(062) Early Versus Delayed Initiation of Letermovir Prophylaxis for Cytomegalovirus in High-Risk Allogeneic Stem Cell Transplantation (Top Ten Poster)

Poster Abstract:

Background:
Cytomegalovirus (CMV) is a common opportunistic infection in recipients of allogeneic hematopoietic stem cell transplantation (allo-HCT) leading to increased morbidity and mortality. Letermovir, a CMV viral terminase inhibitor, was approved by the Food and Drug Administration in 2017 for prophylaxis of CMV infection and disease beginning between day 0 and day 28 post-allo-HCT for CMV-seropositive recipients through day 100. Studies with varying initiation dates of letermovir relative to transplant have resulted in a range (8 to 14%) of cumulative incidences of clinically significant CMV infection (CS-CMVi) by day 100 post-allo-HCT. To date, there is no published data that has compared the impact of different initiation times of letermovir post-allo-HCT on CMV-based outcomes.

Objective(s):
This study aims to evaluate the outcomes of early versus delayed initiation of letermovir for CMV prophylaxis in high-risk allo-HCT recipients.

Methods:
This was an IRB-approved, retrospective, single-center study of adult patients undergoing allo-HCT who were seropositive for CMV and considered at high risk for CMV infection between June 2019 and August 2023. Patients were excluded if they had current or history of CMV end-organ disease within 6 months prior to transplant or received antiviral agents with anti-CMV activity within 7 days prior to transplant. High risk of CMV infection was defined as one or more of the following: haploidentical donor, umbilical cord blood (UCB) stem cell source, ex-vivo T-cell depleted grafts, or anti-thymocyte globulin (ATG) containing preparative regimens. The primary outcome was CS-CMVi by day 100 post-allo-HCT, defined as initiation of preemptive therapy for CMV disease or CMV viremia. Secondary outcomes include time to CS-CMVi, acute graft-versus-host disease (GVHD), and overall survival at day 100 post-allo-HCT. For patients on the delayed letermovir initiation arm, inpatient cost savings was also evaluated. Chi-square and Mann-Whitney U tests will be performed to analyze the primary and secondary outcomes.

Results:
Results pending.

Discussion/

Conclusion:
Results pending.

References (must also be included in final poster): 1. Derigs P, Radujkovic A, Schubert ML, et al. Letermovir prophylaxis is effective in preventing cytomegalovirus reactivation after allogeneic hematopoietic cell transplantation: single-center real-world data. Ann Hematol. 2021;100(8):2087-2093. doi:10.1007/s00277-020-04362-2.
2. Marty FM, Ljungman P, Chemaly RF, et al. Letermovir Prophylaxis for Cytomegalovirus in Hematopoietic-Cell Transplantation. N Engl J Med. 2017;377(25):2433-2444. doi:10.1056/NEJMoa1706640.