Merck Pursues Expanded Pediatric Use After Positive Phase 3 RSV Trial Data
Merck’s Phase 3 SMART trial second RSV season data in children under two showed safety profiles consistent with first-season infants and similar monoclonal antibody serum concentrations. The findings underpin Merck’s FDA submission to expand Enflonsia for a second RSV season in high-risk pediatric patients.
1. Positive Phase 3 SMART Trial Results
The Phase 3 SMART trial evaluated Enflonsia in children under two during their second RSV season, demonstrating safety profiles consistent with the first-season cohort and achieving monoclonal antibody serum concentrations on par with earlier healthy-infant studies. Efficacy trends suggest potential for extended protection.
2. FDA Submission for Expanded Indication
Merck plans to submit these second-season SMART results to the U.S. Food and Drug Administration to seek an expanded pediatric indication for high-risk children, aiming to extend protection beyond the initial five-month period covered by the current approval.
3. Safety and Pharmacokinetic Consistency
Safety assessments showed no new adverse events compared with the pivotal Phase 2b/3 CLEVER trial in infants, and pharmacokinetic data confirmed serum levels remain within the therapeutic range, supporting the rationale for an additional dosing option in a second season.
4. Competitive Landscape
GSK’s AREXVY vaccine has shown 75.6% effectiveness against RSV-related hospitalization, highlighting competitive dynamics that could influence Enflonsia’s market positioning and uptake in pediatric RSV prevention.