Monrovia, CA—June 29, 2009 – Xencor, Inc., a company using Fc engineering for the discovery and development of next-generation antibodies, today announced the addition of Jeffrey Ravetch, M.D., Ph.D., a leader in the study of Fc receptors for immunological research, to its Scientific Advisory Board. He is a professor and head of the Leonard Wagner Laboratory of Molecular Genetics and Immunology at The Rockefeller University, and joins Richard Lerner, M.D., Professor and President of the Scripps Research Institute, on Xencor's advisory board.

"Jeff is the pioneer in the study of Fc receptors, the antibody region that Xencor's antibody-enhancing technology and current product development engineer to optimize antibody function," said Bassil Dahiyat, Ph.D., chief executive officer of Xencor. "His expertise will provide valuable guidance to our scientific team as we progress additional antibody candidates into the clinic and complete our Phase 1 trial with XmAb2513."

"The synergy between my research and Xencor's approach to antibody optimization, combined with strong preclinical and preliminary Phase 1 data to date, make this an ideal time to join the advisory board," Dr. Ravetch said. "I look forward to bringing insights and experience gained from my work with the Fc region to bear on the advancement of Xencor's pipeline of enhanced antibodies."

Dr. Ravetch is a leading expert in antibody-mediated effector mechanisms and immune regulation, and contributed to the discovery of the key mechanisms by which Fc receptors operate. His current research focuses on the cellular and molecular mechanisms of how healthy immune cells are made to respond to specific antibodies and how a dysfunctional immune system attacks the body's own tissues. Dr. Ravetch's prior work led to the cloning and mapping of the first malarial parasite chromosome, and more recently to the cloning of the first Fc receptor genes. He was also responsible for discovering how immunoglobulin receptors mediate antibody-triggered inflammation, and determining the mechanism by which intravenous immunoglobulin causes immunosuppression.

Dr. Ravetch received his Ph.D. from Rockefeller University, his M.D. from Cornell University Medical College, and completed his postdoctoral research at the National Institutes of Health in the Laboratory of Molecular Genetics. He later joined the faculty at Memorial Sloan-Kettering Cancer Center and Cornell University Medical College before joining The Rockefeller University.

About Xencor

Xencor, Inc. engineers superior biotherapeutics using its proprietary Protein Design Automation® technology platform, and is a leader in the field of antibody Fc engineering to significantly improve antibody potency and half-life. The company is advancing multiple XmAb® antibody drug candidates into the clinic, led by anti-CD30 candidate XmAb®2513 in a Phase I clinical trial for the treatment of Hodgkin lymphoma and anaplastic large cell lymphoma, and anti-CD19 candidate XmAb®5574 in pre-clinical development for the treatment for non-Hodgkin lymphoma and B-cell leukemia. With multiple partners, such as industry leaders Merck, Pfizer, CSL Ltd., Boehringer Ingelheim, MedImmune and Human Genome Sciences, Xencor is applying its suite of proprietary antibody Fc domains to improve antibody drug candidates for traits such as potency and sustained half-life. For more information, please visit www.xencor.com.

Contact

Kim Richards
Porter Novelli Life Sciences for Xencor
619-849-5377
krichards@pnlifesciences.com