– Company to pursue Phase 3 development strategy designed to deliver best-in-class efficacy with a high-dose quarterly regimen in broad patient populations in both severe asthma and CRSwNP –

– Company plans to initiate dosing in Phase 3 trials in both severe asthma and CRSwNP in Q1 2027 –

– Reported positive top-line results from Phase 2 VALIANT trial of verekitug in patients with severe asthma in February 2026, demonstrating significant improvements in asthma exacerbations and lung function –

– Presented additional analyses from Phase 2 VIBRANT trial at AAAAI, reinforcing verekitug's therapeutic potential in CRSwNP –

– Strong cash position of $341.5 million expected to fund planned operations through 2027 –

WALTHAM, Mass., March 26, 2026 (GLOBE NEWSWIRE) -- Upstream Bio, Inc. (NASDAQ:UPB), a clinical-stage company developing treatments for inflammatory diseases, with an initial focus on severe respiratory disorders, today reported financial results for the fourth quarter and full year ended December 31, 2025, and highlighted its Phase 3 development strategy for verekitug in severe asthma and chronic rhinosinusitis with nasal polyps (CRSwNP). The Company is developing verekitug, the only known antagonist currently in clinical development that targets and inhibits the thymic stromal lymphopoietin (TSLP) receptor, in multiple severe respiratory diseases including severe asthma, CRSwNP, and chronic obstructive pulmonary disease (COPD).