Everolimus and Sirolimus in Combination with Cyclosporine Have Different Effects on Renal Metabolism in the Rat

Abstract

Enhancement of calcineurin inhibitor nephrotoxicity by sirolimus (SRL) is limiting the clinical use of this drug combination. We compared the dose-dependent effects of the structurally related everolimus (EVL) and sirolimus (SRL) alone, and in combination with cyclosporine (CsA), on the rat kidney. Lewis rats were treated by oral gavage for 28 days using a checkerboard dosing format (0, 3.0, 6.0 and 10.0 CsA and 0, 0.5, 1.5 and 3.0 mg/kg/day SRL or EVL, n = 4/dose combination). After 28 days, oxidative stress, energy charge, kidney histologies, glomerular filtration rates, and concentrations of the immunosuppressants were measured along with 1H-magnetic resonance spectroscopy (MRS) and gas chromatography- mass spectrometry profiles of cellular metabolites in urine. The combination of CsA with SRL led to higher urinary glucose concentrations and decreased levels of urinary Krebs cycle metabolites when compared to controls, suggesting that CsA+SRL negatively impacted proximal tubule metabolism. Unsupervised principal component analysis of MRS spectra distinguished unique urine metabolite patterns of rats treated with CsA+SRL from those treated with CsA+EVL and the controls. SRL, but not EVL blood concentrations were inversely correlated with urine Krebs cycle metabolite concentrations. Interestingly, the higher the EVL concentration, the closer urine metabolite patterns resembled those of controls, while in contrast, the combination of the highest doses of CsA+SRL showed the most significant differences in metabolite patterns. Surprisingly in this rat model, EVL and SRL in combination with CsA had different effects on kidney biochemistry, suggesting that further exploration of EVL in combination with low dose calcineurin inhibitors may be of potential benefit.

Everolimus and sirolimus in transplantation-related but different

“…In another study, salt-depleted rats treated for 28 days, everolimus or sirolimus alone did not result in pancreatic dysfunction and renal injury, however, when combined with cyclosporine, both sirolimus and everolimus enhanced cyclosporine-induced pancreatic and renal injury [37]. It should be noted that the cyclosporine: everolimus dose ratio was much higher than in both previously discussed studies [36,61] and in contrast to the study described in [36], during which the immunosuppressants were administered by oral gavage, immunosuppressants were administered subcutaneously [37]. …”

“…The effects of cyclosporine or tacrolimus in combination with sirolimus on the rat kidney following 28 days of oral administration were systematically compared with those of cyclosporine or tacrolimus in combination with everolimus [36], The study was based on a model previously developed and verified for cyclosporine toxicity [58,59]. The results showed sirolimus to dose-dependently enhance tacrolimus and cyclosporine nephrotoxicity.…”

“…This was confirmed by histologies, changes in urine metabolite patterns and changes in kidney cell metabolism as assessed using various nuclear magnetic resonance spectroscopy, liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry metabolomics technologies. In contrast, with increasing doses, everolimus in combination with cyclosporine and tacrolimus had less of a negative effect on the kidneys and compared favorably with sirolimus [36] (Figure 4). Similar results were found when in the same model the CNI tacrolimus was combined with sirolimus and everolimus [60] (Figure 4).…”

“…In said clinical trials, trough blood concentration ratios ranged from 1: 10 to 1: 100 (everolimus: cyclosporine) [64], while concentration ratios in the aforementioned in vitro and animal studies were 1:3.3 to 1:5 [34,36,48–51]. When in such in vitro studies everolimus was tested combined with cyclosporine concentrations exceeding this ratio, everolimus-induced inhibition of glycolysis became critical and everolimus behaved just like sirolimus [50].…”

Oral intake of curcumin markedly activated CYP 3A4: in vivo and ex-vivo studies

“…Owing to its narrow therapeutic index, regular blood concentration monitoring of EVL is required to ensure therapeutic efficacy151617. EVL is a substrate of P-glycoprotein (P-gp), a drug-efflux transporter, and primarily metabolized by CYP3A4, an important drug-metabolizing enzyme12.…”