Seralutinib

Portfolio receipts : • Achieved over $50 million of cash receipts, including $33.6 million in royalties and $16.9 million milestones, in full year 2025 • Total receipts increased 9% with royalties up 68% versus full year 2024 Business development : Added 22 assets to portfolio, including five programs in Phase 2 or Phase 3 development Stock buyback program : Repurchased and retired 648,048 shares for an aggregate of $16.0 million Company acquisitions : Completed seven acquisitions, accumulating $11.7 million of non-dilutive capital 1 , economic interests of approximately 25% in up to $1.1 billion of milestones and low to mid-single digit royalties from eight partnered programs Key 2026 pipeline events : • Phase 2b data from volixibat in PSC in Q2 and Phase 3 data from ersodetug in tumor HI in 2H • Potential for EMA decisions on OJEMDA™ and MIPLYFFA™ marketing authorization applications • Regulatory updates related to ersodetug in congenital HI and seralutinib in PAH Webcast at 8:00 am Eastern Time today EMERYVILLE, Calif., March 18, 2026 (GLOBE NEWSWIRE) -- XOMA Royalty Corporation (NASDAQ: XOMA), the biotech royalty aggregator, reported its 2025 fourth quarter and full year financial results and highlighted recent actions that have the potential to deliver additional shareholder value. “We continue to search for innovative ways to drive enhanced optionality in the XOMA portfolio, with the addition of 22 assets and two platform technologies over the past year,” stated Owen Hughes, Chief Executive Officer of XOMA Royalty. “With multiple commercial assets delivering growing royalty receipts, we achieved positive cash flow from operations and were able to return $16 million of capital through a share buyback in 2025. Looking ahead, with 14 programs in registrational studies, we anticipate a number of catalysts over the ensuing years, including several regulatory updates and late-stage clinical readouts in 2026, which, if positive, will further diversify our commercial royalty streams and drive growing free cash flow in 2027 and beyond.” Portfolio Updates Day One OJEMDA New Drug Application filing in Japan triggered $2 million milestone in 4Q25 OJEMDA FY 2026 revenue guidance of $225 – $250 million 2 In February 2026, the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) issued a positive opinion recommending the conditional marketing authorization of OJEMDA 3 In March 2026, Day One and Servier announced that they have entered into a definitive agreement for Servier to acquire Day One for $21.50 per share in cash, representing a total equity value of approximately $2.5 billion 4 Zevra Therapeutics A Marketing Authorization Application for the evaluation of arimoclomol (MIPLYFFA) for the treatment of NPC is under review by the EMA 5 Rezolute In December 2025, Rezolute announced that the Phase 3 clinical study of ersodetug for the treatment of congenital hyperinsulinism (“HI”) demonstrated reductions from baseline in hypoglycemia events by self-monitored blood glucose at both ersodetug dose levels, but the reductions were not statistically significant compared to placebo, due to a pronounced study effect 6 Rezolute will meet with FDA under its Breakthrough Therapy Designation in the first quarter of 2026 to determine next steps for the program 6 Rezolute anticipates topline results of upLIFT, a Phase 3, single-arm, open-label study in participants with tumor HI, in the second half of 2026 6 Gossamer Bio & Chiesi In February 2026, Gossamer Bio announced topline results from the Phase 3 PROSERA clinical trial evaluating seralutinib for the treatment of PAH 7 Seralutinib demonstrated a placebo-adjusted improvement in Six-Minute Walk Distance (6MWD) of +13.3 meters at Week 24 (p = 0.0320), missing the prespecified alpha threshold of 0.025 7 Gossamer plans to meet with the U.S. FDA to discuss the path forward 7 Volixibat Volixibat VISTAS study in primary sclerosing cholangitis (PSC) topline data expected in Q2 2026 8 Volixibat VANTAGE study in primary biliary cholangitis (PBC) expected to complete enrollment in H2 2026 8 Business Development Activity Takeda Strategic Royalty Share Transaction In December 2025, XOMA amended its collaboration with Takeda XOMA will receive low to mid-single-digit royalties and up to $852.6 million in potential milestones across nine development-stage assets, including osavampator, which is being evaluated in Phase 3 studies for major depressive disorder; volixibat, which is being evaluated in PSC and PBC; OHB-607, which