GOSS

- NDA Submission for Seralutinib in PAH On Track for September 2026 Following Receipt of Pre-NDA Type B Meeting Minutes - - Gossamer Reacquired Worldwide Development and Commercial Rights to Seralutinib from Chiesi, Consolidating Global Control and Economics - - Stockholders Approved Proposals Related to Convertible Note Exchange and Reverse Stock Split, Supporting a Strengthened Capital Structure - - Cash, Cash Equivalents and Marketable Securities Totaled $57.0 Million as of June 30, 2026 - SAN DIEGO, August 13, 2026--(BUSINESS WIRE)--Gossamer Bio, Inc. (Nasdaq: GOSS) (the "Company" or "Gossamer"), a clinical-stage 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 second quarter ended June 30, 2026, and provided a business update. "We have worked hard to strengthen Gossamer and prepare the Company for what comes next," said Faheem Hasnain, Chairman, Co-Founder, and CEO of Gossamer. "We completed a productive Pre-NDA Type B meeting with the FDA, received the official minutes and remain on track to submit our NDA for seralutinib in PAH in September. We also reacquired worldwide rights to seralutinib and completed a convertible note exchange that substantially reduced our debt. We are in a better position today, and our focus remains on the work required to move seralutinib forward." Seralutinib (GB002): Inhaled PDGFR, CSF1R and c-KIT Inhibitor Regulatory Interactions: Pre-NDA Type B Meeting, Receipt of FDA Meeting Minutes and Planned NDA Submission The Company held a Pre-NDA Type B meeting with the U.S. Food and Drug Administration (FDA) in mid-June 2026 and has since received the official meeting minutes. Based on those minutes, the FDA characterized the degree of statistical significance and the magnitude of the treatment effect observed in PROSERA as review issues rather than filing issues, and provided feedback on the format and content of the planned submission. On that basis, the Company intends to submit an NDA supported by one adequate and well-controlled study (Phase 3 PROSERA) plus confirmatory evidence (Phase 2 TORREY and supportive analyses) in September 2026. If accepted for filing, seralutinib could be eligible for an FDA approval decision in the third quarter of 2027. While the meeting minutes reflect FDA feedback as of the meeting date, the FDA’s ultimate determination on approvability will be made upon review of the complete NDA. Reacquisition of Worldwide Commercial and Development Rights for Seralutinib from Chiesi Gossamer and Chiesi agreed to terminate their Collaboration and License Agreement, and Gossamer has reacquired worldwide development and commercial rights to seralutinib ahead of the planned NDA submission. The termination dissolves the prior U.S. 50/50 profit share and returns ex-U.S. rights to Gossamer, giving the Company full operational control of development, manufacturing, commercialization, pricing and lifecycle strategy across all geographies. The termination agreement required Chiesi to make a one-time $5 million payment to Gossamer, settling all outstanding and future obligations under the prior collaboration, including second quarter 2026 costs. Gossamer made no upfront cash payment to reacquire the rights. In exchange, Chiesi is entitled to a capped royalty on worldwide net sales of seralutinib, with no further royalty obligation once the cap is reached, as well as payments upon the achievement of specified regulatory and commercial milestones. As a result, Gossamer retains the substantial majority of seralutinib’s global economics versus its prior shared U.S. economics and ex-U.S. royalty. Special Meeting: Approval of Proposals Related to Convertible Note Exchange and Reverse Stock Split At a special meeting held on July 14, 2026, Gossamer’s stockholders approved the proposals related to the previously completed exchange of its 5.00% Convertible Senior Notes due 2027 (the "2027 Notes") and authorized the Board to effect a reverse stock split. Through the exchange, Gossamer exchanged approximately $181.1 million, or 90.5%, of the $200.0 million aggregate principal amount of 2027 Notes outstanding for approximately $65.2 million of new 7.50% Convertible Senior Secured First Lien Notes due 2030, together with equity securities and warrants, reducing the aggregate principal amount of the Company’s debt by approximately $115.9 million and the outstanding balance of the 2027 Notes to approximately $18.9 million. Additionally, Gossamer’s stockholders authorized the Board to effect a reverse stock split, with the timing and final ratio subject to Board approval. Financial Results for the Quarter Ended June 30, 2026 Cash, Cash Equivalents and Marketable Securities: Cash, cash equivalents and marketable securities totaled $57.0 million as of June 30, 2026. Gossamer expects the combination of current cash, cash equivalents and marketable securities will be sufficient to fund its operating and capital expenditures into the first quarter of 2027. Revenue from contracts with collaborators: For the quarter ended June 30, 2026, revenue associated with Gossamer's collaboration with Chiesi was $9.2 million, including $6.1 million of cost reimbursement revenue, compared to $11.5 million of revenue for the same period in 2025. Research and Development (R&D) Expenses: For the quarter ended June 30, 2026, R&D expenses were $26.4 million, compared to $41.6 million for the same period in 2025. The decrease was primarily driven by lower costs associated with clinical trials for seralutinib. General and Administrative Expenses (G&A): For the quarter ended June 30, 2026, G&A expenses were $8.9 million, compared to $8.7 million for the same period in 2025. Net Income (Loss): Net income for the quarter ended June 30, 2026, was $16.9 million, or $0.05 basic net income per share and $0.08 diluted net loss per share, compared to a net loss of $38.3 million, or $0.17 basic and diluted net loss per share, for the same period in 2025. About Gossamer Bio Gossamer Bio is a clinical-stage biopharmaceutical company focused on the development and commercialization of seralutinib for the treatment of pulmonary arterial hypertension and pulmonary hypertension associated with interstitial lung disease. 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 interpretation of the FDA minutes from its Pre-NDA Type B meeting; the timing and potential submission, and potential acceptance for filing and approval, of an NDA for seralutinib in PAH; the potential significance, interpretation and implications of data from the Phase 3 PROSERA study and Phase 2 TORREY study and supportive analyses; the development potential and market opportunity of seralutinib in PAH, PH-ILD and other indications; the anticipated benefits of the termination of the Company’s Collaboration and License Agreement with Chiesi; the anticipated benefits of the Company’s exchange of its previously outstanding 5.00% convertible senior notes due 2027; the anticipated benefits of any reverse stock split, and the timing of the completion of any such reverse stock split; 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: the risk that the Company’s planned NDA submission is based in part on its views following its recent meeting with the FDA and the official minutes therefrom, and later feedback from the FDA may be inconsistent with such meeting or the Company’s views from such meeting; the FDA may determine that the planned NDA does not qualify for filing; the results of the Company’s clinical trials, including the Phase 3 PROSERA and Phase 2 TORREY studies, may not be deemed sufficient by the FDA to serve as the basis for regulatory approval of seralutinib, including the risk that the FDA determines that the overall benefit-risk assessment of seralutinib is not favorable; 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; the Company’s future performance is dependent entirely on the success of seralutinib; whether the anticipated benefits of the exchange of the 2027 Notes or the termination of the Company’s Collaboration and License Agreement with Chiesi are realized; a reverse stock split, if effected, may not result in a sustained increase in the price of the Company’s common stock and may not satisfy the Nasdaq minimum bid price requirement or provide a better share capital structure; potential delays in the commencement, enrollment and completion of clinical trials; disruption to our operations from unexpected events, including clinical trial delays; 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; regulatory developments in the United States and foreign countries; 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; unstable market and economic conditions and changes in healthcare legislation, tariffs and trade policies may adversely affect the Company’s business and financial condition and the broader economy and biotechnology industry; Gossamer may use its capital resources sooner than it expects; and other risks described in the Company’s prior press releases and 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. View source version on businesswire.com: https://www.businesswire.com/news/home/20260813025520/en/ Contacts For Investors and Media: Bryan Giraudo, Chief Financial Officer & Chief Operating OfficerGossamer Bio Investor [email protected]

Wall Street expects a year-over-year increase in earnings on higher revenues when Prime Medicine, Inc. (PRME) reports results for the quarter ended June 2026. While this widely-known consensus outlook is important in gauging the company's earnings picture, a powerful factor that could impact its near-term stock price is how the actual results compare to these estimates. The earnings report might help the stock move higher if these key numbers are better than expectations. On the other hand, if they miss, the stock may move lower. While the sustainability of the immediate price change and future earnings expectations will mostly depend on management's discussion of business conditions on the earnings call, it's worth handicapping the probability of a positive EPS surprise. This company is expected to post quarterly loss of $0.24 per share in its upcoming report, which represents a year-over-year change of +41.5%. Revenues are expected to be $4.4 million, up 292.9% from the year-ago quarter. The consensus EPS estimate for the quarter has remained unchanged over the last 30 days. This is essentially a reflection of how the covering analysts have collectively reassessed their initial estimates over this period. Investors should keep in mind that an aggregate change may not always reflect the direction of estimate revisions by each of the covering analysts. Price, Consensus and EPS Surprise Estimate revisions ahead of a company's earnings release offer clues to the business conditions for the period whose results are coming out. Our proprietary surprise prediction model -- the Zacks Earnings ESP (Expected Surprise Prediction) -- has this insight at its core. The Zacks Earnings ESP compares the Most Accurate Estimate to the Zacks Consensus Estimate for the quarter; the Most Accurate Estimate is a more recent version of the Zacks Consensus EPS estimate. The idea here is that analysts revising their estimates right before an earnings release have the latest information, which could potentially be more accurate than what they and others contributing to the consensus had predicted earlier. Thus, a positive or negative Earnings ESP reading theoretically indicates the likely deviation of the actual earnings from the consensus estimate. However, the model's predictive power is significant for positive ESP readings only. A positive Earnings ESP is a strong predictor of an earnings beat, particularly when combined with a Zacks Rank #1 (Strong Buy), 2 (Buy) or 3 (Hold). Our research shows that stocks with this combination produce a positive surprise nearly 70% of the