Therapeutic Activity of Agonistic, Human Anti-CD40 Monoclonal Antibodies Requires Selective Fc gamma R Engagement

摘要

While engagement of the inhibitory Fc gamma-receptor (Fc gamma R) IIB is an absolute requirement for in vivo antitumor activity of agonistic mouse anti-CD40 monoclonal antibodies (mAbs), a similar requirement for human mAbs has been disputed. By using a mouse model humanized for its Fc gamma Rs and CD40, we revealed that Fc gamma RIIB engagement is essential for the activity of human CD40 mAbs, while engagement of the activating Fc gamma RIIA inhibits this activity. By engineering Fc variants with selective enhanced binding to Fc gamma RIIB, but not to Fc gamma RIIA, significantly improved antitumor immunity was observed. These findings highlight the necessity of optimizing the Fc domain for this class of therapeutic antibodies by using appropriate preclinical models that accurately reflect the unique affinities and cellular expression of human Fc gamma R.