Impaired endogenous neurosteroid signaling contributes to behavioral deficits associated with chronic stress

Chronic stress is a major risk factor for psychiatric illnesses, including depression; however, the pathophysiological mechanisms whereby stress leads to mood disorders remain unclear. The recent FDA approval of antidepressants with novel mechanisms of action, like Zulresso®, a synthetic neuroactive steroid analog with molecular pharmacology similar to allopregnanolone, has spurred interest in new therapeutic targets and, potentially, novel pathophysiological mechanisms for depression. Allopregnanolone acts as a positive allosteric modulator of GABAA receptors (GABAARs), acting preferentially at δ subunit-containing receptors (δ-GABAARs). Accumulating clinical and preclinical evidence supports the antidepressant effects of exogenous administration of allopregnanolone and allopregnanolone analogs; however, the role of endogenous neurosteroids in the pathophysiology of depression remains unknown. Here, we examine whether altered neurosteroid signaling may contribute to behavioral deficits following chronic unpredictable stress (CUS) in mice. We first identified reductions in expression of δ-GABAARs, the predominant site of action of 5a-reduced neuroactive steroids, following CUS. Additionally, utilizing LC-MS/MS we discovered a decrease in levels of allopregnanolone in the BLA, but not plasma of mice following CUS, an indication of impaired neurosteroid synthesis. CRISPR knockdown the rate-limiting enzymes involved in allopregnanolone synthesis, 5α-reductase type 1 and 2, in the BLA mimicked the behavioral deficits associated with CUS in mice. Furthermore, overexpression expression of 5α-reductase type 1 and 2 in the BLA improved behavioral outcomes. Collectively, this suggests chronic stress impairs endogenous neurosteroid signaling in the BLA which is sufficient to induce behavioral deficits similar to those observed following CUS. Further, these studies suggest that the therapeutic efficacy of allopregnanolone-based treatments may be due to their ability to directly target the underlying pathophysiology of mood disorders. Therefore, targeting endogenous neurosteroidogenesis may offer a novel therapeutic strategy for the treatment of mood disorders.

Mifepristone (Korlym ®) Use Interferes With Accurate Serum Measurement of Sex Steroids

Introduction: Mifepristone (MFP) aka RU-486/Korlym is a synthetic steroid analog originally developed in 1980 as an abortifacient that is now used in the management of Cushing’s syndrome (CS). It is both a progesterone (PG) and glucocorticoid (GC) receptor blocker. CS is often associated with reproductive functional anomalies including hypogonadism, menstrual irregularities and infertility. Due to its mode of action, measurement of serum PG and/or cortisol in patients on MFP are inaccurate indices of systemic PG and/or GC deficiency or excess. However, the potential impact of MFP use on other serum steroid assays has not been widely studied. We report the case of a 55 yr old man on treatment with MFP for adrenal CS found to have striking artefactual changes in serum androgen and estrogen levels. Case Summary: A 55 yr old African American man was referred with poorly controlled type 2 diabetes, hypertension, hyperlipidemia, obesity and untreated hypogonadism. He had a 3.2cm left adrenal incidentaloma associated with adrenal CS and he chose medical management rather than surgery. Upon starting MFP at 300mg QD serum total estrogen (by radio-immunoassay; RIA) and estradiol (by chemiluminescence immunoassay; CIA) were markedly elevated while serum total, free, bioavailable testosterone and dihydrotestosterone were all markedly reduced. His HBA1c, weight and energy levels improved on MFP despite these findings. The serum steroid levels normalized to pre-treatment levels after stopping MFP for ~ 4weeks but the changes recurred after restarting therapy. After MFP dose escalation to 300mg BID the serum steroid levels normalized after stopping MFP for ~ 6 weeks. The artefactual low testosterone levels also occured with measurement by equilibrium dialysis but “normal accurate” results were obtained when measured by liquid chromatography-Tandem mass spectrometry (LC-TMS). He remains on MFP 300mg BID without need for androgen repletion. Discussion: With increased use of MFP for CS, indices for tracking its clinical and biochemical effects assume great importance. There are few reports of the possible effects of MFP on estrogen and testosterone serum assays despite its touted low cross reactivity with sex steroids. Our case suggests that the significance, extent and prevalence of artefactual changes on serum sex steroid assays may be underestimated and under- appreciated. Conclusions: Our case of wide disparities in serum estrogen and androgen measures in a patient on MFP indicates that caution needs to be exercised in the interpretation of such results in patients on current MFP therapy. Our clinical observations suggest depending on the dose that a wash out period of 4–6 weeks is required to ensure accurate measures. Studies to ascertain the prevalence of this artefactual effect are needed and it appears testosterone measurement by LC-TMS obviates the testosterone assay artefact.

