FCGR2B and neoplasm: Furthermore, systemic or IT administration of an anti-mouse CD40 Ab (Clone 1C10-mIgG1) failed to induce tumor regression (Extended data Fig. 5b), suggesting that to achieve optimal antitumor activity, anti-CD40 Abs require Fc-engineering to enhance their interaction with the human receptor FcγRIIB and potentiate down-stream signaling.