Summit Therapeutics Inc. (Nasdaq: SMMT) presented updated overall survival data from its Phase III HARMONi clinical trial at the International Association for the Study of Lung Cancer 2026 World Conference on Lung Cancer in Seoul, South Korea.

The trial evaluates ivonescimab, an investigational bispecific antibody, combined with platinum-doublet chemotherapy versus placebo plus chemotherapy in patients with EGFR-mutated, locally advanced or metastatic non-squamous non-small cell lung cancer (NSCLC) who previously received a third-generation EGFR tyrosine kinase inhibitor.

In a June 2026 data cut, the global intention-to-treat population showed an overall survival hazard ratio of 0.76 (95% CI: 0.61–0.95; nominal p=0.0151), compared with a hazard ratio of 0.79 (95% CI: 0.62–1.01; p=0.057) in the April 2025 primary analysis. Median OS was 16.8 months for the ivonescimab arm versus 14.0 months for the placebo arm across analyses. The western patient subgroup, with a median follow-up of 23.2 months in the June 2026 cut, showed a hazard ratio of 0.76 (95% CI: 0.52–1.10), consistent with the overall population. No new safety signals were observed.

Separately, full results from the HARMONi-2 study, sponsored by Akeso Inc. (HKEX: 9926.HK) and conducted solely in China, were also presented. That trial compared ivonescimab monotherapy against pembrolizumab monotherapy in patients with PD-L1-positive NSCLC. At a median follow-up of 36 months, ivonescimab showed a median OS of 30.8 months versus 22.6 months for pembrolizumab, with a hazard ratio of 0.73 (95% CI: 0.57–0.95; p=0.009). Serious treatment-related adverse events occurred in 29.9% of ivonescimab patients versus 21.6% in the pembrolizumab arm.

Summit's Biologics License Application with the U.S. Food and Drug Administration, based on HARMONi results, carries a PDUFA goal action date of November 14, 2026. Ivonescimab is not approved by any regulatory authority in Summit's license territories, which include the United States and Europe.