Xencor has begun the Phase 1 clinical trial of humanised monoclonal antibody XmAb5871 for the treatment of autoimmune diseases.

XmAb5871 uses a selective dual-targeting mechanism for B cell inhibition by targeting the antigen CD19 and co-engaging CD32b (FcyRIIb), and is designed to help in the suppression of autoimmune response.

Preclinical studies demonstrated that XmAb5871 suppresses autoimmune response in humanised mouse models of systemic lupus erythematosus, without the depletion of B cells.

The study results suggest that XmAb5871 could be an effective immunosuppressant in multiple indications, including lupus and rheumatoid arthritis.

The endpoints of the Phase I study include safety, pharmacokinetics and a number of biomarkers of immunomodulatory drug activity.