Upstream's lead program, UPB-101, is a clinical-stage monoclonal antibody that inhibits the TSLP receptor. TSLP is a validated target positioned upstream of multiple signaling cascades that affect a variety of immune cells pivotal to common and rare diseases.

In June 2023, the company announced the completion of a $200 million Series B financing. The capital raised will fund Upstream’s next stage of clinical development for UPB-101, a monoclonal antibody targeting the TSLP receptor (TSLPR) in Phase Ib development for the treatment of asthma as of Q2 2023. Upstream will pursue registrational Phase II clinical trials in asthma and chronic rhinosinusitis with nasal polyps (CRSwNP) thereafter.

In parallel with Phase II studies, Upstream plans to conduct substantial translational, manufacturing and device development activities to be prepared for a swift transition to Phase III development. The Series B raise is sized to support development of a highly differentiated target product profile that will be compelling for regulatory, market access and commercialization activities.