Gossamer Bio Phase 3 PROSERA trial misses primary endpoint, seralutinib shows signals in high-risk PAH

Gossamer Bio, Inc.

Primary 6MWD endpoint missed: +13.3m placebo-adjusted (p=0.0320 vs prespecified α=0.025).
Four key secondary endpoints favored seralutinib; NT-proBNP reduced 120.4 ng/L (p=0.0002).
In intermediate/high-risk (REVEAL Lite 2 ≥6, n=234), 6MWD gain +20.0m (p=0.0207).
Gossamer to meet with FDA to discuss path forward; pauses SERANATA study enrollment.
Seralutinib well tolerated; cough (37%) and transaminase elevations >3x ULN (13%) reported.

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