In the Journals

Motavizumab reduces RSV hospitalizations in Native American infants

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November 30, 2015

The use of motavizumab significantly reduced hospitalizations for respiratory syncytial virus in healthy Native American infants, according to recent findings.

“To our knowledge, this trial is the only study to assess the effect of [respiratory syncytial virus (RSV)] prevention on nonacute RSV-associated, long-term wheezing events occurring in otherwise healthy children, and it is the first to assess the effect of motavizumab [MedImmune] for this purpose,” Katherine L. O’Brien, MD, of the Center for American Indian Health, Johns Hopkins Bloomberg School of Public Health, and colleagues wrote.

The indication of motavizumab to prevent RSV was discontinued by MedImmune, according to researchers.

In the community-based phase 3, double blind, placebo-controlled randomized trial, researchers evaluated data on 2,597 healthy Native American infants aged 6 months and younger who were born at least 36 weeks gestation on the Navajo Nation, the White Mountain Apache reservation and the San Carlos Apache Indian reservation. Infants enrolled during the fall seasons (n = 2,127) from October 2004 to December 2007 were assigned five monthly intramuscular doses of motavizumab (15 mg/kg, n = 1,417) or placebo (n = 710). The primary endpoints were respiratory hospital admission for reverse transcription PCR (RT-PCR)-confirmed RSV and RSV-specific mortality. Secondary endpoints included RSV-specific, medically attended acute lower respiratory tract infections (ALRIs) or otitis media. Participants were observed for wheezing 150 days after the initial dose and were followed until they were aged 3 years.

An intention-to-treat analysis revealed that motavizumab yielded an 87% relative reduction (RR = 0.13; 95% CI, 0.08-0.21) in RSV-associated hospital admissions; 21 patients were hospitalized in the motavizumab group vs. 80 patients in the placebo group (P < .0001).

Moreover, 15% of patients receiving motavizumab experienced a serious adverse event vs. 21% receiving placebo, while there was a higher prevalence of hypersensitivity events among the motavizumab group (14.7% vs. 12.3%). No differences were observed in rates of mortality — none associated with motavizumab — or medically attended wheezing.

In a related editorial, Natalie I. Mazur, MD, from Utrecht University Medical Center, Netherlands, and colleagues wrote the findings “offer compelling evidence that severe RSV disease in healthy term infants is preventable using immunoprophylaxis.” However, the authors reflected on the ethical issue of post-trial obligations regarding motavizumab, which was discontinued after the FDA determined the drug was inferior to Synagis (palivizumab, MedImmune) in preterm infants and those with congenital heart disease.

“Despite the 9.8% reduction in RSV admissions to hospitals using motavizumab, Native American babies were left without RSV immunoprophylaxis because palivizumab is not an option for term children, resulting in ongoing severe RSV infections in this susceptible population,” Mazur and colleagues wrote. – by Jen Byrne

Disclosures: The trial was funded by MedImmune. O’Brien reports receiving grant funding from MedImmune, and Mazur reports no relevant financial disclosures. Please see the full study and the editorial for a list of all other authors’ relevant financial disclosures.