---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-26-045500"
form_type: "8-K"
ticker: "UPB"
cik: "0002022626"
company_name: "Upstream Bio, Inc."
filed_at: "2026-02-11T23:59:59+00:00"
generated_at: "2026-05-16T03:24:21.361747+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.8
calibrated_materiality_score: 0.8
confidence: "high"
source: SEC EDGAR
---

# Upstream Bio reports positive Phase 2 VALIANT results: verekitug reduces asthma exacerbations by 56% and 39%

## Summary
- Verekitug 100 mg q12w reduced AAER by 56% (p<0.0003); 400 mg q24w reduced AAER by 39% (p<0.02) vs placebo.
- Placebo-adjusted FEV1 improvement of 122 mL (q12w) and 139 mL (q24w) at week 60.
- FeNO suppressed vs placebo by 20.4 ppb (q12w) and 26.3 ppb (q24w); mean reductions of 43-45% from baseline.
- Verekitug well tolerated with safety consistent with prior studies; >90% of eligible patients rolled over to VALOUR LTE.
- Company plans to advance verekitug into Phase 3 trials in severe asthma and CRSwNP after regulatory interactions.

## SEC filing metadata
- accession: 0001193125-26-045500
- form_type: 8-K
- ticker: UPB
- cik: 0002022626
- company_name: Upstream Bio, Inc.
- filed_at: 2026-02-11T23:59:59+00:00
- event_type: other_material
- sentiment: positive
- materiality_score: 0.8
- calibrated_materiality_score: 0.8
- confidence: high
- sec_items: 7.01, 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/2022626/000119312526045500/0001193125-26-045500-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/2022626/000119312526045500/d44802d8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-26-045500
- JSON: https://secwatch.observer/filing/0001193125-26-045500.json
- Plain text: https://secwatch.observer/filing/0001193125-26-045500.txt

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