Used in the treatment of advanced or metastatic cancers, particularly Merkel cell carcinoma and other solid tumors. It functions by blocking the PD-1 receptor on T-cells, thereby enhancing the immune system’s ability to detect and attack cancer cells. This antibody helps restore anti-tumor immune responses that are often suppressed by cancer cells through the PD-1 pathway. It is administered intravenously and is part of immune checkpoint inhibitor therapy, offering durable responses in some patients with previously limited treatment options.