MedImmune announced that clinical results of its pivotal multinational, randomized, double-masked trial for motavizumab have been published in the current issue of the peer-reviewed publication, Paediatrics: Official Journal of the American Academy of Paediatrics. Motavizumab is an investigational monoclonal antibody (MAb) being evaluated by the US FDA for its potential to prevent serious disease caused by respiratory syncytial virus (RSV) among infants at high risk.

The phase-3, pivotal trial assessed the safety and RSV hospitalization in 6,635 preterm infants aged six months or younger at enrolment or children aged 24 months or younger with chronic lung disease of prematurity who received either 15 mg/kg palivizumab or motavizumab monthly. Secondary endpoints included outpatient medically attended lower respiratory tract infections (MALRIs), RSV-specific MALRIs, otitis media, antibiotic use, development of anti-motavizumab antibodies and motavizumab serum concentrations.

In this first head-to-head trial, motavizumab demonstrated non-inferiority, but not superiority, to SynagisÒ (palivizumab), meeting the primary endpoint with a 26 per cent relative reduction in RSV hospitalizations versus Synagis (p<0.01 for non-inferiority) due to RSV. Motavizumab also demonstrated superiority compared to Synagis, with a 50 per cent relative reduction in RSV lower respiratory tract infections requiring outpatient management (p=0.005), which was one of the secondary endpoints of the trial. Other secondary endpoints were not statistically significant. Adverse events were similar in both groups, although, motavizumab had two percentage points more adverse events reported for the skin compared to Synagis; the majority were non-specific rashes that did not recur or affect dosing.

In November 2008, the US FDA issued a complete response letter (CRL) to MedImmune seeking clarification on the motavizumab Biologic License Application (BLA). MedImmune filed its response with the US FDA in December 2009 and continues in its ongoing dialogue with the agency.

Each year, up to 125,000 infants in the US are hospitalized with severe RSV infections, the leading cause of lower respiratory tract infections in infants in the United States.

Synagis is the only monoclonal antibody approved by the US FDA to help prevent an infectious disease.

MedImmune, the worldwide biologics business for AstraZeneca PLC, has approximately 3,300 employees worldwide and is headquartered in Gaithersburg, Maryland.