TNFRSF9 and neoplasm: CD137, a representative costimulatory molecule belong to TNF‐receptor superfamily, is an important target for tumor immunotherapy.20 Its gene expression is inducible in activated T cells.21 In early reports, monoclonal antibodies (mAbs) against CD137 have been shown to preferentially induce CD8 T cell proliferation compared to CD4 T cells and to eradicate established tumors in a mouse model.21, 22 Stimulating CD137 in vivo was found to alter the trafficking of CD8+ T lymphocytes and elevate the production of IFN‐γ and TNF‐α.