Low-dose cidofovir in the treatment of symptomatic BK virus infection in patients undergoing allogeneic hematopoietic stem cell transplantation: a retrospective analysis of an algorithmic approach.

BK virus (BKV) reactivation occurs in 50% of allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients. Standardized antiviral management of BKV infection has not been established. In order to develop a uniform guideline, a treatment algorithm for the management of symptomatic BKV replication was implemented for our allo-HSCT population. This is a retrospective analysis of patients treated according to the protocol between January 2008 and January 2009. Eighteen patients developed symptomatic BKV replication a median of 43 days after allo-HSCT. All patients had BK viruria and 12 patients had BK viremia in addition to viruria. Patients with isolated viruria were treated with intravenous (IV) low-dose cidofovir (0.5-1mg/kg IV weekly) until symptom resolution. In patients with BK viremia, therapy was continued until virological clearance was achieved in the blood. Four patients also received intravesical instillation of cidofovir per physician discretion. Thirteen of 18 (72%) patients with viruria and 8 of 12 (75%) patients with viremia responded to treatment. Three patients developed transient renal dysfunction. Low-dose cidofovir is safe and effective in allo-HSCT recipients. In absence of randomized prospective data, an institutional algorithmic protocol removes variance in practice pattern and derives data that may be used for research and improved patient care.