Pre-treatment analyses of T-cell subset/subpopulations provide a method of enriching for responders with identification of specific PD-1 and CTLA-4 expressing CD8 subsets that associate with response, with intriguing implications on the interactions between these immune subsets, EBV-positive tumor cells, and drugs targeting PD-1 and CTLA-4. This evidence concerns the gene CD8A and neoplasm.