Gossamer Bio's Phase 3 PROSERA trial of seralutinib for pulmonary arterial hypertension (PAH) missed its primary endpoint of statistically significant improvement in six-minute walk distance, with a placebo-adjusted gain of 13.3 meters after 24 weeks.457
The company's stock plummeted over 80%, closing at $0.42 per share from $2.13.4
Gossamer plans to meet with the FDA to explore a path forward, citing stronger signals in intermediate- and high-risk patients (20-meter improvement) and reductions in NT-proBNP biomarker.45
Enrollment suspended in the Phase 3 SERANATA trial for pulmonary hypertension with interstitial lung disease pending FDA discussions and review of placebo response discrepancies.49
Analysts at Guggenheim express doubt on market path due to results falling short of clinical meaningfulness and financial position ($180M cash as of Sept 2025), while H.C. Wainwright sees potential in subgroups.4
Seralutinib, an inhaled tyrosine kinase inhibitor developed with Chiesi Group, was generally well-tolerated but had higher rates of transaminase elevations and cough.75
Sources:
4. https://www.biospace.com/drug-development/gossamer-nosedives-as-late-stage-failure-plunges-pah-program-into-uncertainty
5. https://whtc.com/2026/02/23/gossamer-bios-experimental-lung-disease-drug-fails-in-late-stage-trial/
7. https://au.investing.com/news/company-news/gossamer-bios-seralutinib-misses-primary-endpoint-in-pah-trial-93CH-4271105
9. https://www.fiercebiotech.com/biotech/gossamer-bio-fails-phase-3-pulmonary-arterial-hypertension-trial-tries-thread-path-market