---
schema_version: "secwatch.filing_event.v1"
accession: "0001728117-26-000018"
form_type: "8-K"
ticker: "GOSS"
cik: "0001728117"
company_name: "Gossamer Bio, Inc."
filed_at: "2026-03-17T23:59:59+00:00"
generated_at: "2026-05-15T10:33:25.173962+00:00"
event_type: "other_material"
sentiment: "negative"
materiality_score: 0.9
calibrated_materiality_score: 0.9
confidence: "high"
source: SEC EDGAR
---

# Gossamer Bio reports 2025 net loss $170.4M; seralutinib Phase 3 narrowly missed primary endpoint

## Summary
- PROSERA Phase 3 in PAH showed placebo-adjusted 6MWD +13.3 meters but missed prespecified statistical alpha of 0.025 (p=0.0320).
- Enrollment in Phase 3 SERANATA (PH-ILD) paused; Company evaluating implications and plans FDA Type C meeting in June 2026.
- Implemented reduction in force and cost-containment measures to align resources with near-term priorities.
- Cash, equivalents and marketable securities $136.9M at Dec 31, 2025; expected to fund operations into Q1 2027.
- Net loss for FY2025 was $170.4M ($0.75 per share) compared to $56.5M ($0.25 per share) in FY2024.

## SEC filing metadata
- accession: 0001728117-26-000018
- form_type: 8-K
- ticker: GOSS
- cik: 0001728117
- company_name: Gossamer Bio, Inc.
- filed_at: 2026-03-17T23:59:59+00:00
- event_type: other_material
- sentiment: negative
- materiality_score: 0.9
- calibrated_materiality_score: 0.9
- confidence: high
- sec_items: 2.02, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1728117/000172811726000018/0001728117-26-000018-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1728117/000172811726000018/goss-20260317.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001728117-26-000018
- JSON: https://secwatch.observer/filing/0001728117-26-000018.json
- Plain text: https://secwatch.observer/filing/0001728117-26-000018.txt

This AI-assisted summary is a reading aid. Review the linked SEC EDGAR filing before relying on any specific claim.