Gossamer Bio's Seralutinib Phase 3 Misses Primary Endpoint, Shows Strong Subgroup Efficacy

summarizeSummary

Gossamer Bio announced mixed topline results for its Phase 3 PROSERA study of seralutinib in pulmonary arterial hypertension (PAH). While the study narrowly missed its primary endpoint for the overall patient population, it demonstrated a compelling and clinically meaningful treatment effect in prespecified intermediate- and high-risk subgroups, as well as in patients with connective tissue disease-associated PAH. The company plans to engage with the FDA to discuss these results and evaluate a potential path forward, which introduces uncertainty as evidenced by the pause in enrollment for the ongoing SERANATA study. The generally acceptable safety profile is a positive, but the primary endpoint miss creates a significant hurdle for broad approval.

check_boxKey Events

• Primary Endpoint Missed

  The Phase 3 PROSERA study of seralutinib in pulmonary arterial hypertension (PAH) did not meet its primary endpoint (change in 6-minute walk distance) at Week 24, with a p-value of 0.0320 against a prespecified threshold of 0.025.

• Strong Subgroup Efficacy

  Seralutinib demonstrated a compelling signal in intermediate- and high-risk PAH patients, showing a +20.0m placebo-adjusted improvement in 6MWD (p=0.0207). A robust +37.0m gain was also observed in connective tissue disease-associated PAH (p=0.0104).

• Positive Secondary Endpoints

  All four key secondary endpoints favored seralutinib versus placebo in the overall population, including a significant reduction in NT-proBNP (p=0.0002), though formal statistical significance could not be evaluated due to the primary endpoint miss.

• Acceptable Safety Profile

  Seralutinib was generally well tolerated, with a safety profile consistent with existing PAH therapies. Common adverse events included cough (37.0% vs 13.7% for placebo) and transaminase elevations (13% vs 1% for placebo).

auto_awesomeAnalysis

Gossamer Bio announced mixed topline results for its Phase 3 PROSERA study of seralutinib in pulmonary arterial hypertension (PAH). While the study narrowly missed its primary endpoint for the overall patient population, it demonstrated a compelling and clinically meaningful treatment effect in prespecified intermediate- and high-risk subgroups, as well as in patients with connective tissue disease-associated PAH. The company plans to engage with the FDA to discuss these results and evaluate a potential path forward, which introduces uncertainty as evidenced by the pause in enrollment for the ongoing SERANATA study. The generally acceptable safety profile is a positive, but the primary endpoint miss creates a significant hurdle for broad approval.