---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-26-220578"
form_type: "8-K"
ticker: "UPB"
cik: "0002022626"
company_name: "Upstream Bio, Inc."
filed_at: "2026-05-13T11:05:16+00:00"
generated_at: "2026-05-13T11:14:19.391813+00:00"
event_type: "earnings"
sentiment: "neutral"
materiality_score: 0.5
calibrated_materiality_score: 0.5
confidence: "high"
source: SEC EDGAR
---

# Upstream Bio reports Q1 net loss $40.6M; Phase 3 plans on track for 2027

## Summary
- Cash, cash equivalents and short-term investments $294.6M as of March 31, 2026; expected to fund operations through 2027.
- Net loss $40.6M vs $27.3M YoY; R&D expenses $36.6M (up from $25.8M) driven by clinical and manufacturing costs.
- End-of-Phase 2 meetings with FDA planned mid-2026; Phase 3 initiations in severe asthma and CRSwNP expected Q1 2027.
- Phase 2 VENTURE COPD trial capping enrollment at >400 participants; data now expected H2 2027.
- Phase 2 VALOUR LTE study in severe asthma completed enrollment with >90% retention of eligible patients.

## SEC filing metadata
- accession: 0001193125-26-220578
- form_type: 8-K
- ticker: UPB
- cik: 0002022626
- company_name: Upstream Bio, Inc.
- filed_at: 2026-05-13T11:05:16+00:00
- event_type: earnings
- sentiment: neutral
- materiality_score: 0.5
- calibrated_materiality_score: 0.5
- confidence: high
- sec_items: 2.02, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/2022626/000119312526220578/0001193125-26-220578-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/2022626/000119312526220578/upb-20260513.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-26-220578
- JSON: https://secwatch.observer/filing/0001193125-26-220578.json
- Plain text: https://secwatch.observer/filing/0001193125-26-220578.txt

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