time, and a solid Zacks Rank actually increases the predictive power of Earnings ESP. Please note that a negative Earnings ESP reading is not indicative of an earnings miss. Our research shows that it is difficult to predict an earnings beat with any degree of confidence for stocks with negative Earnings ESP readings and/or Zacks Rank of 4 (Sell) or 5 (Strong Sell). For Prime Medicine, Inc., the Most Accurate Estimate is lower than the Zacks Consensus Estimate, suggesting that analysts have recently become bearish on the company's earnings prospects. This has resulted in an Earnings ESP of -15.86%. On the other hand, the stock currently carries a Zacks Rank of #2. So, this combination makes it difficult to conclusively predict that Prime Medicine, Inc. will beat the consensus EPS estimate. While calculating estimates for a company's future earnings, analysts often consider to what extent it has been able to match past consensus estimates. So, it's worth taking a look at the surprise history for gauging its influence on the upcoming number. For the last reported quarter, it was expected that Prime Medicine, Inc. would post a loss of$0.24 per share when it actually produced a loss of -$0.28, delivering a surprise of -16.67%. Over the last four quarters, the company has beaten consensus EPS estimates just once. An earnings beat or miss may not be the sole basis for a stock moving higher or lower. Many stocks end up losing ground despite an earnings beat due to other factors that disappoint investors. Similarly, unforeseen catalysts help a number of stocks gain despite an earnings miss. That said, betting on stocks that are expected to beat earnings expectations does increase the odds of success. This is why it's worth checking a company's Earnings ESP and Zacks Rank ahead of its quarterly release. Make sure to utilize our Earnings ESP Filter to uncover the best stocks to buy or sell before they've reported. Prime Medicine, Inc. doesn't appear a compelling earnings-beat candidate. However, investors should pay attention to other factors too for betting on this stock or staying away from it ahead of its earnings release. Gossamer Bio (GOSS), another stock in the Zacks Medical - Biomedical and Genetics industry, is expected to report loss per share of $0.1 for the quarter ended June 2026. This estimate points to a year-over-year change of +41.2%. Revenues for the quarter are expected to be $3.4 million, down 70.4% from the year-ago quarter. The consensus EPS estimate for Gossamer Bio has remained unchanged over the last 30 days. However, a lower Most Accurate Estimate has resulted in an Earnings ESP of -40.00%. This Earnings ESP, combined with its Zacks Rank #3 (Hold), makes it difficult to conclusively predict that Gossamer Bio will beat the consensus EPS estimate. Over the last four quarters, the company surpassed EPS estimates just once. Stay on top of upcoming earnings announcements with the Zacks Earnings Calendar. Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report Prime Medicine, Inc. (PRME) : Free Stock Analysis Report Gossamer Bio, Inc. (GOSS) : Free Stock Analysis Report This article originally published on Zacks Investment Research (zacks.com). Zacks Investment Research

This article first appeared on GuruFocus. Cash and Cash Equivalents: $99 million as of March 31, 2026. Cash Runway: Expected to extend into the first quarter of 2027. Convertible Senior Notes: $200 million aggregate principal amount approaching maturity in 2027. Debt Reduction: Convertible debt reduced from $200 million to under $72 million, extending maturity to 2030. Interest Rate on New Notes: 7.5% cash interest paid semiannually. Operating Expenses: Expected reduction following the wind-down of the PROSERA study and reduction in force. Warning! GuruFocus has detected 5 Warning Signs with GOSS. Is GOSS fairly valued? Test your thesis with our free DCF calculator. Release Date: May 18, 2026 For the complete transcript of the earnings call, please refer to the full earnings call transcript. Gossamer Bio Inc (NASDAQ:GOSS) reported a clinically meaningful improvement in the Phase III Procera study of seralutinib, showing a placebo-adjusted improvement of 13.3 meters in 6-minute walk distance. The company has engaged with the FDA, advancing from a Type C meeting to a Type B pre-NDA meeting, indicating progress in regulatory discussions. The CT FRI substudy showed multi-compartment structural reverse remodeling, providing anatomical support for seralutinib's efficacy. Gossamer Bio Inc (NASDAQ:GOSS) has taken decisive financial actions, including a significant reduction in force and operating expenses, to preserve financial stability. The company successfully negotiated a convertible note exchange, reducing outstanding convertible debt from $200 million to under $72 million and extending debt maturity to 2030. The Phase III Procera study did not meet the prespecified 0.025 alpha threshold for statistical significance, creating some uncertainty around the results. A significant reduction in force affected approximately half of the company, indicating potential operational challenges. The company faces risks and uncertainties related to regulatory approval and commercialization of seralutinib. The upcoming 2027 maturity of convertible senior notes required proactive capital structure adjustments, highlighting financial pressures. The CT FRI substudy results are exploratory and the p-values are nominal and unadjusted for multiplicity, which may limit their impact on regulatory decisions. Q: Could you help us understand how the Procera-CTFRI data supports the upcoming pre-NDA Type B meeting and potentially a differentiated label? A: Caryn Peterson, Executive Vice President - Regulatory Affairs, explained that the data will be included in the NDA submission and highlighted at the pre-NDA meeting. It provides confirmatory evidence of the drug's biological and mechanistic plausibility. Robert Smith, Chief Commercial Officer, added that the data shows unprecedented reverse remodeling capabilities, which could lead to a highly differentiated label. Q: Can you walk us through the timeline between now and a potential September filing? A: Caryn Peterson stated that the NDA submission is actively being worked on, with analyses to be completed by late August for a mid-September filing. Bryan Giraudo, COO and CFO, added that the decision to move to a Type B meeting was supported by FDA advisers due to the high unmet medical need. Q: What is the clinical relevance of the CT FRI measures, and will patients have more imaging done at a later time point? A: An unidentified company representative explained that the FRI data provides mechanistic insight into structural changes, adding credibility to the totality of evidence. Faheem Hasnain, CEO, noted that while this technology is not standard in clinical practice, it provides valuable mechanistic evidence. Future imaging at later time points is being considered. Q: What communications should we expect post the FDA meeting, and how do the results impact commercialization plans? A: Bryan Giraudo mentioned that updates will be provided during the second quarter results. Faheem Hasnain and Robert Smith discussed that the data supports using seralutinib across a spectrum of patients, potentially motivating earlier use due to its safety profile and efficacy. Q: How do the patients in the CT FRI sub-study compare to the broader study population in terms of clinical endpoints? A: Robert Smith noted that patients in the sub-study showed significant improvements in 6-minute walk distance and NT-proBNP, consistent with the overall intent-to-treat population. Faheem Hasnain added that the clinical community is interested in using the drug across various patient types due to its potential to prevent long-term progression. For the complete transcript of the earnings call, please refer to the full earnings call transcript.

SAN DIEGO, June 17, 2026--(BUSINESS WIRE)--Gossamer Bio, Inc. (NASDAQ: GOSS) (the "Company" or "Gossamer"), 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 the final tender results of its previously announced exchange offer (the "Exchange Offer") to exchange any and all of its 5.00% Convertible Senior Notes due 2027 (the "Existing Convertible Notes") for a pro rata portion of (i) up to $72.0 million in aggregate principal amount of its new 7.50% Convertible Senior Secured First Lien Notes due 2030 (the "New Convertible Notes"), (ii) up to 317,647,058 shares of its common stock (the "Common Stock") or, in lieu of issuing shares of Common Stock to the extent such shares would cause any holders of Existing Convertible Notes that are "qualified institutional buyers" as defined in Rule 144A under the Securities Act ("Eligible Holders") to beneficially own greater than 9.99% of the outstanding Common Stock, prefunded warrants to purchase shares of Common Stock (the "Prefunded Warrants" and, together with the Common Stock, the "Equity Securities") and (iii) with respect to Eligible Holders who tender prior to the Extended Early Tender Date (as defined below), warrants to purchase shares of Common Stock (the "Purchase Warrants" and, together with the New Convertible Notes and Equity Securities, the "Offered Securities"). As previously announced, as of 5:00 p.m., New York City time, on June 2, 2026 (the "Extended Early Tender Date"), $181,052,000 in aggregate principal amount of Existing Convertible Notes was validly tendered in the Exchange Offer and not validly withdrawn (such notes, the "Early Tendered Notes") and related consents to the Proposed Amendments (as defined below) were validly delivered and not validly withdrawn as of such time, and the Company and the Required Supporting Noteholders agreed to amend the condition to the Exchange Offer that a minimum of 98% of the aggregate principal amount of Existing Convertible Notes be validly tendered to a minimum of 90.5% of the aggregate principal amount of Existing Convertible Notes be validly tendered. As a result, early settlement of Offered Securities in exchange for the Early Tendered Notes validly tendered and not validly withdrawn as of the Extended Early Tender Date occurred on June 4, 2026, and the Company entered into a supplemental indenture eliminating substantially all of the restrictive covenants in the indenture governing the Existing Convertible Notes, as well as certain events of default and related provisions applicable to the Existing Convertible Notes (the "Proposed Amendments"). As of 5:00 p.m., New York City time, on June 16, 2026, based on information provided by D.F. King & Co., Inc., which is acting as the exchange agent and information agent for the Exchange Offer, no additional Existing Convertible Notes were validly tendered in the Exchange Offer. As a result, $18,948,000 in aggregate principal amount of the Existing Convertible Notes will remain outstanding following this Exchange Offer. 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. Gossamer Bio Forward-Looking Statements The Company 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 Exchange Offer and Consent Solicitation relating to its Existing Convertible Notes, including the timing and anticipated benefits thereof. 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: the Company may not be able to complete the Exchange Offer on the anticipated timeline or at all, and the Company may not realize the anticipated benefits therefrom; and other risks described in the Company’s prior press releases and 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. View source version on businesswire.com: https://www.businesswire.com/news/home/20260617149554/en/ Contacts For Investors and Media: Bryan Giraudo, Chief Financial Officer & Chief Operating OfficerGossamer Bio Investor [email protected]

