Avelumab is a fully human IgG1 monoclonal antibody that targets the PD-L1 protein, blocking its interaction with PD-1 receptors on T cells. This inhibition restores T cell activity and enhances immune-mediated destruction of tumor cells. It is primarily used in cancer immunotherapy.

Avelumab is approved for the treatment of metastatic Merkel cell carcinoma, a rare and aggressive form of skin cancer, offering durable responses in a subset of patients. It is also used in combination with axitinib for first-line treatment of advanced renal cell carcinoma, where it improves overall survival and progression-free survival. Additionally, it has been studied in platinum-treated locally advanced or metastatic urothelial carcinoma, showing clinically meaningful response rates.

Beyond oncology, research is exploring its potential in modulating immune responses in chronic viral infections and autoimmune diseases, although these uses remain investigational. Avelumab's role in enabling the immune system to recognize and attack cancer cells makes it a key agent in modern immuno-oncology.