Alemtuzumab is an immunosuppressive antibody that depletes normal T cells and B 
cells. Prophylaxis for herpes virus and Pneumocystis carinii is standard with 
this agent. Approximately 20% to 25% of patients will experience cytomegalovirus 
(CMV) reactivation. We conducted a randomized trial wherein patients being 
treated with an alemtuzumab-containing regimen received prophylaxis with either 
valaciclovir 500 mg orally daily or valganciclovir 450 mg orally twice daily. 
The study design planned to enroll 128 patients, but stopping rules for early 
termination were met. Forty patients were evaluable. Median age was 58 years 
(range, 25-83 years); median number of prior therapies was 2 (range, 0-10). 
Diagnoses included chronic lymphocytic leukemia (29), T-cell prolymphocytic 
leukemia (3), hairy cell leukemia (1), adult T-cell leukemia/lymphoma (ATLL) 
(1), marginal zone leukemia (1), large granular lymphocyte leukemia (2), acute 
lymphoblastic leukemia (1), and T-cell lymphoma (2). Patients received various 
alemtuzumab-containing regimens, including single agent (5) or combined with: 
rituximab (2), pentostatin (6), fludarabine, cyclophosphamide, and rituximab 
(23), or fractionated cyclophosphamide, vincristine, adriamycin, and 
dexamethasone (hyper-CVAD) (4). Seven of 20 patients enrolled on the 
valaciclovir arm experienced CMV reactivation. None of the 20 patients 
randomized to valganciclovir experienced CMV reactivation (P = .004). In 
conclusion, this agent was highly effective for prophylaxis of CMV reactivation 
in patients receiving alemtuzumab. This trial was registered at 
www.ClinicalTrials.gov as #NCT00562770.