Genetic Profiling of Glucocorticoid (NR3C1) and Mineralocorticoid (NR3C2) Receptor Polymorphisms before Starting Therapy with Androgen Receptor Inhibitors: A Study of a Patient Who Developed Toxic Myocarditis after Enzalutamide Treatment

Abstract

Enzalutamide is a nonsteroidal inhibitor of the androgen receptor (AR) signaling pathway and is used to treat patients with metastatic castration-resistant prostate cancer. However, the risk of cardiovascular-related hospitalization in patients with no contraindications for the use of enzalutamide is about 1–2%. To date, the underlying molecular basis of this has not been established. The androgen receptor, glucocorticoid receptor (GR) and mineralocorticoid receptor (MR) are nuclear receptors that share structural similarities and have closely related DNA-binding sites and coregulators. In non-epithelial cells, a fine balance of the activities of these receptors is essential to ensure correct cellular function. In this study, we present a molecular characterization of these nuclear receptors in a prostate cancer patient who developed congestive heart failure after enzalutamide treatment. White cell RNAseq revealed a homozygous rs5522 MR polymorphism and both the rs143711342 and rs56149945 GR polymorphisms, carried in different alleles. No different specific splice isoforms were detected. Recent research suggests that AR inhibition by enzalutamide makes available a coregulator that specifically interacts with the rs5522-mutated MR, increasing its activity and producing adverse effects on cardiovascular health. We suggest an evaluation of the MR rs5522 polymorphism before starting therapy with AR inhibitors.

Drug Resistance and Cardiovascular Safety of Second-Generation Anti-Androgens in Patients with Advanced Prostate Cancer

“…Furthermore, a case report showed that the administration of abiraterone acetate to a 70-year-old male resulted in cardiovascular dysfunction and syncope [77] Similarly, ventricular repolarization is reported as a possible adverse effect of enzalutamide therapy in male patients with hypogonadism [88]. Furthermore, enzalutamide could cause toxic myocarditis by affecting a co-regulator that interacts with and hyperactivates the rs5522-mutated mineralocorticoid receptor [89]. A randomized, double-blind, phase II study documented high grades of cardiac adverse events such as myocardial infarction, congestive HF, and atrial fibrillation upon treatment with enzalutamide [90].…”