Tislelizumab in People With Colorectal Cancer

The researchers are doing this study to find out whether tislelizumab is an effective treatment for people with colorectal cancer who are living in Nigeria. The researchers will also look at the safety of the study drug. All participants in this study will be treatment naïve (they have not yet received treatment for their cancer), and their cancer will be mismatch repair deficient (dMMR). dMMR cancer can happen when your cells are unable to repair mistakes made during the cell division process.