The human immune system has T cells that help fight off diseases. T cells help the body fight infections and other diseases, including cancer. However, cancer cells can escape this attack by expressing a protein called PD-L1. PD-L1 works like a “stop sign” to inactivate T cells.
PD-L1 works by attaching to receptors on T cells called PD-1and B7.1. Both PD-1 and B7.1 can inactivate T cells.

Clinical Utility

One approach to fighting cancer is blocking the PD-L1 protein, which may prevent cancer cells from inactivating T cells through both PD-1 and B7.1. The goal of cancer immunotherapy is to increase the activity of the immune system to generate an effective anticancer response.