Immune checkpoint inhibitors (ICIs), including antiprogrammed death 1 (anti-PD-1), antiprogrammed death 1 ligand (anti-PD-L1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) inhibitors, have been approved as first-line treatment strategy for a variety of advanced cancers, such as melanoma, gastric cancer, and hematological malignancies (3). The gene discussed is CTLA4; the disease is cancer.