Upstream Bio Presents New Data from VIBRANT Trial

Upstream Bio presented new data from the Phase 2 VIBRANT trial evaluating verekitug in participants with chronic rhinosinusitis with nasal polyps. The data, presented in two posters at the American Thoracic Society 2026 International Conference in Orlando, FL, demonstrated the positive effect of verekitug in participants with CRSwNP and comorbid asthma, as well as its impact on type 2 inflammatory biomarkers in blood and nasal secretions. Approximately 60% of the 81 participants in the VIBRANT trial had comorbid asthma. Among participants with comorbid asthma, verekitug 100 mg administered every 12 weeks led to improvement in asthma symptom control at Week 24, with a placebo-adjusted least squares mean reduction in ACQ-6 of -0.9 compared with placebo-well above the minimal clinically important change in ACQ-6 of -0.5. Verekitug also led to improvements in NPS at Week 24 in participants with and without comorbid asthma, consistent with the previously reported VIBRANT top-line results. In participants with comorbid asthma, generally greater improvements were observed across sinonasal symptom measures, including nasal congestion score, total symptom score, difficulty with sense of smell and Lund-Mackay score, compared with participants without comorbid asthma. Among participants with comorbid asthma, verekitug reduced the need for rescue systemic corticosteroids or CRSwNP surgery by 83% compared with placebo. In a separate post hoc analysis, verekitug 100 mg administered every 12 weeks led to rapid and sustained reductions in key type 2 inflammatory cytokines, including IL-4, IL-5, and IL-13, in both blood and nasal secretions over 24 weeks of treatment with generally greater reductions observed in nasal secretions. Verekitug also reduced additional mediators of local inflammation and fibrotic activity, including periostin, thymus and activation-regulated cytokine, macrophage-derived chemokine, and eotaxin-3, shedding light on the mechanisms by which a thymic stromal lymphopoietin receptor blockade may benefit patients with inflammatory airway disease. Verekitug reduced blood eosinophils by 50% as early as Week 2, with reductions sustained through Week 24. Reductions in IgE were observed beginning at Week 4 and continued to decline through Week 24. The magnitude of IL-5 reduction in blood correlated with the magnitude of reduction in blood eosinophils following verekitug treatment, VIBRANT was a Phase 2 global, randomized, double-blind, placebo-controlled, parallel group clinical trial that evaluated the efficacy and safety of verekitug over 24 weeks in 81 adults with CRSwNP. Upstream Bio designed the VIBRANT trial using endpoints that, pending interactions with regulatory authorities, could produce data to support submissions for product approval. The Company plans to initiate dosing in Phase 3 registrational trials in both CRSwNP and severe asthma in the first quarter of 2027.