After the initial treatment with anti-PD-1 antibody, a total of 20 out of 60 mice were selected as mice harboring anti-PD-1 antibody-poorly responsive tumors by tumor volume (larger than 450 mm3) for further evaluation, and the other mice harboring small tumor volume (less than 450 mm3, as anti-PD-1 antibody responsive) or too large volume (not applicable for evaluation) to be evaluated were excluded (Figures 5A and 5B). Here, PDCD1 is linked to neoplasm.