To assess the effect of a DSP-0509-anti-PD-1 antibody combination on immune cells, we administered DSP-0509 intravenously at a dosage of 5 mg/kg once weekly, in conjunction with an anti-PD-1 antibody intraperitoneally at a dosage of 200 μg/mouse twice weekly, to CT26 tumor-bearing mice. Here, DDX53 is linked to neoplasm.