MONROVIA, Calif.--(BUSINESS WIRE)--Xencor, Inc., a company developing protein and antibody therapeutics, announced today that it will present new data from pre-clinical studies evaluating XmAb®5574, an Fc engineered monoclonal antibody targeting the antigen CD19, showing that it elicited complete B cell depletion compared to undetectable B cell depletion seen with an equal dose of a non-Fc engineered anti-CD19 1gG1 analog. Additionally, the pharmacokinetics of XmAb5574 were shown to be indistinguishable from that of the 1gG1 analog. These data will be presented on June 1, 2008 during the American Society of Clinical Oncology (ASCO) 44th Annual Meeting in a poster session entitled, “XmAb®5574: In vitro and in vivo efficacy of an Fc-engineered anti-CD19 monoclonal antibody against lymphoma and leukemia and its effect on B cells in non-human primates.” (Poster: 20G; Abstract: 3078)