Oak Hill Bio Ltd and its partner are developing for the prevention of bronchopulmonary dysplasia in extremely premature infants; REC-4881, which is in Phase 2 development for familial adenomatous polyposis; and five early-stage Oak Hill Bio assets Prior to amending the collaboration, XOMA held a mid-single digit royalty and $16.25 million in potential milestones associated with mezagitamab Following the transaction, XOMA will retain a low single-digit royalty entitlement on mezagitamab and up to $13.0 million in milestones Company Acquisitions Completed or served as the structuring agent in the acquisition of seven companies since the beginning of 2025 Accumulated non-dilutive capital of $11.7 million, net of transaction expenses Obtained economic interests of approximately 25% in up to $1.1 billion of potential milestone payments and low to mid-single-digit royalties from eight partnered assets Eligible for 25-70% of proceeds related to any future out license or sale of legacy assets or platform technology from these companies, including the ctLNP delivery platform from Generation Bio Fourth Quarter and Full-Year 2025 Financial Results In the fourth quarter of 2025, XOMA Royalty received $3.2 million in cash receipts from royalties and commercial payments and $3.3 million in milestone payments and paid $1.4 million in dividends on the XOMA Royalty Perpetual Preferred stocks. For the full year of 2025, XOMA Royalty received $50.5 million in cash receipts, including $33.6 million in royalties and commercial payments and $16.9 million in milestone payments and fees. During 2025, XOMA Royalty deployed $25.0 million to acquire additional assets for its royalty and milestone portfolio, repurchased 648,048 shares of its common stock for a cost of $16.0 million, and paid $5.5 million in dividends on the XOMA Royalty Perpetual Preferred stocks. Income and Revenue : Income and revenues for the three months ended December 31, 2025 and 2024, were $13.8 million and $8.7 million, respectively. Income and revenues for the years ended December 31, 2025 and 2024, were $52.1 million and $28.5 million, respectively. The increase in both periods was primarily driven by increased income related to VABYSMO® (faricimab-svoa) and OJEMDA™ (tovorafenib) and milestone payments received from Rezolute and Takeda. General and Administrative (G&A) Expenses : G&A expenses for the three months ended December 31, 2025 and 2024, were $10.4 million and $7.0 million, respectively. G&A expenses for the years ended December 31, 2025 and 2024, were $36.1 million and $34.5 million, respectively. The increase of $1.6 million in 2025 was primarily due to an increase in business development and deal-related costs of $3.7 million and an increase in lease costs of $1.0 million primarily related to the HilleVax acquisition partially offset by $3.6 million in costs related to exit packages for Kinnate senior leadership in 2024. G&A expenses for the year ended December 31, 2025, also include an increase of approximately $1.1 million associated with ongoing litigation initiated by XOMA Royalty against Janssen Biotech, Inc., asserting claims for breach of contract and unjust enrichment arising from Janssen's unauthorized use of XOMA’s intellectual property in the commercialization of TREMFYA (guselkumab). XOMA Royalty expects to continue to incur legal fees and other professional service costs associated with pursuing this litigation. Litigation is inherently uncertain, and there can be no assurance regarding the outcome of the matter or the timing or amount of any potential recovery. XOMA Royalty’s G&A expenses for the three months ended December 31, 2025 and 2024, included non-cash stock-based compensation expenses of $3.9 million and $2.2 million, respectively, and $9.3 million and $10.3 million for the full years of 2025 and 2024, respectively. Interest Expense : Interest expense for the three months ended December 31, 2025 and 2024, was $3.0 million and $3.4 million, respectively. Interest expense for the twelve months ended December 31, 2025 and 2024, were $13.0 million and $13.8 million, respectively. Interest expense relates to the Blue Owl Loan established in December 2023. Net Income (Loss) : XOMA Royalty reported net income of $6.1 million and $31.7 million for the three months and year ended December 31, 2025, as compared to net losses of $4.0 million and $13.8 million in the corresponding periods of 2024. Cash Position : On December 31, 2025, XOMA Royalty had cash and cash equivalents