We enrolled 35 children less than 2 years of age without BPD and who were being mechanically ventilated for RSV infection into a multicenter, randomized, double blind placebo controlled trial. Patients received a single 15mg/kg intravenous infusion of Medi-493 (a humanized RSV monoclonal antibody to the F protein) or placebo within 36 hours (mean 18 hr) of intubation. Nasal and deep tracheal secretions were obtained before study drug infusion, 24 hours later and serially thereafter. RSV concentration was measured by plaque assay performed on fresh specimens. The log geometric mean (SE) of the RSV concentrations (RSV conc.) in log plaque forming units (log pfu/ml) from deep tracheal secretions were as follows: Table There was a significantly greater decline in the RSV concentration in deep tracheal secretions in the treated group vs. controls at 24 and 48 hours. When covariates including gender, age, race, gestational age and weight were included in a regression model, treatment with MEDI-493 was the only factor related to this decline. A decline in RSV concentration was not seen in the nasal secretions. In the deep tracheal secretions, there were no significant differences at any time point in white cell counts, percentage of neutrophils, myeloperoxidase, or eosinophilic cationic protein between groups. There were no significant differences in adverse events. No differences in clinical measurements of disease severity were seen. Treatment with Medi-493 at 15mg/kg reduces RSV concentrations in the deep tracheal secretions of RSV infected children. Future studies should address increased dose, the role of inflammation and timing of treatment.

Table 1 No caption available.
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