Immune checkpoints are key regulatory factors of immune system function. Acting as inhibitory pathways, they are crucial for maintaining self-tolerance and for regulating the duration and extent of immune responses in peripheral tissues. The development of antibody drugs targeting immune checkpoints for the treatment of cancer, tumors, autoimmune diseases, and other conditions has become an important strategy in immunotherapy. Immune checkpoint proteins are a series of molecules that generate co-stimulatory or inhibitory signals during immune responses. They hold a significant position in the field of cancer immunotherapy research. For instance, cytotoxic T lymphocyte-associated antigen-4 (CTLA-4), programmed death-1 (PD-1), and its ligand (PD-L1) are currently the most widely used targets for immune checkpoint inhibitors.