ​ ​ ​ ​ ​ Amount ​ Additional Paid-in Capital ​ Accumulated Other Comprehensive Income ​ Accumulated Deficit ​ Total Stockholders' Equity Balance as of December 31, 2024 ​ 41,793,412 ​ $ 4 ​ $ 699,651 ​ $ 194 ​ $ ( 387,391 ) ​ $ 312,458 Exercises of common stock options ​ 28,475 ​ ​ — ​ ​ 99 ​ ​ — ​ ​ — ​ ​ 99 Stock-based compensation expense ​ — ​ ​ — ​ ​ 5,386 ​ ​ — ​ ​ — ​ ​ 5,386 Unrealized gain on investments ​ — ​ ​ — ​ ​ — ​ ​ 12 ​ ​ — ​ ​ 12 Foreign currency translation adjustment ​ — ​ ​ — ​ ​ — ​ ​ ( 65 ) ​ ​ — ​ ​ ( 65 ) Net loss ​ — ​ ​ — ​ ​ — ​ ​ — ​ ​ ( 33,573 ) ​ ​ ( 33,573 ) Balance as of March 31, 2025 ​ 41,821,887 ​ $ 4 ​ $ 705,136 ​ $ 141 ​ $ ( 420,964 ) ​ $ 284,317 ​ The accompanying notes are an integral part of these condensed consolidated financial statements. ​ 9 Table of Contents Zenas BioPharma, Inc. Condensed Consolidated Statements of Cash Flows (Unaudited) (in thousands) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ ​ ​ ​ ​ 2026 ​ ​ ​ ​ 2025 Cash flows from operating activities: ​ ​ ​ ​ ​ ​ Net loss ​ $ ( 80,987 ) ​ $ ( 33,573 ) Adjustments to reconcile net loss to net cash used in operating activities: ​ ​ ​ ​ ​ ​ Depreciation expense ​ ​ 6 ​ ​ 23 Loss on disposal of property and equipment ​ ​ — ​ ​ 107 Net amortization of premiums and accretion of discounts on investments ​ ​ ( 110 ) ​ ​ ( 382 ) Non-cash interest expense on royalty obligation ​ ​ 6,263 ​ ​ — Non-cash interest expense on senior secured term loan ​ ​ 34 ​ ​ — Stock-based compensation expense ​ ​ 9,195 ​ ​ 5,386 Non-cash lease expense ​ ​ 264 ​ ​ 246 Changes in operating assets and liabilities: ​ ​ ​ ​ ​ ​ Prepaid expenses and other assets ​ ​ ( 6,482 ) ​ ​ ( 353 ) Accounts payable ​ ​ 1,795 ​ ​ 2,882 Accrued expenses ​ ​ ( 4,963 ) ​ ​ ( 11,165 ) Operating lease liabilities ​ ​ ( 211 ) ​ ​ ( 222 ) Net cash used in operating activities ​ ​ ( 75,196 ) ​ ​ ( 37,051 ) Cash flows from investing activities: ​ ​ ​ ​ ​ ​ Purchases of property and equipment ​ ​ ( 2 ) ​ ​ ( 18 ) Purchases of investments ​ ​ ( 76,520 ) ​ ​ ( 99,114 ) Proceeds from sales and maturities of investments ​ ​ 108,133 ​ ​ 12,858 Net cash provided by (used in) investing activities ​ ​ 31,611 ​ ​ ( 86,274 ) Cash flows from financing activities: ​ ​ ​ ​ ​ ​ Payments of other offering costs for the ATM offering ​ ​ ( 38 ) ​ ​ — Payments of debt issuance costs ​ ​ ( 474 ) ​ ​ — Proceeds from exercise of stock options ​ ​ 367 ​ ​ 99 Proceeds from issuance of common stock under employee stock purchase plan ​ ​ 592 ​ ​ — Proceeds from issuance of common stock under ATM offering, net of commissions ​ ​ 71,532 ​ ​ — Proceeds from issuance of common stock in connection with an equity offering, net of underwriting discounts and commissions ​ ​ 94,000 ​ ​ — Proceeds from senior secured term loan, net of discount ​ ​ 73,500 ​ ​ — Proceeds from the issuance of convertible senior notes, net of commissions ​ ​ 194,000 ​ ​ — Net cash provided by financing activities ​ ​ 433,479 ​ ​ 99 Effect of exchange rate changes on cash and cash equivalents ​ ​ ( 311 ) ​ ​ ( 52 ) Net increase (decrease) in cash and cash equivalents ​ ​ 389,583 ​ ​ ( 123,278 ) Cash and cash equivalents at beginning of period ​ ​ 110,641 ​ ​ 319,832 Cash and cash equivalents at end of period ​ $ 500,224 ​ $ 196,554 ​ ​ ​ ​ ​ ​ ​ Supplemental disclosure of non-cash investing and financing activities: ​ ​ ​ ​ ​ ​ Right-of-use assets obtained under operating lease arrangements ​ $ — ​ $ 445 Deferred offering costs and debt issuance costs in accounts payable and accrued expenses ​ $ 1,758 ​ $ — ​ The accompanying notes are an integral part of these condensed consolidated financial statements. ​ 10 Table of Contents Zenas BioPharma, Inc. Notes to Condensed Consolidated Financial Statements (unaudited) ​ 1. Nature of Business Organization Zenas BioPharma, Inc. (“Zenas” or the “Company”) was incorporated in November 2019 as Zenas BioPharma (Cayman) Limited, an exempted company incorporated in the Cayman Islands with limited liability and commenced operations in 2020. On August 2, 2023, the Company (then known as Zenas BioPharma (Cayman) Limited) de-registered from the Cayman Islands and registered by way of continuation in the State of Delaware. Zenas is a clinical-stage global biopharmaceutical company committed to being a leader in the development and commercialization of transformative immunology-based therapies for patients in need. The Company’s goal is to build an immunology and inflammation (“I&I”) focused biopharmaceutical company. The Company has in-licensed and is developing several product candidates for the treatment of various auto-immune and rare diseases. The Company is headquartered in Waltham, Massachusetts and operates in one segment, which is the business of acquiring and developing immune-based therapies for potential commercialization. The Company’s condensed consolidated financial statements include the accounts of its wholly owned subsidiaries which include Zenas BioPharma (HK) Limited (“Zenas HK”), Zenas BioPharma (USA) LLC, Shanghai Zenas Biotechnology Co. Limited, Zenas BioPharma Securities Corp., Zenas BioPharma GmbH and Zenas BioPharma B.V. Liquidity and Capital Resources Since its inception, the Company has devoted its efforts principally to research and development and raising capital. The Company is subject to risks and uncertainties common to clinical stage companies in the biopharmaceutical industry, including, but not limited to, completing preclinical studies and clinical trials, obtaining regulatory approval for product candidates, market acceptance of products, development by competitors of new technological innovations, dependence on key personnel, the ability to attract and retain qualified employees, reliance on third-party organizations, protection of proprietary technology, compliance with government regulations, and the ability to raise additional capital to fund operations. The Company’s capital to date has been generated primarily with proceeds received through the sale and issuance of preferred stock, convertible senior notes, the sale of common stock from its initial public offering (“IPO”), private and public equity offerings (please see Note 10, Common Stock , to these unaudited condensed consolidated financial statements), as well as from payments received under the Company’s license, collaboration and royalty purchase agreements (please see Note 7, License and Collaboration Revenue and Note 9, Royalty Obligation , to these unaudited condensed consolidated financial statements) and the senior secured term loan with Pharmakon Advisors, LP (“Pharmakon”) (please see Note 6, Long-Term Obligations , to these unaudited condensed consolidated financial statements”). The Company has not generated any revenue from product sales since inception, and its product candidates currently under development will require significant additional research and development efforts, including extensive clinical testing and regulatory approval prior to commercialization. The Company has incurred operating losses and negative cash flows, since its inception, including net losses of $ 81.0 million and $ 33.6 million for the three months ended March 31, 2026 and 2025, respectively. As of March 31, 2026, the Company had an accumulated deficit of $ 846.1 million. Management expects operating losses and negative operating cash flows to continue for the foreseeable future. During the first quarter of 2026, the Company alleviated the uncertainty associated with its ability to continue as a going concern through the execution of its senior secured term loan, the issuance of convertible senior notes and the concurrent equity offering, see Note 6, Long – Term Obligations and Note 10 – Common Stock to these unaudited condensed 11 Table of Contents consolidated financial statements. The Company expects that its existing cash, cash equivalents and investments of $ 718.5 million as of March 31, 2026, will be sufficient to fund its operating and capital expenditures for at least twelve months from the date of the issuance of these unaudited condensed consolidated financial statements. 