Phase 1 Study of Letermovir to Evaluate Safety and Body Processing in Children Under 18 Years Weighing Less Than 40 kg After Kidney Transplant

What this Trial Is About

Researchers are evaluating letermovir in children and adolescents under 18 years old who weigh less than 40 kilograms and have received a kidney transplant. The study aims to understand how letermovir behaves in the body over time and to assess its safety and how well participants tolerate it. This phase 1, open-label study focuses on cytomegalovirus CMV prevention in this specific pediatric transplant population. Participants who are between 4 and 52 weeks post-kidney transplant will receive letermovir either orally as tablets or pellets, or through a gastrostomy or nasogastric tube as pellets, for 7 consecutive days. The dosing is adjusted based on weight bands. This is a single-group study without a placebo or comparator arm. During the study, participants will be closely monitored through blood samples to measure drug levels and CMV DNA, including the primary outcome of the drug concentration area under the curve over 24 hours on Day 7. Safety will be assessed by recording any adverse events up to 21 days and study discontinuations due to adverse events up to 7 days. The study is expected to last until 2028 and includes assessments of kidney function stability and medication absorption tolerability.

A Clinical Study of Letermovir (MK-8228) in Children and Adolescents Who Receive a Kidney Transplant (KT) (MK-8228-077)