PD-1/PD-L1 inhibitor 1 is primarily used in immunotherapy for cancer treatment. It works by blocking the interaction between PD-1, a protein on immune cells, and PD-L1, a protein on cancer cells. This blockade helps to activate the immune system, enabling it to recognize and attack cancer cells more effectively. It is particularly significant in treating various types of cancers, including melanoma, non-small cell lung cancer, and renal cell carcinoma, where traditional therapies may have limited effectiveness. By enhancing the body's natural immune response, this inhibitor plays a crucial role in improving patient outcomes and survival rates in advanced or metastatic cancer cases.