Antibody drug development has traditionally focused on engineering the tops of the “arms” of the Y-shaped antibody — a component known as the Fv domain because this region is responsible for binding to a specific target. This approach has created wildly successful drugs, yet many targets cannot be effectively addressed this way. Indeed, the great majority of successful antibody drugs bind one of a handful of targets because of the often limited impact of simply binding to a target of interest.
Xencor takes a different approach, focusing its antibody engineering on the “stem” of the antibody — a region known as the Fc domain — which has proven to be a powerful new axis for differentiation and novel function. By fine-tuning the functionality of the Fc domain, Xencor develops XmAb antibody drug candidates with significantly improved potency, half-life and stability over existing antibodies, and open doors to biology previously inaccessible with traditional antibodies.