Akeso (HKEX: 9926.HK) reported on Saturday that ivonescimab, its PD-1/VEGF bispecific antibody, cut the risk of death by 34% compared with a PD-1 inhibitor plus chemotherapy in first-line squamous NSCLC. The result marks the first time any therapy has beaten a PD-1-based regimen in a head-to-head Phase III overall survival test for the indication. The results were simultaneously published in The Lancet and selected for the ASCO 2026 plenary session, the first time a China-originated oncology drug has reached that platform in the society's 61-year history.
The HARMONi-6 study enrolled 532 patients with advanced squamous NSCLC and randomized them to ivonescimab plus chemotherapy or BeiGene's Tevimbra (tislelizumab) plus chemotherapy. With a median follow-up of 21.36 months and a data cutoff of February 27, 2026, ivonescimab overall survival reached a median of 27.9 months versus 23.7 months in the tislelizumab arm (HR=0.66; 95% CI: 0.50–0.87; P=0.0017). The 24-month OS rate diverged meaningfully: 64.7% versus 48.6%. At a prespecified interim analysis, progression-free survival also favored ivonescimab, with a median of 11.1 months versus 6.9 months (HR=0.60; 95% CI: 0.46–0.78; P < 0.0001). The OS benefit was consistent across PD-L1 subgroups and in patients with higher metastatic burden, including those with liver metastases (HR=0.69) and three or more metastatic sites (HR=0.47). Grade ≥3 treatment-related adverse events occurred in 69.2% of patients in the ivonescimab arm versus 58.9% in the tislelizumab arm — a numerically higher rate, though rates of discontinuation and treatment-related death were described as similar between arms.
Ivonescimab is designed to block both PD-1 and VEGF through a single bispecific molecule, with the rationale that simultaneous immunologic and anti-angiogenic activity may produce more durable tumor control than either pathway alone — particularly in squamous NSCLC, where anti-VEGF agents such as bevacizumab have historically been avoided due to bleeding risk. The HARMONi-6 trial results now provide OS-level evidence for that hypothesis in this histology.
The result is particularly noteworthy since ivonescimab is being developed globally by Summit Therapeutics outside China. Positive OS data from HARMONi-6 may strengthen expectations for ongoing global Phase III studies and increase pressure on established PD-1 franchises led by Merck's Keytruda.