2. Summary of Significant Accounting Policies The Company’s significant accounting policies are disclosed in Note 2, Summary of Significant Accounting Policies, in the audited consolidated financial statements for the year ended December 31, 2025, and notes thereto, included in the Company’s Annual Report on Form 10-K that was filed with the SEC on March 16, 2026. Since the date of those financial statements, other than disclosed herein, there have been no material changes to the Company’s significant accounting policies. Basis of Presentation and Consolidation The accompanying condensed consolidated financial statements include the operations of the Company and its wholly-owned subsidiaries. All intercompany accounts, transactions, and balances have been eliminated in consolidation. The accompanying condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) and pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Update (“ASU”) of the Financial Accounting Standards Board (“FASB”). Unaudited Interim Financial Information The accompanying unaudited condensed consolidated financial statements have been prepared on the same basis as the annual audited financial statements and in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement of the Company’s financial position as of March 31, 2026, and the results of operations and its cash flows for the three months ended March 31, 2026 and 2025. The financial data and other information disclosed in these notes related to the three months ended March 31, 2026 and 2025 are not necessarily indicative of the results to be expected for the year ending December 31, 2026, any other interim periods, or any future year or period. These interim financial statements should be read in conjunction with the audited financial statements as of and for the year ended December 31, 2025, and the notes thereto, which are included in the Company’s Annual Report on Form 10-K as filed with the SEC, on March 16, 2026. ​ Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make certain estimates and assumptions that affect the reported amounts of assets, liabilities, expenses, and related disclosures. The Company bases its estimates on historical experience, known trends and other market-specific factors or other relevant factors that it believes to be reasonable under the circumstances. The Company evaluates its estimates and assumptions on an ongoing basis using such factors and adjusts those estimates and assumptions as facts and circumstances dictate. Actual results may differ from those estimates or assumptions. Significant estimates in these unaudited condensed consolidated financial statements include estimates made in connection with accrued research and development expenses, stock-based compensation, valuations of embedded features within its senior secured term loan and the liability related to the sale of future royalties including the estimation of future payments and the related non-cash interest expense. Estimates and assumptions about future events and their effects cannot be determined with certainty and therefore require the exercise of judgement. As of the date of the issuance of these unaudited condensed consolidated financial statements, the Company is not aware of any specific event or circumstance that would require the Company to update its estimates, assumptions and judgements or revise the carrying value of its assets or liabilities. These estimates may change as new events occur and additional information is obtained and are recognized in the financial statements as soon as they become known. Actual results could differ from those estimates and any such differences may be material to the Company’s financial statements. 12 Table of Contents Embedded Derivative Financial Instruments The Company evaluates its financial instruments, including its convertible senior notes and senior secured term loan to determine if such instruments are derivatives or contain features that qualify as embedded derivatives in accordance with ASC 815 “Derivatives and Hedging.” ASC 815 generally provides three criteria that, if met, require companies to bifurcate embedded features from their host instruments and account for them as free-standing derivative financial instruments. The three criteria include circumstances in which (a) the economic characteristics and risks of the embedded derivative instrument are not clearly and closely related to the economic characteristics and risks of the host contract, (b) the hybrid instrument that embodies both the embedded derivative instrument and the host contract is not remeasured at fair value under otherwise applicable generally accepted accounting principles with changes in fair value reported in earnings as they occur, and (c) a separate instrument with the same terms as the embedded derivative would be considered a derivative instrument. If liability accounting is required, the Company’s derivative instruments are recorded at fair value with an offsetting amount recorded as a debt discount, which offsets the carrying amount of the debt. The derivative is revalued at the end of each reporting period and any change in fair value is recorded as a gain or loss in the statement of operations. The debt discount is amortized through interest expense over the life of the debt using the straight-line method. ​ Convertible Instruments When the Company issues debt with a conversion feature, in accordance with ASC 815, “Derivatives and Hedging” it must first assess whether the conversion feature meets the requirements to be treated as a derivative. An embedded equity-linked component that meets the definition of a derivative does not have to be separated from the host instrument if the component qualifies for the scope exception for certain contracts involving an issuer’s own equity. The scope exception applies if the contract is both (a) indexed to its own stock; and (b) classified in stockholders’ equity in its balance sheet. ​ Debt and Debt Issuance Costs Debt issuance costs and expenses paid by the Company to its lenders are presented on the unaudited condensed consolidated balance sheet as a direct deduction from the related liability. Debt issuance costs represent costs that are paid directly to third parties and directly attributable to the issuance of a debt or equity instrument, which includes lender fees, legal expenses and other direct costs. These costs are amortized as a non-cash component of interest expense using the effective interest method over the term of the debt. Costs and discounts are presented as a reduction of the related debt in the accompanying balance sheet if related to the issuance of debt or presented as a reduction of additional paid in capital if related to the issuance of an equity instrument. Recently Adopted Accounting Standards In September of 2025, the FASB issued ASU 2025-07: Derivates and Hedging (ASC 815) and Revenue from Contracts with Customers (ASC 606). This ASU expands the scope exceptions in the derivative guidance to exclude certain non-exchange-trade contracts with underlyings based on the operations or activities of one of the parties to the contract, including the occurrence or nonoccurrence of an event specific to those operations or activities. The ASU also clarifies that share-based noncash consideration received from a customer in exchange for goods or services should be accounted for as noncash consideration under ASC 606 unless and until the entity’s rights to receive or retain such consideration becomes unconditional. The Company early adopted the ASU at the beginning of fiscal year 2026, using the prospective method. The adoption of this new accounting standard was applied to the evaluation of the senior secured term loan that was executed during the first quarter. Recent Accounting Pronouncements In November 2024, the FASB issued 2024-03, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses (“ASU 2024-03”) , which requires entities to disclose additional information about specific expense categories in the notes to the financial statements. ASU 2024-03 is effective for annual periods beginning after December 15, 2026 and for interim periods within fiscal years 13 Table of Contents beginning after December 15, 2027, with early adoption permitted. ASU 2024-03 may be applied retrospectively or prospectively to the financial statements. The Company is currently evaluating the impact of ASU 2024-03 on its unaudited condensed consolidated financial statements and related disclosures. ​ From time to time, new accounting pronouncements are issued by the FASB or other standard setting bodies that the Company adopts as of the specified effective date. Unless otherwise discussed, the Company does not believe that the adoption of recently issued standards have or may have a material impact on its unaudited condensed consolidated financial statements or disclosures. ​ 3. Fair Value Measurements The following table presents information about the Company’s assets and liabilities that are regularly measured and carried at fair value and indicate the level within the fair value hierarchy of the valuation techniques the Company utilized to determine such fair value (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of March 31, 2026 Description ​ ​ ​ ​ Total Carrying Value ​ ​ Quoted Prices in Active Market (Level 1) ​ ​ ​ ​ Significant Other Observable Inputs (Level 2) ​ ​ ​ ​ Significant Other Observable Inputs (Level 3) Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash ​ $ 454,062 ​ $ 454,062 ​ $ — ​ $ — Money market funds ​ ​ 46,162 ​ ​ 46,162 ​ ​ — ​ ​ — Short-term investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commercial paper ​ ​ 4,952 ​ ​ — ​ ​ 4,952 ​ ​ — Corporate debt securities ​ ​ 53,212 ​ ​ — ​ ​ 53,212 ​ ​ — Government securities ​ ​ 158,817 ​ ​ 158,817 ​ ​ — ​ ​ — Long-term investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate debt securities ​ ​ 1,340 ​ ​ — ​ ​ 1,340 ​ ​ — Total assets ​ $ 718,545 ​ $ 659,041 ​ $ 59,504 ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2025 Description ​ ​ ​ ​ Total Carrying Value ​ ​ Quoted Prices in Active Market (Level 1) ​ ​ ​ ​ Significant Other Observable Inputs (Level 2) ​ ​ ​ ​ Significant Other Observable Inputs (Level 3) Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash ​ $ 13,038 ​ $ 13,038 ​ $ — ​ $ — Money market funds ​ ​ 97,603 ​ ​ 97,603 ​ ​ — ​ ​ — Short-term investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Commercial paper ​ ​ 5,959 ​ ​ — ​ ​ 5,959 ​ ​ — Corporate debt securities ​ ​ 44,299 ​ ​ — ​ ​ 44,299 ​ ​ — Government securities ​ ​ 182,293 ​ ​ 182,293 ​ ​ — ​ ​ — Long-term investments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Corporate debt securities ​ ​ 1,467 ​ ​ — ​ ​ 1,467 ​ ​ — Government securities ​ ​ 15,805 ​ ​ 15,805 ​ ​ — ​ ​ — Total assets ​ $ 360,464 ​ $ 308,739 ​ $ 51,725 ​ $ — ​ There have been no material impairments of the Company’s assets measured and carried at fair value as of March 31, 2026 and December 31, 2025. In addition, there have been no changes in valuation techniques as of March 31, 2026 and December 31, 2025. The fair value of Level 1 instruments classified as money market funds and government securities are valued using quoted market prices in active markets. The fair value of Level 2 instruments classified as short-term investments was determined using other than quoted prices in active markets, which are either directly or indirectly 14 Table of Contents observable as of the reporting date and fair value is determined using models or other valuation methodologies. During the three months ended March 31, 2026 and year ended December 31, 2025, there were no transfers between levels. The short and long-term investments are classified as available-for-sale securities. As of March 31, 2026, the remaining contractual maturities of the available-for-sale securities were 1 to 13 months , and the balance in the Company’s accumulated other comprehensive income was comprised of activity related to the Company’s available-for-sale securities. There were no realized gains or losses recognized on the sale or maturity of available-for-sale securities during the three months ended March 31, 2026 and 2025. As a result, the Company did not reclassify any amounts out of accumulated other comprehensive income for the same period. The Company had a limited number of available-for-sale securities in insignificant loss positions as of March 31, 2026, which the Company does not intend to sell and has concluded it will not be required to sell before recovery of amortized cost for the investment maturity. The following table summarizes the available-for-sale securities (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of March 31, 2026 ​ ​ Amortized Cost ​ ​ Gross Unrealized Gains ​ ​ Gross Unrealized Losses ​ ​ Fair Value Commercial paper $ 4,957 ​ $ — ​ $ ( 5 ) ​ $ 4,952 Corporate debt securities ​ 54,618 ​ ​ 5 ​ ​ ( 71 ) ​ ​ 54,552 Government securities ​ 158,900 ​ ​ 12 ​ ​ ( 95 ) ​ ​ 158,817 Total $ 218,475 ​ $ 17 ​ $ ( 171 ) ​ $ 218,321 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2025 ​ ​ Amortized Cost ​ ​ Gross Unrealized Gains ​ ​ Gross Unrealized Losses ​ ​ Fair Value Commercial paper $ 5,957 ​ $ 2 ​ $ — ​ $ 5,959 Corporate debt securities ​ 45,740 ​ ​ 28 ​ ​ ( 2 ) ​ ​ 45,766 Government securities ​ 197,939 ​ ​ 162 ​ ​ ( 3 ) ​ ​ 198,098 Total $ 249,636 ​ $ 192 ​ $ ( 5 ) ​ $ 249,823 ​ Certain short-term debt securities with original maturities of less than 90 days are included in cash and cash equivalents on the condensed consolidated balance sheets and are not included in the table above. 4. Other Non-Current Assets Other non-current assets consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2026 ​ ​ ​ December 31, 2025 Clinical trial deposits ​ $ 14,535 ​ $ 12,882 Deferred offering costs ​ ​ 439 ​ ​ 709 Other ​ ​ 86 ​ ​ 218 Total other assets ​ $ 15,060 ​ $ 13,809 ​ ​ 15 Table of Contents 5. Accrued Expenses Accrued expenses consisted of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2026 ​ ​ ​ December 31, 2025 External research, development and manufacturing expenses $ 41,779 ​ $ 38,855 Employee compensation and benefits ​ 5,618 ​ ​ 13,080 Professional and consultant fees ​ 2,729 ​ ​ 1,500 Income taxes payable ​ 118 ​ ​ 118 Other ​ 936 ​ ​ 870 Total accrued expenses $ 51,180 ​ $ 54,423 ​ ​ 6 . Long – Term Obligations Senior Secured Term Loan In March 2026, the Company entered into the Loan Agreement with the Collateral Agent, BPCR Limited Partnership and BioPharma Credit Investments V (Master) LP, which are funds managed by Pharmakon and the guarantors party thereto. The Loan Agreement provides for a five-year senior secured term loan, which matures on March 27, 2031 (“Term Loan Maturity Date”), for up to $ 250.0 million and consists of five tranches (collectively, the “Term Loans”). Two of the tranches are committed tranches: (i) Tranche A in an aggregate of $ 75.0 million, which was funded on the date the Loan Agreement was executed; and (ii) Tranche B in an aggregate of $ 50.0 million (and up to an additional $ 25.0 million that the Company may elect to draw), which is available until November 1, 2027, subject to the occurrence of certain approval conditions (the “Tranche B/C Approval Condition”). Three of the tranches may be drawn upon at the discretion of the Company: (i) Tranche C in an aggregate of $ 25.0 million (less any amounts elected to be (and actually) drawn under Tranche B in excess of $ 50.0 million), which is available until April 28, 2028; (ii) Tranche D in an aggregate of $ 50.0 million, which is available until October 30, 2028; and (iii) Tranche E in an aggregate of $ 50.0 million, which is available until April 30, 2029. Tranche C through E are subject to the occurrence of certain approval conditions and achievements of certain milestones in respect of certain net sales levels. The Loan Agreement bears interest at annual interest rate of 3-month secured overnight financing rate (“SOFR”) subject to a 3.25 % floor, plus 5.75 % payable quarterly in arrears. The Company may elect for 100 % of the interest for the first 24 months following the Tranche A Loan funding date to be paid-in-kind without an increase in the interest rate. ​ The Company is required to pay a funding fee equal to (i) 2.00 % of the funding amount of the Tranche A on the funding date of such loan, (ii) 2.00 % of $ 50,000,000 of the funding amount of the Tranche B on the funding date for such loan, (iii) 1.00 % of any amounts in excess of $ 50,000,000 of the funding amount for the Tranche B on the funding date for such loan, and (iv) 1.00 % of each of the funding amount of the Tranche C, Tranche D, and Tranche E on each respective funding date. The Company paid the funding fee of $ 1.5 million for Tranche A as of March 31, 2026. The Company’s obligations under the Loan Agreement are secured by substantially all of its assets, including its intellectual property, and are guaranteed by certain of its subsidiaries, each of which has pledged substantially all of their assets, including intellectual property, to secure such guarantee. The Company is also obligated to maintain a liquidity of not less than $ 50.0 million, immediately following the Tranche A closing date and until the satisfaction of the Tranche B/C Approval Condition. The Company determined that all of the embedded features identified in the Loan Agreement were either clearly or closely related to the debt host and did not require bifurcation as a derivative liability, or the fair value of the bifurcated features was immaterial to the Company’s condensed consolidated financial statements. 16 Table of Contents The Company received net proceeds of $ 73.0 million after deducting discounts and debt issuance costs as of March 31, 2026. No repayment of principal or payment of interest was made during the three months ended March 31, 2026. The following table reflects the Company’s senior secured term loan as of March 31, 2026 (in thousands): ​ ​ ​ ​ ​ ​ March 31, ​ ​ 2026 Outstanding principal balance ​ $ 75,000 Unamortized debt discounts and issuance costs ​ ​ ( 2,916 ) Carrying value ​ $ 72,084 ​ The carrying value of the outstanding liability, which bears a variable interest rate indexed to the 3-month SOFR, approximates fair value as it reprices when market interest rates change and represents a Level 2 measurement within the fair value hierarchy. ​ The Company incurred $ 2.9 million of debt discounts and issuance costs, which were capitalized and deferred when incurred and subsequently amortized over the term of the Loan Agreement. The effective interest rate of the Loan Agreement, including the amortization of the debt issuance cost was 11.06% for the three months ended March 31, 2026. Interest expense in relation to the Loan Agreement, including amortization of debt discounts and issuance costs amortization is as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ March 31, ​ ​ 2026 Cash interest expense ​ $ 334 Amortization of debt discounts and issuance costs ​ ​ 34 Total interest expense ​ $ 368 ​ Pursuant to the Loan Agreement, each tranche may be voluntarily prepaid at any time, in whole or subject to certain conditions, in part, prior to the Term Loan Maturity Date. Prepayments are subject to an amount equal to the sum of all interest that would have been accrued and payable from such date of prepayment through the second year anniversary of each respective tranche’s closing date on the amount of principal prepaid, using an interest rate in effect on such date. Pursuant to the Loan Agreement, each tranche has a required prepayment premium, in an amount equal to the product of the amount of any prepaid principal, multiplied by: (i) if prepayment occurs prior to the third year anniversary of each respective tranche’s closing date, 3 %; (ii) if prepayment occurs on or after the third year anniversary of each respective tranche's closing date but prior to the fourth year anniversary of each respective tranche's closing date, 2 %; and (iii) if prepayment occurs on or after the four year anniversary of each respective tranche’s closing date but prior to the Term Loan Maturity Date, 1 %. Pursuant to the Loan Agreement, each tranche has a required exit consideration fee, with respect to any prepayment, repayment or as a result of the acceleration of maturity, an amount equal to the product of the amount of principal prepaid or repaid, multiplied by 1 % to 2 % based on the specific tranche. The Loan Agreement requires repayment in full of all term loans in four equal payments commencing on September 30, 2028 to the extent the Tranche B/C Approval Condition is not met on or prior to June 30, 2028. The Loan Agreement contains customary prepayment fees and provisions, events of default, including a material adverse change to the Company, and representations, warranties and covenants, including financial covenants. The financial covenants include (i) at all times prior to the satisfaction of the Tranche B/C Approval Condition, a minimum liquidity requirement and (ii) subject to the outstanding aggregate principal amount of Term Loans advanced under the Loan Agreement being equal to or greater than $ 200.0 million, a minimum trailing twelve months consolidated net revenue covenant. As of March 31, 2026, the Company was in compliance with its debt covenants under the Loan Agreement. 