Summit Therapeutics To Present Data From Phase III HARMONi Trial Featuring Investigational Bispecific Antibody, Ivonescimab, At WCLC 2025

Ivonescimab to be Featured at WCLC Presidential Symposium for Second Consecutive Year

Summit Therapeutics Inc. (NASDAQ:SMMT) ("Summit," "we," or the "Company") today announced that data from the Phase III HARMONi trial featuring the novel, potential first-in-class investigational bispecific antibody, ivonescimab, will be presented as part of the Presidential Symposium at the International Association for the Study of Lung Cancer's (IASLC) 2025 World Conference on Lung Cancer (WCLC 2025) in Barcelona on Sunday, September 7, 2025, at 8:15am CET (2:15am ET). This is the second consecutive year ivonescimab has been featured in the WCLC Presidential Symposium.

HARMONi is a multiregional, double-blinded, placebo-controlled, Phase III study sponsored by Summit evaluating ivonescimab plus platinum-doublet chemotherapy compared to placebo plus platinum-doublet chemotherapy in patients with epidermal growth factor receptor (EGFR)-mutated, locally advanced or metastatic non-squamous non-small cell lung cancer (NSCLC) who have progressed after treatment with a 3rd generation EGFR tyrosine kinase inhibitor (TKI). This is a clinical setting with a patient population where PD-1 monoclonal antibodies have previously been unsuccessful in Phase III global clinical trials in showing either a progression-free survival (PFS) or overall survival (OS) benefit.

On May 30, 2025, we announced, via a press release, topline results from our multiregional, double-blinded, placebo-controlled, Phase III study, HARMONi. At the prespecified primary data analysis, ivonescimab in combination with chemotherapy demonstrated a statistically significant and clinically meaningful improvement in progression-free survival (PFS), with a hazard ratio of 0.52 (95% CI: 0.41 – 0.66; p<0.00001). PFS was measured by blinded independent central radiology review committee (BICR) compared to placebo in combination with chemotherapy. Ivonescimab in combination with chemotherapy showed a positive trend in overall survival (OS) in the primary analysis without achieving a statistically significant benefit with a hazard ratio of 0.79 (95% CI: 0.62 – 1.01; p=0.057).

The trial results will be presented by Jonathan Goldman, MD, Professor of Medicine at UCLA in the Hematology/Oncology Division, UCLA Director of Clinical Trials in Thoracic Oncology, Associate Director of Early Drug Development, and Chair of University of California Lung Cancer Consortium.