of $133.7 million, including $50.8 million in restricted cash. The restricted cash balance included $42.3 million related to the assumed HilleVax lease and $2.2 million related to the Blue Owl Loan. Cash and cash equivalents of $106.4 million as of December 31, 2024, included $4.8 million in restricted cash related to the Blue Owl Loan. Webcast The Company will host a webcast on March 18, 2026, at 8:00 am Eastern Time to discuss the results and provide a business update. The webcast will be accessible on the “News & Events” page in the Investors section of XOMA Royalty’s website ( ). A replay of the webcast will be available for 30 days following the live event. About XOMA Royalty Corporation XOMA Royalty is a biotechnology royalty aggregator playing a distinctive role in helping biotech companies achieve their goal of improving human health. XOMA Royalty acquires the potential future economics associated with pre-commercial and commercial therapeutic candidates that have been licensed to pharmaceutical or biotechnology companies. When XOMA Royalty acquires the future economics, the seller receives non-dilutive, non-recourse funding they can use to advance their internal drug candidate(s) or for general corporate purposes. The Company has an extensive and growing portfolio of assets (asset defined as the right to receive potential future economics associated with the advancement of an underlying therapeutic candidate). For more information about the Company and its portfolio, please visit or follow XOMA Royalty Corporation on LinkedIn . Forward-Looking Statements/Explanatory Notes Certain statements contained in this press release are forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934, including statements regarding the timing and amount of potential commercial payments to XOMA Royalty, expectations around future royalty cash flows covering XOMA Royalty’s core operating expenses (the inflection point) and other developments related to VABYSMO® (faricimab-svoa), OJEMDA™ (tovorafenib), MIPLYFFA™ (arimoclomol), XACIATO™ (clindamycin phosphate) vaginal gel 2%, IXINITY® [coagulation factor IX (recombinant)], DSUVIA® (sufentanil sublingual tablet), and DARE to PLAY™ Sildenafil Cream and Sildenafil Cream, 3.6%; the potential occurrences and timing of the events listed under “ Key 2026 Pipeline Events”; expectations regarding the inflection point in XOMA Royalty’s business model of breakeven operating cash flows; the anticipated timings of regulatory filings and approvals related to assets in XOMA Royalty’s portfolio; and the potential of XOMA Royalty’s portfolio of partnered programs and licensed technologies generating substantial milestone and royalty proceeds over time. In some cases, you can identify such forward-looking statements by terminology such as “anticipate,” “intend,” “believe,” “estimate,” “plan,” “seek,” “project,” “expect,” “may,” “will”, “would,” “could” or “should,” the negative of these terms or similar expressions. These forward-looking statements are not a guarantee of XOMA Royalty’s performance, and you should not place undue reliance on such statements. These statements are based on assumptions that may not prove accurate, and actual results could differ materially from those anticipated due to certain risks inherent in the biotechnology industry, including those related to the fact that our product candidates subject to out-license agreements are still being developed, and our licensees may require substantial funds to continue development which may not be available; we do not know whether there will be, or will continue to be, a viable market for the products in which we have an ownership or royalty interest; and if the therapeutic product candidates to which we have a royalty interest do not receive regulatory approval, our third-party licensees will not be able to market them. Other potential risks to XOMA Royalty meeting these expectations are described in more detail in XOMA Royalty's most recent filing on Form 10-K and in other filings with the Securities and Exchange Commission. Consider such risks carefully when considering XOMA Royalty's prospects. Any forward-looking statement in this press release represents XOMA Royalty's beliefs and assumptions only as of the date of this press release and should not be relied upon as representing its views as of any subsequent date. XOMA Royalty disclaims any obligation to update any forward-looking statement, except as required by applicable law. EXPLANATORY NOTE: Any references