SAN DIEGO, June 03, 2026--(BUSINESS WIRE)--Gossamer Bio, Inc. (NASDAQ: GOSS) (the "Company" or "Gossamer"), 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 the early tender results of its previously announced exchange offer (the "Exchange Offer") to exchange any and all of its 5.00% Convertible Senior Notes due 2027 (the "Existing Convertible Notes") for a pro rata portion of (i) up to $72.0 million in aggregate principal amount of its new 7.50% Convertible Senior Secured First Lien Notes due 2030 (the "New Convertible Notes"), (ii) up to 317,647,058 shares of its common stock (the "Common Stock") or, in lieu of issuing shares of Common Stock to the extent such shares would cause any Eligible Holder (as defined below) to beneficially own greater than 9.99% of the outstanding Common Stock, prefunded warrants to purchase shares of Common Stock (the "Prefunded Warrants" and, together with the Common Stock, the "Equity Securities") and (iii) with respect to Eligible Holders who tender prior to the Extended Early Tender Date (as defined below), warrants to purchase shares of Common Stock (the "Purchase Warrants" and, together with the New Convertible Notes and Equity Securities, the "Offered Securities"). As of 5:00 p.m., New York City time, on June 2, 2026 (the "Extended Early Tender Date"), based on information provided by D.F. King & Co., Inc., which is acting as the exchange agent and information agent for the Exchange Offer (the "Exchange Agent"), $181,052,000 in aggregate principal amount of Existing Convertible Notes was validly tendered in the Exchange Offer and not validly withdrawn (such notes, the "Early Tendered Notes") and related consents to the Proposed Amendments (as defined below) were validly delivered and not validly withdrawn as of such time. The Early Tendered Notes represent 90.526% of the aggregate outstanding principal amount of Existing Convertible Notes. The Company and the Required Supporting Noteholders have agreed to amend the condition to the Exchange Offer that a minimum of 98% of the aggregate principal amount of Existing Convertible Notes be validly tendered to a minimum of 90.5% of the aggregate principal amount of Existing Convertible Notes be validly tendered. As a result, the Company also announced that it has elected to accept for exchange the Early Tendered Notes (the "Early Settlement"), with settlement expected to occur on June 4, 2026 (the "Early Settlement Date"), the second business day immediately following the Extended Early Tender Date. The following table describes the early tender results at 5:00 p.m., New York City time, on June 2, 2026 (which is the Extended Early Tender Date of the Exchange Offer and the Consent Solicitation, as defined below) as well as the Offered Securities expected to be issued at the Early Settlement: In addition, holders of Early Tendered Notes accepted for exchange will receive accrued and unpaid interest on such Early Tendered Notes from, and including, the most recent interest payment date to, but excluding, the Early Settlement Date. By tendering Existing Convertible Notes in the Exchange Offer, each participating holder of Existing Convertible Notes is deemed to have agreed to substantially the same terms as those in the voting agreements entered into by the Supporting Noteholders, which includes having agreed with the Company that from and after the Early Settlement Date and until 5:00 p.m., New York City time, on June 5, 2026, which is the record date of the special meeting to be held following the Exchange Offer, it will not transfer, sell, exchange, assign or convey any legal or beneficial ownership interest in, or any right, title or interest therein (including any right or power to vote), or otherwise dispose of (whether by sale, liquidation, dissolution, dividend, distribution or otherwise) any New Shares, or enter into any contract, option, or other agreement with respect to any of the foregoing. Simultaneously with the Exchange Offer, the Company solicited consents (the "Consent Solicitation") from holders of the Existing Convertible Notes to adopt certain proposed amendments (the "Proposed Amendments") to the indenture governing the Existing Convertible Notes (the "Existing Convertible Notes Indenture"). The Proposed Amendments will eliminate substantially all of the restrictive covenants in the Existing Convertible Notes Indenture as well as certain events of default and related provisions applicable to the Existing Convertible Notes. As of 5:00 p.m., New York City time, on the Extended Early Tender Date, the Company had obtained sufficient consents to effectuate the Proposed Amendments. As a result, the Proposed Amendments will become effective upon the Early Settlement Date. For the remaining holders of Existing Convertible Notes that did not tender their Existing Convertible Notes prior to the Extended Early Tender Date, the Exchange Offer will expire at 5:00 p.m., New York City time, on June 16, 2026 (such time and date, as the same may be extended, the "Expiration Deadline"), unless extended or earlier terminated. The withdrawal deadline for the Exchange Offer and Consent Solicitation occurred at 5:00 p.m., New York City time, on June 1, 2026 (the "Withdrawal Deadline"). As a result, and because the Withdrawal Deadline is not being extended, tenders of the Existing Convertible Notes and related consents may no longer be withdrawn, except in limited circumstances where additional withdrawal rights are required by law. If all conditions to the Exchange Offer have been or are concurrently satisfied or waived at or prior to the Expiration Deadline, unless extended, the Company will accept for exchange any remaining Existing Convertible Notes that were validly tendered in the Exchange Offer following the Extended Early Tender Date and at or prior to the Expiration Deadline, and not validly withdrawn at or prior to the Withdrawal Deadline (the date of such exchange, the "Final Settlement Date"). The Final Settlement Date, if any, will be promptly after the Expiration Deadline and is currently expected to occur on June 18, 2026, the second business day immediately following the Expiration Deadline. Except as set forth herein, all other terms and conditions of the Exchange Offer and Consent Solicitation remain unchanged as set forth in the offering memorandum relating to the Exchange Offer and Consent Solicitation (the "Offering Memorandum"). The Exchange Offer and Consent Solicitation may each be amended or extended at any time prior to the Expiration Deadline and for any reason, and may be terminated or withdrawn if any of the conditions of the Exchange Offer and Consent Solicitation are not satisfied or waived by the Expiration Deadline (as it may be extended), subject to applicable law and, if applicable, the terms of the Transaction Support Agreement. Subject to applicable law and, if applicable, the terms of the Transaction Support Agreement, the Company may extend the Expiration Deadline at any time. The New Convertible Notes, Purchase Warrants, Prefunded Warrants and shares of Common Stock offered in the Exchange Offer are being offered only to holders of Existing Convertible Notes that are "qualified institutional buyers" as defined in Rule 144A under the Securities Act ("Eligible Holders"). Cantor Fitzgerald & Co. is acting as exclusive capital markets and financial advisor, sole dealer manager and sole solicitation agent to the Company (the "Dealer Manager") in connection with the Exchange Offer and Consent Solicitation. D.F. King & Co., Inc. is acting as the exchange agent and the information agent (the "Exchange Agent") in connection with the Exchange Offer and Consent Solicitation. Questions concerning the Exchange Offer and Consent Solicitation may be directed to the Dealer Manager at 110 East 59th Street, New York, NY 10022, email: [email protected] or to the Exchange Agent at 28 Liberty Street, 53rd Floor, New York, NY 10005, tel: (866) 620-9554 or (646) 582-7109, e-mail: [email protected]. The eligibility letter is available electronically at: www.dfking.com/goss. Eligible Holders should also consult their broker, dealer, commercial bank, trust company or other institution for assistance concerning the Exchange Offer and Consent Solicitation. Latham & Watkins LLP is acting as legal counsel to the Company in connection with the Exchange Offer and Consent Solicitation. Akin Gump Strauss Hauer & Feld LLP is acting as legal counsel to certain holders of Existing Convertible Notes that are party to the Transaction Support Agreement. DLA Piper LLP (US) is acting as legal counsel to the Dealer Manager for the Exchange Offer and Consent Solicitation. Only Eligible Holders may receive a copy of the Offering Memorandum and participate in the Exchange Offer and Consent Solicitation. None of the Company, the Dealer Manager, the Exchange Agent, any trustee or collateral agent for the Existing Convertible Notes or New Convertible Notes, or any affiliate of any of them makes any recommendation as to whether any Eligible Holder of Existing Convertible Notes should exchange or refrain from exchanging the principal amount of such Eligible Holder's Existing Convertible Notes in the Exchange Offer or submit consents in the Consent Solicitation. No one has been authorized by any of them to make such a recommendation. Eligible Holders must make their own decision whether to tender Existing Convertible Notes in the Exchange Offer or submit consents in the Consent Solicitation. No Eligible Holder may tender less than all of its Existing Convertible Notes in the Exchange Offer. The offering, issuance and sale of the Offered Securities has not been, and will not be, registered under the Securities Act of 1933, as amended, or any other securities laws. This press release shall not constitute an offer to sell, or the solicitation of an offer to buy, the New Convertible Notes, shares of Common Stock (or Prefunded Warrants) and Purchase Warrants offered in the Exchange Offer, the shares of Common Stock issuable upon conversion of the New Convertible Notes, Prefunded Warrants or Purchase Warrants, the Existing Convertible Notes or any other securities, nor will there be any sale of such securities or any other securities, in any state or other jurisdiction in which such offer, sale or solicitation would be unlawful. 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. Gossamer Bio Forward Looking Statements The Company 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 Exchange Offer and Consent Solicitation relating to its Existing Convertible Notes, including the timing and anticipated benefits thereof; and the Company’s ability to consummate the Exchange Offer. 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: the Company may not be able to complete the Exchange Offer on the anticipated timeline or at all, and the Company may not realize the anticipated benefits therefrom; and other risks described in the Company’s prior press releases and 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. View source version on businesswire.com: https://www.businesswire.com/news/home/20260603588950/en/ Contacts For Investors and Media: Bryan Giraudo, Chief Financial Officer & Chief Operating OfficerGossamer Bio Investor [email protected]

