*Purpose: For kidney transplant recipients (KTR) there are limited choices of immunosuppression (IS) maintenance regimens. The most commonly used regimen consists of a calcineurin inhibitor (CNI) as the anchor, with mycophenolate +/- prednisone. The adverse effects of this regimen are abundant, including nephrotoxicity, diabetes, neuropathy, and hypertension. Our center implemented an innovative IS regimen to avoid CNI and prednisone administration, by utilizing belatacept (bela) and sirolimus following alemtuzumab induction.The aim of this study is to review patient and allograft outcomes, and the tolerability of this novel regimen.

*Methods: A retrospective analysis of KTR with more than 2 years of available follow up (f/u) data, who were given alemtuzumab for induction at time of kidney transplant (KT), followed by bela infusion and oral sirolimus per our center’s protocol for maintenance IS. Relevant clinical and graft outcome data were obtained. Descriptive statistics were expressed as absolute numbers (%) for categorical data and as median with interquartile range (IQR) for skewed distribution.

*Results: A total of 47 KTR patients received de novo bela/sirolimus protocol between 1/2016-11/2019. Majority were men(64%), white(66%), and received a LDKT(80%). Etiology of kidney disease was most often diabetes(19%), followed by IgA nephropathy(15%).All patients were alive with a working allograft at a f/u of 24 months [median serum creatinine (SCr) 1.3mg/dL (1.1;1.65) at 12 months, and 1.17mg/dL (1;1.4) at 24 months; with GFR of 58mL/min/1.73 m2 (49.5;62) and 61mL/min/1.73 m2 (52.5;70), respectively]. Mean f/u for the entire cohort was 44 months (SD+ 16), with 23 KTR with 36 months of f/u (SCr 1.3mg/dL (1.05;1.5), GFR 61mL/min/1.73 m2 (52;69), and 16 of those with 60 months of f/u (SCr 1.3mg/dL (1.1;1.5), GFR 59.5mL/min/1.73 m2 (51.5;65). Nine KTR had ‘per cause’ biopsy, with six of them demonstrating BPAR. Seven patients were diagnosed with a new malignancy during the study period, with two deaths. Issues with tolerability were documented in 18 KTR, and included proteinuria(2), oral ulcers(4), BK viremia(4), wound healing(5), and other(3).

*Conclusions: There is a dire need in kidney transplantation for innovative, non-nephrotoxic immunosuppressive drugs. Our center’s maintenance regimen of bela/sirolimus, was effective in preserving kidney allograft function, yielded low rates of rejection, and was overall well tolerated. Limitations of this study include a small cohort and majority of patients receiving a LDKT. Nonetheless, this regimen offers promise of improved long-term outcomes by avoiding CNIs and prednisone for our patients.

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