European Commission approves Merck’s Enflonsia for RSV prevention in infants

UK—Merck & Co has secured approval from the European Commission for Enflonsia (clesrovimab), a preventive monoclonal antibody designed to protect newborns and infants against respiratory syncytial virus (RSV) during their first RSV season.

The approval grants the pharmaceutical giant the right to market Enflonsia across all 27 member states of the European Union, as well as Iceland, Liechtenstein, and Norway.

Enflonsia represents a breakthrough in RSV prevention through its innovative long-acting formula.

A single dose provides five months of continuous protection, perfectly timed to shield infants throughout the typical RSV season.

The medication uses non-weight-based dosing, simplifying administration for healthcare providers and families.

However, doctors must avoid prescribing Enflonsia to infants with known hypersensitivity to its active ingredient or any excipients.

Access dependent on national policies

While the European Commission has approved Enflonsia, its availability across different countries will ultimately hinge on individual national reimbursement decisions.

This means patients in some nations may gain access sooner than in others, depending on local healthcare policies and funding mechanisms.

Robust clinical evidence supports approval

The European Commission’s decision rests on compelling clinical data from two major trials.

The pivotal Phase IIb/III CLEVER trial (MK-1654-004) evaluated Enflonsia’s safety and effectiveness in both premature and full-term infants.

Results demonstrated that a single dose cut the risk of RSV-related medically attended lower respiratory infections by 60.4 per cent and reduced hospitalisations by 84.2 per cent over five months compared with placebo.

Additionally, the antibody showed substantial reductions in severe cases and hospital admissions while maintaining a safety profile comparable to placebo.

Supporting this data, interim findings from the Phase III SMART trial (MK-1654-007) compared Enflonsia directly to palivizumab, an existing RSV preventive.

The two treatments showed similar rates of RSV-associated infections, hospitalizations, and adverse effects, establishing Enflonsia as an effective alternative.

Industry recognition of global significance

Dr. Macaya Douoguih, global clinical development therapeutic area head and vice-president at Merck Research Laboratories, emphasized the milestone’s importance.

He noted that bringing Enflonsia to European infants represents a critical step toward reducing RSV disease burden globally.

 The company aims to equip families and healthcare providers with this new preventive option to combat a widespread and potentially severe infection.

Looking ahead

Earlier this month, Merck and Daiichi Sankyo achieved another milestone when the FDA granted priority review status to ifinatamab deruxtecan, a new treatment for extensive-stage small cell lung cancer.

This development underscores the company’s ongoing commitment to advancing treatments across multiple therapeutic areas.