Amgen and Xencor to Co-Develop Xencor's Antibody for Autoimmune Diseases

Amgen (Thousand Oaks, CA) and Xencor, Inc. (Monrovia, CA) will collaborate to develop XmAb5871, an Fc-engineered monoclonal antibody dually targeting CD19 and CD32b. XmAb5871 is currently in late-stage preclinical development for the treatment of autoimmune diseases.

Xencor's CD32b technology is an 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.

Under the terms of the agreement, Amgen has the option to an exclusive worldwide license following the completion of a predefined Phase 2 study. Xencor will lead all clinical development until that time. Xencor will receive an upfront payment, 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 upfront 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.