Take a Closer Look at Immune Checkpoint Inhibitors

One way that cancer has been able to evade the immune system is through overexpression of immune checkpoint proteins (immune inhibitory pathway), which allow cancer cells to be considered “self” instead of foreign and block T-cell action. Immune checkpoint proteins cytotoxic T-lymphocyte–associated 4 (CTLA-4) and programmed cell death protein (PD-1) are receptors that are expressed on the surface of cytotoxic T cells. Immune checkpoint inhibitors prevent those receptors from binding to their natural ligands, disrupting the immune inhibitory pathway. See Table 1 for a list of approved agents and indications.