Bispecific Fc Domains

Unlike traditional monoclonal antibodies that target and bind to a single antigen, bispecific antibodies are designed with two variable domains to elicit biological effects that require simultaneous binding to two targets. For example, one variable domains binds to a tumor cell and the other variable domain binds to a cytotoxic immune cell.

Efforts in bispecific antibody design have historically been frustrated by poor molecular stability, difficulties in production and short in vivo half-life. Xencor’s bispecific Fc domain technology maintains full-length antibody properties in a bispecific antibody and can be made and purified with standard antibody production methods.

Xencor’s bispecific Fc domains have generated a broad array of novel drug candidates, the first of which are tumor-targeted antibodies that contain both a tumor antigen binding domain and a cytotoxic T-cell binding domain (CD3 binding domain). They activate T cells at the site of the tumor for highly potent killing of malignant cells. Our format allows us to tune the potency of the T-cell killing, potentially improving the tolerability of tumor immunotherapy. We have demonstrated highly effective and well-tolerated killing of target cells in a variety of in vivo and in vitro models for our lead candidates.