Image source: The Motley Fool. Monday, May 18, 2026 at 8:00 a.m. ET Chief Executive Officer — Faheem Hasnain Chief Financial Officer — Bryan Giraudo Chief Regulatory Officer — Caryn Peterson Chief Development Officer — Robert Roscigno Chief Commercial Officer — Bob Smith Chief Medical Officer — Jean-Marie Bruey Need a quote from a Motley Fool analyst? Email [email protected] Faheem Hasnain: Yes. Thanks, Bryan, and good morning, everybody. In February, we reported top line results from PROSERA, our Phase III study of seralutinib in patients with PAH. At a high level, PROSERA showed a clinically meaningful placebo-adjusted improvement of 13.3 meters in 6-minute walk distance at week 24, with patients on seralutinib improving 28.2 meters from baseline versus 13.5 meters on placebo and a p-value of 0.032. That p-value met the traditional 0.05 threshold for statistical significance, but it did not meet the prespecified 0.025 alpha threshold. At the same time, all 4 key secondary endpoints favored seralutinib over placebo, and we saw a stronger effect in the prespecified risk-enriched subgroup. Taken together, we believe the totality of the PROSERA data supports a real and clinically meaningful treatment signal. Now since the PROSERA top line readout, we've been focused on 3 work streams in parallel. First, we engaged with the FDA on the path forward for seralutinib. That process advanced from the previously disclosed Type C meeting to a Type B pre-NDA meeting, which is the most formal pre-submission meeting type. The meeting has been confirmed as in person and the briefing book has been submitted. Caryn will cover that in more detail shortly. Second, we completed the analysis of the prespecified CT FRI substudy, which enrolled 162 patients with 125 evaluable paired scans at week 24. Those results showed multi-compartment structural reverse remodeling across arterial, venous, fibrosis-like and vascular complexity parameters. You will hear the full data shortly in the FRI section of the call. Third, we moved quickly on capital stewardship. We recognized immediately that while the top line results were clinically meaningful, it also created uncertainty, and we needed to act decisively to protect the company's financial position and preserve our ability to get seralutinib to patients. That included a significant reduction in force affecting approximately half the company, a sharp reduction in operating expenses as PROSERA winds down and the pause of other development activities and broader cost containment across the organization. At the same time, we engaged constructively with our convertible noteholders to address the upcoming 2027 maturity. Bryan will cover the outcome of that process later in the call. All of these actions were taken for the same reason, to make sure this company has the runway, the focus and the resources to pursue an NDA submission and ultimately get an approved treatment to patients with PAH. Our conviction in seralutinib has increased since the top line readout, not decreased. That conviction is based on the totality of evidence, consistent drug arm performance in PROSERA, confirmatory data from TORREY, multi-compartment mechanistic evidence from the CT FRI and the regulatory path we are advancing with the FDA. This is a first-in-class inhaled tyrosine kinase inhibitor for a rare and fatal disease with high unmet need, and we believe we owe it to patients to pursue this path with discipline and urgency. Now I'll turn it over to Caryn to discuss our regulatory interactions and next steps. Caryn? Caryn Peterson: Thanks, Faheem. Let me start with the regulatory pathway we are pursuing. We are pursuing an NDA submission under the framework of one adequate and well-controlled clinical investigation plus confirmatory evidence. This is consistent with FDA's recent guidance to articulate the flexibility in the amount and type of evidence needed to meet the substantial evidence standard in place since 1998. For Gossamer, that approach is supported by the totality of the Phase III PROSERA data set together with the Phase II TORREY study. We also believe the seriousness of PAH, the high unmet medical need and seralutinib's novel mechanism of action, complementary to existing PAH therapies all support this regulatory pathway. We plan to file the NDA based on the totality of the PROSERA and TORREY data sets and any adjustments to patient population will be guided by regulatory feedback. Turning to our engagement with FDA. We are now moving forward with a Type B pre-NDA meeting rather than a Type C initially under consideration. A Type B meeting is a formal pre-submission interaction with FDA where we provide an overview of the NDA in the form of a briefing book that FDA will provide written responses with a defined time line and formal meeting minutes. We submitted the meeting request in April 2026 and an in-person meeting has been granted by FDA and will be held in mid-June. Based on that timing, our NDA submission target remains in September this year, subject to the outcome of the pre-NDA meeting. If that process proceeds as expected, a potential approval could follow in the third quarter of 2027. So to summarize, we believe PROSERA provides one adequate and well-controlled study. TORREY provides the confirmatory evidence and the seriousness of the disease, the unmet medical need and the novel mechanism of action all support this NDA pathway. The Type B meeting is an important step in that process and supports our current NDA timing of September 2026. With that regulatory context in mind, I'll hand it over to Dr. Rob Roscigno to discuss the CT FRI substudy findings. Rob? Robert Roscigno: Thank you, Caryn. I will now spend the next few minutes walking through the PROSERA CT FRI substudy and what it adds to our understanding of seralutinib's effect in PAH. So let's focus on what CT FRI adds to the PROSERA story. Clinical endpoints can tell us whether patients improved. And CT FRI helps us to understand the anatomical basis for that improvement. These analyses were performed with Fluidda's functional respiratory imaging or FRI platform, which allows us to quantify anatomical changes in the pulmonary vasculature and surrounding lung parenchyma. That is especially important for seralutinib because it is not simply a vasodilator. Its mechanism is designed to address remodeling biology in the lung. In TORREY, the FRI substudy gave us an early hint that seralutinib could drive arterial reverse remodeling. The PROSERA substudy was designed to go much deeper. It was a much larger prespecified exploratory substudy designed to test whether the TORREY signal held up at scale and whether the effect extended beyond the arterial compartment. I want to acknowledge that this is the largest and most comprehensive CT FRI data set ever generated from a controlled therapeutic trial in pulmonary hypertension. A total of 162 patients enrolled in the substudy and 125 patients had paired baseline and week 24 CT scans available for analysis. These effects were observed on top of highly intensive background therapy, including patients receiving double, triple and quadruple PAH therapy. The substudy was balanced across arms and representative of the broader PROSERA intent-to-treat or ITT population on demographics, hemodynamics and risk profile. The clinical endpoints in the substudy were also consistent with the broader ITT population, including improvement in 6-minute walk distance, NT-proBNP and REVEAL Lite 2. I'll walk you through what we found and why we think it matters. This slide gives a high-level result. Seralutinib showed statistically significant treatment effects across arterial, venous and fibrosis-like parenchymal parameters. The CT FRI signal was not confined to one vascular compartment. The breadth and internal consistency of these effects go beyond the arterial-specific signal we first saw in TORREY. Importantly, the imaging parameters correlated more tightly with clinical endpoints in PROSERA, including 6-minute walk distance, NT-proBNP and REVEAL Lite 2. The overall pattern is biologically coherent and consistent with seralutinib's inhibition of PDGFR, CSF1R and c-KIT. In other words, the findings form a coherent anatomical pattern that maps back to seralutinib's mechanism of action. So I want to point out the patient image on the right side of this slide is illustrative, but it gives a first visual sense of what we mean by reverse remodeling. At a high level, you want to see more red appear than blue. We'll come back to this case a little later and go through it in more detail. So let's first discuss the pulmonary vasculature. To interpret the CT FRI findings, it helps to start with the biology. PAH affects an integrated vascular and parenchymal system. PAH has historically been treated as an arterial disease, but it is not only an arterial disease. The pathology involves arteries, the capillary bed, venous filling, inflammation and parenchymal remodeling around the vascular bed. Those compartments are connected. If the arteries are obstructed, the capillaries are underperfused, transpulmonary flow is reduced and the veins become underfilled, inflammation and fibrosis add to the problem throughout the system. So if a therapy is truly modifying disease biology upstream, you would expect downstream effects to move in a coherent direction as well. If you look at the right-hand side of this slide, you can see each pulmonary vascular compartment, its structure and function, how it is affected by disease in addition to calling out what CT can actually detect. So this next slide maps each target of seralutinib, PDGFR, CSF1R, c-KIT and its anti-proliferative, anti-inflammatory and anti-fibrotic effects to each compartment of the pulmonary vasculature where we would expect it to act and to the imaging signal we observed. Starting in the pulmonary arteries, PDGFR inhibition maps to the arterial reverse remodeling signal, including reduced large atrial blood volume proportion. Next, in the parenchyma, PDGFR, CSF1R and c-KIT inhibition map to reduced fibrosis-like parenchymal ProACT features. The parenchymal signal is important because it points to potential anti-fibrotic effects beyond vasodilation. Finally, in the veins, we see increased venous volume and branching, which we view as an integrated downstream readout of improved upstream arterial parenchymal and capillary bed biology. The key point is that each compartment moves in a direction that is consistent with seralutinib's mechanism of action. With that, I'll walk through each compartment individually. So PROSERA reproduced and extended the reverse remodeling signal we first saw in the TORREY study. In the figure on the right, seralutinib significantly reduced BV10A percentage, which measures large arterial blood volume as a proportion of total blood volume. That is consistent with proximal arterial decompression and blood volume redistribution away from larger remodeled proximal vessels towards smaller peripheral arteries. This is the compartment where we would expect PDGFR inhibition to show up most clearly. BV10A percentage also demonstrated among the strongest clinical correlations of any FRI parameter. Towards the bottom of the slide, we show these clinical correlations. Importantly, changes in this arterial parameter correlated with improvements in 6-minute walk distance, NT-proBNP, REVEAL Lite 2 and ESC/ERS risk. So this arterial signal is not only statistically significant, it is also clinically connected and consistent with the signal we first observed in the TORREY substudy. Next, we look at the parenchymal signal. This may be one of the more important new findings in this data set. In the figure on the right, seralutinib significantly reduced fibrosis-like parenchymal volume and also normalized fibrosis-like parenchymal volume, while placebo progressed. To our knowledge, this is the first demonstration of a statistically significant reduction in fibrosis-like parenchymal features in a controlled PAH trial. These measures are CT-derived imaging metrics. They are not histology, but they quantify voxel-level features characteristic of fibrotic tissue using a deep learning algorithm trained on confirmed IPF patient data sets analogous to high attenuation area or HAA approaches reported by Insmed. The reductions were consistent across subgroups, including non-CTD patients, which supports a broader anti-inflammatory and antifibrotic effect rather than a CTD-specific