Glucocorticoid Receptor Antagonist Mifepristone Research Articles

The Role of Glucocorticoid and Nicotinic Acetylcholine Receptors in the Reward-Enhancing Effects of Nicotine in the ICSS Procedure in Male and Female Rats.

Tobacco use disorder is a chronic disorder that affects more than one billion people worldwide and causes the death of millions each year. The rewarding properties of nicotine are critical for the initiation of smoking. Previous research has shown that the activation of glucocorticoid receptors (GRs) plays a role in nicotine self-administration in rats. However, the role of GRs in the acute rewarding effects of nicotine are unknown. In this study, we investigated the effects of the GR antagonist mifepristone and the nicotinic acetylcholine receptor (nAChR) antagonist mecamylamine on the reward-enhancing effects of nicotine using the intracranial self-stimulation (ICSS) procedure in adult male and female rats. The rats were prepared with ICSS electrodes in the medial forebrain bundle and then trained on the ICSS procedure. Nicotine lowered the brain reward thresholds and decreased response latencies similarly in male and female rats. These findings suggest that nicotine enhances the rewarding effects of ICSS and has stimulant properties. Treatment with the GR antagonist mifepristone did not affect the reward-enhancing effects of nicotine but increased response latencies, suggesting a sedative effect. Mecamylamine did not affect the brain reward thresholds or response latencies of the control rats, but prevented the nicotine-induced decrease in brain reward thresholds and reward latencies. These findings indicate that the rewarding effects of nicotine are mediated via the activation of nAChRs, and that the activation of GRs does not contribute to the acute rewarding effects of nicotine. These studies enhance our understanding of the neurobiological mechanisms underlying tobacco use disorder.

Study protocol for a prospective, multicentre study of hypercortisolism in patients with difficult-to-control type 2 diabetes (CATALYST): prevalence and treatment with mifepristone

IntroductionEven with recent treatment advances, type 2 diabetes (T2D) remains poorly controlled for many patients, despite the best efforts to adhere to therapies and lifestyle modifications. Although estimates vary, studies...

TBCRC 058: A randomized phase II study of enzalutamide, enzalutamide with mifepristone, and treatment of physician’s choice in patients with androgen receptor-positive metastatic triple-negative or estrogen receptor-low breast cancer (NCT06099769).

TPS1138 Background: Triple-negative breast cancer (TNBC) refers to a heterogenous group of breast cancers that lack expression of ER, PR, and HER2. Despite recent advances with immunotherapy (IO) and antibody-drug conjugates (ADCs), TNBC remains the most aggressive subtype, characterized by a high risk of recurrence and a short overall survival in the metastatic setting. Breast tumors with low levels of ER and PR expression (1-10%) clinically behave like TNBC, and clinical management follows the TNBC treatment (tx) paradigm. We and others have identified a subset of ER/PR/HER2 negative breast cancers (BC) that express the androgen receptor (AR). Enzalutamide (enza), an AR-antagonist, has demonstrated activity in AR+ metastatic TNBC (Traina et al, JCO 2018). Activation of the glucocorticoid receptor (GR) has been implicated as a mechanism of resistance to AR inhibition in prostate and BCs (Kach et al, Sci Transl Med 2015). Effective therapies for advanced TNBC remain an unmet need, particularly in patients who are ineligible for or progress following a checkpoint inhibitor. This randomized study will evaluate the efficacy of enzalutamide or enzalutamide plus the GR antagonist mifepristone (mif) as compared to physician’s choice chemotherapy (TPC). Methods: This is a randomized phase II trial; 201 patients (pts) will be randomized in a 1:1:1 fashion to enza, enza with mif, or TPC (carboplatin, paclitaxel, eribulin, or capecitabine). The primary endpoint (endpt) is progression free survival (PFS), and the trial is designed to test the hypothesis that PFS in the pooled enzalutamide arms is superior to TPC; there is 80% power to detect a hazard ratio (HR) of 0.70, corresponding to increase in PFS from 3.5 months (mos) with TPC to 5.0 mos with enza-based tx. Secondary endpts include comparisons of PFS among 3 arms and evaluation of response rate, clinical benefit rate, duration of response, overall survival, safety/toxicity, and patient-reported outcomes by arm. Exploratory endpts include correlation of tumor and circulating markers (constitutively active AR variants in circulating tumor cells and circulating tumor cell DNA) with tx response. Eligible pts must have: ECOG 0-2, metastatic ER/PR low or negative, HER2 negative breast cancer (BC), measurable or evaluable disease (dz), < 2 prior lines of chemotx, any # prior endocrine txs, no prior anti-AR tx, no prior mif, concurrent CYP17 inhibitors prohibited. Pts with PD-L1+ BC must have received prior IO if not contraindicated. Tumors must have AR ≥10%, normal organ function, no history of brain mets. As of 1/15/2024, 2 of 201 pts have begun protocol-specified tx. Clinical trial information: NCT06099769 .

