Over the past 5 years, immune therapy represented by immune checkpoint inhibitors (ICIs) targeting programmed death 1 (PD-1), programmed death ligand-1 (PD-L1) and cytotoxic T lymphocyte-associated antigen-4 (CTLA-4), have been important therapeutic drugs second only to chemotherapy, radiotherapy and targeted therapy, because ICIs have significantly improved clinical outcomes in multiple cancer types (Vaddepally et al., 2020). Here, CTLA4 is linked to cancer.