In this study, we investigated the efficacy of irinotecan in combination with an anti-PD-L1 monoclonal antibody (PD-L1 mAb) by using a syngeneic mouse tumor model, and we investigated the targets upon which irinotecan acts to activate antitumor immunity and which may contribute to the combination effect of irinotecan plus anti-PD-L1 therapy. Here, CD274 is linked to neoplasm.