Letermovir Prophylaxis for Cytomegalovirus Infection in Children After Hematopoietic Cell Transplantation

Background/Aim: Cytomegalovirus (CMV) infection is one of the major causes of morbidity following hematopoietic cell transplantation (HCT). Allogeneic HCT (allo-HCT) recipients are at the highest risk of clinically significant CMV reactivation. While letermovir has been approved for prophylactic use in CMV seropositive adults, reports on pediatric data are very limited. The objective of the study was to examine the use of letermovir for prophylaxis from CMV infection in children undergoing allo-HCT in a single center. Patients and Methods: This retrospective matched-pair analysis study included 39 CMV-seropositive pediatric patients undergoing allo-HCT receiving letermovir as a primary prophylaxis for CMV infection on a compassionate-use basis (LMV group, n=13) or not (control group, n=26). There were no differences in basic characteristics between the analyzed groups. Among patients of the study group, 12 received primary prophylaxis with letermovir from day +1 after HCT. One patient, previously treated with ganciclovir received secondary prophylaxis from day +18. Results: Prophylactic dose of letermovir was adjusted to cyclosporine co-administration, varied in between 120-480 mg, and given orally, once daily. No CMV reactivation was observed during administration of letermovir. Cumulative incidence of CMV reactivation was significantly higher for the control group not receiving prophylaxis. Of the 13 patients of the study group, three died; however, deaths were not attributable to CMV infection. We did not observe any toxicities related to letermovir. Conclusion: Our data support letermovir prophylaxis efficacy and safety in pediatric patients after allo-HCT. Compared with the historical group, prophylactic use of letermovir decreased the number of CMV reactivations in children.