Botensilimab + Balstilimab vs Best Supportive Care as Therapy in Chemo-refractory, Unresectable, Colorectal Adenocarcinoma

This study is being done to answer the main question of: Do patients with colorectal cancer that cannot be removed by surgery, that is treated with two new immunotherapy drugs, botensilimab and balstilimab, live longer? Other important questions include: Is their quality of life better? Do their tumours slow in growth or possibly shrink in size? Are there markers in their tumour or blood that can predict whether they achieve any of these benefits? In addition, the study is done to confirm the safety of these immunotherapy drugs and to determine how long it takes for the body to metabolize them.