to “portfolio” in this press release refer strictly to milestone and/or royalty rights associated with a basket of drug products in development. Any references to “assets” in this press release refer strictly to milestone and/or royalty rights associated with individual drug products in development. As of the date of this press release, the commercial assets in XOMA Royalty’s milestone and royalty portfolio are VABYSMO® (faricimab-svoa), OJEMDA™ (tovorafenib), MIPLYFFA™ (arimoclomol), XACIATO™ (clindamycin phosphate) vaginal gel 2%, IXINITY® [coagulation factor IX (recombinant)], DARE to PLAY™ (Sildenafil Cream), and DSUVIA® (sufentanil sublingual tablet). All other assets in the milestone and royalty portfolio are investigational compounds. Efficacy and safety have not been established. There is no guarantee that any of the investigational compounds will become commercially available. XOMA ROYALTY CORPORATION CONSOLIDATED STATEMENTS OF OPERATIONS (in thousands, except per share amounts) Three Months Ended December 31, Year Ended December 31, 2025 2024 2025 2024 Income and revenues: Income from purchased receivables under the EIR method $ 7,706 $ 5,081 $ 26,745 $ 15,066 Income from purchased receivables under the cost recovery method 4,619 1,291 13,744 3,201 Revenue from contracts with customers 1,100 600 10,350 6,650 Revenue recognized under units-of-revenue method 332 1,742 1,310 3,570 Total income and revenues 13,757 8,714 52,149 28,487 Operating expenses: Research and development 281 864 1,712 2,875 General and administrative 10,410 6,993 36,092 34,478 Credit losses on purchased receivables — 7,904 — 30,904 Amortization of intangible assets 884 206 2,961 206 Total operating expenses 11,575 15,967 40,765 68,463 Income (loss) from operations 2,182 (7,253 ) 11,384 (39,976 ) Other income (expense), net: Gains on acquisitions 3,220 — 21,224 19,316 Change in fair value of embedded derivative related to RPA — — — 8,100 Interest expense (3,027 ) (3,394 ) (13,031 ) (13,840 ) Other income, net 3,782 1,021 12,238 6,921 Net income (loss) before tax 6,157 (9,626 ) 31,815 (19,479 ) Income tax (expense) benefit (54 ) 5,658 (103 ) 5,658 Net income (loss) $ 6,103 $ (3,968 ) $ 31,712 $ (13,821 ) Net income (loss) available to (attributable to) common stockholders, basic $ 3,319 $ (5,336 ) $ 18,516 $ (19,293 ) Basic net income (loss) per share available to (attributable to) common stockholders $ 0.27 $ (0.45 ) $ 1.53 $ (1.65 ) Weighted average shares used in computing basic net income (loss) per share available to (attributable to) common stockholders 12,208 11,868 12,081 11,701 Net income (loss) available to (attributable to) common stockholders, diluted $ 4,679 $ (5,336 ) $ 26,184 $ (19,293 ) Diluted net income (loss) per share available to (attributable to) common stockholders $ 0.26 $ (0.45 ) $ 1.46 $ (1.65 ) Weighted average shares used in computing diluted net income (loss) per share available to (attributable to) common stockholders 18,095 11,868 17,982 11,701 XOMA ROYALTY CORPORATION CONSOLIDATED BALANCE SHEETS (in thousands, except share and per share amounts) December 31, December 31, 2025 2024 ASSETS Current assets: Cash and cash equivalents $ 82,908 $ 101,654 Short-term restricted cash 5,441 1,330 Investment in equity securities 382 3,529 Trade and other receivables, net 4,896 1,839 Short-term royalty and commercial payment receivables under the EIR method 22,780 14,763 Short-term royalty and commercial payment receivables under the cost recovery method - 413 Prepaid expenses and other current assets 852 2,076 Total current assets 117,259 125,604 Long-term restricted cash 45,361 3,432 Property and equipment, net 21 32 Operating lease right-of-use assets 256 319 Long-term royalty and commercial payment receivables under the EIR method 4,433 4,970 Long-term royalty and commercial payment receivables under the cost recovery method 55,888 55,936 Exarafenib milestone asset 3,600 3,214 Investment in warrants 697 — Intangible assets, net 44,756 25,909 Other assets - long term 427 1,861 Total assets $ 272,698 $ 221,277 LIABILITIES AND STOCKHOLDERS’ EQUITY Current liabilities: Accounts payable $ 2,208 $ 1,053 Accrued and other liabilities 9,885 5,752 Contingent consideration under RPAs, AAAs, and CPPAs - 3,000 Operating lease liabilities 2,464 446 Unearned revenue recognized under units-of-revenue method 1,268 1,361 Preferred stock dividend accrual 1,424 1,368 Current portion of long-term debt 12,526 11,394 Contingent value rights liabilities - current portion 