17 Table of Contents Convertible Senior Notes In March 2026, the Company issued an aggregate principal amount of $ 200.0 million of 2.50 % convertible senior notes due 2032 (the “Convertible Notes”) with multiple individual investors (the “Holders”) in an underwritten public offering. The Convertible Notes were issued pursuant to, and are governed by, an indenture (the “Base Indenture”), dated March 31, 2026, between the Company and U.S. Bank Trust Company, National Association, as trustee (the “Trustee”), as supplemented by a first supplemental indenture (the “Supplemental Indenture,” and the Base Indenture, as supplemented by the Supplemental Indenture, the “Indenture”), dated as of March 31, 2026, between the Company and the Trustee. The Convertible Notes are general, unsecured, senior obligations of the Company. The Convertible Notes bear interest at 2.50 % per annum, to be paid semi-annually in arrears on April 1 and October 1 of each year, beginning October 1, 2026. In addition, special interest will accrue on the notes upon the occurrence of certain events relating to the Company’s failure to file certain reports with the SEC as provided in the Indenture. The Convertible Notes mature on April 1, 2032 (the “Convertible Notes Maturity Date”), unless earlier converted, redeemed or repurchased by the Company. The Holders may convert their notes into shares of common stock, at their option only in the following circumstances: (i) during any calendar quarter commencing after the calendar quarter ending on June 30, 2026; if the last reported sale price per share of the Company’s common stock exceeds 130 % of the conversion price for each of at least 20 trading days, whether or not consecutive, during the 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding quarter; (ii) during the five consecutive business days immediately after any 10 consecutive trading day period (the “Measurement Period”) in which the trading price per $1,000 principal amount of notes for each trading day of the Measurement Period was less than 98 % of the product of the last reported sales price per share of the common stock on such trading day and the conversion rate on such trading day; (iii) upon the occurrence of certain corporate events or distributions of the Company’s common stock; (iv) if the Company calls such notes for redemption; and (v) at any time from, and including January 1, 2032 until the close of business on the scheduled trading day immediately before the Convertible Notes Maturity Date. The Convertible Notes are redeemable, in whole or in part, subject to certain limitations, at the Company’s option any time and from time to time, on or after April 8, 2030 and on or before the twenty-sixth scheduled trading day immediately before the Convertible Notes Maturity Date, at a cash redemption price equal to the principal amount of Convertible Notes to be redeemed, plus accrued and unpaid interest, if any, to, but excluding, the redemption date only if the last reported sale price per share of the Company’s common stock exceeds 130 % of the conversion price on (i) each of at least 20 trading days, whether or not consecutive, during the 30 consecutive trading days ending on, and including, the trading day immediately before the date the Company sends the related redemption notice; and (ii) the trading day immediately before the date the Company sends such notice. However, the Company may not redeem less than all of the outstanding Convertible Notes unless at least $ 75.0 million aggregate principal amount of the Convertible Notes are outstanding and not called for redemption. In addition, calling any note for redemption will constitute a Make-Whole Fundamental Change, in which case the conversion rate applicable to the conversion of the note will be increased in certain circumstances if it is converted after it is called for redemption. The initial conversion rate is 37.7358 shares of common stock per $1,000 principal amount of notes, which represents an initial conversion price of approximately $ 26.50 per share, and is subject to adjustment as described in the indenture. However, if a fundamental change occurs, generally a change of control, merger, consolidation, asset sale or similar transaction, takes place prior to April 1, 2030, and it results in the Convertible Notes immediately being due, the noteholders may be entitled to an increase in the conversion rate (“Make-Whole Rate”). The amount of the increase is determined pursuant to the contractual make-whole table based on the effective date of the transaction. No increase in the conversion rate will be provided if the stock price used to determine the adjustment is greater than $ 160.00 per share or less than $ 20.00 per share of common stock and the conversion rate as increased to the Make-Whole provision will not exceed 50.00 shares of common stock per $1,000 principal amount of the Convertible Notes. The Company will settle conversions by paying or delivering cash, shares of its common stock or a combination of cash and shares of its common stock, at the Company’s election. If the Company elects to deliver cash or a combination of cash and shares of its common stock, then the consideration due upon conversion will be determined over a period consisting of 25 volume-weighted average price (“VWAP”) trading days. 18 Table of Contents The Convertible Notes were accounted for in accordance with ASC Subtopic 470-20, Debt with Conversion and Other Options (“ASC 470-20”) and ASC Subtopic 815-40, Contracts in Entity’s Own Equity (“ASC 815-40”). Under ASC 81-40, to qualify for equity classification (or non-bifurcation, if embedded), the instrument (or embedded feature) must be both (i) indexed to the issuer’s stock and (ii) meet the requirements of the equity classification guidance. Based upon our analysis, it was determined that the Convertible Notes do contain embedded features indexed to our common stock, but do not meet the requirements for bifurcation, and therefore do not need to be separately accounted for as an equity component. Since the embedded conversion feature meets the equity scope exception from derivative accounting, and, also since the embedded conversion option does not need to be separately accounted for as an equity component under ASC 470-20, the proceeds from the issuance of the Convertible Notes were recorded as a liability. The Company incurred issuance costs related to the Convertible Notes of $ 6.4 million, which was recorded as debt issuance costs and were included as a reduction to the Convertible Notes on the unaudited condensed consolidated balance sheet. The debt issuance costs are amortized to interest expense using the effective interest rate method over the term of the Convertible Notes, resulting in an effective interest rate of 3.07 % as of March 31, 2026. The outstanding balance of the Convertible Notes consisted of the following as of March 31, 2026 (in thousands): ​ ​ ​ ​ ​ ​ March 31, ​ ​ 2026 Outstanding principal balance ​ $ 200,000 Unamortized commissions and offering costs ​ ​ ( 6,369 ) Carrying value ​ $ 193,631 ​ The carrying value of the convertible notes approximates the fair value and was determined based on the actual last traded price of the underlying shares of common stock and represents a Level 1 measurement within the fair value hierarchy. ​ For the three months ended March 31, 2026, no interest expense was recognized. The indenture contains customary events of default and covenants, including (i) certain payment defaults on the notes (ii) a default by the Company in its other obligations or agreements under the Indenture or the Notes if such default is not cured or waived within 60 days after notice is given in accordance with the Indenture; (iii) certain defaults by the Company or any of its significant subsidiaries with respect to indebtedness for borrowed money of at least $ 30,000,000 ; (iv) certain final judgments being rendered against the Company or any of its significant subsidiaries for the payment of at least $ 30,000,000 , where such judgments are not discharged or stayed within 60 days after the date on which the right to appeal has expired or on which all rights to appeal have been extinguished; and (v) certain events of bankruptcy, insolvency and reorganization involving the Company or any of its significant subsidiaries. As of March 31, 2026, the Company was in compliance with its covenants under the Indenture. 