Summit ivonescimab shows OS hazard ratio of 0.76 in lung cancer trial

Summit Therapeutics Inc. (Nasdaq: SMMT) released updated overall survival data from its global Phase III HARMONi clinical trial evaluating ivonescimab, an investigational bispecific antibody, combined with platinum-doublet chemotherapy in patients with EGFR-mutated non-small cell lung cancer (NSCLC).

In the most recent analysis, using a June 2026 data cut-off, the full intention-to-treat population showed a hazard ratio of 0.76. The western patient subgroup, which now has a median follow-up time of 23.2 months, also showed a hazard ratio of 0.76, compared with 0.98 at the primary April 2025 analysis when median follow-up for western patients was 9.2 months.

The primary OS analysis in April 2025 showed a hazard ratio of 0.79 (95% CI: 0.62–1.01; p=0.057), which did not reach statistical significance. A September 2025 interim analysis with 13.7 months of follow-up for western patients showed a hazard ratio of 0.78 (95% CI: 0.62–0.98; nominal p=0.0332). Median OS in the primary analysis was 16.8 months for the ivonescimab plus chemotherapy arm versus 14.0 months for placebo plus chemotherapy, and remained unchanged in the September 2025 analysis.

Detailed data from the June 2026 cut-off, including median OS and confidence intervals, are planned for presentation at an upcoming medical conference. Summit stated the updated results have been shared with the U.S. Food and Drug Administration.

Summit's Biologics License Application for ivonescimab is under FDA review with a Prescription Drug User Fee Act goal action date of November 14, 2026. The HARMONi trial enrolls patients with locally advanced or metastatic non-squamous NSCLC previously treated with a third-generation EGFR tyrosine kinase inhibitor.

The company reported no new safety signals in the latest data cut, stating the safety profile remained consistent with prior Phase III data.

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