CTLA4 and cancer: Immune checkpoint blockade (ICB) therapy is an effective cancer therapy, and immune checkpoint inhibitor (ICI) therapy, such as programmed cell death protein 1/programmed cell death ligand 1 (PD-1/PD-L1) inhibitors and cytotoxic T lymphocyte antigen 4 (CTLA-4) inhibitors, has been successful in different cancers (Ribas and Wolchok, 2018; Fares et al., 2019; Mizrahi and Pant, 2020; Tong et al., 2021).