Pharmacodynamic profile of anti-CD20 mAbs. (A) Type I, non-Fc-optimized mAbs. As a typical type I anti-CD20 IgG1 mAb, RTX is able to eliminate target cells through complement activation, recruitment of FcγRIIIA-expressing effector cells, and also to some extent by direct cytotoxicity. (B) Type I, Fc-optimized mAbs. This category of mAbs includes ocaratuzumab and ublituximab. They behave similarly as in panel A, except for FcγRIIIA-dependent mechanisms, which are exhausted. (C) Type II, non-Fc-optimized mAbs. This is currently a virtual category because no mAb of this type is currently under development. As compared with panel A, they would have an enhanced direct cytotoxicity effect, and a reduced ability to trigger complement activation. (D) Type II, Fc-optimized mAbs, such as OBZ. These mAbs have a reduced ability to activate complement, but an enhanced ability to recruit FcγRIIIA-expressing cytotoxic and phagocytic effectors and to induce direct cytotoxicity.