Proteomic analysis of central amygdala systems regulated by the glucocorticoid receptor antagonist mifepristone in the context of alcohol dependence

Alcohol use disorder (AUD) is a chronic psychiatric disorder characterized by escalated alcohol use and emergence of negative emotional states during withdrawal. Studies show a dysregulation of glucocorticoid signaling in AUD, affecting the hypothalamic-pituitary-adrenal (HPA) axis and the central amygdala (CeA). Excessive activation of glucocorticoid receptors (GRs) is hypothesized to promote cognitive dysfunction, negative emotional states, and escalated drinking. Previous work demonstrates a functional increase in GR activity in the CeA during alcohol withdrawal in alcohol-dependent animal models. Importantly, the GR antagonist mifepristone reduces alcohol-seeking and drinking behaviors in rodents and humans. The aims of this study were to determine differential CeA protein expression in alcohol-dependent rats and examine the effects of mifepristone treatment. We hypothesized that male and female rats will show sex differences in their CeA protein expression and that alcohol-induced reductions in brain anti-stress signaling (e.g., endocannabinoid system) will be normalized by mifepristone treatment. Male and female Wistar rats were exposed to chronic intermittent ethanol vapor (CIEV) or air (control) for 10 weeks. In week 7, half of each group received subcutaneous placebo pellets while the other half received mifepristone pellets (150mg, 21-day slow release). At the end of Week 10, the rats were sacrificed during acute (6-hour) CIEV withdrawal (and identical time in control groups). The CeA was analyzed using proteomics and ingenuity pathway analysis (IPA). In males, a total of 3050 proteins were detected in the CeA. Of these, 142 proteins were altered by alcohol (but not mifepristone), whereas an additional 253 proteins were altered by alcohol and “normalized” by mifepristone. In females, among the 2632 detected proteins, 46 were affected by alcohol (but not mifepristone), and 25 were altered by alcohol and restored by mifepristone. IPA revealed significant changes in canonical pathways, including the endocannabinoid neuronal synapse pathway and oxidative phosphorylation, affected by alcohol but normalized by mifepristone. Future studies will incorporate alcohol self-administration procedures in male and female rats to functionally examine proteins within these pathways as promising “druggable” targets that offer novel therapeutic avenues for AUD. Supported by NIH-NIAAA R01AA025996, P60AA009803, T32AA007577. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

CATALYST: A Phase 4 Study of Hypercortisolism in Patients with Difficult-to-Control Type 2 Diabetes Despite Receiving Standard-of-Care Therapies Assessing Prevalence and Treatment with Mifepristone

The prevalence of hypercortisolism in persons with difficult-to-control type 2 diabetes (T2D) may be higher than currently appreciated, particularly in persons who require a greater number of antihyperglycemic agents and/or have more comorbidities. To better understand the prevalence and whether treatment of hypercortisolism may result in better control of diabetes and other hypercortisolism-associated comorbidities, we have designed CATALYST, a prospective phase 4 study in adults with difficult-to-control T2D (HbA1c 7.5–11.5%) despite receiving multiple antihyperglycemic agents. CATALYST is being conducted at about 30 sites in the United States. In Part 1, about 1000 persons with difficult-to-control T2D will be screened with a 1-mg dexamethasone suppression test (cutoff: serum cortisol >1.8 µg/dL; dexamethasone ≥140 ng/dL). Patients with ACTH-dependent hypercortisolism will be referred out of the study. The primary study endpoint—the prevalence of ACTH-independent hypercortisolism—will be evaluated in Part 1. Patients with ACTH-independent hypercortisolism may advance to Part 2, a prospective, 2:1 randomized, double-blind, placebo-controlled trial to evaluate the efficacy and safety of treatment with the competitive glucocorticoid receptor antagonist mifepristone. Patients will be randomized (stratified by the presence/absence of adrenal adenomas on CT) and receive treatment for 24 weeks. The mifepristone dose will be 300 mg QD for 4 weeks, then increased to 600 mg QD for 20 weeks based on glycemic efficacy and tolerability (option to increase to mifepristone 900 mg). Secondary endpoints include changes in HbA1c from baseline to 24 weeks and changes in hypercortisolism-related comorbidities (e.g., blood pressure, weight, waist circumference, quality of life).

