COMBINED USE OF UBENIMEX AND IMMUNE CHECKPOINT INHIBITOR

An object of the present disclosure is to provide a more effective therapeutic method in cancer therapy using the tumor immune mechanism. An object of the present disclosure is to provide a drug that enhances the production of antitumor, inflammatory, and anti-inflammatory cytokines as the more effective tumor immune therapy. Alternatively, an object of the present disclosure is to provide a drug that increases tumor-infiltrating lymphocytes as the more effective tumor immune therapy. An antitumor agent to be administered in combination with an anti-PD-1 antibody, an anti-PD-L1 antibody, and/or an anti-CTLA-4 antibody, which are immune checkpoint inhibitors (ICIs), comprising: ubenimex as an active ingredient. The combination therapy of ubenimex and an ICI improves the tumor immune function as compared with the use of each of these alone, and brings many benefits to the treatment of malignant tumors.