Efficacy of Eplerenone in the Management of Mineralocorticoid Excess in Men With Metastatic Castration-resistant Prostate Cancer Treated With Abiraterone Without Prednisone

Prednisone is typically coadministered with abiraterone in the treatment of castrate-resistant prostate cancer to prevent the toxicities of secondary mineralocorticoid excess. However, many patients do not desire or cannot tolerate chronic glucocorticoid therapy. In the present retrospective study, we report that eplerenone, a mineralocorticoid antagonist, can be safely used with abiraterone, obviating the need for concomitant prednisone in this patient population. Background Abiraterone acetate has been approved for metastatic castration-resistant prostate cancer (mCRPC). Coadministration with prednisone has been recommended to prevent the toxicity from secondary mineralocorticoid excess, such as hypertension, hypokalemia, and edema. However, the use of prednisone is often not desired by patients because of the potential for detrimental effects of long-term therapy with corticosteroids, especially in those with comorbidities such as diabetes or who have received previous immunotherapeutic agents. Eplerenone is a nonsteroidal mineralocorticoid antagonist demonstrated to abrogate mineralocorticoid excess. In the present retrospective study, we report our real-world experience with the use of eplerenone with abiraterone in men with mCRPC who wished to avoid concomitant prednisone therapy. Patients and Methods The incidence and grade (Common Terminology Criteria for Adverse Events, version 4) of mineralocorticoid excess toxicities, baseline demographics, disease characteristics, and progression-free survival (PFS) were collected retrospectively. The patient population included men with mCRPC treated with abiraterone, who were not willing to receive corticosteroids, and thus received eplerenone. Their data were compared with the data from those treated with abiraterone and prednisone during the same period. Continuous variables were assessed using the Wilcoxon rank sum test or Student t test, and categorical variables were assessed using Fischer's exact test or χ² test, as appropriate. PFS was compared using the Kaplan-Meier method. Results Of the 106 men treated with abiraterone, 40 received eplerenone and 66 received prednisone. The baseline and disease characteristics, incidence and grade of adverse events related to the syndrome of mineralocorticoid excess, and the median PFS were similar in both cohorts. Conclusion In a real-world population of men with mCRPC treated with abiraterone, corticosteroids can be avoided by concomitant treatment with eplerenone. These data require further validation.