Risk stratification and molecular heterogeneity of endometrial cancer and expression profile of TIM-3: A retrospective cohort study

The present study aimed to implement ProMisE classification and risk grouping on a retrospective cohort of 628 patients with endometrial cancer (EC) and determine the molecular heterogeneity across subtypes and subgroups, as well as to investigate the potential beneficiary for TIM-3 checkpoint inhibition in ECs.Protein expressions of p53, MMR, TIM-3 and CD8 were measured by immunohistochemistry, and massively parallel sequencing was conducted for 128 cancer-related genes. Patients were categorized into four ProMisE subtypes: MMR-deficient (MMRd), POLE-ultramutated (POLEmut), p53-wild type (p53wt), and p53-abnormal (p53abn), and were subjected to risk classification.43 (6.9%) patients belonged to POLEmut, 118 (18.8%) to MMRd, 69 (11%) to p53abn, and 398 (63.3%) to p53wt. Compared to the 2016 stratification system, the 2021 ESGO/ESTRO/ESP risk stratification integrated with molecular classification revealed that 11 patients (11/628, 1.8%) were upgraded due to the p53abn signature, whereas 23 patients (23/628, 3.7%) were downgraded due to the POLEmut signature. JAK1 and RAD50 mutations showed higher frequencies in patients with aggressive phenotypes. RAD51B mutation was significantly related to poor RFS of the p53wt subtype but not of the other three molecular subgroups. TIM-3 expression was detected in 30.9% immune cells (ICs) and 29.0% tumor cells (TCs) in ECs, respectively. It was frequently expressed in POLEmut and MMRd ECs as compared to that in the other two molecular subtypes in TCs and ICs.Our study revealed the molecular heterogeneity across subtypes and subgroups. The new risk stratification system changed the risk grouping of some patients due to the integration of molecular features. RAD51B mutation can further stratify the recurrence risk in the p53wt subtype. Patients with MMRd or POLEmut may benefit most from immunotherapy against TIM-3.