The influence of pharmacological mineralocorticoid and glucocorticoid receptor blockade on the cortisol response to psychological stress

The glucocorticoid cortisol is the end product of the hypothalamic–pituitary–adrenal (HPA) axis and crucial for the stress response in humans. Cortisol regulates numerous biological functions by binding to two different types of receptors: the mineralocorticoid receptor (MR) and the glucocorticoid receptor (GR). Both receptors are found in the brain where they are crucially involved in various mental functions and in feedback inhibition of cortisol release. The precise role of both receptors in the human stress response is not completely understood. In this study, we examined the effects of pharmacological blockade of the MR or the GR on stress-induced cortisol release in a sample of 318 healthy young men (M = 25.42, SD = 5.01). Participants received the MR antagonist spironolactone (300 mg), the GR antagonist mifepristone (600 mg), or a placebo and were subjected 90 min later to a social-evaluative stressor (Trier Social Stress Test) or a non-stressful control condition. We found significantly higher stress-induced cortisol release in the spironolactone group, whereas participants after mifepristone administration did not differ from the control groups. These results suggest that MR blockade results in attenuated fast negative feedback processes and emphasize the important role of the MR during the early phase of the stress response.

FRI183 Phase 4 Study Of Hypercortisolism In Patients With Difficult-to-Control Type 2 Diabetes Despite Receiving Standard-of-Care Therapies: Prevalence And Treatment With Mifepristone

FRI183 Phase 4 Study Of Hypercortisolism In Patients With Difficult-to-Control Type 2 Diabetes Despite Receiving Standard-of-Care Therapies: Prevalence And Treatment With Mifepristone

Acute effects of mifepristone on emotional processing related brain activity: A functional MRI study

The Hypothalamic-pituitary-adrenal (HPA) axis plays an important role in the pathophysiology of mood disorders, and preliminary data suggests that glucocorticoid receptor (GR) antagonism may be an important therapeutic mechanism. The effects of modulating HPA axis function on emotional processing related brain activity, which may be abnormal in depressed mood, is poorly understood. This study used a pharmacological functional magnetic resonance imaging (fMRI) design to determine the effects of the GR and progesterone receptor antagonist mifepristone on emotional faces processing task related brain activations in 19 right-handed healthy male participants. Each participant received 600 mg mifepristone or placebo on two separate imaging days and then performed an emotional processing fMRI task four hours later. The effect of mifepristone on task related brain activations was determined using Region-of-Interest (ROI) analyses and an exploratory whole brain voxel-wise analyses. No significant changes were observed in the defined ROIs (amygdala, anterior cingulate cortex, insula) or in the exploratory whole brain analyses that was associated with mifepristone administration in either the angry vs happy faces or angry and happy faces vs implicit baseline contrasts. Task reaction times and accuracy were similar in both mifepristone and placebo conditions (all p > 0.05). Our study failed to show significant evidence of modulation of emotional processing related brain activity associated with acute mifepristone administration. Future research should use fMRI to investigate the longer-term administration effects of mifepristone on mood in healthy participants and people with mood disorders to provide a deeper understanding of the potential effects on depressive symptoms.

Glucocorticoid receptors regulate central amygdala GABAergic synapses in Marchigian-Sardinian alcohol-preferring rats

