Gossamer Bio completes enrollment in Phase 3 PROSERA study for seralutinib in PAH (n=390)

Gossamer Bio, Inc.

Global registrational Phase 3 PROSERA study fully enrolled; topline results expected February 2026.
Enrolled 390 patients vs 86 in Phase 2; mean 6MWD 374 m (vs 408 m), NT-proBNP 987 ng/L (vs 628).
74% of patients are Functional Class III vs 42% in Phase 2; enrichment criteria applied to target responders.
Study is double-blind, placebo-controlled, primary endpoint change in 6MWD at week 24.
Seralutinib developed with Chiesi Group; positive milestone for first-in-class PAH treatment.

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