PDCD1 and melanoma: In AJCC (American Joint Committee on Cancer) stage IV melanoma patients, anti-PD-1 monotherapy or in combination with IPI induces unprecedented long-term responses in a subset of patients, with a 36% and 29% progression-free survival (PFS) rate at 5 years, and with 44% and 52% overall survival (OS) rate at 5 years, for anti-PD-1 or IPI+anti-PD-1, respectively (19).