 Maribavir showed promise in Phase II clinical trials and was granted fast track status, but failed to meet study goals in a Phase III trial.However, the dosage used in the Phase III trial may have been too low to be efficacious.A Phase II study with maribavir demonstrated that prophylaxis with maribavir displayed strong antiviral activity, as measured by statistically significant reduction in the rate of reactivation of CMV in recipients of hematopoietic stem cell/bone marrow transplants.