TNFRSF9 and neoplasm: As several studies have shown the importance of CD137+ TILs and IFN-γ-producing cytotoxic CD8+ T cells for effective antitumor immunity (69, 70), the VNS-mediated stimulation of these CTLs could, next to the Treg decrease, also be responsible in part for the modest reduction in tumor burden upon VNS monotherapy.