TNFRSF9 and neoplasm: Similar combination strategies with the CD137 agonist to enhance efficacy have received considerable attention since the early discovery of the CD137 agonist (31–33), such as chemotherapy (34, 35), radiotherapy (36, 37), or cancer vaccines (38, 39), possibly through the enhanced immunogenicity with more tumor antigen cross-presentation to improve the efficacy of the immune checkpoint inhibitors (40).