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Upstream Bio Presents Phase 2 Results for Verekitug

Upstream Bio presented results from the Phase 2 VALIANT clinical trial evaluating the safety and efficacy of verekitug in adults with severe asthma in a late-breaking oral presentation at the European Respiratory Society Congress 2026 in Barcelona. Verekitug is the only known antagonist currently in clinical development that targets and inhibits the thymic stromal lymphopoietin receptor. As previously reported, VALIANT met the study's primary endpoint of a statistically significant and clinically meaningful reduction in the annualized asthma exacerbation rate across all dose regimens studied. Verekitug, 100 mg dosed every 12 weeks, reduced AAER by 56% compared to placebo. Statistically significant reductions in AAER were also observed in the two other dose arms. Verekitug improved the key secondary outcomes of forced expiratory volume in one second, fractional exhaled nitric oxide, and asthma symptom control as measured by Asthma Control Questionnaire versus placebo at week 24, with improvements seen as early as week 2 across all key secondary outcomes. Verekitug was generally well tolerated across all active doses, demonstrating a favorable safety profile consistent with previous studies. Immunogenicity had no meaningful impact on safety or efficacy results. Eligible participants who completed the Phase 2 VALIANT clinical trial were offered enrollment in VALOUR, a long-term extension study designed to evaluate the long-term safety and efficacy of verekitug. VALOUR completed enrollment in March 2026 with more than 90% retention of eligible patients from the Phase 2 VALIANT study, with data expected in the second half of 2027. As previously announced, Upstream Bio remains on track to initiate Phase 3 clinical trials with verekitug administered every 12 weeks in severe asthma and CRSwNP in the first quarter of 2027. The Phase 3 trials will evaluate 400 mg of verekitug administered every 12 weeks, versus placebo, with the goal to deliver efficacy with quarterly at-home administration for patients with severe asthma and CRSwNP, in broad study populations without restriction based on baseline biomarkers.

Upstream Bio Announces Phase 3 Development Plans for Verekitug

Upstream Bio announced its pivotal Phase 3 development plans for Verekitug in severe asthma and chronic rhinosinusitis with nasal polyps. Verekitug is the only known antagonist currently in clinical development that targets and inhibits the thymic stromal lymphopoietin receptor. Following productive End-of-Phase 2 meetings with the U.S. FDA, the company is moving quickly to initiate one placebo-controlled Phase 3 trial each in severe asthma and CRSwNP. Leveraging the data from its extensive development program to date, the company's goal is to deliver best-in-class efficacy with quarterly at-home administration for patients with severe asthma and CRSwNP, irrespective of biomarker status. The company plans to evaluate a single high-dose regimen of 400 mg, administered every 12 weeks, in broad and representative patient populations, with the intent to robustly demonstrate Verekitug's efficacy and safety profile in these diseases with substantial unmet medical need.

Upstream Bio to Initiate Phase 3 Trials for Severe Asthma in 2027

"We continued to make progress toward the initiation of our Phase 3 trials in severe asthma and CRSwNP in the first quarter of 2027. Our End-of-Phase 2 interactions with the FDA are on schedule, and we look forward to sharing more details about our Phase 3 development plans soon," said Rand Sutherland, Chief Executive Officer of Upstream Bio. "With more than 500 participants treated in verekitug clinical trials thus far, and with compelling Phase 2 results now demonstrated in both severe asthma and CRSwNP, we have built a substantial and consistent body of clinical evidence supporting verekitug's potential to deliver durable, best-in-class efficacy with convenient quarterly dosing. In addition, our CMC and device development efforts continue to advance, and we are working diligently to provide options for both at-home and in-office administration at launch."