phenomenon. This signal is consistent with seralutinib's PDGFR, CSF1R and c-KIT biology and supports a potential effect on inflammatory and fibrotic remodeling distinct from vasodilation. Clinical correlations are noted at the bottom of the slide. One important point is that CT likely underestimates the full remodeling burden in PAH because much of this relevant perivascular and capillary bed biology occurs below the resolution of the CT. So the detectable reduction in fibrosis like parenchymal features may capture only part of the total remodeling effect. The same fibrotic and inflammatory pathobiology is also relevant to PH-ILD and other fibrotic lung diseases, which supports the potential relevance of seralutinib beyond PAH. Finally, the venous compartment then gives us an integrated view of how these upstream effects may translate into improved blood flow. Let's look at seralutinib's effects on the pulmonary veins. In the figure on the right, seralutinib significantly increased total venous blood volume while placebo decreased. Clinical correlations are noted on the bottom of the slide. We also saw consistent increases across venous vessel sizes and vascular branching, including fractal dimension. To our knowledge, this is the first demonstration of venous vascular recovery in a controlled PAH trial. Why does that matter? In PAH, venous underfilling reflects reduced transpulmonary flow. It is not primarily a venous disease. If upstream arterial obstruction, parenchymal remodeling and capillary bed impairment begin to improve, the downstream consequence should be improved venous filling. This is why we view the venous signal as more than another isolated parameter. It may be an integrated readout of the broader treatment effect upstream. The increase in venous branching is also important because it suggests improved vascular complexity, not simply passive volume redistribution. The next question is whether these anatomical changes relate to clinical trajectory. In the PROSERA substudy, the correlation support that connection. The tables at the bottom of this slide show a baseline arterial, venous and vascular complexity parameters correlated with hemodynamic and clinical measures, including pulmonary vascular resistance, mean pulmonary arterial pressure, cardiac output, NT-proBNP and risk scores. Changes in FRI parameters also correlated with improvements in 6-minute walk distance, NT-proBNP and risk scores. These relationships were not detectable in the smaller TORREY substudy. In PROSERA, the larger sample size and updated algorithm allowed us to see a stronger link between anatomical imaging findings and clinical outcomes. That gives us confidence that these are not just imaging observations. They are biologically and clinically relevant measures that help connect structural remodeling to clinical benefit. So this table pulls the compartment level findings together all in one place. In the arterial category, BV10A percentage decreased, consistent with reduced large artery blood volume proportion and proximal decompression. In the parenchymal category, both fibrosis-like parenchymal volume and normalized fibrosis-like parenchymal volume decreased. In the venous category, total venous blood volume, small venous blood volume, midsized venous blood volume and venous fractal dimension all increased. The key point here is not any single parameter in isolation. It's the consistency of the signal across arterial, parenchymal and venous measures. This pattern is what we would expect from seralutinib's mechanism, arterial reverse remodeling, reduced fibrosis-like parenchymal features and improved downstream venous filling and vascular branching. More broadly, the pattern is directionally supportive across the data set, including parameters that did not individually reach statistical significance. Again, I want to remind you this was a prespecified exploratory substudy. The p-values are nominal and unadjusted for multiplicity. So to make the concept more tangible, this slide shows 2 patient examples. These are individual patients, not the trial result, and they are not representative of the full study population. Both patients were on triple stable background therapy and were functional Class III at baseline. In the placebo case on the left, the patient remained on intensive background therapy, but the vasculature worsened over time. Total venous volume decreased, proximal arterial volume increased and 6-minute walk distance stayed essentially flat. Let's compare this to the seralutinib case on the right. I showed this image to you earlier. Here, we see the visual pattern we mean by reverse remodeling. Large arterial volume decreased, small arterial volume increased, total venous volume increased, 6-minute walk distance improved and NT-proBNP declined. The important point is that the visual pattern lines up with the population level data, arterial decompression, venous filling and clinical improvement, all moving together. This next example focuses specifically on the fibrosis-like parenchymal signal. The images on the left are from a single seralutinib-treated patient on double background therapy who had a visible reduction in fibrosis-like CT features from baseline to week 24. The patient also had improvement in 6-minute walk distance and NT-proBNP. The important point is not the individual patient alone. It is that the visual change is directionally consistent with the broader parenchymal treatment effect seen in the substudy. So fibrosis volume was quantified using FibroNet, a deep learning algorithm trained on confirmed IPF patient data and analogous to high attenuation area or HAA approaches used in ILD imaging. Again, CT only detects changes above a certain resolution. It likely understates the full burden of remodeling, particularly around the capillary bed. This supports the potential relevance of seralutinib in diseases where vascular remodeling, inflammation and fibrosis overlap, including PH-ILD and other fibrotic lung diseases. So to summarize, if we step back, PAH is a multi-compartment disease and seralutinib appears to affect these compartments in a coherent way even on top of intensive background therapy. The importance of these data is the consistency of the signal across anatomy, mechanism and clinical outcomes. Multi-compartment, vascular remodeling effects of this breadth have not been shown by traditional vasodilator therapies, which suggest added structural benefit rather than something redundant with existing vasodilator therapy. The arterial remodeling signal we first saw in the TORREY substudy is now reproduced and extended in a much larger Phase III substudy and the parenchyma seralutinib-reduced fibrosis-like features supporting potential anti-fibrotic activity that is distinct from vasodilation. In the vein, seralutinib showed what we believe is the first controlled trial evidence of venous vascular recovery, including gains in venous blood volume and branching. Taken together, these imaging signals point to a mechanism-based effect on disease biology consistent with PDGFR, CSF1R and c-KIT pathway inhibition. The clinical correlations are also important. These structural imaging findings correlated with improvements in 6-minute walk distance, NT-proBNP and Reveal Lite 2. That links anatomical remodeling to clinical benefit. These data strengthened the cumulative weight of evidence for seralutinib across the program, including the placebo-controlled Phase Ib, the Phase II TORREY study and the Phase III PROSERA study. Taken together, we believe the CT FRI data provide important anatomical support for the clinical benefit observed in PROSERA and reinforce seralutinib's differentiated profile in PAH. With that, I'll turn the call back over to Bryan to discuss our financial position and recent capital structure actions. Bryan Giraudo: Thanks, Rob. As of March 31, 2026, we had cash and cash equivalents and marketable securities of $99 million. Based on our current plans, we expect our cash runway to extend to the first quarter of 2027. Operating expenses will come down now that the PROSERA study has wound down. Additionally, we have implemented a reduction in force and broader cost containment measures. To this end, the first quarter included onetime charges and our go-forward quarterly burn should be lower. I will leave the detailed financials to the press release and our 10-Q filing that we did on Friday afternoon. Moving on to the bond exchange. We have $200 million of aggregate principal amount convertible senior notes approaching maturity in 2027. With that maturity coming closer, addressing the capital structure proactively was a necessary step to keep the company focused on NDA execution and potential commercialization. We've been working constructively with our noteholders since the PROSERA top line readout in February, and both sides recognize the value of aligning the capital structure with the path forward as soon as practical. We were able to come to terms efficiently, and we view the outcome as an important step in removing the overhang and improving our focus on execution. Under the exchange for each $1,000 of existing notes tendered holders will receive a combination of equity consideration, new secured convertible notes and for those who tender early warrants. The new notes are secured by a priority -- first priority lien on substantially all the company's assets and bear cash interest at 7.5% paid semiannually. On a fully subscribed basis, this takes our outstanding convertible debt from $200 million down to $72 million, a reduction of $128 million and extends our debt maturity from 2027 to 2030. The exchange requires a minimum participation of 98%, which may be waived. We are also running a concurrent consent solicitation to remove substantially all restricted covenants from the existing indenture. Cantor Fitzgerald is serving as dealer manager and Latham & Watkins is serving as our legal counsel. Additional details are included in the press release and our Form 8-K that was filed with the SEC this morning. With that, let me turn it back over to Faheem for some closing remarks. Faheem Hasnain: Thanks, Bryan. So stepping back, the key point today is that our conviction has strengthened. We've taken the balance sheet actions needed to align the company with a path forward. We now have a confirmed Type B pre-NDA meeting and expect to submit the NDA in September of 2026. We also have CT FRI data showing multi-compartment reverse remodeling across arterial, venous, fibrosis-like and complexity parameters with clinical correlations that support the biological relevance of those findings. Taken together with the Phase III PROSERA data and the Phase II TORREY data, we believe the overall evidence supports an NDA path for seralutinib. So with that, operator, we're ready to open the line for questions. Operator: [Operator Instructions] And our first question comes from the line of Yasmeen Rahimi with Piper Sandler. Dominic Lorenzi: This is Dominic on for Yasmeen Rahimi. Congrats on all the great updates in the PROSERA CT FRI data. Could you help us understand how this data not only helps for the upcoming pre-NDA Type B meeting, but also potentially support a differentiated label? Kind of what are your thoughts on that and the plan with those data? Faheem Hasnain: Yes. Caryn, we'll ask you to take the first part of that question. Caryn Peterson: Sure. Thank you, Faheem. The data that was presented today is going to go into the NDA. We did not get it in time to put it into the pre-NDA briefing package, although we will highlight it at the meeting. We believe it's going to be very important in terms of confirmatory evidence as we look at the biology and mechanistic plausibility. So the data set once fully complete, will be a big part of the NDA. And we -- if we do get