5,045 - Total current liabilities 34,820 24,374 Unearned revenue recognized under units-of-revenue method – long-term 3,193 4,410 Exarafenib milestone contingent consideration 3,600 3,214 Long-term operating lease liabilities 20,114 483 Long-term debt 96,451 106,875 Contingent value rights liabilities - long-term 10,457 - Deferred tax liability 103 - Total liabilities 168,738 139,356 Convertible preferred stock, $0.05 par value, 5,003 shares authorized, issued and outstanding as of December 31, 2025 and December 31, 2024 20,019 20,019 Stockholders’ equity: 8.625% Series A cumulative, perpetual preferred stock, $0.05 par value, 984,000 shares authorized, issued and outstanding as of December 31, 2025 and December 31, 2024 49 49 8.375% Series B cumulative, perpetual preferred stock, $0.05 par value, 3,600 shares authorized, 1,760.5 and 1,600 shares issued and outstanding as of December 31, 2025 and December 31, 2024, respectively — — Common stock, $0.0075 par value, 277,333,332 shares authorized, 11,858,955 and 11,952,377 shares issued and outstanding as of December 31, 2025 and December 31, 2024, respectively 89 90 Additional paid-in capital 1,305,200 1,298,747 Accumulated other comprehensive income 53 73 Accumulated deficit (1,221,450 ) (1,237,057 ) Total stockholders’ equity 83,941 61,902 Total liabilities, convertible preferred stock and stockholders’ equity $ 272,698 $ 221,277 XOMA ROYALTY CORPORATION CONSOLIDATED STATEMENTS OF CASH FLOWS (in thousands) Year Ended December 31, 2025 2024 Cash flows from operating activities: Net income (loss) $ 31,712 $ (13,821 ) Adjustments to reconcile net loss to net cash used in operating activities: Income from purchased receivables under the EIR method (5,925 ) (15,066 ) Stock-based compensation expense 9,273 10,312 Gains on acquisitions (21,224 ) (19,316 ) Credit losses on purchased receivables — 30,904 Gain on sale of equity securities (3,663 ) — Income tax expense (benefit) 103 (5,658 ) Common stock contribution to 401(k) 141 118 Amortization of intangible assets 2,961 206 Depreciation 11 10 Accretion of long-term debt discount and debt issuance costs 1,385 1,350 Non-cash lease expense 64 60 Change in fair value of equity securities (90 ) (131 ) Change in fair value of available-for-sale debt securities classified as cash equivalents (20 ) 73 Change in fair value of derivatives (93 ) — CVR liability working capital adjustment (394 ) — Changes in assets and liabilities: Trade and other receivables, net (2,426 ) (835 ) Prepaid expenses and other assets 3,839 302 Accounts payable and accrued liabilities (10,597 ) 1,598 Operating lease liabilities (876 ) (284 ) Unearned revenue recognized under units-of-revenue method (1,310 ) (3,570 ) Net cash provided by (used in) operating activities 2,871 (13,748 ) Cash flows from investing activities: Net cash acquired in Kinnate acquisition — 18,926 Net cash acquired in Turnstone acquisition 3,850 — Net cash and restricted cash acquired in HilleVax acquisition 46,384 — Net cash, cash equivalents, and restricted cash acquired in LAVA acquisition 15,263 — Net cash and cash equivalents acquired in Mural acquisition 4,464 — Payments of consideration under RPAs, AAAs, and CPPAs (8,000 ) (53,000 ) Receipts under RPAs, AAAs, and CPPAs 3,300 29,248 Net payment for IP acquired under the Pulmokine Acquisition — (20,176 ) Payment for BioInvent contract-based intangible asset (20,725 ) — Payment of contingent consideration related to Kinnate IP asset (550 ) — Purchase of property and equipment — (20 ) Purchase of equity securities (99 ) (3,237 ) Sale of equity securities 6,999 — Payment to issue short-term loan to Xeno (5,877 ) — Receipt from short-term loan repayment by Xeno 5,877 — Net cash provided by (used in) investing activities 50,886 (28,259 ) Cash flows from financing activities: Proceeds from issuance of common stock 323 — Proceeds from issuance of preferred stock 4,019 — Payments of preferred and common stock issuance and financing costs (672 ) — Principal payments – debt (10,598 ) (6,902 ) Debt issuance costs and loan fees paid in connection with long-term debt (80 ) (740 ) Payment of preferred stock dividends (5,472 ) (5,472 ) Repurchases of common stock (16,043 ) (13 ) Proceeds from exercise of options and other share-based compensation 5,046 5,214 Taxes paid related to net share settlement of equity awards (2,986 ) (3,214 ) Net cash used in financing activities (26,463 ) (11,127 ) Net increase (decrease) in cash, cash equivalents, and restricted cash 27,294 (53,134 ) Cash, cash