An immune checkpoint inhibitor works by blocking checkpoint proteins, such as PD-1, on T-cells from binding to their partner proteins on normal or cancer cells, like PD-L1. By doing this, the inhibitor prevents the "off signal" that would normally stop an immune response. This allows T-cells to effectively target and kill cancer cells.
Immunotherapy toxicities are different from those encountered with standard chemotherapy or targeted therapies. The immune system may become dysregulated during immunotherapy, leading to symptoms and findings which mimic autoimmune disorders. Adverse events can occur during or following treatment and can be life threatening. Any organ system in the body is at risk.