TORONTO – The investigational drug motavizumab may offer high-risk infants additional protection against respiratory syncytial virus disease, Dr. Xavier Carbonell-Estrany reported in a poster presentation at the annual meeting of the Pediatric Academic Societies.
Motavizumab demonstrated noninferiority to palivizumab with a 26% relative reduction in the primary end point of respiratory syncytial virus (RSV) hospitalizations in a phase III multicenter study with 6,635 preterm infants, the investigators wrote.
The overall incidence of hospitalization was low in both groups: 1.4% for patients treated with motavizumab and 1.9% for those treated with palivizumab.
Additionally, in a subset of patients, motavizumab significantly reduced the secondary end point of outpatient medically attended lower respiratory tract infections (LRIs) by 50%, compared with palivizumab: 2% of 1,227 patients vs. 4% of 1,183 patients.
Motavizumab (Numax) is an enhanced-potency, RSV-specific, humanized monoclonal antibody that has shown a similar safety and pharmacokinetic profile in phase I and II trials to palivizumab (Synagis), an RSV-specific monoclonal antibody that is the standard of care for infants at high-risk for RSV, they said.
MedImmune Inc., which markets palivizumab and is developing motavizumab, sponsored the trial. Dr. Carbonell-Estrany is a member of the steering committee of the Motavizumab Study Group and was acting as consultant on this occasion for MedImmune.
“I am very pleased with the study results for motavizumab,” lead author Dr. Carbonell-Estrany, chair of neonatology at the University of Barcelona's Hospital Clinic and vice president of the Spanish Neonatal Society, said in a statement. “As a practicing neonatologist, I look forward to the potential to use this next-generation antibody to help reduce RSV-related hospitalizations and LRIs in the outpatient setting.”
The study was conducted at 347 centers in 24 countries.
It included both infants who were 6 months of age or younger at the time of randomization with a gestational age of 35 weeks or fewer at birth, and children who were 24 months of age or younger with a diagnosis of chronic lung disease of prematurity requiring treatment within 6 months before the time of randomization.
Over two consecutive RSV seasons, 6,635 patients were randomized to receive motavizumab or palivizumab 15 mg/kg intramuscularly monthly, with 150 days of follow-up. Each child participated in the study for a single RSV season.
A total of 3,329 children were randomized to motavizumab and 3,306 to palivizumab.
Overall, 59 motavizumab patients and 60 palivizumab patients were lost to follow-up, had consent withdrawn, or died.
No death was considered to be related to the study drugs, and there were no RSV-related deaths.
The most frequently reported cause of death in both groups was SIDS, with four in the motavizumab and two in the palivizumab group.
Drug-related adverse events were comparable between the motavizumab group and the palivizumab group (258 vs. 298), as were drug discontinuations (10 vs. 13).
Injection site reactions were more common in the motavizumab group than the palivizumab group (110 vs. 89), the authors reported.