Letermovir prophylaxis through day 100 post transplant is safe and effective compared with alternative CMV prophylaxis strategies following adult cord blood and haploidentical cord blood transplantation

We compared CMV outcomes of three prophylactic approaches used for CBT and haploidentical cord transplants from December 2009 through 2018: letermovir (n = 32) through day 100 post transplant, valacyclovir day 100 (valacyclovir 2 g orally three times daily through day 100) (n = 60), and valacyclovir hospital discharge (valacyclovir 2 g orally three times daily through hospital discharge then acyclovir 800 mg twice daily) (n = 41). Through day 100, none in the letermovir group, six (10%) in the valacyclovir day 100, and nine (22%) in the valacyclovir hospital discharge group required CMV directed treatment (p = 0.005 and 0.06 comparing letermovir to valacyclovir hospital discharge and valacyclovir day 100). Fewer patients in the letermovir group (n = 7, 22%) had any CMV reactivation versus the valacyclovir day 100 group (n = 20, 33%) versus the valacyclovir hospital discharge group (n = 23, 57%) (p = 0.003 and 0.21 comparing letermovir to valacyclovir hospital discharge and valacyclovir day 100). Among patients not reactivating CMV before 100 days, reactivation rates between day 100 and 180 were higher in the letermovir and valacyclovir day 100 groups than the valacyclovir hospital discharge group. Letermovir is safe and effective compared with alternative prophylaxis approaches following CBT through day 100. Reactivation and monitoring after day 100 remain potential concerns.