HB0025-C-0301: A Study to Investigate HB0025 Combined With Chemotherapy as First-Line Treatment for Advanced or Recurrent MMR-proficient Endometrial Cancer

This is a multicenter, randomized, double-blind, placebo controlled Phase III clinical trial, aiming to evaluate the efficacy and safety of HB0025 combined with chemotherapy (paclitaxel plus carboplatin) versus placebo combined with chemotherapy (paclitaxel plus carboplatin) as a first-line treatment for advanced (Stage III/IV) or recurrent proficient Mismatch Repair Endometrial Cancer（pMMR EC). The trial will take progression-free survival (PFS) assessed by Blinded Independent Central Review (BICR) as the primary endpoint, and plans to enroll approximately 333 participants. After being eligible for screening, participants will be randomly assigned to the study arms at a ratio of 2:1 to receive either HB0025 combined with chemotherapy (experimental group) or placebo combined with chemotherapy (control group). Both regimens will be administered once every 3 weeks (Q3W). After completing 6 cycles of combination treatment, patients will enter the maintenance therapy phase with HB0025 or placebo (Q3W) only. The treatment will last until intolerable toxicity occurs, disease progression, lost to follow up or death, withdrawal of consent, pre-scheduled study treatment are completed, receiving new anticancer therapy or sponsor discontinue the study, whichever comes first.