Upstream Bio, Inc.

Upstream Bio shares jumped 8% in premarket trading Tuesday after the company presented Phase 2 VALIANT trial data for its severe asthma candidate verekitug at the European Respiratory Society Congress 2026 in Barcelona. Verekitug is the only known antagonist in clinical development targeting the thymic stromal lymphopoietin receptor, and the trial showed statistically significant reductions in annualized asthma exacerbation rate across dose arms, along with clinically meaningful improvements in lung function and exhaled nitric oxide with every 12-week dosing. The company remains on track to initiate Phase 3 trials in severe asthma and chronic rhinosinusitis with nasal polyps in Q1 2027, evaluating a 400 mg quarterly regimen of verekitug in broad patient populations.

Upstream Bio, a clinical-stage company developing treatments for severe inflammatory respiratory diseases, announced pivotal Phase 3 development plans for verekitug in severe asthma and chronic rhinosinusitis with nasal polyps (CRSwNP). Following productive End-of-Phase 2 meetings with the U.S. FDA, the company will study a single high-dose subcutaneous regimen of 400 mg administered every 12 weeks, versus placebo, in one pivotal Phase 3 trial for each indication. The two trials will enroll a total of approximately 1,500 patients across both studies, with broad patient populations unrestricted by baseline biomarkers. Primary endpoints include annualized asthma exacerbation rate over 48 weeks for asthma, and change from baseline in nasal polyp score and nasal congestion score at 48 weeks for CRSwNP. Upstream Bio remains on track to initiate both Phase 3 trials in the first quarter of 2027, and with supportive results, expects to submit a Biologics License Application to the FDA for both indications, potentially enabling launch as early as 2030.