WALTHAM, Mass., June 08, 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 announced that additional data from its Phase 2 VIBRANT trial of verekitug in patients with chronic rhinosinusitis with nasal polyps (CRSwNP) will be presented in an oral session at the European Academy of Allergy and Clinical Immunology (EAACI) 2026 Congress in Istanbul, Turkey, on Sunday, June 14, 2026. The presentation will feature a responder analysis examining the proportion of patients who achieved clinically meaningful improvements in key measures of disease with verekitug. Verekitug is the only known antagonist of the thymic stromal lymphopoietin (TSLP) receptor currently in clinical development.

Presentation details:

Presentation Title: Verekitug, a novel TSLP receptor antagonist antibody, in participants with chronic rhinosinusitis with nasal polyps in VIBRANT: responder analysis using clinically meaningful efficacy outcome thresholds

Presenting Author: Joaquim Mullol, MD, PhD, Universitat de Barcelona

Session: OAS23 - Transforming disease course: clinical outcomes and remission with biologics

Presentation Date and Time: Sunday, June 14, 2026 – 15:15 – 16:45 TRT

Location: Room Munich

About Verekitug

Verekitug is a novel recombinant fully human immunoglobulin G1 (IgG1) monoclonal antibody that binds to the thymic stromal lymphopoietin (TSLP) receptor and inhibits proinflammatory signaling initiated by TSLP. It is the only known antagonist currently in clinical development that targets and inhibits the TSLP receptor.

TSLP is a cytokine that is a key driver of the inflammatory response in major allergic and inflammatory diseases, such as asthma, where disruption of TSLP signaling has been clinically validated as an effective therapeutic strategy. TSLP activation is one of the first events in the inflammatory cascade stimulated by allergens, viruses and other triggers, initiating the activation of downstream targets such as IL-4, IL-5, IL-13, IL-17 and IgE. Because TSLP is a target upstream in the inflammatory cascade, blocking the TSLP receptor presents an opportunity for a single treatment to impact the drivers of multiple pathological inflammatory processes across a broad set of diseases.

Verekitug has advanced into three separate global, placebo-controlled, randomized Phase 2 clinical trials including the recently completed positive VIBRANT trial (NCT06164704) in patients with CRSwNP and VALIANT trial (NCT06196879) in patients with severe asthma. The VENTURE trial (NCT06981078) in patients with moderate-to-severe chronic obstructive pulmonary disease (COPD) is ongoing. Additionally, in May 2025, Upstream Bio initiated the VALOUR trial (NCT06966479), a long-term extension study in eligible participants with severe asthma who completed the VALIANT Phase 2 clinical trial.

About Upstream Bio

Upstream Bio is a clinical-stage biotechnology company developing treatments for inflammatory diseases, with an initial focus on severe respiratory disorders. The Company is developing verekitug, the only known antagonist currently in clinical development that targets and inhibits the receptor for thymic stromal lymphopoietin (TSLP), a cytokine which is a clinically validated driver of inflammatory response positioned upstream of multiple signaling cascades that affect a variety of immune-mediated diseases. The Company has advanced this highly potent monoclonal antibody into separate Phase 2 trials for the treatment of chronic rhinosinusitis with nasal polyps (CRSwNP), severe asthma, and chronic obstructive pulmonary disease (COPD). Upstream Bio's team is committed to maximizing verekitug's unique attributes to address the substantial unmet needs for patients underserved by today's standard of care. To learn more, please visit www.upstreambio.com.

Investor and Media Contact:

Meggan Buckwell

Director, Corporate Communications and Investor Relations

ir@upstreambio.com

Upstream Bio to Showcase Additional Efficacy Data from the Phase 2 VIBRANT Trial of Verekitug in CRSwNP in Oral Session at EAACI 2026