Immune checkpoint inhibitors (ICIs) and immune checkpoint blockade (ICB) are major therapeutic advances in the field of cancer immunotherapies. Relying on the interaction of a checkpoint with a ligand, ICIs block the inhibitory action of checkpoints; the major checkpoints are anti-CTLA-4 (ipilimumab, trememumlimab), anti-PD-1 (nivolumab, pembrolizumab), and anti-PD-L1 (durvalumab, atezolizumab). A new generation of therapeutic agents, including anti-LAG-3, anti-TIM3, anti-TIGIT, and anti-V-domain immunoglobulin suppressor of T-cell activation (VISTA) antibodies, are being developed and investigated in the context of nonresponders and recurrence/relapse in clinical settings. Novel clinical studies are being conducted to evaluate innovative applications of these agents for tumors such as melanoma, breast cancer, and non–small cell lung cancer (NSCLC), tumors that are highly immunogenic. Tumors such as prostate cancer, hepatocellular carcinoma, and pancreatic cancer have low immunogenicity and are less responsive to immune checkpoint inhibitors. Combination therapies are also being developed. Immune-related adverse events and resistance accompany the use of ICIs and frequently require patient management and monitoring.