CTLA4 and colorectal cancer: PD-1 blockade (pembrolizumab, nivolumab, sintilimab, toripalimab, camrelizumab, and others) and CTLA-4 blockade (ipilimumab and others) have been applied in immunotherapy for colorectal cancer, while the application of PD1 blockade is more widespread than CTLA-4 blockade.