Summit Therapeutics Presents Updated Overall Survival Results From Global Phase III HARMIONi Clinical Trial Of Ivonescimab At The International Association For The Study Of Lung Cancer Conference; Sustained OS Improvement Seen With Longer Follow-Up In Western Patients, Consistent Across Geographic Regions; No New Safety Signals Observed

Updated overall survival (OS) results from the global Phase III HARMONi clinical trial featuring the novel, potential first-in-class investigational bispecific antibody ivonescimab were presented today at the International Association for the Study of Lung Cancer (IASLC) 2026 World Conference on Lung Cancer (WCLC 2026) in Seoul, Republic of Korea.

As Summit previously announced on July 22, 2026, ivonescimab plus platinum-doublet chemotherapy in the HARMONi trial continued to show a positive OS trend and a consistent efficacy and safety profile in Asian and western patients when compared to placebo plus chemotherapy.

"Updated results from the global Phase III HARMONi study show that ivonescimab combined with chemotherapy continued to demonstrate a consistent overall survival improvement compared with placebo plus chemotherapy in patients with EGFR-mutated non-small cell lung cancer following prior treatment with a third-generation EGFR TKI," said Antonio Passaro, M.D., Ph.D., Director of the Division of Thoracic Oncology, European Institute of Oncology (IEO) in Milan, Italy, and presenting author. "Importantly, with longer follow-up, the survival improvement observed in western patients was consistent with the global population, reinforcing the relevance of these results across geographic regions in a setting where patients continue to need additional treatment options after progression on EGFR-targeted therapy."

HARMONi Detailed Efficacy and Safety Results

The HARMONi study is evaluating ivonescimab combined with chemotherapy compared to placebo plus chemotherapy in patients with epidermal growth factor receptor (EGFR)-mutated, locally advanced or metastatic non-squamous non-small cell lung cancer (NSCLC) who were previously treated with a third-generation EGFR tyrosine kinase inhibitor (TKI). The study demonstrated a statistically significant benefit in the primary analysis for progression-free survival (PFS), one of the study’s two primary endpoints, the other being OS.

In April 2025, the primary OS analysis was performed, whereby ivonescimab in combination with chemotherapy showed a positive trend without achieving a statistically significant benefit with a hazard ratio of 0.79 (95% CI: 0.62 – 1.01; p=0.057). Median OS was 16.8 months for those patients administered ivonescimab plus chemotherapy vs. 14.0 months for those receiving placebo plus chemotherapy. At the time of the primary analysis, median follow-up time for western patients was 9.2 months which was less than the median OS.

An additional analysis was performed with a data cut-off date in June 2026, whereby most western patients have discontinued or completed two years of treatment (median follow-up time 23.2 months for western patients). Median follow-up time for Asian patients was 32.7 months (this was reached in April 2025 and Asian patient data was locked at the time of that analysis). The updated June 2026 analysis continued to show consistent, favorable OS results, with an OS hazard ratio of 0.76 (95% CI: 0.61 – 0.95; nominal p=0.0151) in the global intention-to-treat (ITT) population. An OS hazard ratio of 0.76 was demonstrated in the western patient subgroup (95% CI: 0.52 – 1.10), which was consistent with the ITT population and Asian subgroup.

In this most recent analysis, ivonescimab continued to demonstrate an acceptable and manageable safety profile that was consistent with previous Phase III data of ivonescimab plus chemotherapy. No additional safety signals were noted in this latest HARMONi data cut.

"The updated HARMONi overall survival analysis presented at WCLC 2026 provides important additional evidence of the consistency of ivonescimab’s clinical profile across patient populations, with western patients showing consistent survival improvement to what was observed in Asian patients," stated Dr. Maky Zanganeh, President and Co-Chief Executive Officer of Summit. "Together with the continued acceptable and manageable safety profile, these data reinforce our confidence in the HARMONi results as we work toward the potential approval of ivonescimab in the U.S."

"What continues to distinguish ivonescimab is not only the strength of these HARMONi results, but the expanding clinical data sets emerging across studies and tumor types, including recent positive results from HARMONi-2 and HARMONi-GI1 in biliary tract cancer," added Robert W. Duggan, Chairman and Co-Chief Executive Officer of Summit. "Together, these data reinforce our belief in the potential breadth of ivonescimab’s differentiated bispecific design as an important new therapeutic approach in oncology, beginning with EGFR-mutated non-small cell lung cancer and extending across our broader ambition to address serious needs in solid tumors where patients urgently need better options."

Summit’s Biologics License Application (BLA) with the U.S. Food and Drug Administration (FDA) is based on the results from the HARMONi trial and has a Prescription Drug User Fee Act (PDUFA) goal action date of November 14, 2026.

HARMONi-2 Detailed OS Efficacy and Safety Results

Previously, key findings from the HARMONi-2 primary OS analysis were announced by Summit’s partner, Akeso Inc. Today, the full detailed results were presented at WCLC 2026, with highlights provided below. HARMONi-2 (AK112-303) is a single-region, multi-center Phase III study conducted in China and sponsored by Akeso, with all relevant data exclusively generated, managed, and analyzed by Akeso.

In this protocol-specified interim analysis of OS, a secondary endpoint in the HARMONi-2 study, ivonescimab monotherapy demonstrated a statistically significant and clinically meaningful improvement compared to pembrolizumab monotherapy, achieving a hazard ratio (HR) of 0.73 (95% CI: 0.57, 0.95; p=0.009). A clinically meaningful benefit was demonstrated across important clinical subgroups, including those with PD-L1 low expression (PD-L1 Score 1-49%) and PD-L1 high expression (PD-L1 Score ≥ 50%), along with those with squamous and non-squamous histologies.