Everolimus-based immunosuppression therapy for BK virus nephropathy.

Background. Mammalian target of rapamycin inhibitors (mTOR-i) have been proposed as possible immunosuppressants of choice in BK virus nephropathy (BKN) because of their antiviral capacity. On this basis, in 2007, our Service proposed a conversion to everolimus (EVE)-based therapy from calcineurin inhibitors with an anti calcineurin-free therapy protocol in those patients diagnosed of BKN. Methods. A prospective, single-center case series study was performed. Fifteen cases of BKN were diagnosed from 2007 to the end of 2010. According to our protocol, immunosuppressant treatment was modified in 9 of these patients with suspension of mycophenolate and conversion from tacrolimus to EVE. Results. The renal function achieved by our patients after the transplantation was excellent. Mean serum creatinine (sCr) achieved was 1.16 +/- 0.2 mg/dL. Evolution of the renal function after BKN diagnosis and conversion to mTOR-i was positive in all the patients. sCr on diagnosis was 1.85 +/- 0.22 mg/dL, sCr at the point in time of conversion to EVE was 2 +/- 0.21 mg/dL, and final sCr of the follow-up was 1.6 +/- 0.39 mg/dL (P = .05). BK viremia became negative in 5 of our patients and decreased more than 95% in the remaining 4. None of the patients had an acute rejection episode after the change of immunosuppressant. Conclusions. Conversion to mTOR-i based therapy could provide an added benefit in BKN and could be an effective strategy for the decrease of the viremia and increase of graft survival in selected patients.