WALTHAM, Mass. — September 8, 2026
Upstream Bio, Inc. presented results from the Phase 2 VALIANT trial of verekitug in adults with severe asthma during a late-breaking oral presentation at the European Respiratory Society (ERS) Congress 2026 in Barcelona. The data support the company’s continued development of verekitug as a potential long-acting treatment for severe inflammatory respiratory diseases and reinforce Upstream Bio’s plans to move the program into Phase 3 development in severe asthma and chronic rhinosinusitis with nasal polyps (CRSwNP) in the first quarter of 2027. Verekitug is an investigational antibody designed to target the thymic stromal lymphopoietin (TSLP) receptor, with the company pursuing a differentiated profile based on potent pathway inhibition and extended dosing. In the Phase 2 VALIANT study, which enrolled 478 patients with severe asthma, the therapy met its primary endpoint across all evaluated dose regimens, providing the clinical foundation for Upstream Bio’s next-stage development strategy.
Quarterly Dosing Supports Commercial Development Strategy
A 100 mg dose of verekitug administered every 12 weeks reduced annualized asthma exacerbation rates (AAER) by 56% compared with placebo, with statistically significant reductions also reported for the other dose groups. The company also reported improvements in lung function measured by FEV1, exhaled nitric oxide (FeNO), and asthma symptom control measured by ACQ-6. Importantly for the program’s development strategy, improvements were observed as early as week two, while key secondary outcomes were assessed at week 24. Upstream Bio said verekitug was generally well tolerated across active doses, with a safety profile consistent with previous studies and no meaningful impact from immunogenicity on safety or efficacy. The company is positioning infrequent quarterly administration as an important potential differentiator as it prepares for larger registrational studies. Rather than limiting enrollment based on baseline blood eosinophil count or other Type 2 biomarkers, the VALIANT program evaluated a broad severe asthma population, supporting Upstream Bio’s objective of developing a treatment with wide applicability..
Upstream Bio Prepares Phase 3 Expansion
Upstream Bio remains on track to initiate Phase 3 trials of verekitug in severe asthma and CRSwNP during Q1 2027, with the planned studies evaluating a 400 mg regimen administered every 12 weeks against placebo. The company said the Phase 3 program is designed to evaluate verekitug’s potential to deliver best-in-class efficacy while offering quarterly at-home administration to patients. The move follows a broader clinical development program in which more than 500 participants have been treated with verekitug to date. Eligible VALIANT participants were also offered enrollment in the VALOUR long-term extension study, which completed enrollment in March 2026 with more than 90% retention among eligible patients. Data from VALOUR are expected in the second half of 2027, providing additional information on long-term safety and efficacy. Upstream Bio is simultaneously evaluating verekitug in an ongoing Phase 2 COPD program, extending the company’s development strategy across major inflammatory respiratory diseases.
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TSLP Program Strengthens Upstream Bio Pipeline
The VALIANT results strengthen Upstream Bio’s position as a clinical-stage company focused on severe inflammatory respiratory diseases, while advancing its strategy around TSLP receptor inhibition. Verekitug is described by the company as the only known antagonist currently in clinical development that directly targets and inhibits the TSLP receptor. By acting upstream of multiple inflammatory pathways, the program is intended to address broad disease-driving mechanisms rather than individual downstream inflammatory signals. With positive Phase 2 results in both severe asthma and CRSwNP and planned Phase 3 initiation in 2027, verekitug represents the company’s central development asset and a key driver of its future pipeline value. The transition toward a 400 mg quarterly regimen and broad Phase 3 populations will be an important next milestone for Upstream Bio, potentially establishing whether the clinical profile demonstrated in Phase 2 can translate into late-stage development and support a future regulatory pathway across respiratory indications.
Source:Upstream Bio press release
