Preliminary results suggest that patients with MSI mCRC are highly sensitive to ICI even chemoresistant tumors receiving several lines of chemotherapy. Recently, another anti-PD1 alone or in combination with an anti-CTLA4 (antigen associated with cytotoxic T-lymphocyte 4) was tested in the MSI CRCs and a selection of interesting results in heavily pretreated patients with a disease control rate of 56% for monotherapy and 81% for combinated therapy.