equivalents, and restricted cash as of the beginning of the period 106,416 159,550 Cash, cash equivalents, and restricted cash as of the end of the period $ 133,710 $ 106,416 Supplemental Cash Flow Information: Cash paid for interest $ 11,906 $ 9,985 Cash paid for taxes $ 277 $ — Non-cash investing and financing activities: Accrual of contingent value rights liability in the Turnstone acquisition $ 1,110 $ — Accrual of contingent value rights liability in the HilleVax acquisition $ 5,673 $ — Accrual of contingent value rights liability in the LAVA acquisition $ 9,114 $ — Right-of-use assets obtained in exchange for operating lease liabilities in the HilleVax acquisition $ 22,525 $ — Relative fair value basis reduction of right-of-use assets in the HilleVax acquisition $ (22,525 ) $ — Transaction costs in connection with Mural acquisition included in accrued expenses $ 320 $ — Excise tax accrual due to stock repurchases $ 68 $ — Reclassification of equity classified awards to liabilities $ (739 ) $ — Reclassification of deferred issuance cost to equity $ 578 $ — Preferred stock dividend accrual $ 1,424 $ 1,368 Estimated fair value of the Exarafenib milestone asset $ — $ 2,922 Estimated fair value of the Exarafenib milestone contingent consideration $ — $ (2,922 ) Right-of-use assets obtained in exchange for operating lease liabilities in the Kinnate acquisition $ — $ 824 Relative fair value basis reduction of rights-of-use assets in the Kinnate acquisition $ — $ (824 ) Accrual of contingent consideration under the Affitech CPPA $ — $ 3,000 Accrual of contingent consideration under the LadRx AAA $ — $ 1,000 Investor contact: Media contact: Juliane Snowden Kathy Vincent XOMA Royalty Corporation KV Consulting & Management +1-646-438-9754 kathy@kathyvincent.com juliane.snowden@xoma.com 1 This amount includes structuring agent fees associated with Repare Therapeutics and ESSA Pharmaceuticals. 2 3 4 5 6 7 8

- Following PROSERA Phase 3 topline results, the Company is focused on evaluating the totality of the dataset, engaging with the FDA, and assessing strategic options and capital allocation - - Enrollment in the Phase 3 SERANATA Study in PH-ILD has been paused while the Company evaluates implications of PROSERA results - - The Company implemented a reduction in force to align resources with near-term priorities - - Cash, cash equivalents and marketable securities totaled $137 million at year-end 2025 - SAN DIEGO--(BUSINESS WIRE)--Gossamer Bio, Inc. (Nasdaq: GOSS), a biopharmaceutical company focused on the development and commercialization of seralutinib for the treatment of pulmonary arterial hypertension (PAH) and pulmonary hypertension associated with interstitial lung disease (PH-ILD), today announced its financial results for the fourth quarter and year ended December 31, 2025, and provided a corporate update. Gossamer Bio and the Chiesi Group are jointly developing seralutinib under a global collaboration agreement. “Following our PROSERA topline results, we are focused on fully understanding the PROSERA dataset, engaging with the FDA, and evaluating strategic options and capital allocation to position the Company for the future,” said Faheem Hasnain, Chairman, Co-Founder and CEO of Gossamer Bio. “PROSERA narrowly missed the prespecified statistical threshold for its primary endpoint; however, we believe the totality of evidence supports that seralutinib is an active drug in PAH, with the most pronounced effects observed in patients with more advanced disease.” Seralutinib (GB002): Inhaled PDGFR, CSF1R and c-KIT Inhibitor In February 2026, the Company announced topline results from PROSERA, its Phase 3 study of seralutinib in PAH. At Week 24, seralutinib demonstrated a placebo-adjusted improvement in six-minute walk distance (6MWD) of approximately +13.3 meters versus placebo (p = 0.0320), which did not meet the prespecified statistical alpha threshold of 0.025; therefore, all other p-values are nominal. In the prespecified intermediate- and high-risk subgroup (REVEAL Lite 2 score ≥6 at screening), seralutinib demonstrated a placebo-adjusted improvement in 6MWD of approximately +20.0 meters at Week 24 (n = 234; nominal p = 0.0207). In this subgroup, three of four key secondary endpoints had nominal p-values below 0.0125, with results favoring seralutinib versus placebo. Across the overall population, key secondary endpoints favored seralutinib versus placebo, including NT-proBNP (location shift of approximately -120.4 ng/L at Week 24; nominal p = 0.0002), as well as measures of clinical improvement, reduction in risk score, and time to clinical worsening. In a prespecified subgroup of patients with connective tissue disease-associated pulmonary arterial hypertension (CTD-PAH), seralutinib demonstrated a placebo-adjusted improvement in six-minute walk distance of approximately +37 meters at Week 24 versus placebo (n = 87; nominal p = 0.0104). The Company has paused enrollment in the Phase 3 SERANATA Study in PH-ILD while it evaluates the implications of PROSERA results, including regional variability in placebo response, and engages with regulators on potential paths forward. The Company continues to conduct additional analyses of the PROSERA dataset. Based on the PROSERA results, the Company plans to request a Type C meeting with the U.S. Food and Drug Administration (FDA), to occur potentially in June 2026, to discuss the data and potential regulatory paths forward. RT234: Inhaled PDE5 Inhibitor (Vardenafil) As planned, the Company continues to support limited work on RT234 pursuant to its option agreement to support an ongoing assessment of the program. RT234-related spend is expected to remain modest and is not a near-term strategic focus as the Company prioritizes its evaluation of PROSERA and related regulatory and strategic planning. Corporate Update In connection with its ongoing evaluation of strategic options and capital allocation priorities, the Company implemented a reduction in force and other cost-containment measures intended to better align resources with its near-term priorities. The Company remains focused on advancing its regulatory and strategic planning related to seralutinib. Financial Results for Quarter and Full Year Ended December 31, 2025 Cash, Cash Equivalents and Marketable Securities : Cash, cash equivalents and marketable securities as of December 31, 2025, were $136.9 million. As a result, the Company expects its current cash, cash equivalents and marketable securities will be sufficient to fund operating and capital expenditures into the first quarter of 2027. Research and Development (R&D) Expenses : For the quarter ended December 31, 2025, R&D expenses were $48.9 million compared to R&D expenses of $36.1 million for the same period in 2024. R&D expenses for the full year ended December 31, 2025, were $174.1 million compared to $138.5 million for the full year ended December 31, 2024. General and Administrative (G&A) Expenses : For the quarter ended December 31, 2025, G&A expenses were $10.9 million compared to $9.4 million for the same period in 2024. G&A expenses for the full year ended December 31, 2025, were $37.6 million compared to $36.1 million for the full year ended December 31, 2024. Net Loss : Net loss for the three months ended December 31, 2025, was $47.2 million, or $0.21 per share, compared to a net loss of $33.0 million, or $0.15 per share, for the same period in 2024. Net loss for the full year ended December 31, 2025, was $170.4 million, or $0.75 per share compared to a net loss of $56.5 million, or $0.25 per share, for the full year ended December 31, 2024. About Gossamer Bio Gossamer Bio is a biopharmaceutical company focused on the development of treatments for pulmonary hypertension. Its goal is to be an industry leader in, and to enhance the lives of patients living with, pulmonary hypertension. Forward-Looking Statements Gossamer cautions you that statements contained in this press release regarding matters that are not historical facts are forward-looking statements. These statements are based on the Company’s current beliefs and expectations. Such forward-looking statements include, but are not limited to, statements regarding: the Company’s additional analyses and interpretation of the PROSERA dataset; the therapeutic potential of seralutinib; the expected plan to discuss topline results with the FDA and the potential to identify a development path forward for seralutinib, including the timing of a potential meeting in the June 2026 timeframe; the plans to pause the Phase 3 SERANATA Study; the Company’s evaluation of strategic options and capital allocation; the intended objectives and benefits of the workforce reduction; the expected spend related to RT234; and the expected timeframe for funding the Company’s operating plan with current cash, cash equivalents and marketable securities. The inclusion of forward-looking statements should not be regarded as a representation by Gossamer that any of its plans will be achieved. Actual