Confirmatory population pharmacokinetic analysis for bapineuzumab phase 3 studies in patients with mild to moderate Alzheimer's disease

The population pharmacokinetics of bapineuzumab, a humanized monoclonal IgG1 antibody that was generated from a murine monoclonal antibody and binds specifically to amino acids 1 to 5 of the free N-terminus of human amyloid-beta peptide, were characterized in patients with mild-to-moderate alzheimer's disease in two Phase 3 studies (ELN115727-301 and ELN115727-302). A total of 8,040 serum concentration measurements were analyzed from 1,458 patients who received 6 doses of bapineuzumab intravenously once every 13 weeks. A confirmatory analysis was conducted using a prespecified two-compartment model with first-order elimination. After the primary covariate effect assessment, a reduced model was obtained. Based on the reduced model, the typical population values for clearance (CL) and volume (Vc ) from the central compartment in a Caucasian subject with a standardized body weight of 70 kg were 0.17 L/day and 3.13 L, respectively. Bapineuzumab CL and Vc increased with body weight. Furthermore, CL was 15% higher in non-Caucasian subjects; however, this was not considered clinically relevant. None of the other evaluated covariates had a meaningful impact on CL. The median terminal elimination half-life was estimated to be approximately 29 days. Sensitivity analyses and bootstrapping results supported model stability.