Merck Virus Treatment Shows 60.4% Effectiveness, Reduces Certain Infections In Infants

Merck & Co Inc MRK unveiled results from a Phase 2b/3 trial (MK-1654-004) evaluating clesrovimab, the company’s investigational prophylactic monoclonal antibody designed to protect infants from respiratory syncytial virus (RSV) disease during their first RSV season.

The results and interim findings from the ongoing Phase 3 trial (MK-1654-007) of clesrovimab were presented during IDWeek 2024.

Results from the Phase 2b/3 pivotal trial evaluating a single dose of clesrovimab administered to healthy preterm and full-term infants (birth to 1 year of age) met all prespecified endpoints, with consistent results through both the 5-month and 6-month time points.

Also Read: GSK, Pfizer Face Declining Respiratory Syncytial Virus Vaccine Sales Due To Narrow Age Recommendations.

The incidence of adverse events (AEs) and serious AEs were comparable between the clesrovimab and placebo groups, and there were no treatment or RSV-related deaths during the study.

The primary efficacy endpoint of the trial, the reduction in the incidence of RSV-associated medically attended lower respiratory infections (MALRI) requiring ≥ 1 indicator of lower respiratory infection (LRI) or severity compared to placebo through Day 150 (5 months) postdose, was 60.4%.

Clesrovimab also reduced RSV-associated hospitalizations (secondary endpoint) and RSV-associated LRI hospitalizations (tertiary endpoint) through Day 150 (5 months) compared to placebo by 84.2% and 90.9%, respectively.

Clesrovimab reduced the incidence of severe MALRI (tertiary endpoint) by 91.7%.

In addition, in a post hoc analysis, the reduction in the incidence of MALRI requiring ≥ 2 indicators of LRI and severity (an endpoint of more severe MALRI than the primary MALRI endpoint) was 88.0% through Day 150.

Merck also announced data from a planned interim analysis of the MK-1654-007 trial, a Phase 3 trial evaluating the safety and efficacy of clesrovimab versus palivizumab in infants and children at increased risk for severe RSV disease.

Palivizumab is sold under the brand name Synagis by Swedish Orphan Biovitrum AB or Sobi BIOVF

The study’s primary endpoint is the safety and tolerability of clesrovimab in infants entering their first RSV season.

Interim results showed clesrovimab had a comparable safety profile to palivizumab, and no drug-related serious AEs were reported to date.

Incidence rates of RSV-associated MALRI requiring ≥ 1 indicator of LRI or severity and RSV-associated hospitalizations (secondary endpoints) were also comparable between clesrovimab (3.6% and 1.3%, respectively) and palivizumab (3.0% and 1.5%, respectively) through Day 150 (5 months).

Price Action: MRK stock closed at $109.75 on Thursday.

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