GZ402668, a Next-Generation Anti-CD52 Antibody, Displays Decreased Proinflammatory Cytokine Release In Vitro (P3.068)

OBJECTIVE: To characterize in vitro and in vivo binding of GZ402668, a novel antibody against the human CD52 (huCD52) protein and to assess its effect on cytokine release and lymphocyte depletion. BACKGROUND: Alemtuzumab is an anti-CD52 humanized monoclonal antibody that depletes circulating lymphocytes, followed by a distinctive repopulation pattern. A next-generation anti-huCD52 antibody is in development to potentially decrease immunogenicity, improve infusion-associated reaction (IAR) profile, and explore subcutaneous administration route while maintaining high efficacy. DESIGN/METHODS: The binding interaction of GZ402668 and alemtuzumab with huCD52 was characterized using crystallography. Lymphocyte cytolysis was assessed in vitro. Samples were collected at different timepoints to determine cell killing by flow cytometry and cytokine release by human whole blood assay in response to GZ402668 and alemtuzumab in vitro. Lymphocyte depletion was characterized in vivo in huCD52 transgenic mice. RESULTS: In vitro analysis and crystallographic data indicate that GZ402668 and alemtuzumab bind to different epitopes on huCD52. Comparable in vitro cytolytic activity was observed with both antibodies. In the whole blood assay, GZ402668 induced significantly lower proinflammatory cytokine response than alemtuzumab at most test article concentrations. Compared with alemtuzumab, GZ402668 induced a markedly lower degree of IFN-γ release at 24 hours, and TNF-α at both 4 and 24 hours. Differences in cytokine release were also observed over 24 hours. GZ402668 administration to huCD52 transgenic mice resulted in dose-dependent lymphocyte depletion comparable to alemtuzumab. CONCLUSIONS: GZ402668 is a next-generation anti-CD52 antibody with lymphocyte-depleting activity similar to that of alemtuzumab. Based on in vitro analysis, GZ402668 displays reduced cytokine release, suggesting a potentially improved IAR profile. The decreased proinflammatory cytokine release in vitro may be attributable to altered cell depletion kinetics observed with GZ402668 compared to alemtuzumab. GZ402668 is currently being tested in a phase 1 study in MS patients. STUDY SUPPORTED BY: Genzyme, a Sanofi company. Disclosure: Dr. Siders has received personal compensation for activities with Genzyme Corporation as an employee. Dr. Wei has received personal compensation for activities with Genzyme 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. Dr. Best has received personal compensation for activities with Genzyme as an employee. Dr. Brondyk has received personal compensation for activities with Genzyme as an employee. Dr. Havari 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. 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.