secwatch.observer — SEC 8-K summary
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Issuer:     Gossamer Bio, Inc. (GOSS)
CIK:        0001728117
Form:       8-K
Filed at:   2026-02-23T23:59:59+00:00
Accession:  0001728117-26-000004
Event type: other_material
Sentiment:  neutral
Materiality: 0.85
Item codes: 8.01, 9.01
LLM model:  deepseek-v4-flash:cloud@v2

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

Source:
  EDGAR index:    https://www.sec.gov/Archives/edgar/data/1728117/000172811726000004/0001728117-26-000004-index.htm
  Primary doc:    https://www.sec.gov/Archives/edgar/data/1728117/000172811726000004/goss-20260223.htm
  HTML page:      https://secwatch.observer/filing/0001728117-26-000004

License: Source filings: public domain (SEC EDGAR). Summaries (headline + bullets): CC-BY-4.0; attribute https://secwatch.observer