CD22 is rapidly internalized after binding the MoAb so that the exposure to epratuzumab results in downregulation of B-cell activation and signaling, with proliferation inhibition.28 In a phase I protocol ofthe Children’s Oncology Group (COG), applied to children with R/R BCP ALL, 15 children received four doses of epratuzumab twice weekly for two weeks, then four weekly doses with a standard reinduction chemotherapy. Here, CD22 is linked to acute lymphoblastic leukemia.