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The Ohio State University, Columbus, OH, USA.
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Editor’s note: Targeting of the pan-B cell antigen CD20 with monoclonal antibodies (mAb) has proved successful for a range of B cell lymphoproliferations. Another potential target, CD19, is expressed throughout B cell development from pre-B cells to plasma cell differentiation and is, in fact, present at higher densities on the surface of mature B cells than CD20. Clinical studies of therapeutic antibodies directed to CD19 have, to date, been limited to B cell lymphoma. The present study investigated the preclinical efficacy of XmAb5574, an immunoglobulin G1 (IgG1) humanized CD19 mAb that, importantly, contains a modified Fc-domain that increases its affinity for FcγIIIa receptor on effector cells, thus enhancing its cytotoxic potential.