secwatch.observer — SEC 8-K summary
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Issuer:     Upstream Bio, Inc. (UPB)
CIK:        0002022626
Form:       8-K
Filed at:   2026-09-01T11:05:15+00:00
Accession:  0001193125-26-377485
Event type: other_material
Sentiment:  positive
Materiality: 0.80
Item codes: 7.01, 8.01, 9.01
LLM model:  deepseek-v4-flash:cloud@v2

Upstream Bio announces Phase 3 plans for verekitug in severe asthma and CRSwNP
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- Phase 3: 400mg verekitug SC every 12 weeks vs placebo; one trial each in severe asthma and CRSwNP.
- ~1,500 patients total across both trials; broad populations, no biomarker restriction.
- Primary endpoints: asthma AAER over 48 weeks; CRSwNP co-primary NPS and NCS at 48 weeks.
- Trials to start Q1 2027; BLA submission expected with supportive results; potential launch as early as 2030.
- Based on productive End-of-Phase 2 FDA meetings; data from 500+ treated patients.

Source:
  EDGAR index:    https://www.sec.gov/Archives/edgar/data/2022626/000119312526377485/0001193125-26-377485-index.htm
  Primary doc:    https://www.sec.gov/Archives/edgar/data/2022626/000119312526377485/upb-20260901.htm
  HTML page:      https://secwatch.observer/filing/0001193125-26-377485

License: Source filings: public domain (SEC EDGAR). Summaries (headline + bullets): CC-BY-4.0; attribute https://secwatch.observer