Engagement of CD137 enhanced the therapeutic efficacy of direct-targeting mAb; rituximab (anti-CD20)18, trastuzumab (anti-HER2)19 and cetuximab (anti-EGFR)20 in B-cell lymphoma, breast and head and neck cancer models respectively. The gene discussed is TNFRSF9; the disease is B-cell non-Hodgkin lymphoma.