Background: Everolimus is an mTOR generally utilized in CNI minimization or withdrawal regimens for kidney transplantation. The aim of this study was to compare pharmacokinetic (PK) and pharmacodynamic (PD) properties of everolimus (ERL) between ethnicities.

Methods: This was a retrospective cross-sectional PK/PD analysis of all patients that received ERL within our transplant center between 2005 and 2011. Pediatrics, multi-organ transplants, and those with limited or no ERL concentrations were excluded.

Results: 43 patients received ERL and were included (22 were African-American (AA), 21 were Caucasian). Baseline demographics were similar between ethnicities, except for pre-existing HTN, donor type, and cold ischemic time. Baseline immunologic risk and immunosuppression were similar as well. PK analysis revealed AA patients received higher ERL doses in the early period, which led to higher ERL concentrations (Table 1). Efficacy analysis demonstrated similar pre and post ERL conversion effects on rejection, chronic allograft changes, and renal function (Figure 1). Safety analysis demonstrated that AA patients had higher rates of ERL discontinuation, proteinuria, and diarrhea/GI intolerance; statistical modeling suggested early elevated ERL concentrations were associated with these toxicities (Table 1).

Conclusions: Contrary to previous mTOR PK/PD analyses in AA patients, this study cohort demonstrated higher early ERL levels in the AA patients related to higher baseline doses, which potentially led to higher rates of toxicities in the AA patients.

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