Abstract IA004: Metabolic mechanisms of prostate cancer progression that feed nuclear receptors

Abstract

Abstract The androgen axis is central to prostate cancer physiology and therapy. Androgens are gonadal and extragonadal in origin, both of which stimulate the androgen receptor (AR). The use of medical castration (ADT), adrenal androgen ablation (i.e., abiraterone) and potent AR antagonists (i.e., enzalutamide, apalutamide, darolutamide), has yielded complex clinical states of prostate cancer, including disease states that are resistant to multiple forms of hormonal therapy. One of the major questions that arises is whether men can be identified who will benefit from earlier intensive hormonal therapy. Another question is whether alternative hormonal treatment strategies can be used to address resistance to the current generation of hormonal therapies. We propose that identification of steroid metabolic dependencies is part of the answer to both of these questions. Approximately half of men with prostate cancer inherit an activating missense in the first and rate-limiting enzyme that converts extragonadal precursor steroids to dihydrotestosterone (DHT). The “adrenal-permissive” HSD3B1(1245C) allele encodes for a 3β-hydroxysteroid dehydrogenase-1 (3βHSD1) enzyme that increases tumor DHT synthesis from adrenal DHEA. Heterozygous or homozygous HSD3B1(1245C) inheritance confers poor outcomes after ADT. Furthermore, men with HSD3B1(1245C) inheritance and castration-resistant prostate cancer (CRPC) treated with abiraterone or enzalutamide still have poorer outcomes. Together, these data suggest that directly targeting this metabolic lesion is necessary for optimal therapy in these men. We recently discovered that phosphorylation of the 3βHSD1 tyrosine 344 by the BMX kinase is necessary for androgen biosynthesis and CRPC in xenograft models. These findings have led to the launch of the Maverick clinical trial in the Prostate Cancer Clinical Trials Consortium (PCCTC) that combines abiraterone plus BMX inhibition with abivertinib in men with CRPC. In sum, this accumulating body of evidence suggests that steroid metabolic dependencies should be considered as an essential part of cancer metabolism, particularly in the context of developmental therapeutics for prostate cancer. Citation Format: Nima Sharifi. Metabolic mechanisms of prostate cancer progression that feed nuclear receptors [abstract]. In: Proceedings of the AACR Special Conference: Advances in Prostate Cancer Research; 2023 Mar 15-18; Denver, Colorado. Philadelphia (PA): AACR; Cancer Res 2023;83(11 Suppl):Abstract nr IA004.