Indications in melanoma trials that tumor PD-L1 expression, density of TILs, and proportion of T cells expressing PD-1 or PD-L1 was associated with response led to the categorization schema outline above in an attempt to identify subsets of melanoma patients who would be most likely to respond to treatment (Table 1) [3, 9]. This evidence concerns the gene PDCD1 and neoplasm.