In Lsp1 KO mice treated with anti-PD-1 Ab, the contribution of anti-PD-1 Ab treatment and Lsp1 deficiency to tumor suppression was 59.6% and 40.4%, respectively, as estimated by the degree of decrease in mean tumor volume 14 days after the melanoma inoculation (figure 6D). This evidence concerns the gene PDCD1 and neoplasm.