To exemplify, in a phase I/II clinical trial by Monge et al. [23], Pexastimogene devacirepvec was combined with Tremelimumab (anti-CTLA-4) and Durvalumab (anti-PD-L1), which enhanced anti-tumor immune response by increasing tumor antigen release in patients with standard chemotherapy-refractory mismatch repair proficient (pMMR) metastatic colorectal cancer (mCRC). This evidence concerns the gene CTLA4 and metastatic colorectal cancer.