Gossamer Bio, Inc.

Gossamer Bio, Inc. (Nasdaq: GOSS) is a clinical-stage biopharmaceutical company focused on the development and commercialization of seralutinib for the treatment of pulmonary hypertension. The company maintains its website at www.gossamerbio.com.

The company's lead product candidate, seralutinib, is an investigational inhaled small molecule inhibitor targeting platelet-derived growth factor receptor, colony-stimulating factor 1 receptor, and c-KIT pathways. Seralutinib is being evaluated for pulmonary arterial hypertension, a rare and progressive disease characterized by abnormally high blood pressure in lung blood vessels, and pulmonary hypertension associated with interstitial lung disease. In February 2026, the company announced topline results from its Phase 3 PROSERA trial in 390 PAH patients, demonstrating a placebo-adjusted improvement in six-minute walk distance of 13.3 meters at week 24, though this narrowly missed the prespecified statistical threshold. The drug showed more compelling results in intermediate and high-risk patient subgroups and in patients with connective tissue disease-associated PAH.

Seralutinib was designed to build upon the efficacy demonstrated by imatinib in prior trials while addressing systemic safety and tolerability issues associated with oral administration. The inhaled delivery mechanism is intended to provide a more tolerable safety profile with convenient, portable administration. The company completed Phase 1a studies in healthy volunteers and a Phase 1b trial in PAH patients, followed by the Phase 2 TORREY study which demonstrated statistically significant improvements in pulmonary vascular resistance.

In May 2024, Gossamer Bio entered into a collaboration agreement with Chiesi, whereby the companies will jointly develop seralutinib with Gossamer leading global development in PAH and PH-ILD and leading U.S. commercialization efforts, with both parties contributing equally to commercial activities. Chiesi holds exclusive commercialization rights outside the United States.

The company also holds an option agreement with Respira Therapeutics for RT234, an investigational inhaled, on-demand formulation of vardenafil, a phosphodiesterase type 5 inhibitor designed for rapid symptom relief in pulmonary hypertension patients. Seralutinib has received orphan drug designation from the FDA, European Commission, and Japan's PMDA.