Pembrolizumab clinical trial studies, on the other hand, investigated the impact of six INF-γ genes on patient tumor prototypes, including Indoleamine 2, 3-dioxygenase 1 (IDO1), C-X-C motif chemokine (CXCL)10, CXCL9, Human Leukocyte Antigen (HLA)-DRA, Signal transducer and activator of transcription (STAT) 1, and IFN-γ (135–137). The gene discussed is IDO1; the disease is neoplasm.