Key Takeaways
Upstream Bio (Nasdaq: UPB) reported that its experimental drug verekitug significantly improved asthma control and reduced the need for rescue interventions in a study of patients with chronic rhinosinusitis with nasal polyps (CRSwNP) and comorbid asthma. The data, from a post-hoc analysis of the Phase 2 VIBRANT trial, were presented at the American Thoracic Society 2026 International Conference.
"These new analyses indicate that verekitug improves asthma control in CRSwNP patients with comorbid asthma, while delivering consistent improvements in nasal polyp burden, sinonasal symptoms, and reduced reliance on surgery or systemic steroids," Aaron Deykin, Chief Medical Officer at Upstream Bio, said. He added that the results reinforce the company's belief in the drug's ability to address disease broadly across the airway.
The analysis showed that among patients with comorbid asthma, treatment with 100 mg of verekitug every 12 weeks resulted in an 83 percent reduction in the need for rescue systemic corticosteroids or surgery compared with placebo. The treatment also produced a placebo-adjusted improvement of -0.9 on the Asthma Control Questionnaire-6 (ACQ-6), a measure of asthma symptoms, surpassing the -0.5 threshold considered clinically important. The VIBRANT trial enrolled 81 adults, approximately 60 percent of whom had comorbid asthma.
These results position verekitug to compete in a market for severe inflammatory conditions that includes other biologics targeting similar pathways. Verekitug is the only clinical-stage antagonist targeting the thymic stromal lymphopoietin (TSLP) receptor. This mechanism is distinct from but related to Amgen and AstraZeneca's tezepelumab, a TSLP-blocking antibody approved in 2021. By blocking the receptor, Upstream aims to inhibit inflammatory signaling further downstream. The company plans to initiate Phase 3 trials in both severe asthma and CRSwNP in the first quarter of 2027, with a cash runway of $341.5 million expected to fund operations through 2027.
Verekitug's mechanism of action is designed to block a key upstream trigger in the inflammatory cascade. TSLP is a cytokine that initiates signaling through multiple pathways involving IL-4, IL-5, and IL-13, which are central to type 2 inflammation common in both asthma and CRSwNP.
In the VIBRANT trial, verekitug led to rapid and sustained reductions in these key biomarkers. Blood eosinophils, a type of white blood cell that drives inflammation, were reduced by 50 percent as early as week two, a reduction that was sustained through 24 weeks. The company also reported that the magnitude of IL-5 reduction in the blood correlated with the drop in eosinophils, supporting the drug's proposed mechanism.
Despite a series of positive clinical readouts over the past year for verekitug, Upstream Bio's stock has shown a volatile reaction to trial news. According to an analysis by StockTitan, the five previous clinical-trial headlines for UPB produced an average next-day stock move of -5.73 percent, suggesting market caution.
The company's stock gained 3.41 percent on the day of the latest announcement, closing at $9.09, while several biotech peers traded lower. The trading volume of 979,799 shares was nearly double the 20-day average, indicating elevated investor interest in the new data. Upstream Bio's research and development expenses rose to $40.2 million in the fourth quarter of 2025, up from $21.8 million a year earlier, primarily driven by the verekitug programs.
This article is for informational purposes only and does not constitute investment advice.
