Upstream Bio, Inc., a clinical-stage biotechnology company, develops treatments for inflammatory diseases that focuses on severe respiratory disorders. It develops verekitug, a monoclonal antibody that targets and inhibits the thymic stromal lymphopoietin receptor. The company also develops therapies to treat severe asthma, chronic rhinosinusitis with nasal polyps, and chronic obstructive pulmonary disease. Upstream Bio, Inc. was incorporated in 2021 and is based in Waltham, Massachusetts.