ARMOR2: Galeterone in progressive CRPC patients who have failed oral therapy.

71 Background: Galeterone is a first-in-class multitargeted oral steroid analog; it suppresses prostate cancer by a combination of AR modulation (antagonism and degradation) and CYP17 inhibition. Safety and proof of concept of galeterone in CRPC was assessed in ARMOR1. Galeterone was reformulated by spray dry dispersion technology (SDD) to optimize PK and remove food effect. ARMOR2 (NCT 01709734) is an open label, 2-part phase 2 trial that evaluates safety and efficacy of SDD galeterone in 4 populations of CRPC patients. These results report Part 1. Methods: Objectives of Part 1: confirm dose equivalence of SDD formulation with evaluation of PK, safety and PSA response. Metastatic (M1) and non-metastatic (M0) treatment naïve CRPC pts enrolled to groups of 1,700, 2,550 or 3,400 mg PO daily. An abiraterone refractory (Abi-R) group of 3 patients opened at 2,550mg. Results: 28 were enrolled in part 1. Safety: All groups were safe by IMC assessment. There were 4 grade 3 adverse events. 2 were unrelated to study drug. 2 had transient G3 ALT elevations (did not recur with rechallenge). There was no AME: supplemental steroids were not required. G4 angioedema occurred in a pt receiving lisinopril (known association with angioedema). Efficacy: PSA response was improved compared to ARMOR1 (AACR 2012. Taplin et al abstract: CT-07). At early follow up Abi-R pts showed improvements in PSA with 1 PSA30% response, 2 with stablized PSA (decline in PSA-V from +0.44 to -0.39 ng/day). Conclusions: Galeterone in SDD formulation is tolerated at doses up to 3,400mg daily. SDD galeterone provides improved PSA response and durability vs. prior formulation. There is evidence of activity in abiraterone refractory patients. Clinical trial information: 01709734. [Table: see text]

Comparison of the pharmacokinetics (PK) of galeterone novel oral formulations.

e16075 Background: Galeterone (gal) is an orally available steroid analog for the treatment of castration resistant prostate cancer (CRPC). A significant food effect, similar to abiraterone, was found when gal, as powder in capsule (PIC), was dosed in a phase I CRPC trial and confirmed in a PK study in human volunteers.The objective of this study was to assess single-dose PK of gal after reformulation and to evaluate effect of food. Methods: In this single-center open-label study, 24 male subjects were assigned to receive once daily doses of between 100 and 3400 mg in either a 3-treatment, 3-period or 4-treatment, 4-period dose scheme. Treatment periods were separated by 7-day washout intervals. Plasma concentrations were measured over 72 hours to assess PK. Two novel tablet formulations were administered in 100 mg doses under fasted and/or fed condition compared to 2600 mg-PIC administered under fed conditions. Escalating doses of PIC (975 to 2600 mg) and tablet (850 to 3400 mg) formulations were evaluated to assess linearity. Results: Gal was well tolerated. Food effect has been negated with the tablet. Exposure from 1700 mg galeterone tablet (fed or fasted) is comparable to a 2,600 mg dose of PIC (fed) (Table). For tablet, AUC(inf) increased in a dose-related and dose-proportional manner from 6,689 ± 2,602 hxng/mL (850 mg) to 20131 ± 9,930 hxng/mL (2,550 mg). Conclusions: The tablet formulation negates the food effect previously observed. Gal may be dosed either fed or fasted with no difference in absorption, which reduces intra-patient variability in exposure. Tablet has more consistent bioavailability and a linear increase in AUC between escalating doses. [Table: see text]