CD8+ TIL (n = 43,380) from three Merkel cell polyomavirus (MCPyV)-driven MCC were subjected to scRNA/TCR-seq and MCPyV antigen specific T cells were identified using CITEseq with various barcoded MCPyV peptide-HLA multimers matched to each patient’s HLA genotype17 (Supplementary Data 8). The gene discussed is CD8A; the disease is Merkel cell skin cancer.