Upstream Bio Inc. (Nasdaq: UPB), a clinical-stage biotechnology company focused on treatments for inflammatory diseases, has presented new data on its investigational drug verekitug at the European Respiratory Society (ERS) Congress 2025. The data highlight verekitug's unique mechanism of action, which involves targeting the thymic stromal lymphopoietin $(TSLP)$ receptor and preventing TSLP binding by occupying its ligand binding sites. Structural and mechanistic studies reveal that verekitug outcompetes TSLP even in the presence of preformed heterodimeric receptor complexes, supporting its potential for differentiated therapeutic effects in a variety of severe respiratory diseases driven by TSLP. Clinical findings from a recent Phase 2 study in chronic rhinosinusitis with nasal polyps indicate statistically significant and clinically meaningful effects with dosing every 12 weeks. Additional Phase 2 top-line data in severe asthma are expected in the first quarter of 2026. The full presentation is available on the Upstream Bio website.