Everolimus Therapeutic Concentration Range Defined from a Prospective Trial with Reduced-Exposure Cyclosporine in De Novo Kidney Transplantation

Abstract

Prospective therapeutic drug monitoring of everolimus was performed in a 1-year multicenter trial in 237 de novo kidney transplant patients. Trough blood levels, rejection episodes, and safety parameters were evaluated to define an appropriate therapeutic concentration range for everolimus in this setting. Patients were randomized to everolimus starting doses of 0.75 mg bid (n = 112) or 1.5 mg bid (n = 125). Doses were then individualized based on everolimus trough blood levels (C0) in an attempt to maintain troughs ≥3 ng/mL; no upper limit was specified. The regimen also contained corticosteroids and cyclosporine with an early dose reduction in months 2–3 posttransplant based on concentrations 2 hours postdose (C2). Cyclosporine C0 levels were also collected. Prospective therapeutic drug monitoring of everolimus C0 in patients starting at 0.75 mg bid led to dose adjustments in 52% of patients to an average long-term dose of 0.93 ± 0.36 mg bid. This gave median (10th to 90th percentile) C0 levels of 5.3 (3.4–7.9) ng/mL. In patients starting at 1.5 mg bid, 55% had dose adjustments leading to an average long-term dose of 1.24 ± 0.35 mg bid. This yielded C0 levels of 7.2 (4.4–11.6) ng/mL. Cyclosporine dosing began on average at 274 ± 78 mg bid, was down-titrated in months 2–3 from 181 ± 80 mg to 81 ± 33 mg bid, and stabilized at 70 ± 26 mg bid thereafter. This yielded median C2 levels of 1165 ng/mL in month 1, a down-titration with levels of 853 and 630 ng/mL in months 2 and 3, and a posttitration level of 472 ng/mL. The corresponding median cyclosporine C0 was 242 ng/mL initially and 70 ng/mL in the posttitration phase. In patients starting at 0.75 mg bid everolimus and an early down-titration of cyclosporine, everolimus C0 between 3 and 8 ng/mL was an effective and safe concentration range. Concentrations up to 12 ng/mL were tolerated over the first year posttransplant. This trial demonstrated that therapeutic monitoring of everolimus can be prospectively performed for dose individualization. Maintaining everolimus troughs in the range 3 to 8 ng/mL in the first posttransplant year with reduced-exposure cyclosporine is associated with good efficacy and safety profiles.