Phase I Study of Safety and Pharmacokinetics of a Human Anticytomegalovirus Monoclonal Antibody in Allogeneic Bone Marrow Transplant Recipients

This study examined the safety and pharmacokinetic profile of a potentially therapeutic and fully human anti-CMV monoclonal antibody (SDZ MSL-109) in a phase I dose escalation trial in patients receiving allogeneic bone marrow transplants. Fifteen adult marrow transplant patients, twelve with chronic myelogenous leukemia and three with acute nonlymphocytic leukemia, in cohorts of five patients each, were administered monoclonal antibody intravenously at doses of 50, 250, and 500 micrograms/kg at approximately three-week intervals for six months. Administration of the monoclonal antibody was associated with minimal side effects and no dose-related toxicity. Antibody elimination curves in all dose groups were consistent with a two-compartment model with an alpha half-life at the low, middle, and high dose groups of 1.03, 0.82, and 0.79 days, and a beta half life of 13.9, 14.0, and 16.5 days, respectively. The volume of distribution decreased with repetitive dosing to approximate the plasma volume in each patient and the pharmacokinetic profile was comparable to that of human IgG. There was no host antiidiotypic or antiallotypic antibody formation, indicating that MSL-109 was not immunogenic. Further studies are warranted to assess the potential efficacy of human monoclonal anti-CMV disease in marrow transplant recipients and other patients with immunodeficiency disorders.