it in the label, it will be in the pharmacodynamic section of the label. Those discussions will occur at the meeting in June. Faheem Hasnain: And Bob Smith, can you handle the last part of the question around differentiation? Bob Smith: Sure. Absolutely. We feel like, first of all, the profile of seralutinib between the data in Phase I and Phase II is extremely strong. I think it even gets stronger with our Phase III data. With the FRI imaging data, this is unprecedented in the market. To my knowledge, we have not seen any other PAH therapy have this sort of information to clearly in humans show a strong reverse remodeling capability. And so we expect the label to be highly differentiated because of this. Operator: Your next question comes from the line of Joseph Schwartz with Leerink Partners. Heidi Jacobson: This is Heidi on for Joe. Can you walk us through the time line between now and a potential September filing? What steps are getting to a potential NDA filing in addition to the Type B meeting? Faheem Hasnain: Caryn? Caryn Peterson: Yes, sure. We're actively working on the NDA submission as we speak. Obviously, it's a very large dossier and all of the analyses are ongoing and will be completed late August so that we can get the filing in mid-September. Everything is happening in parallel to the meeting, and we have been planning this for quite some time. So we're on track, and we'll be ready to file in September. Bryan Giraudo: And it's Bryan. I would just add the following that the decision to go from a Type C to a Type B meeting, again, not only was on the basis of the totality of the evidence that we've seen through all of the clinical work with seralutinib, but at the recommendation of a number of our FDA advisers and consultancies that we have been using that upon their review of the data as well as the competitive landscape suggests that we should move aggressively forward because of the high unmet medical need. So again, I think it's very important that you take into consideration that it's not just Gossamer making this decision, but really robust support from those who have walked the walk, if you will, with the FDA within cardiorenal for many, many years. Operator: Your next question comes from the line of Ellie Merle with Barclays. Jasmine Fels: This is Jasmine on for Ellie. Congratulations on the data. I'm trying to understand the clinical relevance of these CT FRI measures. Is it common for physicians to do imaging like this when they manage these PAH patients to measure progression or when diagnosing? And then secondly, would you expect the imaging results to deepen over time? And will patients in the substudy have more imaging done at a later time point? Faheem Hasnain: Jean-Marie? Jean-Marie Bruey: So to answer the question, I think when we look at the standard endpoint, the PVR, the 6-minute walk, the NT-proBNP, they measure the functional hemodynamic consequence of disease, but you don't visualize underlying structural change. So the clinical endpoint can be affected by placebo or background therapy. So what we have, the data we have with FRI, it provides a mechanistic insight. It separately quantify arterial, venous and fibrotic like feature and vascular complexity change. So we're trying to directly tie those markers with the disease pathology. I think the value is biological plausibility, FRI strengthen understanding of how seralutinib works. So we have a structural reverse remodeling versus acute vasodilation. So it's not a surrogate endpoint. I want to make sure that it does add mechanistic credibility to support totality of evidence for regulator and clinician. Concerning the questions at 48 weeks or 72 weeks, we don't have the data yet, but we will look into it. Faheem Hasnain: And just to be clear, this technology is not something that's standard in the context of physician and clinical practice. But as what Jean-Marie said, is it really does bring the mechanistic evidence and the structural evidence to the table as to what seralutinib is doing in the context of the lungs. We will certainly be looking at the possibility of repeating some of this imaging in -- at later time points. And then obviously, when we have that data, we'll present it back to you. Bryan Giraudo: And I think to add to what Faheem said, what's most important here -- I think what's most important here is no other sponsor has ever done this robust level of analysis using CT. So we do think that what Gossamer has achieved with this Fluidda CT study is going to set a new standard for how the community will look at a pharmaceutical intervention in PAH to see, as Rob laid out, all 3 compartments having statistically significant effect, we think is not only very beneficial for patients, but it's certainly setting a new standard for drugs in pulmonary artery hypertension. Operator: Your next question comes from the line of Vamil Divan with Guggenheim Securities. Vamil Divan: Maybe 2, if I could. So one, just curious in terms of communications post the meeting with the FDA. Should we assume to hear back sort of once you get the minutes, I don't know, I guess, maybe in the July sort of time frame or next updates we'd get from the company there. And then my other question is sort of tied to one of the earlier questions and just sort of based on the results here, I guess there's a couple of parts to the question. One, you mentioned that these patients in general seem to do similar to the patients in the broader study population on the clinical endpoint. Maybe you can provide a little bit more detail on that just in terms of the PVR 6-minute walk results you've seen with these patients. And I'm sort of curious what this means in terms of how you think about commercialization? Like are there certain patient types or patient severities that you think may be better candidates for seralutinib than others based on the competitive dynamics out there and the other options that doctors have available? Faheem Hasnain: Bryan, do you want to take the first piece? Bryan Giraudo: Yes. So Vamil, we'll provide an update on our FDA disclosures during our second quarter results that we'll do later in the summer after the meeting. But Faheem, I'll let you direct the more important question for Vamil. Faheem Hasnain: Yes. Rob, do you want to handle the second piece? Robert Roscigno: So the second question, I believe, was how these patients, if you will, perform regarding their clinical endpoints as compared to the overall PROSERA intent-to-treat population. These patients did show significant improvement in 6-minute walk and significant lowering or decrease in NT-proBNP, exactly what we would expect and very if you will, supportive of this cohort. As far as your second question? Faheem Hasnain: Yes. Well, I think the last part of your question was about commercial utilization and how would seralutinib get used in a commercial context. Bob, you can add in. But basically, clearly, you can see a very pronounced effect in the intermediate to high-risk subgroup. That's pretty clear. But the story doesn't end there. When you see the CT FRI data, you realize that something profound is going on in the context of the lung and even through the TORREY data, the ECHO data showing us what's going on in the right heart, that kind of so-called reverse remodeling context. I would like to tell you that the clinical community is quite intrigued about using this drug across the spectrum of patients because even in the lower-risk patients, the patients that are otherwise functionally quite capable, there is the potential to be able to use this drug earlier to prevent longer-term progression. And given the safety profile of the drug, not impact quality of life and that quality of life component becomes very important as you're using it in a patient that has otherwise pretty good functional capabilities. So we do see the potential for seralutinib to be used across the spectrum of PAH patients. Bob Smith: Yes. Faheem, that's exactly what I was going to say. I would just say with this data, I think it will motivate the market to start patients sooner on seralutinib. And as Faheem said, because of what we're seeing from a safety and tolerability standpoint and efficacy standpoint now as imaging data that they'll be able to stay on for a much longer time with that, hopefully portending better outcomes for these patients. Faheem Hasnain: Yes. I don't think we can stress enough how important a new mechanism is for these patients, especially a new mechanism that doesn't carry the significant burden of toxicities that many of the current therapies do. Operator: With no further questions in queue. I will now hand the call back over to Faheem Hasnain, CEO, for closing remarks. Faheem Hasnain: Yes. Thank you very much, and thanks all for listening into the call. I just want to end this call by, first off, thanking the patients that participated in the PROSERA study. Obviously, without that participation, we're not able to advance treatments here for PAH. I'd also like to thank the patient advocacy groups that have been very supportive of Gossamer and the opportunity that seralutinib represents to their patients. And I want to thank the investigators and more broadly, the clinical community where we have been experiencing, I'm here at ATS now as we speak in Orlando, just the tremendous amount of support that we're getting and encouragement and quite frankly, the expectation that we will continue to push forward and get this drug approved. So thank you, everybody, and we look forward to further updates. Operator: Thank you, again, for joining us today. This does conclude today's conference call. You may now disconnect. Before you buy stock in Gossamer Bio, consider this: The Motley Fool Stock Advisor analyst team just identified what they believe are the 10 best stocks for investors to buy now… and Gossamer Bio wasn’t one of them. The 10 stocks that made the cut could produce monster returns in the coming years. Consider when Netflix made this list on December 17, 2004... if you invested $1,000 at the time of our recommendation, you’d have $472,852!* Or when Nvidia made this list on April 15, 2005... if you invested $1,000 at the time of our recommendation, you’d have $1,317,207!* Now, it’s worth noting Stock Advisor’s total average return is 984% — a market-crushing outperformance compared to 210% for the S&P 500. Don't miss the latest top 10 list, available with Stock Advisor, and join an investing community built by individual investors for individual investors. See the 10 stocks » *Stock Advisor returns as of May 27, 2026. This article is a transcript of this conference call produced for The Motley Fool. While we strive for our Foolish Best, there may be errors, omissions, or inaccuracies in this transcript. 