PD-1/PD-L1

PD-1 (Programmed Death-1) and PD-L1 (Programmed Death Ligand-1) are key components of the immune checkpoint pathway, critical in regulating the body's immune response to prevent overactivity that could lead to autoimmunity. PD-1 is a receptor on the surface of T-cells, while PD-L1 is its ligand, expressed on tumor cells and some immune cells. This interaction between PD-1 and PD-L1 inhibits T-cell activation and allows cancer cells to evade the immune system. Targeting this pathway with inhibitors—checkpoint inhibitors—such as those blocking PD-1 or PD-L1, enhances the immune system's ability to attack cancer cells, marking a breakthrough in cancer immunotherapy, particularly for melanoma, non-small cell lung cancer, and renal cell carcinoma.