Oral valganciclovir as preemptive therapy for cytomegalovirus infection post allogeneic stem cell transplantation

Antiviral compounds including ganciclovir, foscarnet, and cidofovir are routinely used in the treatment of cytomegalovirus (CMV) infection and disease; however, these agents have a poor oral bioavailability and have the inconvenience and expense of intravenous administration. Aim of the study. To evaluate the safety and efficacy of oral valganciclovir (VGCV) for preemptive treatment of CMV reactivation in the setting of allogeneic hematopoietic stem cell transplantation (HSCT). Patients and methods. We treated 15 patients receiving allogeneic HSCT from related (n=9) or unrelated (n=6) donors. In all patients, either the donor, host, or both were CMV Ig G positive pretransplant. Indication for therapy was preemptive treatment of CMV infection defined as one or two consecutive positive tests of pp65 antigenemia assay or CMV-polymerase chain reaction (PCR). VGCV was administered orally in a dosage of 900 mg b.i.d. for 2 weeks, followed by 450 mg b.i.d. for 2 additional weeks. Results. Patients developed a positive CMV-PCR after a median of 52 days (range 37-427) post HSCT and a positive pp65 antigenemia after a median time of 74 days (range 37-427) post HSCT. Preemptive treatment with VGCV was started a median time of 56 days (range 37-429) after transplant. In all, 11 patients (73%) completed the 28 days of therapy with VGCV. All patients showed a complete clearance of the virus. The median time to achieve a negative CMV-PCR was 6 days (range 4-18). A relapse of CMV infection after VGCV preemptive therapy occurred in 6 patients (40%). No patient developed early or late CMV disease. Six patients (40%) presented hematological toxicity including neutropenia and/or thrombocytopenia that required drug discontinuation in 4 cases. Conclusion. VGCV administered as preemptive therapy for CMV infection in patients receiving an allogeneic HSCT showed promise for treating this frequent complication. Prospective randomized studies in this setting are mandatory to yield more definitive results.