Letermovir Prophylaxis in Patients at High Risk for CMV Disease Following Hematopoietic Cell Transplant

Objective Starting January 2018 all adult HCT recipients at Stanford University who were at high risk (HR) for CMV disease received Letermovir prophylaxis (LET PPX). HR included: (1) ATG containing regimen, (2) an umbilical cord blood (UBC) graft, or (3) a haplo-identical, (4) unrelated (URD) (5) mismatched-related donor (misM-RD). We performed a retrospective analysis of the impact of LET PPX on the impact of CMV compared to historical controls. Methods 629 adults HCT patients from Jan 2013 - May 2019 were analyzed. 76 of these patients received LET PPX. Plasma CMV PCR was performed weekly through D+100. Prior to 2018, UCB patients received valacyclovir 2000 mg TID. PET was started if viral load (VL) was > 400 copies/ml (2009-2012) or 400 IU/ml (2013-2019). CMV disease was defined by published criteria. Results • LET PPX was well-tolerated without hematopoietic/organ toxicity. • CMV viremia occurred during LET PPX in 71 % of patients which was comparable to 74% in the controls; however, 34% LET PPX (34%) were started on a different CMV-active agent compared to 50% of controls. In 52% of LET PPX patients viremia cleared without change of antiviral or disease. (Table 1) • Although median hospital stays were the same in the LET PPX and control groups, there was a trend to greater number of hospitalizations in the control group. • Median Day post-transplant of first detection of CMV viremia for patients who received PET/change in CMV-active agent was later in the LET PPX group (D+45) than in the controls (D+ 18) • 3 of 76 (3.9%) LET PPX developed disease compared with 48 of 553 controls (8.7%). None of 24 ATG patients on LET PPX developed disease compared to 23/235 controls. (Table 2) Conclusion • Compared to controls, LET prophylaxis decreased the burden of CMV. • Other analyses not shown: hospitalizations, transfusions, infections, GHVD, relapse, survival