---
schema_version: "secwatch.filing_event.v1"
accession: "0000950170-25-063954"
form_type: "8-K"
ticker: "UPB"
cik: "0002022626"
company_name: "Upstream Bio, Inc."
filed_at: "2025-05-06T23:59:59+00:00"
generated_at: "2026-05-22T14:48:36.962073+00:00"
event_type: "earnings"
sentiment: "neutral"
materiality_score: 0.75
calibrated_materiality_score: 0.75
confidence: "high"
source: SEC EDGAR
---

# Upstream Bio Q1 net loss $27.3M; cash $431.4M; Phase 2 CRSwNP data on track for Q3 2025

## Summary
- Net loss $27.3M in Q1 2025 vs $10.9M in Q1 2024; R&D expenses $25.8M (up $14.1M YoY).
- Cash, equivalents and short-term investments $431.4M as of March 31, 2025, funding operations through 2027.
- Phase 2 CRSwNP top-line data expected Q3 2025; Phase 2 severe asthma data now expected H1 2026.
- First patient dosing in Phase 2 COPD trial expected mid-2025.
- General and administrative expenses $6.8M vs $4.0M YoY, driven by personnel and professional fees.

## SEC filing metadata
- accession: 0000950170-25-063954
- form_type: 8-K
- ticker: UPB
- cik: 0002022626
- company_name: Upstream Bio, Inc.
- filed_at: 2025-05-06T23:59:59+00:00
- event_type: earnings
- sentiment: neutral
- 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/2022626/000095017025063954/0000950170-25-063954-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/2022626/000095017025063954/upb-20250506.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0000950170-25-063954
- JSON: https://secwatch.observer/filing/0000950170-25-063954.json
- Plain text: https://secwatch.observer/filing/0000950170-25-063954.txt

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