ICI-based therapies targeting CTLA-4 or PD-1/PD-L1 have led to significant improvements in overall survival and progression-free survival in patients with hematologic malignancies, as well as solid cancers, including Hodgkin’s lymphoma, melanoma, colon, renal cell, and Merkel cell carcinomas and non-small cell lung carcinoma (NSCLC) (Hodi et al., 2010; Brahmer et al., 2012; Ansell et al., 2015; Borghaei et al., 2015; Le et al., 2015; Motzer et al., 2015). The gene discussed is PDCD1; the disease is melanoma.