Real-World Efficacy and Safety of Letermovir Prophylaxis in Adolescent Patients Undergoing Allogenic Hematopoietic Stem Cell Transplantation: A Single Center Observational Study

Letermovir, an inhibitor of the cytomegalovirus (CMV) terminase complex, has demonstrated remarkable efficacy in the prevention of CMV infections in adult patients through randomized controlled trials. Nevertheless, its application in adolescent patients has been relatively limited. This observational study, conducted at a single center, sought to assess and compare the efficacy and safety of letermovir (n=20) and valganciclovir (n=32) for CMV prophylaxis in adolescent patients (aged 14-18 years) undergoing allogenic hematopoietic stem cell transplantation (aHCT).

The incidence of CMV DNAemia following aHCT was 45.0% in the letermovir group and 59.4% in the control group receiving valganciclovir. Notably, 20.0% of patients receiving letermovir required preemptive therapy (PET), in contrast to 40.6% of those receiving valganciclovir. Furthermore, 10 patients in the letermovir group and 15 in the valganciclovir group developed grades Ⅱ-Ⅳ acute graft-versus-host disease (aGVHD). Among patients with grades Ⅱ-Ⅳ aGVHD, the proportion of adolescents requiring PET was significantly lower in the letermovir group compared to the valganciclovir group (10% vs 53.3%, p=0.04). The 1-year overall survival rates were 87.4% and 85% in the letermovir and valganciclovir groups, respectively (p=0.928). Importantly, no patients succumbed to CMV infection in both groups . The most common adverse events observed in the letermovir group were aGVHD (60.0%), diarrhea (25.0%), and nausea (15.0%). Leukopenia was reported in only one patient, and did not necessitate an adjustment of letermovir dosage. In this single-center real-world study, letermovir exhibited a superior efficacy and safety profile for CMV prophylaxis in adolescent patients undergoing aHCT, as compared to valganciclovir. In particular, for patients with grades Ⅱ-Ⅳ aGVHD, the administration of letermovir prophylaxis can significantly decrease the likelihood of PET. However, further prospective multi-center studies are warranted to validate the efficacy and safety of letermovir for CMV prevention in adolescent patients.

No relevant conflicts of interest to declare.