Thousand Oaks-based Amgen, and Monrovia-based Xencor said Thursday that the two firms are in a co-development dual around a new novel antibody for treating autoimmune diseases. According to the two, Amgen has gained an option to an exclusive, worldwide license on Xencor's XmAb5871. The deal is worth up to $75M in a combination of up-front and early development milestone payments, as well as up to $425M in clinical, regulatory and commercialization milestone payments. The deal also includes tiered royalties on future sales of XmAb5871. The firms said that XmAb5871 is currently in late-stage preclinical development for the treatment of autoimmune diseases.