Summit Therapeutics Inc. (NASDAQ: SMMT) announced that ivonescimab combined with chemotherapy demonstrated a statistically significant overall survival benefit compared to tislelizumab plus chemotherapy in patients with squamous non-small cell lung cancer.

The Phase III HARMONi-6 trial, conducted in China by Summit's partner Akeso Inc. (HKEX: 9926.HK), showed ivonescimab plus chemotherapy reduced the risk of death by 34% with a hazard ratio of 0.66 compared to the control arm. The study included 532 patients with locally advanced or metastatic squamous NSCLC.

Median overall survival reached 27.89 months for patients receiving ivonescimab plus chemotherapy versus 23.69 months for those receiving tislelizumab plus chemotherapy. At 24 months, survival rates were 64.7% and 48.6% respectively, with a median follow-up of 21.4 months.

The survival benefit was observed across clinical subgroups regardless of PD-L1 expression levels. In PD-L1 negative patients, the hazard ratio was 0.64, while PD-L1 positive patients showed a hazard ratio of 0.68.

Treatment-related serious adverse events occurred in 41.4% of patients receiving ivonescimab combination therapy compared to 34.3% receiving tislelizumab combination therapy. Grade 3 or higher hemorrhage events were observed in 2.6% of ivonescimab patients versus 0.8% in the control group.

The results were presented at the American Society of Clinical Oncology Annual Meeting and simultaneously published in The Lancet. Ivonescimab is a bispecific antibody that blocks both PD-1 and VEGF pathways in a single molecule.

Summit submitted a Biologics License Application to the FDA for ivonescimab in January 2026, with a target review completion date of November 14, 2026, based on data from a separate trial in EGFR-mutated NSCLC.