However, while immune checkpoint blockade antibodies, such as those against programmed cell death-1 (PD-1) or cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), have shown remarkable efficacy in certain cancer types such as melanoma and non-small-cell lung carcinoma (3, 4), limited therapeutic benefit has been also observed in other types of cancers such as colorectal cancer, ovarian cancer, and pancreatic ductal adenocarcinoma. The gene discussed is PDCD1; the disease is melanoma.