7 . License and Collaboration Revenue License and Collaboration Agreement with Bristol-Myers Squibb In August 2023, the Company entered into a license and collaboration agreement (the “BMS Agreement”) with Bristol-Myers Squibb (“BMS”), under which the Company granted BMS an exclusive license to (i) develop, manufacture (subject to the Company’s rights to be the exclusive manufacturer for BMS for a certain period of time), commercialize or otherwise exploit obexelimab and any biological product (irrespective of presentations, formulations or dosages) containing obexelimab but not any of the Company’s other proprietary active ingredient (the “BMS Product”) into Japan, South Korea, Taiwan, Singapore, Hong Kong and Australia (collectively, the “BMS Territory”) and (ii) develop and manufacture obexelimab and the BMS Product outside the BMS Territory provided that obexelimab and the BMS Product are solely used in the BMS Territory. Pursuant to the BMS Agreement, BMS paid the Company a one-time non-refundable upfront cash payment of $ 50.0 million. The Company is entitled to receive further separate development, regulatory milestone payments from BMS of 19 Table of Contents up to approximately $ 79.5 million. The Company is also entitled to receive one-time sales milestone payments up to $ 70.0 million upon BMS achieving certain net sales milestones in a given year in the BMS Territory. The Company is also eligible to receive tiered high single-digit to low double-digit royalties on net sales in the BMS Territory, subject to specified reductions. The Company will continue to perform and oversee the ongoing Phase 3 trial of obexelimab in the immunoglobulin G4-related disease (“IgG4-RD”) indication and BMS will participate in the performance of the study. BMS will fund their pro rata share of the total global study costs up to a specified percentage of the patients enrolled in the study from the BMS Territory. Should the percentage of patients from the BMS Territory fall below the specified percentage, BMS’s funding would proportionately decrease. The global development activities under the agreement do not represent a transaction with a customer and reimbursement payments received by the Company for global development activities are accounted for as a reduction of the related research and development expenses. As of March 31, 2026 and 2025, the Company recorded $ 1.1 million and $ 1.7 million, respectively, as a receivable included in prepaid expenses and other current assets, as a reduction to research and development expense for global development costs to be reimbursed by BMS. The Company did no t recognize revenue related to the BMS Agreement during the three months ended March 31, 2026 and 2025. License Agreement with Zai Lab (Hong Kong) Limited In January 2025, the Company entered into a license agreement (the “Zai License Agreement”), with Zai, under which the Company granted Zai an exclusive sublicense to develop, manufacture and commercialize ZB001 and related programs in greater China. Under the Zai License Agreement, Zai will be responsible for conducting all research and development activities, manufacturing, regulatory and commercialization in greater China. ​ Pursuant to the Zai License Agreement, Zai paid the Company a one-time non-refundable upfront cash payment of $ 10.0 million. The Company is entitled to receive further development, regulatory and sales milestones from Zai up to approximately $ 117.0 million if certain milestones are successfully achieved, with passthrough obligations of $ 21.0 million due to Viridian Therapeutics, Inc. (“Viridian”). The Company is also eligible to receive tiered royalties on net sales in greater China, ranging from the low to mid-single digits, net of passthrough obligations due to Viridian. The Company evaluated the terms of the Zai License Agreement and determined it is within the scope of ASC 606. The Company identified the following promises in the Zai License Agreement that were evaluated under the scope of ASC 606: (i) transfer of the license for ZB001, (ii) licensed technology transfer (iii) licensed material transfer and (iv) continued licensed technology transfer. The Company also evaluated whether certain options outlined in the Zai License Agreement represented material rights that would give rise to a performance obligation and concluded that none of the options conveyed a material right to Zai or were immaterial and, therefore, are not considered separate performance obligations within the Zai License Agreement. The Company assessed the above promises and determined that the license for ZB001 and technology transfer are a combined distinct performance obligation within the scope of ASC 606. The licensed material transfer and the continued technology know-how transfer services are promises that are separately identifiable and considered to be distinct. The Company determined the transfer of the licensed materials and continued technology know-how transfer services were immaterial in the context of the contract based on the minimal resources required to fulfill the obligations and the estimated standalone selling price of the licensed materials. Therefore, the sublicense and technology transfer represent a single performance obligation at contract inception. The Company concluded that the transaction price of $ 10.0 million was allocated to the combined performance obligation, which was recognized upon delivery prior to March 31, 2025. The Company used the most likely amount method to estimate variable consideration and estimated that the most likely amount for each potential developmental and regulatory variable consideration milestone payment under the agreement is zero, as achievement of those milestones is uncertain and susceptible to factors outside the Company’s control. Accordingly, all such milestone payments were excluded from the transaction price. Management will reevaluate the transaction price at the end of each reporting period and as uncertain events are resolved or other changes in circumstances occur, will adjust the transaction price as necessary. Sales and 20 Table of Contents royalty based milestones structured on the level of sales, were also excluded from the transaction price, as the license is deemed to be the predominant item to which the transaction price relates. The Company will recognize such milestone and royalty revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). ​ As of March 31, 2026 and 2025, no milestones were achieved or deemed probable of achievement. 8 . License Agreements License Agreements with Xencor, Inc. 2020 Xencor Agreement In September 2020, the Company entered into a license agreement (the “2020 Xencor Agreement”) with Xencor, Inc. (“Xencor”), under which the Company is required to pay Xencor tiered royalties on annual net sales of successfully commercialized products, including ZB002 and ZB004. The royalty percentage rates vary by geographic areas as defined in the 2020 Xencor Agreement and range from the mid-single digits to mid-teens. The Company is also obligated to reimburse Xencor for third-party costs incurred for certain patent filings, prosecution and maintenance as further specified in the 2020 Xencor Agreement. During the three months ended March 31, 2026 and 2025, the Company did no t incur any such reimbursable costs. 2021 Xencor Agreement In May 2021, the Company entered into a license agreement with Xencor (the “2021 Xencor Agreement”), under which the Company obtained an exclusive, royalty-bearing, sublicensable worldwide license to research, develop, manufacture, market and sell obexelimab. The Company is obligated to make regulatory milestone payments up to $ 75.0 million, including $ 10.0 million for FDA marketing authorization submission and $ 20.0 million for marketing approval, and one-time sales milestone payments up to $ 385.0 million upon achieving milestone events of net sales in a given calendar year in the territory equal to certain threshold amounts. In addition, the Company is required to pay Xencor tiered royalties on annual net sales of successfully commercialized products utilizing obexelimab, with the royalty percentages varying based on regions and ranging from the mid-single digits to the mid-teens. For the three months ended March 31, 2026 and 2025, the Company did not record any reimbursable patent-related costs. License Agreement with Viridian Therapeutics, Inc. In October 2020, the Company entered into a license agreement with Viridian (the “Viridian Agreement”) to obtain an exclusive, royalty-bearing, sublicensable license to research, develop, manufacture, market and sell certain antibody product candidates based on Viridian’s proprietary technology. The Company’s license rights are limited to non-oncology indications and are limited to China, Hong Kong, Macau and Taiwan (“Zenas Territories”). The Viridian Agreement, as amended, obligates the Company to make payments to Viridian, totaling $ 21.0 million, based on achievement of certain specified development and sales milestones, and royalties on net sales. ​ In January 2025, the Company entered the Zai License Agreement under which