SAT-059 Treatment Of Primary Aldosteronism With The mTORC1 Inhibitor Everolimus

Abstract

Background: Primary aldosteronism, characterized by inappropriately high and relatively autonomous aldosterone production, is one of the most frequent causes of secondary hypertension. In most cases, primary aldosteronism results from unilateral or bilateral adrenal hyperplasia and aldosterone-producing adenoma. Depending on the subtype, patient characteristics and preference, treatment comprises unilateral adrenalectomy or mineralocorticoid receptor antagonists. However, these treatments are not always well tolerated or suitable. Histological studies have shown up-regulation of mTOR activity in the adrenal cortex of primary aldosteronism patients and mTORC1 inhibition decreases aldosterone production in adrenocortical cells. Consistently, we found that treatment of mice with the mTORC1 inhibitor rapamycin decreased plasma aldosterone levels without affecting other adrenal steroid hormones. Therefore, we aimed to evaluate the mTORC1-inhibitor everolimus as an aldosterone-lowering drug in patients with primary aldosteronism. Methods: In this open-label, proof-of-concept study, we measured plasma aldosterone levels after a standardized, recumbent saline infusion test in 12 primary aldosteronism patients at baseline, following a two-week everolimus treatment (0.75mg twice daily) and after a two-week washout period. To investigate whether everolimus affects other steroid hormone levels, we measured steroid hormone metabolites in a 24-hour urine collected before each saline infusion test. Results: Median post-infusion plasma aldosterone levels after treatment did not differ significantly from baseline (386 pmol/l, IQR 248-495 vs. 312 pmol/l, IQR 245-426; p = 0.677). However, a marked decrease in aldosterone levels after treatment was observed in four subjects. Their aldosterone levels returned to baseline values after the washout period. This pattern was mirrored by changes in urinary aldosterone/creatinine and tetrahydroaldosterone/creatinine ratios, suggesting that the observed effect was treatment-related. No consistent changes were detected for other steroid metabolites. Conclusion: This is a first in human study on the treatment of primary aldosteronism with the mTORC1 inhibitor everolimus. Overall, we observed a numerical reduction in aldosterone levels after a 2-week treatment which did not reach statistical significance. However, 4 patients appeared to respond to treatment. Further studies with a larger patient cohort are required to further elucidate the effects of mTORC1 inhibitors in primary aldosteronism and to characterize the differences between potential responders and non-responders.