PDCD1 and neoplasm: A significant increase in TEM following reovirus treatment, and concordant decrease in naïve T cells, is characteristic of long-term immunological memory following antigen recognition34 35; moreover, the induction of antitumor immunity was further supported by the increase in PD-1 on CD4 and CD8 T cells, the presence of 5TGM1-specific CD8+ cells and the negative correlation of CD8+ TEM cells with tumor burden.