Upstream Bio Inc. (Nasdaq: UPB) presented detailed Phase 2 results for verekitug in severe asthma at the European Respiratory Society Congress on September 8, 2026. The company reported that 100 mg of verekitug administered every 12 weeks reduced the annualized asthma exacerbation rate by 56% compared with placebo, meeting the trial’s primary endpoint with a p-value below 0.001.
The company previously released topline findings from the VALIANT trial in February. The latest announcement provides additional results presented during a late-breaking oral session at the Barcelona medical meeting.
VALIANT was a global, randomized, double-blind and placebo-controlled Phase 2 trial involving 478 adults with severe asthma. Participants were enrolled regardless of their baseline blood eosinophil count or other type-2 inflammatory biomarkers.
All three verekitug dosing regimens produced statistically significant reductions in annualized asthma exacerbations compared with placebo. Upstream also reported improvements at Week 24 in forced expiratory volume in one second, or FEV1; fractional exhaled nitric oxide, or FeNO; and asthma symptoms measured using the ACQ-6 questionnaire. Improvements were observed as early as Week 2.
The company said verekitug was generally well tolerated across the active treatment groups and that immunogenicity had no meaningful effect on the safety or efficacy findings. Detailed results will still need to be evaluated through scientific review and subsequent clinical studies.
Verekitug is a monoclonal antibody designed to block the receptor for thymic stromal lymphopoietin, or TSLP, an upstream driver of several inflammatory pathways. Upstream describes verekitug as the only known TSLP-receptor antagonist currently in clinical development.
Chief Medical Officer Aaron Deykin said the findings “reinforce the potential of targeting the TSLP receptor to potently address key measures of disease.”
The next test will involve a different dose. Following discussions with the FDA, Upstream plans to evaluate 400 mg of verekitug every 12 weeks in separate Phase 3 trials for severe asthma and chronic rhinosinusitis with nasal polyps. The two studies are expected to enroll approximately 1,500 participants in total and begin during the first quarter of 2027.
The positive 100 mg Phase 2 result supports continued development but does not establish the efficacy or safety of the planned 400 mg Phase 3 regimen.
Upstream reported $261.3 million in cash, cash equivalents and short-term investments as of June 30, 2026. Its second-quarter net loss was $39.7 million, and management expects available capital to fund planned operations through 2027.
Upcoming Catalysts
- Initiation of the severe-asthma Phase 3 trial in the first quarter of 2027
- Initiation of the Phase 3 nasal-polyp trial during the same period
- Phase 2 VALOUR long-term extension data expected in the second half of 2027
- Phase 2 VENTURE COPD results expected in the second half of 2027
- Updates concerning Phase 3 enrollment, manufacturing and cash requirements
Sources
- Upstream Bio presents Phase 2 VALIANT results — September 8, 2026
- Upstream Bio announces Phase 3 development plans — September 1, 2026
- Upstream Bio second-quarter 2026 financial results
- VALIANT trial record — NCT06196879
- VALOUR extension-study record — NCT06966479
Editorial Disclosure
This article is based entirely on publicly available information, including company announcements, SEC filings and the federal clinical-trial registry. Securities discussed or referenced include Upstream Bio Inc. (Nasdaq: UPB). Biotech Stocks Daily has not received compensation from Upstream Bio, its management, investor relations representatives or any third party for this specific article. Biotech Stocks Daily may have current or past paid business relationships with other companies, which do not influence the content or conclusions of this article. No staff member or principal of Biotech Stocks Daily holds a position in any security mentioned at the time of publication.
Sources used include Upstream Bio’s September 8, 2026 VALIANT presentation announcement, its September 1 Phase 3 development update, its August 11 financial results and ClinicalTrials.gov. Information concerning verekitug’s mechanism, clinical potential and anticipated development schedule originated primarily from the company and has not been independently validated by Biotech Stocks Daily.
Verekitug remains investigational and has not received FDA approval. Phase 2 results may not be replicated in Phase 3, and the positive findings do not establish the safety or efficacy of the planned 400 mg regimen. The clinical program remains subject to regulatory, enrollment, manufacturing, safety and operational risks.
Financial information reflects Upstream Bio’s position as of June 30, 2026. The company reported continuing operating losses and may require substantial additional funding to complete development and pursue commercialization. Management’s projected cash runway through 2027 is a forward-looking estimate and may change. No real-time securities prices are included.
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