Maribavir use in pediatric immunocompromised hosts: A case series to talk about real-world experience

Abstract Background Cytomegalovirus (CMV) is a common infection affecting pediatric immunocompromised hosts. The treatment of CMV in solid organ (SOT) or hematopoietic stem cell transplant (HSCT) patients is challenged by the toxicities associated with antiviral therapies (myelosuppression with valganciclovir, ganciclovir and cidofovir; nephrotoxicity with foscarnet and cidofovir) and the prevalence of resistant/refractory CMV. Maribavir, a novel benzimidazole, competitively inhibits CMV UL97 protein kinase to inhibit DNA synthesis and block nuclear exit of viral particles from CMV-infected cells. It is FDA approved for use in patients at least 12 years of age and weighing at least 35 kg. The use of maribavir in pediatric patients is of interest due to its availability as an oral dosage formulation and improved side effect profile. To date, there are no pediatric case series or studies describing the use of maribavir for CMV treatment. Methods This study is a retrospective case series compiling the findings the first pediatric patients at Children’s National Hospital, DC that received maribavir. We included children who received maribavir from 01/2017 – 10/2023. Patients were included if they were on maribavir monotherapy, or combination therapy with additional anti-CMV agent(s). The medical records were reviewed for indication of medication use, viral response to therapy and side effects. Side-effects review specifically evaluated for increased LFTs, increased serum creatinine, and decreased absolute neutrophil count or factors that may contribute to early discontinuation of maribavir. Results (table) Maribavir was used in three male patients with varied conditions – including solid organ transplant (SOT), hematopoietic stem cell transplant (HSCT) and Severe Combined Immunodeficiency (SCID) s/p HSCT. Two cases had signs of CMV disease, and one had CMV viremia. All cases included documented CMV resistance (n=2) or refractory CMV (n=1) and had previously been receiving at least one antiviral with CMV activity for at least 14 days and had increasing CMV DNA-emia in the blood. None of the patients had side effects such as nephrotoxicity, liver toxicity or myelosuppression that aggravated after starting maribavir. Dosing of 400mg BID (range 12mg/kg/day to 55mg/kg/day) was used. Once started, maribavir was continued until CMV quantitative levels were undetectable for two weeks. Clearance of CMV and was achieved in all the patients on maribavir or combination of maribavir with other drugs (n=1). Duration of maribavir treatment ranged from 4.2 to 6.2 weeks. Conclusion This is the first case series describing use of maribavir in a pediatric population. In this small cohort maribavir is effective and well tolerated. Further studies are needed to better CMV care in children with immunocompromised conditions.