Phase I study on human monoclonal antibody against cytomegalovirus: pharmacokinetics and immunogenicity.

MAb C23, a human immunoglobulin G1 (IgG1) monoclonal antibody (MAb) against cytomegalovirus, was administered to 20 healthy volunteers. Sixteen of them received a single infusion of a dose ranging from 5 to 80 mg. The plasma clearance curves fit a two-compartment model, with half-lives of 31.0 +/- 23.6 h in the diffusion phase and 24.2 +/- 5.8 days in the equilibration phase. The plasma after administration had the virus neutralization activities that were equivalent to the plasma MAb C23 levels. The remaining four subjects, who received three infusions of 60, 20, and 20 mg at 1-week intervals, showed pharmacokinetics that were very consistent with those of the single infusion. No antibody response against MAb C23 was observed in any of the subjects at any time, when monitored for approximately 60 days after the single infusion or the third infusion of the three repeated doses. None of the 20 subjects showed any treatment-related clinical signs or changes. These results suggest that a human IgG MAb has the same pharmacokinetic characteristics as those of natural human serum IgG, and that it is not immunogenetic and is safe in humans.