the Company granted Zai an exclusive sublicense to develop, manufacture and commercialize ZB001 and related programs in greater China. In connection with the Zai License Agreement, the Company assigned the Viridian Supply Agreement to Zai. For additional information on the Zai License Agreement, please see License Agreement with Zai Lab (Hong Kong) Limited in Note 7 – License and Collaboration Revenue to these unaudited condensed consolidated financial statements. ​ During the three months ended March 31, 2026 and 2025, the Company recognized no expense related to Viridian contract manufacturing organization (“CMO”) costs. Viridian has agreed to reimburse the Company for certain services the Company performs on Viridian’s behalf, with reimbursements being recorded as a reduction in research and development expenses. During the three months ended March 31, 2026, the Company did not incur any reimbursable expenses. During 21 Table of Contents the three months ended March 31, 2025, the Company recorded $ 0.1 million in reimbursable expenses. Additionally, during the three months ended March 31, 2026 and 2025, the Company did not achieve any milestones. License Agreement with InnoCare Pharma Inc. In October 2025, the Company entered into a License Agreement (the “InnoCare License Agreement”) with InnoCare Pharma Inc. (“InnoCare”). Under the InnoCare License Agreement, InnoCare granted the Company exclusive rights to develop, manufacture, and commercialize: i) orelabrutinib, in the multiple sclerosis (“MS”) field worldwide, and in all non-oncology indications outside greater China and Brunei, Burma, Cambodia, Timor-Leste, Indonesia, Laos, Malaysia, Philippines, Singapore, Thailand and Vietnam (“Southeast Asia”), ii) ZB021 (an IL-17AA/AF inhibitor) in all fields of use worldwide, excluding greater China and Southeast Asia and iii) ZB022 (a TYK2 inhibitor) in all fields of use worldwide. The Company also obtained certain non-exclusive rights to perform development and manufacturing activities in greater China and Southeast Asia to support each program in its respective licensed territories. Pursuant to the InnoCare License Agreement, the Company made one-time non-refundable upfront cash payments totaling $ 35.0 million and issued 5,000,000 shares of common stock to InnoCare (“InnoCare Shares”) in exchange for these rights. The Company is also required to make an additional one-time non-refundable cash payment of $ 25.0 million and issue an additional 2,000,000 shares of common stock to InnoCare upon the initiation of Zenas’ Phase 3 clinical trial for orelabrutinib in any indication other than primary progressive MS, or by March 31, 2026, upon the occurrence of certain specified events, whichever comes first (the “Near-term Milestone”). In addition, the Company has agreed to make one-time, potential near-term milestone payments of $ 20.0 million each, upon the achievement of certain regulatory milestones for ZB021 and ZB022 (the “Regulatory Milestones”). The Company is further obligated to pay future regulatory and commercial milestones of up to $ 723.0 million related to orelabrutinib, and future development, regulatory, and commercial milestones of up to $ 656.0 million, inclusive of the two $ 20.0 million Regulatory Milestones specified above, for each preclinical compound if certain milestones are successfully achieved. In addition, the Company is obligated to pay royalties on net sales at rates ranging from high-single digits to high-teens for orelabrutinib, and mid-single digits to mid-teens for the preclinical compounds. Under the InnoCare License Agreement, the Company was obligated to reimburse InnoCare for certain clinical trial startup costs and Investigational New Drug (“IND”) enabling activities which were incurred prior to and after the effective date of the agreement. During the three months ended March 31, 2026, the Company incurred $ 1.2 million of expense, of which $ 0.8 million was paid to InnoCare related to the acquired programs. 9. Royalty Obligation In September 2025, the Company and Royalty Pharma entered into the Royalty Purchase Agreement. Pursuant to the Royalty Purchase Agreement, the Company received a $ 75.0 million upfront payment in exchange for which Royalty Pharma purchased the right to receive, for each calendar quarter, (i) 5.5 % of net sales of obexelimab products sold by the Company and its affiliates worldwide, (ii) 5.5 % of net sales of obexelimab products sold by licensees of Zenas and its affiliates in the U.S., the United Kingdom and the European Union, (iii) 25 % of royalty income payable to Zenas or any of its affiliates on sales of obexelimab products in countries other than the U.S., the United Kingdom, and in the European Union by its licensees pursuant to out-licenses less royalty payments payable by Zenas to Xencor Inc. and (iv) 25 % of non-royalty income attributable to obexelimab products payable to Zenas or any of its affiliates by its licensees (other than certain milestone payments payable by Bristol-Myers Squibb) pursuant to out-licenses and allocated to countries other than the U.S., the United Kingdom and in the European Union. The Royalty Purchase Agreement provides for an additional $ 225.0 million of payments to be paid to the Company by Royalty Pharma upon the occurrence of certain triggering events which includes (1) $ 75.0 million payable upon the achievement of certain milestones with respect to Zenas’ INDIGO Phase 3 Trial, noting the Company is not currently eligible for this milestone, (2) $ 75.0 million payable following receipt of marketing approval for obexelimab from the U.S. Food and Drug Administration (the “FDA”) for the treatment of IgG4-Related Disease on or before a specified date and (3) $ 75.0 million payable following receipt of marketing approval for obexelimab from the FDA for the treatment of systemic lupus erythematosus on or before a specified date. 22 Table of Contents ​ The Company accounted for the Royalty Purchase Agreement as a debt financing, primarily because it has significant continuing involvement in generating the future revenue on which the royalty payments are based. The $ 75.0 million upfront payment received was recorded as a liability, net of issuance costs of $ 3.7 million. The effective interest rate was determined based on the Company’s projections of future payments to Royalty Pharma. The Company will evaluate the estimated timing and amount of future royalty payments for each reporting period and will revise the effective interest rate prospectively if those estimates change materially. ​ The fair value of the liability approximates the carrying value and was determined based on the current estimate of the timing and amount of expected future royalty payments expected to be paid over the estimated term of the Royalty Purchase Agreement, which are subject to significant estimation uncertainty and are based on various assumptions made by the Company. These assumption inputs are determined to be Level 3 inputs in the fair value hierarchy as they involve significant unobservable inputs and judgment. ​ The following table shows the activity within the liability account of the arrangement (in thousands): ​ ​ ​ ​ ​ ​ ​ Period from inception to March 31, 2026 ​ ​ ​ ​ Amount Proceeds from royalty obligation ​ $ 75,000 Issuance costs ​ ​ ( 3,691 ) Interest expense related to royalty obligation ​ ​ 13,591 Royalty obligation as of March 31, 2026 ​ $ 84,900 Effective interest rate ​ ​ 32.3 % ​ ​ ​ ​ ​ 10. Common Stock In September 2024, upon the completion of the IPO, the Company restated its certificate of incorporation, pursuant to which the Company is authorized to issue 175,000,000 shares of common stock $ 0.0001 par value. The voting, dividend and liquidation rights of the holders of the Company’s common stock were subject to and qualified by the rights, powers and preference of the holders of any preferred stock then issued and outstanding. In October 2025, the Company entered into a sales agreement with Jefferies under which the Company could, from time to time, issue and sell shares of its common stock having aggregate sales proceeds of up to $ 200.0 million, in a series of one or more at-the-market equity offerings (“2025 ATM Program”). The Company’s common stock will be sold at prevailing market prices at the time of the sale; and as a result, prices may vary. For the three months ended March 31, 2026, the Company sold 2,827,723 shares of common stock under the 2025 ATM Program, with proceeds of $ 71.5 million, net of commissions. As of March 31, 2026, $ 96.8 million remained available under the 2025 ATM Program. In October 2025, the Company entered into a securities purchase agreement for a private placement in public entity (“PIPE”) (the “PIPE Purchase Agreement”), pursuant to which the Company sold (i) 6,262,112 shares of common stock to certain institutional and accredited investors at a price of $ 19.00 per share and (ii) 48,918 shares of common stock to certain directors and officers of the Company at a price of $ 20.85 per share. The net proceeds from the PIPE offering, after deducting placement agent fees and other offering costs were $ 111.8 million. In March 2026, the Company completed a follow-on equity offering under which it issued and sold 5,000,000 shares of common stock at a public offering price of $ 20.00 per share. Total proceeds for the follow-on offering were approximately $ 100.0 million, before deducting commissions and estimated offering costs of $ 6.4 million payable by the Company. The holders of the common stock are entitled to one vote for each share of common stock held at all meetings of stockholders (and written actions in lieu of meetings), and there are no cumulative voting rights. 