Multicenter Randomized Two-arms Study Evaluating the BK Viral Clearance in Kidney Transplant Recipients With BK Viremia After Reduction of Immunosuppression Alone vs. Reduction of Immunosuppression and Replacement of Mycophenolate Mofetil by Everolimus

BK virus nephropathy (BKVN), a consequence of the strong immunosuppressive therapy given after kidney transplantation, represents a growing problem in the kidney transplant (KT) setting. In recent cohorts, BKVN concerns up to 10% of kidney transplant recipients and early signs of BK virus (BKV) infection as development of asymptomatic viruria and viremia are even much more frequent (40% and 20% of patients, respectively). In this context, finding strategies to prevent BKV infection or treat patients before the occurrence of BKV nephropathy is challenging. For several years, detection of BKV replication by real-time PCR in urine and/or blood of kidney transplant recipients at early stages of infection allowed adaptation of their therapy. As BKV reactivates essentially in patients with over-immunosuppression, the first step of the treatment is the reduction of immunosuppression. However, reducing immunosuppression (IS) can lead to acute rejection and allograft loss. Other treatments have been proposed (cidofovir, quinolones) but their toxicity profile or their lack of clinical efficacy are now demonstrated. Hence, an efficient and safe strategy against uncontrolled BKV replication is urgently needed. MTor-inhibitors are well known immunosuppressive drugs used in organ transplantation to prevent graft-rejection. They have furthermore anti-viral effects that can be beneficial for prevention of viral infections after transplantation. Recent evidence that inhibition of mTor pathway had an impact on BK infected cells provides additional insight into the observed benefits associated with these drugs. The aim of our study is to evaluate the effect of the mTor inhibitor everolimus on the prevention of severe BKV infection (BKV nephropathy or loss of the allograft) after kidney transplantation compared to the reduction of immunosuppression alone in kidney recipients with BK viremia.