COMPLICATIONS - INFECTIONS

E. Renoult¹, F. Coutlée², M. Pâquet³, G. St-louis², C. Girardin², M. Fortin², H. Cardinal², R. Lévesque³, W. Shürch³, M. Latour², A. Barama³, M. Hébert^2
1Nephrology, Kidney And Pancreas Transplantation, Centre hospitalo-universitaire de Montréal (CHUM), Montreal/CANADA, ², CHUM, Montreal/QC/CANADA, ³, CHUM, Montreal/CANADA

Body: Introduction: BKPVAN is a major cause of renal allograft failure, early after transplantation. The timing of the initial diagnosis is critical for therapeutic success and a good outcome. The present study reports on the preliminary results of the prospective monitoring and pre-emptive strategy for BKPVAN proposed during the first post-transplant year at our center. Methods: We prospectively followed 71 kidney transplant recipients who all received induction immunosuppression, with basilixumab (73%) or ATG, and maintenance immunosuppression, with prednisone, mycophenolate mofetil and tacrolimus. Plasma BKV DNA was measured at 1, 2, 3 6, 9, and 12 months after transplantation. Patients with two or more consecutive positive viral load (> 10 000 copies/ml) were treated with a subsequent stepwise decrease in immunosuppression (a dose reduction or discontinuation of mycophenolate mofetil eventually followed by a reduction of tacrolimus and introduction of leflunomide). During the first year, 55 (76%) recipients underwent allograft biopsy as part of protocol surveillance criteria or as clinically indicated. Results: By one year, 6 (8, 4%) patients had sustained BK viremia (≥ 10 000 copies/ml), at a median of 92 days after transplantation (range, 64 to 349 days). BKPVAN was diagnosed histologically in 7 (9, 8%) recipients (the 6 BK viremic patients and one non-viremic patient) at a median of 15 weeks (range: 11 to 32 weeks) after transplantation. In 5 cases, BKPVAN was diagnosed in patients with stable renal function during their four-month protocol biopsy. Biopsy findings were noted concomitantly with the first viremia in two subjects, 8 months before the first viremia in one case, whereas the viral load remained negative in one patient with BKPVAN. Leflunomide was used in all the patients who developed BKPVAN. At 12 months, serum negative conversion or decrease of viral titer was achieved in 5 viremic patients. Creatinine levels improved or stabilized in 4 patients with BKPVAN. The estimated renal function of patients was 41 ml/min (vs 59, 3 ml/min in patients who never became viremic, p= 0,029). One patient experienced acute rejection two weeks after reduction of immunosuppressive treatment. None of the patients with viremia and/or BKPVAN lost their renal allograft. Conclusion: BKPVAN may occur early after kidney transplantation, at a low or undetectable viremia or concomitantly with the first positive viremia. Intensive monitoring during the first four months after transplantation added to early protocol biopsies or biopsies prompted by the viremia could help to optimize the diagnosis of BKPVAN at a subclinical stage and avoid renal allograft dysfunction.

Disclosure: All authors have declared no conflicts of interest.