Tumor mutational burden as a prognostic biomarker for survival and quality of life in metastatic colorectal cancer patients receiving anti-PD-1/PD-L1 immunotherapy

The aim of this study was to assess the prognostic value of tumor mutational burden (TMB) as a biomarker for metastatic colorectal cancer (mCRC) in patients receiving immunotherapy-containing regimens. This retrospective cohort study analyzed 221 patients with mCRC. From January 1, 2020 to December 31, 2021, patients diagnosed with unresectable mCRC at the time of initial diagnosis were screened and stratified into 2 groups according to baseline TMB status: a TMB-H group (high tumor mutational burden, n = 113) and a TMB-L group (low tumor mutational burden, n = 108). All patients received anti-PD-1/PD-L1 immunotherapy combined with standard chemotherapy. Data on patient characteristics, tumor molecular features, survival outcomes, adverse events, and posttreatment quality of life were collected and compared between groups. Patients in the TMB-H group demonstrated significantly improved progression-free survival (PFS) and overall survival (OS) compared to the TMB-L group (P < .001). The TMB-H group also demonstrated higher scores across all functional domains of the EORTC QLQ-C30 questionnaire. TMB-H status was positively associated with progression-free survival, overall survival, and quality of life, while adverse event rates were comparable between groups (P = .989). High TMB status is associated with improved survival outcomes and better quality of life in mCRC patients receiving immunotherapy, without an increase in adverse events. These findings support the prognostic value of TMB in this population and warrant prospective validation.