Single-center experience with use of letermovir for treatment of CMV infection in stem cell transplant recipients.

The approval of letermovir provided a new option for cytomegalovirus (CMV) prophylaxis in CMV seropositive allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients. Data are limited on the use of letermovir for the treatment of CMV infection. We performed a single-center retrospective review of allo-HSCT recipients who received letermovir off-label for treatment of CMV infection (CMV DNAemia and CMV disease) from November 2017 until November 2019. Fifteen patients were included, 14 of which received letermovir for treatment of CMV DNAemia. The median duration from transplant to CMV DNAemia was 41 days and median duration of letermovir therapy was 53 days (IQR, 43-59). Median time to first undetectable CMV viral load from the start of letermovir was 16 days (IQR, 13-21). No significant correlation was noted between the time to CMV DNA clearance and either CMV DNA at the time of starting letermovir (r = -.12, 95% CI: -0.63-0.46; P = .69) or CMV DNA peak (r = .04, 95% CI: -0.51-0.58, P = .87). Three patients had late reactivation of CMV after completion of letermovir (20%) after 87 days (IQR, 68-103) of therapy cessation. Clinical failure or treatment intolerance occurred in two patients (14%). One patient failed to achieve an undetectable viral load. In another patient, letermovir was discontinued due to documented therapy-related thrombocytopenia. Our analysis suggests that letermovir might have a potential role for the treatment of CMV infection in select patients with contraindication or intolerance to more validated therapies.