Effectiveness of letermovir in preventing cytomegalovirus reactivation after cord blood transplantation

Background Cord blood transplantation (CBT) is associated with a high risk of cytomegalovirus (CMV) infection. Letermovir (LTV) is a prophylactic agent against CMV reactivation after CBT, but data on its effectiveness and the incidence of late CMV reactivation after LTV discontinuation are limited. Methods A single-center retrospective observational study was conducted in 79 adult CMV-seropositive CBT recipients who received their first transplant for acute myeloid leukemia, acute lymphoblastic leukemia, or myelodysplastic syndrome from February 2016 to September 2022. Outcomes were compared between 45 patients who received LTV prophylaxis and 34 patients who did not. Results The cumulative incidence of CMV reactivation was significantly lower in patients who received LTV prophylaxis at both day 100 (11.1 % vs. 82.4 %, p < 0.001) and 1 year (45.3 % vs. 82.4 %, p < 0.001). The incidence of late CMV reactivation after LTV discontinuation was 34.2 %. The cumulative incidence of CMV disease was comparable between patients who received and those who did not (0 % vs. 8.8 % at day 100, 2.3 % vs. 8.8 % at 1 year; p = 0.181). Multivariate analysis showed that LTV prophylaxis reduced the cumulative incidence of CMV reactivation (hazard ratio 0.20, 95 % confidence interval 0.09 to 0.42, p < 0.001). Conclusion LTV prophylaxis is strongly associated with prevention of CMV reactivation after CBT. Due to the high incidence of late CMV reactivation, close monitoring is required after LTV discontinuation and extension of LTV prophylaxis beyond day 100 should be considered.