---
schema_version: "secwatch.filing_event.v1"
accession: "0001728117-25-000037"
form_type: "8-K"
ticker: "GOSS"
cik: "0001728117"
company_name: "Gossamer Bio, Inc."
filed_at: "2025-05-15T23:59:59+00:00"
generated_at: "2026-05-21T05:19:33.566246+00:00"
event_type: "earnings"
sentiment: "positive"
materiality_score: 0.75
calibrated_materiality_score: 0.75
confidence: "high"
source: SEC EDGAR
---

# Gossamer Bio closes new patient screening in PAH Phase 3 PROSERA study; Q1 net loss $36.6M

## Summary
- Enrollment of 343 patients completed; to exceed 350 by early June; topline results expected Feb 2026.
- Baseline characteristics align with target: mean 6MWD 376 m, 74% Functional Class III, NT-proBNP 986 ng/L.
- Phase 3 SERANATA study in PH-ILD to begin site activations in Q4 2025 with ~480 patients.
- Cash $257.9M expected to fund operations into H1 2027; Q1 net loss $36.6M ($0.16/share).
- Revenue from Chiesi collaboration $9.9M ($6.6M cost reimbursement); R&D expenses $38.0M.

## SEC filing metadata
- accession: 0001728117-25-000037
- form_type: 8-K
- ticker: GOSS
- cik: 0001728117
- company_name: Gossamer Bio, Inc.
- filed_at: 2025-05-15T23:59:59+00:00
- event_type: earnings
- sentiment: positive
- materiality_score: 0.75
- calibrated_materiality_score: 0.75
- confidence: high
- sec_items: 2.02, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1728117/000172811725000037/0001728117-25-000037-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1728117/000172811725000037/goss-20250515.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001728117-25-000037
- JSON: https://secwatch.observer/filing/0001728117-25-000037.json
- Plain text: https://secwatch.observer/filing/0001728117-25-000037.txt

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