results may differ from those set forth in this press release due to the risks and uncertainties inherent in Gossamer’s business, including, without limitation; topline results Gossamer reports are based on preliminary analysis of key efficacy and safety data, and such data may change following a more comprehensive review of the data related to the clinical trial and such topline data may not accurately reflect the complete results of a clinical trial; Gossamer may not be able to identify a development path forward for seralutinib, whether as a result of FDA feedback or otherwise, and any path forward may require additional capital and other resources, which may not be available on reasonable terms, if at all, or may limit the commercial opportunity for seralutinib; Gossamer may need to further evaluate its current workforce in light of potential development paths for seralutinib; potential delays in the commencement, enrollment and completion of clinical trials; comparative safety information is not based on a head-to-head comparison and differences exist between study designs and subject characteristics which could confound the results; the Company’s dependence on third parties in connection with product manufacturing, research and preclinical and clinical testing; the results of preclinical studies and early clinical trials with seralutinib are not necessarily predictive of future results; the success of any future Gossamer’s clinical trials and preclinical studies for seralutinib; regulatory developments in the United States and foreign countries; unexpected adverse side effects or inadequate efficacy of seralutinib that may limit its development, regulatory approval and/or commercialization, or may result in clinical holds, recalls or product liability claims; Gossamer’s ability to obtain and maintain intellectual property protection for seralutinib; Gossamer’s ability to comply with its obligations in collaboration agreements with third parties or the agreements under which it licenses intellectual property rights from third parties; Gossamer may use its capital resources sooner than it expects; and other risks described in the Company’s filings with the Securities and Exchange Commission (SEC), including under the heading “Risk Factors” in the Company’s annual report on Form 10-K and any subsequent filings with the SEC. You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof, and Gossamer undertakes no obligation to update such statements to reflect events that occur or circumstances that exist after the date hereof. All forward-looking statements are qualified in their entirety by this cautionary statement, which is made under the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. GOSSAMER BIO, INC. CONDENSED CONSOLIDATED FINANCIAL STATEMENT DATA (UNAUDITED; IN THOUSANDS, EXCEPT SHARE AND PER SHARE DATA) Three months ended December 31, Year ended December 31, STATEMENTS OF OPERATIONS DATA: 2025 2024 2025 2024 Revenue: Revenue from sale of licenses $ — $ 1,931 $ — $ 90,682 Revenue from contracts with collaborators 13,799 7,448 48,471 24,019 Total revenue 13,799 9,379 48,471 114,701 Operating expenses: Research and development $ 48,935 $ 36,112 $ 174,093 $ 138,487 In process research and development (1 ) — 7,475 — General and administrative 10,904 9,395 37,631 36,133 Total operating expenses 59,838 45,507 219,199 174,620 Loss from operations (46,039 ) (36,128 ) (170,728 ) (59,919 ) Other income (expense) Interest income 447 (744 ) 1,970 1,779 Interest expense (2,751 ) (2,738 ) (10,989 ) (11,517 ) Other income, net 1,017 4,171 9,289 14,022 Total other income (loss), net (1,287 ) 689 270 4,284 Loss before provision (benefit) for income taxes (47,326 ) (35,439 ) (170,458 ) (55,635 ) Provision (benefit) for income taxes (88 ) (2,410 ) (88 ) 893 Net loss $ (47,238 ) $ (33,029 ) $ (170,370 ) $ (56,528 ) Net loss per share, basic and diluted $ (0.21 ) $ (0.15 ) $ (0.75 ) $ (0.25 ) Weighted average common shares outstanding, basic and diluted 226,604,138 226,604,138 228,519,130 226,228,016 BALANCE SHEET DATA: December 31, 2025 December 31, 2024 Cash, cash equivalents, and marketable securities $ 136,932 $ 294,518 Working capital 104,209 264,878 Total assets 172,249 315,292 Total liabilities 295,009 285,800 Accumulated deficit (1,438,938 ) (1,268,568 ) Total stockholders' equity (deficit) (122,760 ) 29,492 Contacts For Investors and Media: Bryan Giraudo, Chief Financial Officer & Chief Operating Officer Gossamer Bio Investor Relations ir@gossamerbio.com