Motavizumab, a second-generation humanized mAb for the prevention of respiratory syncytial virus infection in high-risk populations.

Evolved from palivizumab, motavizumab is a second-generation humanized mAb that is in development by MedImmune for the prevention of respiratory syncytial virus (RSV) infection in high-risk populations; the drug is also under investigation for the same indication by Abbott Laboratories. Motavizumab targets a highly conserved epitope in the A antigenic site of the RSV fusion (F) protein, which is important in the invasion of RSV from cell to cell. Motavizumab, which differs from palivizumab by just 13 amino acids, has exhibited a 70-fold enhancement in binding to the RSV F protein compared with the first-generation mAb, with an 11-fold faster association rate and 6-fold slower disassociation rate. Motavizumab was approximately 20-fold more potent than palivizumab in vitro, and was more effective at lower doses in vivo. In phase III clinical trials, motavizumab was non-inferior [corrected] to palivizumab in reducing the incidence [corrected] of RSV-related hospitalizations and was superior to palivizumab in reducing the incidence [corrected] of RSV-related medically attended [corrected] outpatient visits for lower respiratory tract infections in high-risk infants. In terms of safety, motavizumab has been demonstrated to be comparable with palivizumab. Until an effective prophylactic vaccine is developed, motavizumab could potentially become the first-line preventive agent against RSV disease in specific high-risk patients.