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Interested in Gossamer Bio, Inc.? Here are five stocks we like better. Gossamer Bio is still targeting a September 2026 NDA submission for seralutinib in pulmonary arterial hypertension, with a June FDA pre-NDA meeting set to help shape the filing. Management said approval could potentially follow in the third quarter of 2027 if the process stays on track. The company highlighted efficacy and imaging data from PROSERA and the CT-FRI sub-study, saying seralutinib showed a 13.3-meter placebo-adjusted improvement in six-minute walk distance and favorable signals across arterial, venous and fibrosis-like imaging measures. Gossamer believes the totality of evidence could support a differentiated label and commercial profile. Gossamer also addressed its balance sheet, saying it had $99 million in cash at quarter-end and expects runway into Q1 2027. It announced a convertible note exchange that could cut debt from $200 million to $72 million and push maturity out to 2030. Gossamer Bio (NASDAQ:GOSS) said it is moving ahead with plans to seek U.S. approval for seralutinib in pulmonary arterial hypertension, outlining a September 2026 target for a New Drug Application submission while also detailing new imaging data and steps to address its balance sheet during its first-quarter 2026 earnings call. The company’s executives said the regulatory strategy is based on the totality of evidence from the Phase 3 PROSERA study and the Phase 2 TORREY study. Chief Executive Officer Faheem Hasnain said Gossamer’s “conviction in seralutinib has increased since the top-line readout, not decreased,” citing PROSERA, TORREY, new CT imaging results and ongoing engagement with the Food and Drug Administration. → 3 Crucial Aerospace Component Makers That Analysts Love Caryn Peterson said Gossamer is pursuing an NDA under a framework of “one adequate and well-controlled clinical investigation plus confirmatory evidence.” She said the company believes PROSERA can serve as the adequate and well-controlled study, while TORREY provides confirmatory evidence. Peterson said Gossamer had initially considered a Type C meeting with the FDA but is now moving forward with a Type B pre-NDA meeting, which she described as a formal pre-submission interaction. The company submitted the meeting request in April 2026, and the FDA has granted an in-person meeting in mid-June. → McDonald's Is the Cheapest It’s Been in Years—Does That Make It a Buy? “Based on that timing, our NDA submission target remains in September this year, subject to the outcome of the pre-NDA meeting,” Peterson said. If the process proceeds as expected, she said a potential approval could follow in the third quarter of 2027. Hasnain summarized the PROSERA results by noting that seralutinib produced a placebo-adjusted improvement of 13.3 meters in six-minute walk distance at week 24. Patients receiving seralutinib improved 28.2 meters from baseline, compared with 13.5 meters for placebo. The result had a P value of 0.032, which met the traditional 0.05 threshold for statistical significance but did not meet the study’s pre-specified 0.025 alpha threshold. Hasnain said all four key secondary endpoints favored seralutinib, with a stronger effect in a pre-specified risk-enriched subgroup. → 3 Stocks to Own If Gas Prices Keep Rising Dr. Rob Roscigno reviewed findings from the PROSERA CT-FRI sub-study, which used Fluidda’s functional respiratory imaging platform to evaluate anatomical changes in the pulmonary vasculature and lung parenchyma. He said 162 patients enrolled in the sub-study, with 125 patients having paired baseline and week 24 CT scans available for analysis. Roscigno said the imaging data showed statistically significant treatment effects across arterial, venous and fibrosis-like parenchymal parameters. He said the findings extended the arterial reverse remodeling signal first observed in TORREY and suggested effects beyond a single vascular compartment. According to Roscigno, seralutinib significantly reduced BV10A percentage, a measure of large arterial blood volume as a proportion of total blood volume, which he said was consistent with proximal arterial decompression and redistribution toward smaller peripheral arteries. He also said the company observed statistically significant reductions in fibrosis-like parenchymal volume and normalized fibrosis-like parenchymal volume, while placebo progressed. In the venous compartment, Roscigno said seralutinib significantly increased total venous blood volume while placebo decreased. He said increases were also seen across venous vessel sizes and vascular branching, including fractal dimension. The company characterized the venous findings as a potential integrated readout of improved upstream arterial, parenchymal and capillary bed biology. Roscigno said changes in imaging parameters correlated with clinical endpoints, including six-minute walk distance, NT-proBNP and REVEAL Lite 2. However, he emphasized that the CT-FRI work was a pre-specified exploratory sub-study, and that the P values were nominal and unadjusted for multiplicity. During the question-and-answer session, Dr. Jean-Marie Bruey said FRI is not a surrogate endpoint but provides “mechanistic insight” by separately quantifying arterial, venous, fibrosis-like and vascular complexity changes. Hasnain added that the technology is not standard in routine PAH clinical practice. In response to an analyst question, Peterson said the CT-FRI data were not included in the pre-NDA briefing package because they were not ready in time, though the company plans to highlight them at the June meeting. She said the full dataset is expected to be part of the NDA and could be discussed for inclusion in the pharmacodynamic section of the label. Chief Commercial Officer Bob Smith said the company believes seralutinib could have a differentiated profile in the PAH market, pointing to the imaging data and prior Phase 1 and Phase 2 results. He said the company expects the label to be “highly differentiated” if the data are included. Asked about potential commercial use, Hasnain said the treatment effect was “very pronounced” in the intermediate- to high-risk subgroup, but he also suggested clinicians may be interested in using seralutinib across the PAH patient spectrum, including earlier in the disease course, given the company’s view of the drug’s safety profile and mechanism. Chief Operating Officer and Chief Financial Officer Bryan Giraudo said Gossamer ended the first quarter with $99 million in cash, cash equivalents and marketable securities. Based on current plans, the company expects its cash runway to extend into the first quarter of 2027. Giraudo said operating expenses are expected to decline now that the PROSERA study has wound down. He also cited a previously implemented reduction in force affecting approximately half the company, broader cost containment measures and a pause in other development activities. He said the first quarter included one-time charges, and the company’s go-forward quarterly cash burn should be lower. Gossamer also announced a convertible note exchange aimed at addressing $200 million in aggregate principal amount of convertible senior notes maturing in 2027. Under the exchange, holders tendering existing notes will receive a mix of equity consideration, new secured convertible notes and, for early tenders, warrants. Giraudo said that on a fully subscribed basis, the transaction would reduce outstanding convertible debt from $200 million to $72 million and extend the debt maturity from 2027 to 2030. The new notes will be secured by a first-priority lien on substantially all company assets and bear 7.5% cash interest paid semiannually. The exchange requires minimum participation of 98%, which may be waived. Hasnain closed the call by saying the company is focused on advancing seralutinib toward approval and thanked patients, advocacy groups, investigators and the clinical community for their involvement in the PROSERA study and broader development program. Gossamer Bio, Inc is a clinical-stage biopharmaceutical company headquartered in San Diego, California. Founded in 2012, the company is focused on discovering and developing oral, once-daily therapies for immune-mediated and inflammatory diseases, as well as oncology indications. Gossamer Bio leverages a deep pipeline of small-molecule candidates aimed at improving patient outcomes in areas of high unmet need. The company's lead programs include GB004, an S1P1 receptor modulator in late-stage development for ulcerative colitis, and GB1275, a CD11b modulator being investigated in solid tumors and hematologic malignancies. This instant news alert was generated by narrative science technology and financial data from MarketBeat in order to provide readers with the fastest reporting and unbiased coverage. Please send any questions or comments about this story to [email protected]. The article "Gossamer Bio Q1 Earnings Call Highlights" was originally published by MarketBeat. View MarketBeat's top stocks for May 2026.

- FDA Confirms In-Person Pre-NDA Type B Meeting in Mid-June - - Positive PROSERA CT FRI Results Demonstrated Multiple Statistically Significant Treatment Effects, Including Novel Signals Correlated with Clinical Outcomes - - Gossamer Announces Commencement of Exchange Offer and Consent Solicitation for Outstanding 5.00% Convertible Senior Notes Due 2027 - - Cash, cash equivalents and marketable securities totaled $99 million as of March 31 - SAN DIEGO, May 18, 2026--(BUSINESS WIRE)--Gossamer Bio, Inc. (Nasdaq: GOSS), a clinical-stage 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 first quarter ended March 31, 2026, and provided a business update. Gossamer Bio and the Chiesi Group are jointly developing seralutinib under a global collaboration agreement. "We are executing across multiple fronts at Gossamer," said Faheem Hasnain, Chairman, Co-Founder, and CEO of Gossamer Bio. "We have secured an in-person Pre-NDA Type B meeting with the FDA, reflecting our conviction in both the breadth of the PROSERA dataset and in the totality of evidence supporting seralutinib. Subject to the outcomes of that meeting, we expect to submit an NDA for seralutinib in PAH in September of this year. We see a regulatory path forward, toward an NDA submission, and we are executing against it. "The PROSERA CT FRI substudy results further strengthen our confidence in seralutinib. For the first time in a controlled PAH trial, we saw statistically significant imaging signals not only in the arterial compartment, but also across the venous vasculature and the parenchyma, and these signals correlated with clinical outcomes. This expands the seralutinib story well beyond arterial remodeling and provides structural evidence that seralutinib is acting across the lung in a manner consistent with its mechanism of action, even in a well-treated patient population. "We have also taken steps to address our capital structure through a proposed exchange of our convertible notes, which we believe will strengthen our balance sheet as we approach this pivotal regulatory milestone. Our focus remains on disciplined execution as we look to advance seralutinib and prepare for the next phase of the Company’s growth." Seralutinib (GB002): Inhaled PDGFR, CSF1R and c-KIT Inhibitor Regulatory Interactions: Type B Pre-NDA Meeting and Potential NDA Submission The Company has requested and received confirmation of an in-person Pre-NDA Type B meeting with the U.S. Food and Drug Administration (FDA), scheduled for mid-June. Following continued review of the PROSERA dataset, including the efficacy data and consistency of clinical, imaging, and safety findings, the Company elected to pursue a Type B meeting rather than the previously anticipated Type C meeting, to enable a more comprehensive discussion of the totality of evidence supporting a potential NDA submission for seralutinib in PAH. Gossamer is pursuing a New Drug Application (NDA) on the basis of one adequate and well-controlled clinical investigation plus confirmatory evidence. Subject to the outcomes of the Pre-NDA meeting, the Company expects to submit an NDA for seralutinib for the treatment of PAH in September 2026. If the NDA is accepted for filing, seralutinib could be eligible for FDA approval in the third quarter of 2027. PROSERA CT FRI Sub-Study Topline Results The PROSERA CT functional respiratory imaging (FRI) exploratory substudy (n = 162) demonstrated multiple statistically significant exploratory treatment effects across arterial, venous, fibrosis‑related, and vascular complexity parameters, yielding what the Company believes is the broadest multi‑compartment imaging signal reported to date from a controlled therapeutic trial in pulmonary hypertension. Building on the arterial remodeling signal first identified in earlier studies, PROSERA generated