Summit Therapeutics Inc. (NASDAQ: SMMT) announced the publication of primary analysis results from its global Phase III HARMONi clinical trial in The Lancet Oncology, evaluating ivonescimab combined with platinum-doublet chemotherapy in patients with EGFR-mutated non-small cell lung cancer (NSCLC) whose disease progressed after a third-generation EGFR tyrosine kinase inhibitor (TKI).

The trial was conducted across 114 cancer centers and hospitals in Asia, Europe, and North America. At the primary analysis, ivonescimab plus chemotherapy showed a statistically significant improvement in progression-free survival (PFS) compared to placebo plus chemotherapy. Median PFS was 6.8 months in the ivonescimab arm versus 4.4 months in the placebo arm, with a hazard ratio of 0.52 (95% CI: 0.41–0.66; p<0.0001). The PFS benefit was consistent across preplanned subgroups.

At the time of the primary overall survival (OS) analysis, the ivonescimab arm showed a positive OS trend that did not reach statistical significance. Treatment-related grade 3–5 hemorrhage events occurred in less than 1% of patients in the ivonescimab-plus-chemotherapy arm.

Lead author Xiuning Le, M.D., Ph.D., of The University of Texas MD Anderson Cancer Center, said that traditional anti-PD-(L)1 therapies have not established a clear benefit in prior Phase III studies in this patient population, and that "the HARMONi results suggest that ivonescimab's mechanism of action, targeting of PD-1 and VEGF simultaneously in one construct, may offer a clinically meaningful strategy."

An updated OS analysis based on a June 2026 data cut will be presented at the International Association for the Study of Lung Cancer's 2026 World Conference on Lung Cancer on September 15, 2026. That analysis showed a continued positive OS trend and a consistent efficacy and safety profile in both Asian and western patients, with western patients achieving an OS hazard ratio of 0.76.

The FDA has assigned a Prescription Drug User Fee Act goal action date of November 14, 2026, for Summit's Biologics License Application for ivonescimab in this indication. Ivonescimab is not approved by any regulatory authority in Summit's license territories, which include the United States and Europe.