CTLA4 and renal cell carcinoma: ICB, which targets programmed cell death protein (PD-1; e.g., pembrolizumab and nivolumab), its ligand programmed cell death ligand 1 (PD-L1; e.g., atezolizumab and durvalumab), or their combination with cytotoxic T-lymphocyte associated protein 4 (CTLA-4) antagonists (e.g., ipilimumab and tremelimumab), has demonstrated robust efficacy in treating metastatic melanoma (MM), renal cell carcinoma (RCC), and non-small cell lung cancer (NSCLC) through reinforcing and reactivating antitumor immunity [1].