Gossamer Bio(US:GOSS)2026-02-23 14:32Gossamer Bio PROSERA Phase 3 Top Line Results Call Summary Company Overview - Company: Gossamer Bio, Inc. - Focus: Development of seralutinib for the treatment of pulmonary arterial hypertension (PAH) Key Industry and Company Insights Phase 3 Study Results - Study Name: PROSERA - Objective: Evaluate the efficacy of seralutinib in patients with PAH - Primary Endpoint: Change in six-minute walk distance at week 24 - Results: - Seralutinib showed a numerical improvement of approximately 13.3 meters compared to placebo (p-value = 0.032) - Did not meet the pre-specified statistical significance threshold of 0.025, thus considered not statistically significant [4][12][28] Subgroup Analysis - Intermediate and High-Risk Subgroup: - 234 patients defined by REVEAL Lite 2 risk score - Demonstrated a clinically meaningful improvement of 20 meters in six-minute walk distance (p-value = 0.0207) [5][17] - 3 out of 4 key secondary endpoints favored seralutinib with p-values below 0.0125 [5] Placebo Response - Unexpected High Placebo Response: - The placebo group showed a larger improvement than typically seen in PAH studies, which diluted the treatment effect [12][15] - Geographic differences noted, with North America showing more typical placebo responses compared to Latin America, where the placebo response was significantly higher [16][68] Safety Profile - Adverse Events: - Treatment-emergent adverse events (TEAEs) reported in 86.5% of seralutinib patients vs. 80.5% in placebo [24] - Most common TEAE was cough (37% in seralutinib vs. 13.7% in placebo) [25] - Liver enzyme elevations were noted, with 13% of seralutinib patients experiencing elevations ≥3 times the upper limit of normal [26][107] Strategic Decisions - Enrollment Pause: - Gossamer Bio decided to pause enrollment in the SERANATA Phase 3 study to focus resources on the PROSERA dataset and engage with the FDA [9][30] - Next Steps: - Further analysis of PROSERA data and discussions with regulators regarding the implications of the results [31] Commercial Opportunity - Market Potential: - Seralutinib is viewed as a meaningful opportunity in the PAH market, particularly for high-risk patients who face significant morbidity and mortality [30] Regulatory Considerations - FDA Engagement: - Gossamer Bio plans to present the PROSERA results to the FDA, emphasizing the unmet medical need in the high-risk population [56][100] Additional Important Insights - Long-Term Efficacy: - Data suggests that seralutinib may show improved efficacy over time, particularly in patients with more severe disease [15][70] - Comparative Analysis: - The treatment effect of seralutinib aligns well with other approved PAH therapies, especially in patients with higher baseline disease severity [20][21] This summary encapsulates the critical findings and strategic directions from the Gossamer Bio PROSERA Phase 3 results call, highlighting both the challenges and opportunities in the development of seralutinib for PAH treatment.