secwatch.observer — SEC 8-K summary
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Issuer:     Gossamer Bio, Inc. (GOSS)
CIK:        0001728117
Form:       8-K
Filed at:   2025-06-16T23:59:59+00:00
Accession:  0001728117-25-000040
Event type: other_material
Sentiment:  positive
Materiality: 0.85
Item codes: 7.01, 8.01, 9.01
LLM model:  deepseek-v4-flash:cloud@v2

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

Source:
  EDGAR index:    https://www.sec.gov/Archives/edgar/data/1728117/000172811725000040/0001728117-25-000040-index.htm
  Primary doc:    https://www.sec.gov/Archives/edgar/data/1728117/000172811725000040/goss-20250616.htm
  HTML page:      https://secwatch.observer/filing/0001728117-25-000040

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