Characterization of a Next Generation Anti-CD52 Antibody (S20.006)

OBJECTIVE: To assess the in vitro and in vivo activity of GZ402668, a novel anti-CD52 antibody. BACKGROUND: Alemtuzumab is an anti-CD52 humanized monoclonal antibody that causes depletion of circulating lymphocytes followed by a distinctive pattern of repopulation. It is approved for the treatment of relapsing forms of multiple sclerosis (MS) in over 30 countries. A next-generation anti-CD52 antibody is currently being developed to potentially decrease immunogenicity, improve the infusion-associated reaction (IAR) profile, and explore the subcutaneous route of administration while maintaining efficacy. DESIGN/METHODS: In vitro activity of GZ402668 was analyzed in both antibody-dependent cell-mediated cytolysis (ADCC) and complement-dependent cytolysis (CDC) assays as well as in a human whole blood cytokine release assay. In addition, the immunogenicity profile of GZ402668 was assessed using in vitro assays. Pharmacology studies were carried out in the human CD52 transgenic mouse to characterize the depletion profile and lymphocyte repopulation kinetics. RESULTS: GZ402668 mediated in vitro lymphocyte depletion by both ADCC and CDC comparable to alemtuzumab. In the whole blood assay, GZ402668 induced a significantly lower cytokine response than alemtuzumab for most concentrations of test article. In an in vitro immunogenicity assay, 70[percnt] of donors responded to alemtuzumab peptides, whereas only 30[percnt] responded to GZ402668. Subcutaneous and intravenous administration of GZ402668 to huCD52 transgenic mice resulted in dose-dependent lymphocyte depletion followed by lymphocyte repopulation kinetics comparable to alemtuzumab. CONCLUSIONS: GZ402668 is a next-generation anti-CD52 antibody with lymphocyte-depleting activity similar to that of alemtuzumab. GZ402668 displays reduced cytokine release in a human whole blood assay, suggesting a potentially improved IAR profile as well as predicted reduced immunogenicity. A phase 1 study including intravenous and subcutaneous administration in MS patients is currently planned. Study Supported by: Genzyme, a Sanofi company Disclosure: Dr. Siders has received personal compensation for activities with Genzyme Corporation as an employee. Dr. Greene has received personal compensation for activities with Genzyme as an employee. Dr. McVie-Wylie has received personal compensation for activities with Genzyme as an employee. Dr. Bailey has received personal compensation for activities with Genzyme as an employee. Dr. Dhawan has received personal compensation for activities with Genzyme as an employee. Dr. Boutin has received personal compensation for activities with Genzyme as an employee. Dr. Best has received personal compensation for activities with Genzyme as an employee. Dr. Lawendowski has received personal compensation for activities with Genzyme as an employee. Dr. Turner has received personal compensation for activities with Genzyme Corporation as an employee. Dr. Roberts has received personal compensation for activities with Genzyme Corporation as an employee. Dr. Kaplan has received personal compensation for activities with Genzyme as an employee. Dr. Sendak has received personal compensation for activities with Genzyme Corporation as an employee.