Clinical "real-world" experience with letermovir for prevention of cytomegalovirus infection in allogeneic hematopoietic cell transplant recipients

Background Letermovir was approved in 2017 for prevention of cytomegalovirus (CMV) infection in seropositive (R+) allogeneic hematopoietic cell transplantation (HCT) patients. Post-marketing data with this new agent are scarce. Methods We compared the incidence of both CMV reactivation (any viremia) and clinically significant CMV infection (CS-CMVi; CMV DNAemia leading to preemptive treatment or presence of CMV tissue invasive disease) at days +100 and +200 post-HCT in 25 adult allogeneic HCT patients who received letermovir prophylaxis (until day 100) and a historical control group of 106 CMV R+ allogeneic HCT recipients who underwent CMV preemptive therapy. Results CMV reactivation within 100 days post-HCT was lower in the letermovir group vs control group (20% vs 72% respectively, P < .001). The 100-day cumulative incidence of CS-CMVi was significantly lower in the letermovir group vs control group (4% vs 59% respectively, P < .001). Significantly reduced incidence of CMV reactivation and CS-CMVi was also observed at 200 days in the letermovir group. No difference in mortality was observed between the two groups. Conclusion This study confirms the efficacy of letermovir in preventing CMV reactivation in CMV R+ allogeneic HCT recipients in first 100 days post-HCT and suggests sustained efficacy after discontinuation of prophylaxis.