Treatment of BK virus-associated nephropathy with CMX001 after kidney transplantation in a young child.

NC, with renal failure secondary to bilateral dysplastic kidneys, received an LRD renal transplant (tx) at 17 months of age. Her early post-tx course was complicated by persistently elevated blood polyoma BK virus DNA loads. A protocol biopsy at six months post-transplant revealed BKVAN. Blood viral loads did not respond to decreased immunosuppression or treatment with ciprofloxacin and leflunomide. Six months post-tx, her serum creatinine began to rise and we sought experimental therapy to prevent the loss of her graft. At seven months post-tx, with FDA approval under an eIND, the patient was started on a 36-wk course of treatment with the investigational drug. The patient is now more than 24 months after stopping treatment with CMX. BKV viral DNA loads remain at low, but still detectable levels. Urine viral loads have declined, but remain elevated. EBV DNA loads become undetectable. The patient's serum creatinine has declined back to a baseline of 0.5-0.7 mg/dL and has been stable for two yr. Renal function was preserved in association with the use of CMX001 to treat BKV nephropathy in a young pediatric kidney transplant recipient. There were no serious adverse events associated with the use of CMX001. This novel medication may be of value in the treatment of BKVAN in pediatric renal transplant recipients.