Summit Therapeutics (NASDAQ: SMMT) announced that its partner Akeso Inc. (HKEX: 9926.HK) presented updated overall survival data from the Phase III HARMONi-2 trial at the International Association for the Study of Lung Cancer's 2026 World Conference on Lung Cancer in Seoul, South Korea.

The trial evaluated ivonescimab monotherapy against pembrolizumab monotherapy in 398 patients with locally advanced or metastatic non-small cell lung cancer (NSCLC) with positive PD-L1 expression. At a median follow-up of 36 months, ivonescimab produced a median overall survival of 30.8 months compared to 22.6 months for pembrolizumab, a difference of 8.2 months. The overall survival hazard ratio was 0.73 (95% CI: 0.57, 0.95; p=0.009).

In the PD-L1 high expression subgroup (PD-L1 score ≥50%, n=168), the hazard ratio was 0.58 (95% CI: 0.38, 0.89). The squamous histology subgroup showed a hazard ratio of 0.65 (95% CI: 0.45, 0.95). These subgroup analyses were descriptive and not formally powered.

Serious treatment-related adverse events occurred in 29.9% of ivonescimab patients versus 21.6% of pembrolizumab patients. Treatment discontinuation due to adverse events occurred in 4.1% and 5.0% of patients, respectively.

China's National Medical Products Administration granted marketing authorization for ivonescimab based on HARMONi-2's primary analysis in April 2025, which showed a progression-free survival hazard ratio of 0.51 (95% CI: 0.38, 0.69; p<0.0001). Ivonescimab remains investigational and is not approved in Summit's license territories, including the United States and Europe.

Summit is conducting the global Phase III HARMONi-7 study (NCT06767514), comparing ivonescimab to pembrolizumab in first-line metastatic NSCLC patients with PD-L1 high expression, targeting enrollment of 780 patients. The study began in early 2025. Separately, the FDA accepted a Biologics License Application for ivonescimab in a different NSCLC indication, with a PDUFA date of November 14, 2026.