132P An open-label, prospective phase II study of cadonilimab in combination with neoadjuvant chemotherapy for patients diagnosed with advanced ovarian cancer (AK104-IIT-003)

Background: Neoadjuvant treatment of immune checkpoint inhibitors have shown a high pathologic complete response (pCR) rate in patients with dMMR/MSI-H, locally advanced colorectal cancer (LACRC).Cadonilimab (AK104), a novel bispecific antibody simultaneously targeting PD-1 and CTLA-4, was designed to boost anti-tumor activity with a favorable safety profile.Here, we primary reported the efficacy and safety of AK104 in the neoadjuvant treatment of dMMR/MSI-H LACRC, while concurrently exploring the potential for surgery avoidance. Methods:The study was a multi-cohort, phase 2 trial, consisted of Cohort A (locally advanced colon cancer) and B (Locally Advanced Rectal Cancer).Patients (pts) with dMMR/MSI-H, LACRC were enrolled to receive AK104 (10mg/kg, iv, d1, q3w) for up to 8 cycles.The primary endpoint is the complete response rate (CR, pCR plus cCR).Secondary endpoints include MPR rate, R0 resection rate, DFS, OS, and safety.Results: From April 2023 to August 2024, 34 pts were enrolled (26 in Cohort A and 8 in Cohort B).Baseline characteristics of pts are listed in the table.34 pts had at least 2 cycles of treatment.In Cohort B, 4 pts completed the entire neoadjuvant treatment, and all reached the cCR.Currently, 13 pts (12 in Cohort A and 1 in Cohort B) received surgical resection, and the R0 resection rate was 100%.The pCR rate was 84.6% (11/ 13) and the MPR rate was 100 % (13/13).The median DFS was not reached.Treatment-related adverse events (TRAEs) occurred in 18/34(53%) pts. 5 /34 (14.7%) pts experienced grade 3-4 treatment-related adverse events (TRAEs), which included adrenocortical hypofunction (1 pt), myocarditis (1 pt), myositis (2 pts), and thrombocytopenia (1pt).No grade 5 AEs were observed.