Use of letermovir for cytomegalovirus primary prophylaxis in lung transplant recipients

Background: Cytomegalovirus (CMV) is a driver of negative outcomes after lung transplant (LTX) and primary prophylaxis (PPX) with valganciclovir (VGC) is standard-of-care. VGC is associated with myelosuppression, prompting interest in letermovir (LTV). Methods: Adults receiving LTX between April 1, 2015, and July 30, 2022, at our institution were evaluated. Patients were excluded if low CMV risk (D-/R-), survived <90 days post-LTX, or transferred care before PPX withdrawal. Primary outcomes were leukopenia (white blood cell count [WBC] <= 3.0 x 10(9)/L), severe leukopenia (WBC <= 2.0 x 109/L), and neutropenia (absolute neutrophil count <= 1500 cells/<mu>L) requiring granulocyte-colony stimulating factor (GCSF) on PPX. Secondary outcomes included breakthrough CMV infection and post-PPX CMV infection. Results: 204 patients met inclusion criteria: 175 patients on VGC and 29 patients on LTV (after VGC conversion). Most patients received bilateral LTX (62.7%) with non-lymphocyte-depleting induction (96.6%) and moderate-risk serostatus (D+/R+, 48.5%). Patients transitioned from VGC to LTV after a mean of 178 days (SD 80.8 days) post-transplant. Patients on VGC experienced significantly more leukopenia (82.3% vs. 58.6%, p = 0.008), severe leukopenia (57.1% vs. 31.0%, p = 0.016), and neutropenia requiring GCSF (70.9% vs. 51.7%, p = 0.048). Breakthrough (5.7% vs. 3.4%, p = 0.955) and post-PPX (24.6% vs. 37.9%, p = 0.199) infections were similar. A subgroup analysis of patients with high-risk serostatus showed similar trends, though did not reach statistical significance. Conclusions: In this single-center study, the incidence of leukopenia and neutropenia requiring GCSF were reduced with LTV compared to VGC. Breakthrough and post-PPX infections were not significantly different. This evidence suggests that LTV has comparable efficacy with reduced myelosuppression compared to VGC in LTX recipients, and may be an appropriate alternative for PPX. image