Evaluating the hypothalamic-pituitary-adrenal axis (HPAA) in men receiving ketoconazole for castrate-resistant prostate cancer (CRPC).

64 Background: Serum adrenal androgen (AA) levels may be prognostic for survival in men with CRPC treated with androgen synthesis inhibitors (ASIs) including ketoconazole (keto) and abiraterone. We hypothesize that up-regulation of the HPAA and adrenocorticotropic hormone (ACTH) may contribute to therapeutic resistance on ASIs. The current study explores the relationship between ACTH, AA, testosterone (T) and estradiol (E) among CRPC patients (pts) treated with ASI + corticosteroids. Methods: Phase 2 study of keto (400 mg TID) + hydrocortisone (HC) (30 mg/day) in pts with CRPC. Pts who achieved ≥ 30% PSA decline from baseline at week 12 continued keto/HC until progression, at which point HC was replaced by dexamethasone (dex). Serum hormone (H) levels were measured (in AM) at baseline and every 4 weeks using standard assays. Statistical tests include Spearman’s rank test for correlation between baseline H levels; Wilcoxon matched pairs for baseline vs. week 4 distribution; and Fisher’s exact test for asso...