A Single Center Retrospective Analysis of Letermovir for Cytomegalovirus Prophylaxis after Allogeneic Stem Cell Transplant in Cytomegalovirus Seropositive Recipients or Donors

Background: Up to 70% of allogeneic stem cell transplant (alloSCT) recipients who are cytomegalovirus (CMV) seropositive experience CMV reactivation and up to a third are complicated by end-organ disease. Letermovir, an antiviral agent targeting CMV, is FDA-approved for prophylaxis of CMV reactivation in CMV seropositive recipients of alloSCT. 1-4 In CMV seropositive recipients, letermovir use up to week 14 after alloSCT has demonstrated a significantly lower incidence of clinically significant CMV infection (csCMVi) and an overall mortality benefit as far as 24 weeks after transplant. 5-8 However, data on csCMVi beyond 24 weeks is lacking. Additionally, more information is needed on letermovir use in patients who had prior alloSCT, are CMV seronegative, have a detectable CMV viral load but without csCMVi, and/or are high risk*.