23 Table of Contents The Company has reserved the following shares of common stock for the potential conversion of outstanding stock options, restricted stock units (“RSUs”) and employee stock purchase plan: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2026 ​ ​ ​ December 31, 2025 Options to purchase common stock ​ 10,988,118 ​ 10,675,615 Remaining shares reserved for future issuance ​ 3,749,943 ​ 431,863 RSUs ​ 667,600 ​ 599,675 Employee stock purchase plan ​ 1,273,608 ​ 773,122 Common stock reserved under convertible senior notes 1 ​ 11,500,000 ​ — Total ​ 28,179,269 ​ 12,480,275 ​ 1 Represents a maximum conversion rate of 50.0000 shares of common stock per $1,000 principal amount of notes. ​ 11. Stock-Based Compensation 2020 Plan In August 2020, the Company’s sole director adopted the 2020 Equity Incentive Plan (the “2020 Plan”). Upon effectiveness of the 2024 Plan (as defined below), the Company ceased granting additional awards under the 2020 Plan and the remaining available shares for future grants were transferred to the 2024 Plan. The 2020 Plan allowed the Company to grant stock options, restricted stock awards, restricted stock units (“RSUs”) and other stock-based awards to employees, officers, directors and consultants of the Company and its subsidiaries. As of March 31, 2026, 3,203,773 shares of stock options were issued and outstanding under the 2020 Plan. 2024 Plan In September 2024, the Company’s board of directors (the “Board”) adopted the 2024 Equity Incentive Plan (the “2024 Plan”), which became effective immediately prior to the effectiveness of the registration statement for the Company’s IPO. The 2024 Plan provides for the award of incentive stock options, nonstatutory stock options, stock appreciation rights, restricted stock awards, unrestricted stock, restricted stock units and other stock-based awards. The number of shares reserved and available for issuance under the 2024 Plan will automatically increase each January 1, beginning on January 1, 2025 through January 1, 2034, by the number of shares equal to the lesser of (i) five percent of the aggregate number of shares of common stock outstanding as of such date, and (ii) a number of shares as may be determined by the Board on or prior to such date. On January 1, 2026, the number of shares of common stock available for issuance under the Company’s 2024 Plan increased to 3,156,138 . As of March 31, 2026, 3,208,418 shares of common stock were available for issuance under the 2024 Plan. 2026 Inducement Plan In December 2025, the Company’s Board adopted the 2026 Inducement Plan (the “2026 Inducement Plan”), which became effective December 10, 2025. The 2026 Inducement Plan provides for awards of non-qualified stock options and other awards under the 2026 Inducement Plan to persons not previously an employee or director of the Company, or following a bona fide period of non-employment, as an inducement material to such persons entering the employment of the Company. The grants constitute “employment inducement grants” in accordance with Rule 5635(c)(4) of the Nasdaq Listing Rules and are issued outside of the 2024 Plan. The inducement grants include non-statutory options to purchase shares of the Company’s common stock and RSUs. The inducement grants have terms and conditions consistent with those set forth in the 2024 Plan and vest under the same respective vesting schedules as stock options and RSUs granted under the 2024 Plan. The Company initially reserved 1,000,000 shares of common stock for the issuance of awards under the 2026 Inducement Plan. As of March 31, 2026, 541,525 shares of common stock were available for issuance under the 2026 Inducement Plan. 24 Table of Contents Stock Options The Company has granted stock-based awards with either service or performance based vesting conditions. Compensation expense related to awards to employees and directors with service based vesting conditions is recognized on a straight-line basis based on the grant date fair value over the associated service period of the award, which is generally the vesting term. Compensation expense related to awards to employees with performance based vesting conditions is recognized based on the grant date fair value once the achievement of the performance condition is probable. From time to time, the Company grants equity awards to newly hired employees as an inducement to enter into employment with the Company. The grants constitute "employment inducement grants" in accordance with Rule 5635(c)(4) of the Nasdaq Listing Rules and are issued outside of the 2024 and 2026 Plans (the “Individual Inducement Grants”). The Individual Inducement Grants include non-statutory stock options to purchase shares of the Company's common stock and RSUs. The Individual Inducement Grants are granted under individual inducement agreements and have terms and conditions consistent with those set forth under the 2024 Plan and vest under the same respective vesting schedules as stock option awards granted under the 2024 Plan. The Individual Inducement Grants are included in the stock option award tables below. As of March 31, 2026, the Company granted 1,062,000 non-statutory stock options as Individual Inducement Grants, which were awarded during the year ended December 31, 2025. The Company did not grant any stock options or RSUs as Individual Inducement Grants during the three months ended March 31, 2026. ​ The following table presents a summary of the Company’s stock option activity and related information: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Number of Shares ​ ​ ​ Weighted - Average Exercise Price ​ ​ ​ Weighted-Average Remaining Contractual Term (in years) ​ ​ ​ Aggregate Intrinsic Value (in thousands) Outstanding - December 31, 2025 ​ 10,675,615 ​ $ 13.46 ​ 8.60 ​ $ 243,979 Granted ​ 371,400 ​ $ 22.68 ​ ​ ​ ​ ​ Exercised ​ ( 25,767 ) ​ $ 14.24 ​ ​ ​ $ 226 Forfeited or cancelled ​ ( 33,130 ) ​ $ 13.24 ​ ​ ​ ​ ​ Outstanding - March 31, 2026 ​ 10,988,118 ​ $ 13.77 ​ 8.40 ​ $ 68,892 Options vested and exercisable as of March 31, 2026 ​ 3,795,031 ​ $ 12.33 ​ 7.79 ​ $ 27,393 Options vested and expected to vest as of March 31, 2026 ​ 10,988,118 ​ $ 13.77 ​ 8.40 ​ $ 68,892 ​ The aggregate intrinsic value of the stock options outstanding is calculated as the difference between the exercise price of the options and the fair value of the Company’s common stock for those stock options that had an exercise price lower than the fair value of the Company’s common stock as of the measurement date of March 31, 2026. Restricted Stock Units The Company has granted RSUs that are subject to time-based vesting conditions, that vest equally over four years , assuming continued employment. RSUs with time-based vesting conditions are valued on the grant date using the grant date market value price of the underlying shares of the Company’s common stock. The Company did not grant any RSU’s in 2024. The following table summarizes the Company’s RSU activity: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Number of Shares ​ ​ ​ ​ Weighted - Average Grant Date Fair Value Unvested as of December 31, 2025 ​ 599,675 ​ $ 14.23 Granted ​ 87,075 ​ $ 25.41 Vested ​ — ​ $ — Forfeited ​ ( 19,150 ) ​ $ 12.10 Unvested as of March 31, 2026 ​ 667,600 ​ $ 15.75 ​ 25 Table of Contents No RSUs vested during the three months ended March 31, 2026. As of March 31, 2026, unrecognized stock-based compensation expense was $ 80.3 million, which is expected to be recognized over a weighted-average period of 2.7 years. The Company recognized stock-based compensation expense related to the issuance of equity awards to employees and directors in the unaudited condensed consolidated statement of operations as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ ​ ​ 2026 ​ ​ 2025 Research and development ​ $ 3,096 ​ $ 1,581 General and administrative ​ ​ 6,099 ​ ​ 3,805 Total stock-based compensation expense ​ $ 9,195 ​ $ 5,386 ​ Employee Stock Purchase Plan In September 2024, the Board adopted the 2024 Employee Stock Purchase Plan (the “ESPP”), which became effective immediately prior to the effectiveness of the registration statement for the Company’s IPO. The number of shares of common stock available under the ESPP will automatically increase on January 1st of each year, beginning on January 1, 2025 through January 1, 2034, by the number of shares equal to the lesser of (i) one percent of the aggregate number of shares of common stock outstanding as of such date, and (ii) a number of shares as may be determined by the Board on or prior to such date, up to a maximum of 1,000,000 shares in the aggregate per year. On January 1, 2026, the number of shares of common stock authorized for issuance under the ESPP increased to 1,317,977 . As of March 31, 2026, 1,273,608 shares were available for future issuance under the ESPP. There were 44,369 shares issued under the ESPP during the three months ended March 31, 2026. ​ ​ 12. Net Loss Per Share The Company’s potentially dilutive securities, which include stock options, RSUs, convertible senior notes, and the 2,000,000 shares of