In addition, in a transcriptome dataset from the TIGER website that included melanoma patients receiving PD-1 inhibitors or receiving PD-1 inhibitors combined with CTLA4 inhibitors [43], expression of CRABP2 was significantly higher in the non-responder group, and high level of CRABP2 gene suggested poor survival probability (Figs. 2K and 2L). The gene discussed is PDCD1; the disease is melanoma.