GOSS

EX-99.1

2 goss-20261110xexx991xearni.htm

EX-99.1

Document

Exhibit 99.1

Gossamer Bio Announces Third Quarter 2026 Financial Results and Provides Business Update

– New Drug Application for Seralutinib in PAH Submitted to the U.S. FDA in September 2026 –

– Structured Private Placement Provides $25 Million Upfront and Up to $125 Million of Additional Committed Capital Upon FDA Acceptance of the Seralutinib NDA –

– 1-for-80 Reverse Stock Split Completed in September 2026 –

- Cash, Cash Equivalents and Marketable Securities Totaled $51.2 Million as of September 30, 2026 -

SAN DIEGO—(BUSINESS WIRE)— November 10, 2026 — 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 third quarter ended September 30, 2026, and provided a business update.

“Submitting our first NDA marks an important milestone for Gossamer in our continued efforts to bring seralutinib to patients living with PAH,” said Faheem Hasnain, Chairman, Co-Founder and Chief Executive Officer of Gossamer Bio. “Furthermore, FDA acceptance of the application in 2026 would, subject to other customary closing conditions, unlock up to approximately $125 million in additional committed capital to support our priorities, including preparations for a potential launch. We remain focused on supporting the FDA’s review and preparing for a potential commercial launch of seralutinib in 2027.”

Seralutinib (GB002): Inhaled PDGFRα/β, CSF1R and c-KIT Inhibitor

New Drug Application Submitted for Seralutinib in PAH

•    Gossamer submitted a New Drug Application (NDA) to the U.S. Food and Drug Administration (FDA) in September 2026 for seralutinib for the treatment of PAH. This is the Company’s first NDA submission.

•    The NDA is supported by the Phase 3 PROSERA Study as one adequate and well-controlled clinical investigation, together with confirmatory evidence from the Phase 2 TORREY Study and additional supportive analyses.

•    The FDA will determine whether to accept the NDA for filing following its initial review.

•    Seralutinib is investigational and has not been approved by any regulatory authority.

Corporate and Business Updates

Reacquisition of Worldwide Rights to Seralutinib from Chiesi

•    In July 2026, Gossamer entered into an agreement with Chiesi Farmaceutici S.p.A. (“Chiesi”) under which Gossamer reacquired worldwide development and commercial rights to seralutinib, terminating their prior collaboration. The agreement provided for a one-time $5 million payment from Chiesi, with no upfront cash payment by Gossamer. Chiesi remains entitled to a capped royalty and certain regulatory and commercial milestone payments.

Structured Private Placement

•    In August 2026, Gossamer announced a structured private placement with total potential gross proceeds of up to approximately $250 million, including approximately $150 million of committed capital across the initial and second closings.

•    The initial closing provided approximately $25 million of gross proceeds.

•    The second closing provides for up to approximately $125 million of additional gross proceeds upon FDA acceptance of the seralutinib NDA in PAH, subject to the applicable milestone occurring in 2026 and other customary closing conditions.

•    Warrants related to FDA approval could provide up to approximately $100 million of additional gross proceeds, contingent upon FDA approval of seralutinib and cash exercise of the warrants.

Reverse Stock Split

•    Gossamer completed a 1-for-80 reverse stock split in September 2026, and split-adjusted trading commenced under the existing Nasdaq symbol “GOSS.” The reverse stock split was effected to regain compliance with the Nasdaq minimum bid price requirement.

Financial Results for the Quarter Ended September 30, 2026

•Cash, Cash Equivalents and Marketable Securities: Cash, cash equivalents and marketable securities totaled $51.2 million as of September 30, 2026, compared to $57.0 million as of June 30, 2026.

•Revenue from contracts with collaborators: For the quarter ended September 30, 2026, revenue from contracts with collaborators was $38.4 million, compared to $13.3 million for the same period in 2025. The increase of $25.1 million is primarily attributable to revenue recognized upon the termination of the Chiesi Collaboration Agreement in July 2026 in connection with Gossamer’s reacquisition of worldwide rights to seralutinib.

•Research and Development (R&D) Expenses: For the quarter ended September 30, 2026, R&D expenses were $18.8 million, compared to $45.5 million for the same period in 2025. The change was primarily driven by a decrease of $15.7 million of costs associated with clinical trials for seralutinib.

•General

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