Amgen, Xencor collaborate to develop XmAb5871 for autoimmune disease

Amgen and Xencor, Inc. announced today that they will collaborate to develop XmAb^®5871, an Fc- engineered monoclonal antibody dually targeting CD19 and CD32b.  XmAb5871 is currently in late-stage preclinical development for the treatment of autoimmune diseases.  

Under the terms of the agreement, Amgen has the option to an exclusive worldwide license following the completion of a pre-defined Phase 2 study.  Xencor will lead all clinical development until that time.  Xencor will receive an up-front and early development milestone payments.  If Amgen does exercise its option, Amgen will assume responsibility for future development, Xencor will receive an option-exercise fee which, combined with the up-front and early development milestones, will total $75 million, and Xencor could receive up to an additional $425 million in clinical, regulatory and commercialization milestone payments.  Xencor will receive tiered royalties on future sales of XmAb5871.

Xencor's CD32b technology is a novel immunomodulatory platform consisting of engineered Fc domains with selective high affinity binding to FcyRIIb (CD32b), a receptor with dominant inhibitory activity on B cells and other immune cells. The CD32b pathway has never been therapeutically exploited and applied to high affinity antibodies targeting immune cells.

"XmAb5871 provides a novel approach to suppress B-cell function which will enhance Amgen's internal efforts in inflammatory diseases," said Joseph P. Miletich, M.D., Ph.D., senior vice president, Research & Development at Amgen.  "We are delighted to have the opportunity to partner with Xencor in exploring their novel immunomodulatory approach."

"Amgen's long-time leadership in antibody development for oncology and inflammatory diseases aligns seamlessly with Xencor's pipeline development," said Bassil Dahiyat, Ph.D., chief executive officer of Xencor. "We expect that XmAb5871 will soon become the fifth XmAb-engineered antibody in clinical development.  This program is a testament to the progress we've made expanding the XmAb platform into autoimmune disease with our CD32b technology, which is at the core of the XmAb5871 compound. The option deal structure allows us to continue to lead the development of XmAb5871 while also leveraging Amgen's experience in developing novel biologics for unmet medical needs."