Impact of Letermovir Use for Cytomegalovirus Prophylaxis on Re-Hospitalization Following Allogeneic Hematopoietic Stem Cell Transplantation: An Analysis of a Phase III Randomized Clinical Trial.

Background Allogeneic hematopoietic stem cell transplantation (HSCT) is associated with substantial healthcare resource use, particularly when recipients develop cytomegalovirus (CMV) infection. Letermovir reduced post-HSCT CMV infection risk compared with placebo in a previous phase III trial. This analysis evaluated letermovir's impact on re-hospitalization post-transplant. Methods Using data from a phase III, multicenter, randomized clinical trial (NCT02137772, registered May 14, 2014), this study assessed CMV-associated and all-cause re-hospitalizations at weeks 14, 24, and 48 post-transplant among recipients of letermovir versus placebo. Unstandardized re-hospitalization rates and days were reported; standardized rates and days were estimated accounting for censoring due to death or early study discontinuation. Results Unstandardized rates (95% confidence interval [CI]) of all-cause re-hospitalization in letermovir versus placebo recipients at weeks 14, 24, and 48 were 36.6% (31.4-42.1) versus 47.6% (39.9-55.4), 49.2% (43.7-54.8) versus 55.9% (48.1-63.5), and 55.7% (50.1-61.2) versus 60.6% (52.8-68.0), respectively. Unstandardized mean total duration (95% CI) of re-hospitalization with letermovir versus placebo at weeks 14, 24, and 48 were 7.6 (5.9-9.8) versus 11.3 (8.6-14.8), 13.9 (11.2-17.2) versus 15.5 (11.9-20.1), and 18.0 (14.8-21.9) versus 20.7 (15.8-27.1) days, respectively. Similar results were found in CMV-associated re-hospitalization outcomes and standardized rates and days of all-cause re-hospitalizations. Conclusions In this post-hoc analysis, letermovir was associated with lower rates of CMV-associated and all-cause re-hospitalizations with a shorter length of stay (especially within the first 14 weeks post-transplant).