Successful Treatment of BK Viremia Using Reduction in Immunosuppression Without Antiviral Therapy

Abstract

Treatment of BK virus (BKV) infection in renal transplant recipients remains controversial. This retrospective analysis evaluated efficacy and safety of reducing immunosuppression without antiviral therapy. This single center analysis included 24 patients diagnosed with BK viremia between September 2001 and December 2003. Sixteen patients (66%) presented with BKV nephritis and eight patients (34%) presented with viremia without evidence of nephritis on renal biopsy. At time of diagnosis, mean plasma BKV DNA (copies/mL) was 460,409 (range 10,205-1,920,691). Mean doses reduction of mycophenolate mofetil and tacrolimus were 44% and 41%, respectively, from time of diagnosis of BKV infection to complete resolution of viremia. A decline in BK viral load was noticed within 15 to 30 days, with successful elimination of viremia over a mean period of 5.8 months (range, 1-9.5). Mean serum creatinine at time of diagnosis of BK viremia was 1.8 mg/dL (range, 1.2-2.8). Mean follow-up period is 30.9 months postdiagnosis. At the most recent visit, serum creatinine was 2.0 mg/dL (range, 1.0-3.6) (P=0.14). With reduction in immunosuppressive therapy, three patients (13%) developed acute cellular rejection and were treated successfully with intravenous bolus steroids. During follow-up, one patient had a relapse of BKV nephritis during pregnancy and lost her graft. After mean follow-up period of 43.5 months posttransplantation, all 24 patients are alive and 23 have a functioning graft. Seventeen patients (71%) have stable or improved graft function. Our analysis shows that reduction in immunosuppression therapy alone results in clearance of the BK viremia with good long-term outcome.