Upstream Bio Presents Positive Results for Verekitug in Severe Asthma Trial

Upstream Bio, a clinical-stage biotechnology company, presented promising results from the Phase 2 VALIANT trial of its investigational drug, verekitug, for the treatment of severe asthma at the European Respiratory Society (ERS) Congress 2026. Verekitug, a fully human monoclonal antibody that targets and inhibits the thymic stromal lymphopoietin (TSLP) receptor, demonstrated significant reductions in asthma exacerbations and improvements in lung function and inflammatory biomarkers.

In the VALIANT trial, which included 478 adult patients with severe asthma, verekitug, administered at a 100 mg dose every 12 weeks, reduced the annualized asthma exacerbation rate (AAER) by 56% compared to placebo. The trial also showed statistically significant reductions in AAER for the other dose arms tested. Additionally, verekitug improved key secondary outcomes such as forced expiratory volume in one second (FEV1), fractional exhaled nitric oxide (FeNO), and asthma symptom control as measured by the Asthma Control Questionnaire (ACQ-6).

"These findings are particularly compelling because they demonstrate significant and substantial improvements in asthma exacerbations, lung function, and inflammatory biomarkers," said Aaron Deykin, MD, Chief Medical Officer and Head of Research & Development at Upstream Bio. "The 56% reduction in AAER observed in patients receiving verekitug every 12 weeks further reinforces the potential of targeting the TSLP receptor to address key measures of disease."

Dr. Michael Wechsler, a Professor of Medicine and Director of the National Jewish Cohen Family Asthma Institute, and principal investigator on the VALIANT trial, added, "The consistency and magnitude of improvement observed with verekitug in the VALIANT study suggest it has the potential to deliver meaningful clinical benefit for people living with severe asthma. The substantial reduction in asthma exacerbations, together with improvements in lung function and inflammatory biomarkers, demonstrate verekitug’s potential to achieve strong disease control with infrequent dosing."

Upstream Bio plans to initiate Phase 3 clinical trials in severe asthma and chronic rhinosinusitis with nasal polyps (CRSwNP) in the first quarter of 2027. These trials will evaluate the 400 mg quarterly regimen of verekitug in broad patient populations without restrictions based on baseline biomarkers. The company believes that this regimen could deliver best-in-class efficacy and the convenience of quarterly dosing for patients.

The VALIANT trial, which was part of a larger dataset from over 500 trial participants treated with verekitug to date, included a long-term extension (LTE) study, VALOUR, that completed enrollment in March 2026. More than 90% of eligible patients from the Phase 2 VALIANT study enrolled in the LTE, with data expected in the second half of 2027.

Verekitug, a novel recombinant IgG1 monoclonal antibody, is the only known antagonist currently in clinical development that targets and inhibits the TSLP receptor. TSLP is a cytokine that drives the inflammatory response in major allergic and inflammatory diseases such as asthma. Disruption of TSLP signaling has been clinically validated as an effective therapeutic strategy, and blocking the TSLP receptor presents an opportunity to impact multiple pathological inflammatory processes.

Upstream Bio's focus is on leveraging verekitug's differentiated mechanism, potency, and potential for extended dosing to develop a treatment that could deliver best-in-class efficacy and quarterly dosing for patients underserved by today's standard of care. The company continues to advance verekitug through its clinical development programs, with positive results in severe asthma and chronic rhinosinusitis with nasal polyps (CRSwNP).