Valacyclovir for the prevention of cytomegalovirus infection after allogeneic stem cell transplantation: a single institution retrospective cohort analysis

A retrospective single center study was performed to evaluate the safety an d efficacy of valacyclovir for prevention of cytomegalovirus (CMV) infectio n (reactivation) after allogeneic stem cell transplantation (SCT). We compa red a group of 31 patients at risk for CMV reactivation (donor, recipient o r both seropositive for CMV) who received valacyclovir at an oral dose of 1 g three times a day for CMV prophylaxis with a matched cohort of 31 patien ts who did not receive the drug or any other form of CMV prophylaxis. Valac yclovir was used as primary prophylaxis in 12 patients and as secondary pro phylaxis (after a prior CMV reactivation was effectively treated with eithe r ganciclovir or foscarnet and without CMV antigenemia at the start of vala cyclovir) in the remaining 19 patients. The two treatment groups were well matched for the donor-recipient CMV serological status and other pre-transp lant characteristics. CMV reactivation was detected by blood antigenemia te sting using a commercially available immunofluorescence assay for CMV lower matrix protein pp65 in circulating leukocytes. For primary prophylaxis, 3/ 12 patients who received valacyclovir reactivated CMV compared to 24/31 pat ients in the control group (P < 0.001). For secondary prophylaxis, 5/19 val acyclovir patients reactivated compared to 16/24 control patients (P < 0.05 ). Valacyclovir was well tolerated except for infrequent and mild gastroint estinal side-effects. There was no difference in the incidence of CMV disea se in the two groups. Prophylaxis with valacyclovir appears to be safe and efficacious in preventing both primary and secondary CMV reactivation in at -risk patients after allogeneic SCT. Larger prospective randomized studies will be required to confirm these observations.