Gossamer Bio Inc Dossier
Qualitative Analysis
Business overview
Gossamer Bio, Inc. (NASDAQ: GOSS) is a clinical-stage biopharmaceutical company headquartered in San Diego, California, focused on discovering, acquiring, developing, and commercializing therapeutics in the areas of immunology, inflammation, and oncology. The company's primary strategic asset is seralutinib, an inhaled dry powder formulation of a tyrosine kinase inhibitor designed to treat pulmonary arterial hypertension (PAH) and pulmonary hypertension associated with interstitial lung disease (PH-ILD). Gossamer operates under an asset-light model, managing clinical strategy and regulatory affairs internally while outsourcing manufacturing and trial execution. In May 2024, Gossamer entered into a major global collaboration and license agreement with Chiesi Farmaceutici S.p.A. to co-develop and commercialize seralutinib, securing a $160 million development reimbursement and sharing future development costs.
Research as of 19 Jun 2026
Strategic Initiatives
Growth programs, investments, and their expected impact
Advancing the lead candidate seralutinib (GB002), an inhaled PDGFR, CSF1R, and c-KIT inhibitor, through regulatory review for PAH and preparing for registrational trials in PH-ILD.
Expected impact: Establishes a potential first-in-class therapeutic franchise in pulmonary hypertension.
Exchanging $200 million of 5.00% Convertible Senior Notes due 2027 into new 7.50% Convertible Senior Secured First Lien Notes due 2030, common stock, and warrants to extend maturities and reduce debt.
Expected impact: Reduces outstanding debt from $200 million to approximately $72 million, extending the maturity profile to 2030 and strengthening the balance sheet.
Implementing a workforce reduction of approximately 46% (73 employees) and pausing enrollment in the SERANATA trial to conserve capital.
Expected impact: Extends the company's cash runway into the first quarter of 2027 and aligns resources with near-term regulatory priorities.
Mergers, Acquisitions & Partnerships
Recent deals and strategic collaborations
Recent Acquisitions
Acquisition of an option to acquire Respira Therapeutics and its lead candidate RT234 (an inhaled, on-demand vardenafil dry-powder therapy for PAH and PH-ILD). This capital-efficient structure expands Gossamer's pulmonary hypertension franchise with a complementary PRN therapy without upfront cash.
Financial impact: Issued 2.5 million shares of common stock upon signing, with an additional 1.5 million shares due upon option exercise, plus success-based milestones and royalties.
Strategic Partnerships
High. Jointly developing and commercializing seralutinib in PAH and PH-ILD, combining Chiesi's respiratory and rare disease expertise with Gossamer's clinical development platform.
Terms: Gossamer received a $160 million development reimbursement. Development costs are split 50/50 (except for the PROSERA study). US commercial profits and losses are shared 50/50. Chiesi has exclusive ex-US rights and will pay mid-to-high teens royalties. Gossamer is eligible for up to $146 million in regulatory milestones and $180 million in sales milestones.