The coexpression of CD39 (which is encoded by ENTPD1) and CD103 (which is encoded by ITGAE) is the hallmark of tumor-specific CD8+ T cells.4 It was also suggested that clonally expanded TILs were highly correlated in cellular phenotype that was unaffected by PD-1 blockade based on the clustering analysis of TCR sequences that showed that there were shared motifs in the CDR3 sequence among these TILs. The gene discussed is ENTPD1; the disease is neoplasm.