Immunomedics reports epratuzumab effects on B-Cell in preclinical study Immunomedics reported that its lead antibody drug candidate, epratuzumab, has a distinct way of reducing the immune response of B cells, which, in an autoimmune disease such as lupus, are responsible for producing antibodies that attack the patient's own body. Epratuzumab is a humanized antibody targeting the CD22 receptor on B cells. Epratuzumab is being developed in SLE by UCB who hold the worldwide development rights for this compound in autoimmune diseases. Importantly, PBMCs treated with epratuzumab at concentrations ranging from 1 ng/mL to 10 mg/mL produced a U-shaped curve of CD22 with substantial dampening at concentrations lower than 10 ng/mL or greater than 1 mg/mL. These observations may explain why epratuzumab was found in a number of lymphoma and SLE clinical trials to be effective at the mid-doses given and less so at the lower or higher doses. A similar profile was observed for CD19, which was reduced to a similar level over a broad concentration range of epratuzumab.