Molecular Profile-based Recommendations for Postoperative Adjuvant Therapy in Early Endometrial Cancer with High-intermediate or Intermediate Risk: a Chinese Randomized Phase III Trial (PROBEAT)

Background: The use of molecular categorisation is shifting paradigm towards the use of molecular information to refine risk stratification in endometrial cancer (EC). To date, evidence to support molecular-guided therapies is limited to retrospective studies and secondary molecular analyses of patients receiving standard treatment. The PROBEAT study is the first randomized phase III trial to evaluate tailored adjuvant treatment based on WHO-endorsed molecular classification in Chinese EC patients. It is expected to provide a clinical decision-making tool for adjuvant treatment of patients with high-intermediate risk (HIR) or intermediate risk (IR) EC to better optimise and personalise patient care and increase relapse-free survival.

Methods: The PROBEAT trial is a prospective, multicentre study led by Women's Hospital of Zhejiang University Gynaecologic Oncology Group. Recruitment started on January 24, 2022, and 590 patients with HIR or IR endometrioid EC are expected to be recruited from 13 clinical centres in China. All tumor tissues will be classified into four molecular subtypes (mut, MMRd, p53abn, or NSMP) based on WHO-endorsed molecular classification. Patients will be randomly assigned at a 2:1 ratio to either experimental arm and will receive molecular profile-based adjuvant treatment (observation in the mut subgroup, vaginal brachytherapy in the MMRd or NSMP subgroup, or chemoradiotherapy in the p53abn subgroup) or to standard arm and will receive preferred adjuvant radiotherapy as recommended by the recent National Comprehensive Cancer Network guidelines version 1 (2022). The primary outcome is 3-year rates of recurrence. Secondary outcomes are relapse-free survival, overall survival, adverse events and health-related cancer-specific quality of life.

Trial Registration: ClinicalTrials.gov Identifier: NCT05179447.