secwatch.observer — SEC 8-K summary
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Issuer:     Upstream Bio, Inc. (UPB)
CIK:        0002022626
Form:       8-K
Filed at:   2026-03-26T23:59:59+00:00
Accession:  0001193125-26-125057
Event type: other_material
Sentiment:  positive
Materiality: 0.80
Item codes: 2.02, 9.01
LLM model:  deepseek-v4-flash:cloud@v2

Upstream Bio details Phase 3 strategy for verekitug; positive Phase 2 asthma and CRSwNP data
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- Phase 3 development plan for verekitug: high-dose quarterly regimen (up to 400 mg q12w) in severe asthma and CRSwNP; initiation in Q1 2027.
- Phase 2 VALIANT asthma trial met primary endpoint: AAER reduction 56% (p<0.0003) with 100 mg q12w; safety profile favorable.
- Phase 2 VIBRANT CRSwNP data: placebo-adjusted NPS reduction -1.95 (WOCF) and NCS reduction -0.96 at week 24.
- Cash position $341.5M as of Dec 31, 2025, expected to fund operations through 2027.
- Q4 2025 net loss $42.5M vs $21.2M a year ago; R&D expenses rose to $40.2M.

Source:
  EDGAR index:    https://www.sec.gov/Archives/edgar/data/2022626/000119312526125057/0001193125-26-125057-index.htm
  Primary doc:    https://www.sec.gov/Archives/edgar/data/2022626/000119312526125057/upb-20260326.htm
  HTML page:      https://secwatch.observer/filing/0001193125-26-125057

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