Outcomes of mTORi-involving minimized immunosuppression protocols in renal transplantation

Abstract

Aim: Immunosuppression lowering protocols are commonly involving low-dose calcineurin inhibitors (CNIs) and themammalian target of Rapamycin inhibitor (mTORi). In renal transplant (RT) recipients, due to various factors (thedevelopment of polyoma B-K virus [BKV] and cytomegalovirus [CMV] infections, malignancy, and CNIs nephrotoxicity),immunosuppression lowering comes up mandatory. Here, we present the outcomes of renal allografts after switching from astandard immunosuppression protocol to mTORi-containing lower immunosuppression protocol.Material and Method: This single-center, retrospective, and observational study includes RTs performed between 2014-2016.Three hundred twenty-two recipients were evaluated and 231 proper recipients were enrolled in the study. Recipients whoreceived mTORi for at least 12 months were included in mTORi arm. Recipients who did not have a BKV and/or CMVscreening test, and allograft biopsy were excluded. The remains were enrolled in mTORi-free arm. Allograft survival rate andfunction before mTORi and at 1, and 3-year under mTORi treatment were compared.Findings: A total of 231 recipients were followed-up approximately for 5-years. In mTORi arm CMV and BKV viremiapositivity rates were higher than mTORi-free group; p=0.001. Additionally, acute rejection (AR) rate was higher in mTORiarm (p=0.001). Estimated glomerular filtration rate (eGFR) at 1 and 3-year after mTORi arm was less than mTORi-free arm(p=0.001). However, 1 and 3-year recipient and allograft survival rates were similar among two groups; p=0.23 and p=0.06,p=0.52 and p=0.72, respectively.Conclusion: In renal allograft recipients, mTORi is commonly considered in the cases that require lowering immunosuppression,such as BKV and CMV viremias, and CNI nephrotoxicity. Despite these disadvantages, it may provide a similar allograftsurvival rate compared to mTORi-free group. However, mTORi use is associated with more AR episodes and may not preventthe development of a worse eGFR.