PDCD1 and neoplasm: Considering the combined effect of RCE plus Oxa’s suppression of human PD-L1 MC38 tumor growth both in vitro and in vivo and our observations on the activation of tumor-infiltrating CD8+ T Cells by RCE plus Oxa in co-culture cell models, we sought to investigate whether RCE plus Oxa would affect human PD-1 CD8+ T Cell infiltration in human PD-L1 MC38 tumor tissues.