what the Company believes is the most comprehensive CT FRI dataset from a controlled PAH trial, expanding the characterization of seralutinib's biologic activity across the pulmonary vasculature and lung parenchyma. All reported p-values were nominal and unadjusted for multiplicity. In the arterial compartment, seralutinib demonstrated a statistically significant reduction in the proportion of blood volume within larger arterial vessels versus placebo (p = 0.0200), consistent with proximal decompression and arterial remodeling in a larger and more heterogeneous Phase 3 population. PROSERA's analytical scope also extended to include more proximal vessels, broadening the portion of the pulmonary vasculature assessed. Beyond the arterial compartment, PROSERA identified statistically significant venous and fibrosis‑related treatment effects not previously detected in the seralutinib program. Seralutinib increased total venous blood volume (p = 0.0155) and small venous vessel volume (p = 0.0341), reduced absolute and normalized fibrosis-like tissue in the parenchyma (p = 0.0260, p = 0.0250), and increased venous vascular fractal dimension (p = 0.0435), consistent with greater vascular complexity. These multi‑compartment findings were enabled by the scale and scope of the PROSERA dataset. While PAH has historically been characterized as a disease of the pulmonary arteries, pathological and imaging literature increasingly recognize the contributions of impaired microvascular perfusion, venous underfilling, inflammation, and perivascular fibrosis to disease progression. The venous and fibrosis signals in PROSERA may provide structural context for these processes and are aligned with seralutinib's non‑vasodilatory mechanism targeting inflammatory, proliferative, and fibrotic pathways within the pulmonary vasculature and surrounding parenchyma. Imaging changes observed in PROSERA were associated with favorable changes in clinical outcomes, including pulmonary hemodynamics, NT‑proBNP, 6‑minute walk distance, and REVEAL Lite 2 risk score. These correlations reinforce the biological relevance of the CT FRI data. The Company believes these exploratory findings, taken together with their consistency with clinical results and seralutinib's mechanism of action, provide meaningful structural support for seralutinib's activity across the pulmonary vasculature. Convertible Notes Exchange Offer The Company today announced the commencement of an exchange offer (the "Exchange Offer") to exchange any and all of its outstanding 5.00% Convertible Senior Notes due 2027 (the "Existing Notes," $200 million aggregate principal amount outstanding) for a combination of (i) shares of common stock or prefunded warrants, (ii) new 7.50% Senior Secured First Lien Convertible Notes due 2030 (the "New Notes"), and (iii) with respect to Existing Notes tendered prior to the early tender deadline, warrants to purchase shares of common stock (the "Purchase Warrants"), and a concurrent consent solicitation (the "Consent Solicitation") to adopt certain proposed amendments to the indenture governing the Existing Notes. For each $1,000 in aggregate principal amount of Existing Notes validly tendered, holders will receive (i) 1,588.2353 shares of common stock (or prefunded warrants in lieu thereof), (ii) $360 principal amount of New Notes, and (iii) with respect to Existing Notes tendered prior to the early tender deadline only, 750 Purchase Warrants. The New Notes will bear interest at a rate of 7.50% per annum, payable semi-annually in arrears in cash, and will be secured by a first-priority lien on substantially all assets of the Company and its subsidiaries. The New Notes will mature on July 1, 2030 and will have an initial conversion price at a 10% premium to a reference price, subject to certain limitations. The Purchase Warrants will have an exercise price at a 25% premium to a reference price, subject to certain limitations, and will be exercisable beginning six months after issuance through the fifth anniversary of issuance. The Proposed Amendments would eliminate substantially all of the restrictive covenants in the indenture governing the Existing Notes, as well as certain events of default and related provisions applicable to the Existing Notes. Holders of approximately 75.2% of the Existing Notes have entered into a transaction support agreement to tender their Existing Notes in the Exchange Offer. The Exchange Offer is subject to a minimum participation condition of 98% of the aggregate principal amount of Existing Notes, which may be waived. The early tender deadline is expected to be 10 business days following commencement of the Exchange Offer, and the Exchange Offer is expected to expire 21 business days following commencement, unless extended or earlier terminated. Upon full participation, the Exchange Offer would reduce the Company's outstanding convertible indebtedness from $200 million to $72 million in aggregate principal amount, a reduction of $128 million. The Exchange Offer is intended to extend the Company's debt maturity profile and strengthen its balance sheet as seralutinib advances toward a potential NDA submission in pulmonary arterial hypertension. The New Notes will include a minimum cash covenant of $40 million, stepping down upon the completion of certain aggregate financing thresholds and acceptance for filing of the Company's NDA for seralutinib by the FDA. Cantor Fitzgerald & Co. is serving as dealer manager and Latham & Watkins LLP is serving as legal counsel to the Company in connection with the Exchange Offer. The securities offered in the Exchange Offer have not been and will not be registered under the Securities Act of 1933, as amended (the "Securities Act"), and may not be offered or sold in the United States absent registration or an applicable exemption from registration requirements. The Exchange Offer is being made only to holders of Existing Notes that are "qualified institutional buyers" as defined in Rule 144A under the Securities Act. Financial Results for Quarter Ended March 31, 2026 Cash, Cash Equivalents and Marketable Securities: Cash, cash equivalents and marketable securities totaled $99.2 million as of March 31, 2026. We expect the combination of current cash, cash equivalents and marketable securities will be sufficient to fund our operating and capital expenditures into the first quarter of 2027. Revenue from contracts with collaborators: For the quarter ended March 31, 2026, revenue associated with our collaboration with Chiesi was $17.0 million, including $9.3 million of cost reimbursement revenue, compared to $9.9 million of revenue for the same period in 2025. Research and Development (R&D) Expenses: For the quarter ended March 31, 2026, R&D expenses were $43.1 million, compared to $38.0 million for the same period in 2025. The increase was primarily driven by costs associated with clinical trials for seralutinib. General and Administrative Expenses (G&A): For the quarter ended March 31, 2026, G&A expenses were $18.7 million, compared to $8.7 million for the same period in 2025. The increase was primarily driven by one-time severance and related charges associated with the previously announced reduction in force. Net Loss: Net loss for the quarter ended March 31, 2026, was $46.7 million, or $0.20 basic net loss per share, compared to a net loss of $36.6 million, or $0.16 basic net loss per share, for the same period in 2025. Conference Call and Webcast Gossamer’s management team will host a conference call and live audio webcast at 8:00 a.m. ET today, Monday, May 18th, to discuss its first quarter 2026 financial results and business update. The live audio webcast may be accessed through the "Events / Presentations" page in the "Investors" section of the Company's website at gossamerbio.com. Alternatively, the conference call may be accessed through the following: Domestic Dial-in Number: 1-800-715-9871 International Dial-in Number: 1-646-307-1963 Conference ID: 3974570 Live Webcast: https://edge.media-server.com/mmc/p/qud2to75 A replay of the audio webcast will be available for 30 days on the "Investors" section of the Company's website, gossamerbio.com. About Gossamer Bio Gossamer Bio is a clinical-stage biopharmaceutical company focused on the development and commercialization of seralutinib for the treatment of pulmonary arterial hypertension and pulmonary hypertension associated with interstitial lung disease. 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 timing, occurrence and outcome of the Company’s planned Pre-NDA Type B meeting with the U.S. Food and Drug Administration; the timing and potential submission of an NDA for seralutinib in PAH; the potential significance, interpretation and implications of data from the Phase 3 PROSERA study, including the CT FRI substudy; the development potential and market opportunity of seralutinib in PAH, PH-ILD and other indications; the Company’s proposed exchange offer and consent solicitation relating to its outstanding 5.00% convertible senior notes due 2027, including the anticipated benefits thereof; 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: the Company may not be able to identify a development path forward for seralutinib or submit an NDA on the timeframe we expect or at all, 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; topline results the Company reports are based on preliminary analysis of key data, and such data may change following a more comprehensive review of the data related to the clinical trial or substudy and such topline data may not accurately reflect the complete results of a clinical trial or substudy; the Company’s interpretation, significance and regulatory relevance of data from the Phase 3 PROSERA study, including the CT FRI substudy, may be inconsistent with the views of the FDA or others; risks related to the Company’s proposed exchange offer and consent solicitation, including whether the transaction is completed and whether the anticipated benefits are realized; we may not be able to complete the exchange offer on the anticipated timeline or at all and we may not realize the anticipated benefits therefrom; potential delays in the commencement, enrollment and completion of clinical trials; disruption to our operations from unexpected events, including clinical trial delays; 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 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; unstable market and economic conditions and changes in healthcare legislation, tariffs and trade policies may adversely affect the Company’s business and financial condition and the broader economy and biotechnology industry; Gossamer may use its capital resources sooner than it expects; and other risks described in the Company’s prior press releases and 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. The offering, issuance and sale of the new convertible senior notes as part of the exchange offer has not been registered under the Securities Act of 1933, as amended, or any other securities laws. This presentation shall not constitute an offer to sell, or the solicitation of an offer to buy, the new convertible notes, shares of common stock (or prefunded warrants) and purchase warrants offered in the exchange offer, the shares of common stock issuable upon conversion of the convertible notes, prefunded warrants or purchase warrants, the existing convertible notes or any other securities, nor will there be any sale of such securities or any other securities, in any state or other jurisdiction in which such offer, sale or solicitation would be unlawful.   View source version on businesswire.com: https://www.businesswire.com/news/home/20260518356585/en/ Contacts For Investors and Media: Bryan Giraudo, Chief Financial Officer & Chief Operating OfficerGossamer Bio Investor [email protected]