$SMMT · Summit Therapeutics Inc.
Summit Therapeutics filed an 8-K announcing that partner Akeso Inc. will present updated overall survival data from the Phase III HARMONi-2 trial at WCLC 2026 on September 15, 2026. The trial compared ivonescimab monotherapy to pembrolizumab monotherapy in PD-L1-positive advanced NSCLC patients (n=398). Ivonescimab demonstrated a statistically significant OS benefit with HR=0.73 (p=0.009), median OS of 30.8 months vs. 22.6 months — an 8.2-month improvement. The PD-L1 high subgroup showed an even stronger HR of 0.58.
- Ivonescimab reduced risk of death by 27% vs. pembrolizumab (HR=0.73, p=0.009) in the HARMONi-2 ITT population (n=398).
- Median overall survival was 30.8 months for ivonescimab vs. 22.6 months for pembrolizumab — an 8.2-month improvement.
- In the PD-L1 high expression subgroup (n=168), the hazard ratio was 0.58 (95% CI: 0.38, 0.89).
- Serious treatment-related adverse events were 29.9% for ivonescimab vs. 21.6% for pembrolizumab; discontinuation rates were similar (4.1% vs
- HARMONi-2 marks the fourth Phase III study where ivonescimab showed statistically significant OS and PFS benefits against standard-of-care.
SMMT is up +6.44% since the filing, reflecting investor enthusiasm for the first overall survival data from HARMONi-2 showing a clear benefit over the $25B+ franchise drug pembrolizumab. The 8.2-month median OS improvement and HR of 0.58 in PD-L1 high patients strengthen the bull case ahead of the November 14, 2026 PDUFA date.
First randomized Phase III trial to show an overall survival benefit for a PD-1/VEGF bispecific over Keytruda monotherapy in first-line NSCLC — a direct challenge to Merck's dominant franchise.
This is the first randomized Phase III trial to show an overall survival benefit for a PD-1/VEGF bispecific antibody over pembrolizumab monotherapy in first-line NSCLC — a setting where Keytruda has been the dominant standard of care. The data raise the stakes for Merck's Keytruda franchise and forA
HARMONi-2 was conducted entirely in China by Akeso; global HARMONi-7 study (targeting 780 patients) is still recruiting and results may differ. Ivonescimab remains investigational in Summit's territories (U.S., Europe) with no regulatory approval yet. Serious TRAEs were higher for ivonescimab (29.9%
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