Gossamer Bio secured up to $250 million to advance seralutinib toward FDA review for pulmonary arterial hypertension, with $150 million tied to NDA acceptance.
Written By: Khushi Patel, PharmD
Reviewed By: Pharmacally Editorial Team
Gossamer Bio entered into a securities purchase agreement with new and existing institutional investors for a private placement that could provide up to approximately $250 million in gross proceeds. The financing comes as the company prepares to submit an NDA for seralutinib in PAH in September 2026, following a recent pre-NDA meeting with the U.S. Food and Drug Administration (FDA).
The structure includes approximately $25 million at the initial closing and another $125 million that investors are committed to fund if the FDA accepts the seralutinib NDA in 2026. The transaction also includes warrants that could generate up to an additional $100 million if the FDA approves seralutinib.
The financing follows Gossamer’s reacquisition of worldwide rights to seralutinib and provides capital intended to carry the program through regulatory review and potential commercialization.
Seralutinib Targets Pulmonary Vascular Remodeling
Seralutinib is an investigational inhaled tyrosine kinase inhibitor that targets PDGFRα/β, CSF1R and c-KIT. These signaling pathways contribute to the proliferation, inflammation and fibrosis involved in pulmonary vascular remodeling in PAH. Delivering the drug through a dry-powder inhaler is intended to provide local exposure within the lungs.
PAH is a progressive form of pulmonary hypertension characterized by remodeling and narrowing of the pulmonary arteries. The resulting increase in pulmonary vascular resistance places increasing stress on the right ventricle and can ultimately lead to right-heart failure.
Phase 3 PROSERA Provided the Basis for Regulatory Strategy
The regulatory path follows results from the Phase 3 PROSERA study (NCT05934526), which evaluated inhaled seralutinib in patients with PAH receiving background therapy. The primary endpoint was change in six-minute walk distance (6MWD) at Week 24.
Seralutinib produced a placebo-adjusted improvement of 13.3 meters in 6MWD at Week 24, with a nominal p-value of 0.0320. The result did not cross the prespecified statistical threshold of 0.025. However, the treatment effect was more pronounced in the prespecified intermediate- and high-risk subgroup, where the placebo-adjusted improvement reached 20.0 meters.
The Phase 2 TORREY study (NCT04456998) had previously demonstrated a statistically significant reduction in pulmonary vascular resistance. Among 86 adults with PAH receiving background therapy, seralutinib reduced PVR by 96.1 dyn·s/cm⁵ versus placebo at Week 24 (p=0.03).
Gossamer reported that a June 2026 pre-NDA Type B meeting with the FDA characterized the statistical significance and magnitude of the PROSERA treatment effect as review issues rather than filing issues. The company therefore plans to support its NDA with PROSERA as the adequate and well-controlled study, supplemented by TORREY and other analyses.
Financing Tied to Regulatory Milestones
At the expected initial closing on or around August 24, investors will purchase pre-funded warrants for approximately $25 million. Following FDA acceptance of the NDA in 2026, participating investors are obligated to provide another approximately $125 million, subject to customary closing conditions.
At that second closing, investors will also receive FDA approval warrants without additional consideration. If exercised in full at $0.187 per share following FDA approval, these warrants could provide up to approximately $100 million in additional gross proceeds.
The company expects the initial financing, committed second closing proceeds and existing resources to fund operations into 2028.
Next Regulatory Milestones
Gossamer plans to submit the seralutinib NDA in September 2026. If the FDA accepts the application, the company expects the additional $125 million commitment to become available during 2026. Based on the company’s current regulatory timeline, seralutinib could receive an FDA approval decision in the third quarter of 2027 if the application is accepted for review.
The company also intends to use the financing to advance seralutinib in PH-ILD, although enrollment in the Phase 3 SERANATA study (NCT07181382) for this indication remains paused while Gossamer evaluates the implications of the PROSERA results.
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About the Writer
Khushi Patel is a Pharm.D (Linkedin) professional with a strong foundation in clinical pharmacy, patient-centered care, regulatory affairs, and pharmacovigilance, with published work on Brugada syndrome.
Her interests include regulatory affairs, pharmacovigilance, guideline integration, multimodal therapy, pharmacogenomics, and antibiogram utilization, with a focus on evidence-based clinical decision-making and medication safety.
As a Pharmacally healthcare writer, she translates clinical and scientific evidence into clear, accurate, and clinically relevant healthcare content, while continuously developing her expertise in evolving pharmacy practice.