To examine the relationship between PD-1, PD-L1, or CD3 expression in the tumors and antitumor responses elicited by anti-PD-1 antibodies combined with CIK cell transfer, we evaluated pretreatment tumor biopsies from both patients using immunohistochemistry and found that the tumor biopsy from Patient 1 exhibited moderate CD3+ T cell infiltration, but no PD-1 or PD-L1 expression (Figure 2A). Here, PDCD1 is linked to neoplasm.