common stock to be issued to InnoCare, have been excluded from the computation of diluted net loss per share as the effect would be to reduce the net loss per share. Therefore, the weighted-average number of common shares outstanding used to calculate both basic and diluted net loss per share is the same. The Company excluded the following shares from the computation of diluted net loss as of March 31, 2026 and 2025 because including them would have had an anti-dilutive effect: ​ ​ ​ ​ ​ ​ ​ March 31, ​ ​ 2026 ​ 2025 Options to purchase common stock ​ 10,988,118 ​ 8,670,569 Unvested RSUs ​ 667,600 ​ — Common stock to be issued to InnoCare ​ 2,000,000 ​ — Shares of common stock underlying convertible senior notes outstanding 1 ​ 7,547,160 ​ — ​ 1 Represents conversion rate, as of March 31, 2026, of 37.7358 shares of common stock per $1,000 principal amount of notes. ​ 13. Commitments and Contingencies Other Contracts The Company has entered into agreements with certain vendors for the provision of services that the Company is not contractually able to terminate for convenience and thereby avoid any and all future obligations to the vendors. Under such agreements, the Company is contractually obligated to make certain minimum payments to the vendors, with the exact amounts in the event of termination to be based on the timing of the termination and the exact terms of the agreement. As of March 31, 2026, our total non-cancellable clinical manufacturing contract payment obligations are $ 19.7 million of which the full obligation is payable within 12 months. 26 Table of Contents Indemnification Agreements In the ordinary course of business, the Company may provide indemnification of varying scope and terms to vendors, lessors, 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. In addition, the Company has entered into indemnification agreements with members of its board of directors and certain officers that will require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or services as directors. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is, in many cases, unlimited. To date, the Company has not incurred any material costs as a result of such indemnifications. The Company is not currently aware of any indemnification claims and had not accrued any liabilities related to such obligations in its unaudited condensed consolidated financial statements as of March 31, 2026. Litigation and Other Proceedings The Company may periodically become subject to legal proceedings and claims arising in the ordinary course of business. As of March 31, 2026, the Company was not subject to any material legal proceedings which would reasonably be expected to have a material adverse effect on the Company’s financial results. ​ 14. Related Party Transactions Xencor, Inc. The Company has obtained exclusive, worldwide licenses from Xencor to research, develop, manufacture, market and sell three antibody product candidates pursuant to two license agreements. The Company has concluded that Xencor is a related party, due to the issuance of convertible preferred stock in December 2020 and April 2023. In connection with the completion of the IPO, in September 2024, all outstanding shares of preferred stock converted into shares of common stock. As of March 31, 2026, Xencor held less than 10 % of the shares of the Company’s outstanding common stock. Viridian Therapeutics, Inc. The Company has obtained a license from Viridian to research, develop, manufacture, market and sell an antibody product candidate in China. The Company has concluded that Viridian is a related party because although Fairmount Funds Management LLC owns less than 10 % of shares of the Company’s outstanding common stock, they have a seat on the Board and are also a 10% or greater stockholder of Viridian and have two seats on Viridian’s board of directors. As initial consideration for this license, the Company issued 38,707 shares of its common stock to Viridian during the year ended December 31, 2020. As of March 31, 2026, Viridian held 0.1 % of the shares of the Company’s outstanding common stock. Zai Lab (Hong Kong) Limited The Company has granted a sublicense to Zai to develop, manufacture and commercialize ZB001 and related programs in greater China. The Company has concluded that Zai is a related party, as the Company’s CEO and Chairman is a member of Zai’s board of directors. InnoCare Pharma Inc. The Company has obtained the exclusive rights from InnoCare to develop, manufacture and commercialize three product candidates pursuant to the InnoCare License Agreement. Though InnoCare does not hold any direct controlling interest in the Company, the Company has concluded that InnoCare is a related party, due to the 5,000,000 shares of common stock issued and the 2,000,000 shares of common stock to be issued pursuant to the InnoCare License Agreement. As of March 31, 2026, InnoCare held less than 10 % of the shares of the Company’s outstanding common stock. For additional information on these arrangements, please see Note 7, License and Collaboration Revenue and Note 8, License Agreements, to these unaudited condensed consolidated financial statements. 27 Table of Contents 15. Segment Information The Company manages its operations on a consolidated basis as a single reportable segment focused on the research and development of immunology-based therapies. The accounting policies of the single reportable segment are identical to those described in Note 1, Nature of Business , to these unaudited condensed consolidated financial statements. When evaluating the Company’s financial performance, the Company’s chief operating decision-maker (the “CODM”), its Chief Executive Officer regularly reviews consolidated net loss, total expense and direct expenses by program and compared to budget. The CODM allocates resources based on the Company’s available cash resources, and forecasted expenditures on a consolidated basis, as well as an assessment of the probability of success of its research and development activities on a program basis. Segment asset information regularly provided to the CODM is consistent with that reported on the consolidated balance sheets with particular emphasis on the Company’s available liquidity, including its cash, cash equivalents and investment balances. Revenue is primarily attributed to individual countries based on the entity owning the license. During the three months ended March 31, 2026, the Company did no t recognize revenue and for the three months ended March 31, 2025, $ 10.0 million was recognized as revenue which was attributed to Zenas HK. The following table presents certain financial data for the Company’s reportable segment for the three months ended March 31, 2026 and 2025 (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ For the three months ended March 31, ​ ​ ​ 2026 ​ ​ 2025 Revenue ​ $ — ​ $ 10,000 Less: ​ ​ ​ ​ ​ ​ Direct research and development expenses: 1 ​ ​ ​ ​ ​ ​ Obexelimab ​ ​ 31,760 ​ ​ 23,491 Orelabrutinib ​ ​ 10,101 ​ ​ — Other programs (ZB002, ZB004, ZB014, ZB021 & ZB022) ​ ​ 568 ​ ​ 203 Partnered regional programs (ZB001 & ZB005) ​ ​ — ​ ​ 99 Unallocated research and development 2 ​ ​ 14,914 ​ ​ 9,541 General and administrative 3 ​ ​ 10,812 ​ ​ 8,610 Stock-based compensation ​ ​ 9,195 ​ ​ 5,386 Other segment items 4 ​ ​ 3,637 ​ ​ ( 3,757 ) Segment net loss ​ $ ( 80,987 ) ​ $ ( 33,573 ) ​ 1 Direct research and development expenses primarily consist of direct costs incurred to specific program research and development activities, including costs to conduct clinical trials and to manufacture clinical drug supply. 2 Unallocated research and development expenses primarily consist of indirect costs incurred in support of overall research and development activities and non-specific programs, including activities that benefit multiple programs, such as personnel costs for employees involved in research and development activities, excluding stock-based compensation, as well as contract services not allocated to specific programs. 3 General and administrative expenses primarily consist of professional fees, depreciation expense, facilities expenses as well as all other personnel costs, excluding stock-based compensation. 4 Other segment items consist of other (income) expense, net, and income tax (benefit) provision. Other (income) expense, net consists of interest income, interest expense related to the royalty obligation and the senior secured term loan and convertible senior note as well as realized and unrealized gains and losses on foreign currency transactions . ​ 16. Subsequent Events Convertible Senior Notes and Follow-on Public Equity Offering In April 2026, the underwriters of the Company’s offering of the Convertible Notes and follow-on public equity offering exercised their overallotment option in full, pursuant to which the Company received aggregate principal amount of $ 30.0 million, before deducting commission costs of $ 0.9 million for the Convertible Notes and issued 750,000 shares of common stock, at $ 20.00 per share, for gross proceeds of $ 15.0 million before deducting commission costs of $ 0.9 million for the follow-on public equity offering. 28 Table of Contents ZB021 Milestone On May 13, 2026, the Company announced the achievement of the Regulatory Milestone for ZB021 under the InnoCare License Agreement and is required to pay InnoCare $ 20.0 million related to this event. ​