Summit Therapeutics said its phase 2 AK112-206 study in first-line metastatic colorectal cancer produced an objective response rate of 70.8% across both ivonescimab dose groups, with disease control at 100.0% in evaluable patients.
The trial enrolled 49 patients and randomized them evenly between 10 mg/kg and 20 mg/kg doses of ivonescimab, both given with mFOLFOX6 chemotherapy. The analysis cut off on March 31, 2026, with median follow-up of 9.9 months in the 10 mg/kg arm and 9.8 months in the 20 mg/kg arm.
Response durability favored the higher dose. At nine months, the duration-of-response landmark estimate was 79.1% in the 20 mg/kg group versus 41.5% in the 10 mg/kg group. The nine-month progression-free survival rate for the 20 mg/kg arm was 76.1%.
Safety results showed 20.4% of patients experienced serious treatment-related adverse events tied to ivonescimab or chemotherapy. There were no ivonescimab-related deaths and one ivonescimab-related discontinuation. All patients experienced at least one treatment-emergent adverse event related to either ivonescimab or chemotherapy, with the most common being decreased neutrophil count, decreased white blood cell count and anemia.
The company said it is now advancing Harmoni-GI3, a phase 3 trial in first-line unresectable metastatic colorectal cancer comparing ivonescimab plus mFOLFOX6 with bevacizumab plus mFOLFOX6. Following these announcements, the company's shares moved -12.26%, and are now trading at a price of $15.39. For more information, read the company's full 8-K submission here.
