Prospective National Cohort Evaluating Predictive Biomarkers of Resistance to Immunotherapy in Patients With MSI/dMMR Metastatic Colorectal Cancer (CORESIM)

The primary endpoint is the identification of predictive factors of resistance to pembrolizumab in first-line treatment of MSI and/or dMMR metastatic colorectal cancer CORESIM is a retrospective and prospective multicenter national French cohort. National recruitment will be carried out in all French centers, including the FFCD, AGEO, GERCOR, and UNICANCER, representing more than 150 centers and most French sites, public and private hospitals. In France, pembrolizumab for first-line treatment of patients with MSI mCRC was accessible via its compassionate use in February 2021, then its reimbursement was effective in June 2023 Patients treated with pembrolizumab will be included prospectively on the start date of the study, i.e. on February 2024; patients treated since February 2021 via compassionate use of pembrolizumab will be included retrospectively A total of 600 patients are expected. The theoretical duration of inclusion is set at 2 years. All patients will be followed up for 3 years.