Hong Kong, China, and Madrid, Spain, October 25, 2026
Akeso, Inc., in collaboration with Summit Therapeutics, has reported positive Phase 3 results for ivonescimab combined with chemotherapy in patients with previously untreated advanced biliary tract cancer (BTC). Results from the HARMONi-GI1 clinical trial demonstrated statistically significant overall survival improvement compared with durvalumab plus chemotherapy, an established first-line immunotherapy regimen. Presented at the European Society for Medical Oncology (ESMO) Congress 2026 in Madrid, the findings mark an important milestone for an investigational bispecific antibody being evaluated across multiple cancer types. Median overall survival reached 14.9 months with ivonescimab plus chemotherapy, compared with 12.1 months with durvalumab plus chemotherapy, representing a 25% reduction in the risk of death. The trial also met its key secondary endpoints of progression-free survival and objective response rate. These findings could support further development of ivonescimab for advanced biliary tract cancer, although regulatory review and additional clinical evaluation will determine its potential role in routine treatment.
Phase 3 HARMONi-GI1 Trial Demonstrates Survival Benefit
The randomized, double-blind, multicenter HARMONi-GI1 Phase 3 study evaluated ivonescimab plus chemotherapy against durvalumab plus chemotherapy as first-line treatment for patients with advanced biliary tract cancer. The trial enrolled 682 patients in China, with 340 assigned to the ivonescimab combination and 342 to the durvalumab combination. At a median follow-up of 14.3 months, the ivonescimab group demonstrated a statistically significant overall survival advantage, with a hazard ratio of 0.75 and a reported one-sided P-value of 0.0031. The 12-month overall survival rate was 59.7% with ivonescimab compared with 50.7% with durvalumab, while the 18-month survival rates were 44.0% and 32.5%, respectively. The study also showed a meaningful improvement in progression-free survival, with a median of 8.4 months for ivonescimab plus chemotherapy versus 5.8 months for durvalumab plus chemotherapy. This corresponded to a 39% reduction in the risk of disease progression or death. The findings suggest that the investigational combination may offer improved disease control and longer survival in this patient population.
Ivonescimab Combines PD-1 and VEGF Targeting
Ivonescimab is an investigational bispecific antibody designed to target both programmed cell death protein 1 (PD-1) and vascular endothelial growth factor (VEGF). PD-1 is an immune checkpoint that can suppress the activity of T cells responsible for attacking cancer cells, while VEGF promotes the formation of blood vessels that support tumor growth. By blocking both pathways, ivonescimab is designed to enhance antitumor immune activity while interfering with tumor-associated blood vessel formation. This dual-targeting approach distinguishes it from durvalumab, which targets PD-L1, an immune checkpoint protein, but does not directly inhibit VEGF. In the HARMONi-GI1 study, the objective response rate was 53.8% with ivonescimab plus chemotherapy, compared with 32.5% with durvalumab plus chemotherapy. The disease control rate was 91.5% versus 77.8%, respectively. These results indicate a higher proportion of patients experienced tumor shrinkage or disease stabilization with the ivonescimab combination. However, further research is needed to establish how the dual-target mechanism contributes to the observed benefits and which patients are most likely to respond.
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Safety Findings and Future Clinical Development
The reported safety profile of ivonescimab plus chemotherapy was considered manageable, with no new safety signals identified in the trial. The most common adverse events included hematologic toxicities, such as reductions in blood cell counts, which require appropriate clinical monitoring. Serious adverse events occurred at similar rates in the two treatment groups, at 43.4% with ivonescimab and 43.7% with durvalumab. Grade 3 or higher bleeding events were also comparable between groups. Ivonescimab remains investigational for biliary tract cancer and is not an approved treatment for this indication. The HARMONi-GI1 results were generated in China, and further studies will be important to assess the findings across broader patient populations and healthcare settings. Summit Therapeutics is also advancing ivonescimab through additional clinical programs, including research in non-small cell lung cancer and other solid tumors. The positive survival data expand the clinical evidence for this bispecific antibody beyond lung cancer and support continued investigation of dual immune checkpoint and angiogenesis targeting. Future regulatory decisions will depend on the complete clinical evidence, safety assessments and applicable review requirements.
Source: Akeso, Summit Therapeutics press release
