Checkpoint Inhibitors
Today, the most widely used immunotherapies are monoclonal antibodies known as immune checkpoint inhibitors. The immune system has a natural braking system to turn off immune responses that are no longer needed or threaten to attack healthy tissue (known as autoimmunity). PD-1 is an immune “checkpoint” on T cells that acts as a brake on their activity. Some tumors can hijack PD-1 to turn off immune responses against them. Drugs that block PD-1 or its binding partner, PD-L1, can release the brakes and restore T cells’ ability to recognize and attack cancer cells. Medications that block PD-1 or PD-L1 are now approved to treat several types of cancer, including melanoma, lung cancer and bladder cancer.