Impairments in the function of the hypothalamic-pituitary-adrenal (HPA) axis and enhanced glucocorticoid receptor (GR) activity in the central amygdala (CeA) are critical mechanisms in the pathogenesis of alcohol use disorder (AUD). The GR antagonist mifepristone attenuates craving in AUD patients, alcohol consumption in AUD models, and decreases CeA γ-aminobutyric acid (GABA) transmission in alcohol-dependent rats. Previous studies suggest elevated GR activity in the CeA of male alcohol-preferring Marchigian-Sardinian (msP) rats, but its contribution to heightened CeA GABA transmission driving their characteristic post-dependent phenotype is largely unknown.We determined Nr3c1 (the gene encoding GR) gene transcription in the CeA in male and female msP and Wistar rats using in situ hybridization and studied acute effects of mifepristone (10 μM) and its interaction with ethanol (44 mM) on pharmacologically isolated spontaneous inhibitory postsynaptic currents (sIPSCs) and electrically evoked inhibitory postsynaptic potentials (eIPSPs) in the CeA using ex vivo slice electrophysiology.Female rats of both genotypes expressed more CeA GRs than males, suggesting a sexually dimorphic GR regulation of CeA activity. Mifepristone reduced sIPSC frequencies (GABA release) and eIPSP amplitudes in msP rats of both sexes, but not in their Wistar counterparts; however, it did not prevent acute ethanol-induced increase in CeA GABA transmission in male rats.In msP rats, GR regulates CeA GABAergic signaling under basal conditions, indicative of intrinsically active GR. Thus, enhanced GR function in the CeA represents a key mechanism contributing to maladaptive behaviors associated with AUD.

The insula mediates the effects of glucocorticoids in anxiety

Increased activity in the insula has been consistently reported to be associated with anxiety and anxiety-related disorders. However, little is known on how the insula regulates anxiety. The present study aims at determining the role of the insula on the effects of glucocorticoids in anxiety. A combination of pharmacological manipulations, including blockade of adrenal GC synthesis by metyrapone and intra-insular microinjections of corticosterone, corticosterone-BSA, mineralocorticoid receptor (MR) antagonist spironolactone and glucocorticoid receptor (GR) antagonist mifepristone, were used to assess the short-term (5 min) effects of intra-insular corticosterone in two anxiety-like behaviors in male Sprague-Dawley rats. The elevated plus maze (EPM) and Novelty Suppressed Feeding (hyponeophagia) were utilized. We found that corticosterone in the insula is sufficient to prevent the anxiolytic effects corticosterone synthesis blockade in anxiety, and that intra-insular corticosterone has anxiolytic or anxiogenic effects depending on the amount of corticosterone microinjected and the arousal associated to the test, without affecting the HPA axis. Glucocorticoid anxiolytic effects in the insula are mediated by MRs, while its anxiogenic effects are dependent on a mifepristone-sensitive membrane-bound mechanism. Anxiety appears to be modulated at the insula through a competition between fast MR-dependent anxiolytic and membrane-associated anxiogenic signaling pathways that orchestrate the behavioral response to stress and determines the resulting level of anxiety.

Efficacy and Safety of Mifepristone in the Treatment of Male US Veterans With Posttraumatic Stress Disorder

To date, no psychopharmacologic treatment has been found to be uniformly effective in veterans with posttraumatic stress disorder (PTSD); novel targets and approaches are needed to treat this disabling disorder. To examine whether treatment with the glucocorticoid receptor antagonist mifepristone yields a signal for clinical efficacy in male veterans with PTSD. This phase 2a, double-blind, parallel-group randomized clinical trial was conducted from November 19, 2012 (accrual started), through November 16, 2016 (final follow-up), within the US Department of Veterans Affairs. Participants were male veterans with chronic PTSD and a screening Clinician-Administered PTSD Scale score of 50 or higher. A total of 181 veterans consented to participation. Statistical analysis was conducted between August 2014 and May 2017. Participants were randomized in a 1:1 ratio to mifepristone (600 mg) or matched placebo taken orally for 7 days. The clinical outcome was whether a veteran achieved a clinical response status (a reduction of ≥30% of total Clinician-Administered PTSD Scale score from baseline) at 4- and 12-week follow-up. On the basis of a binary statistical selection rule, a difference in the proportion of treatment vs control group responders of 15% would be a clinically relevant difference. Self-report measures of PTSD and associated symptoms were also obtained. Neuroendocrine outcomes and plasma levels of mifepristone were measured. Safety was assessed throughout the study. The primary analysis was based on a multiple imputation technique to address missing outcome data; thus, some participant numbers may not appear as whole numbers. A total of 81 veterans were enrolled and randomized. Excluding 1 participant randomized in error, 80 were included in the modified intention-to-treat analysis (41 randomized to mifepristone and 39 to placebo). The mean (SD) age was 43.1 (13.7) years. A total of 15.6 (38.1%) in the mifepristone group and 12.1 (31.1%) in the placebo group were clinical responders at 4 weeks in the analysis using the multiple imputation technique. The group difference in the proportion of clinical responders (7.0%) was less than the predefined margin of 15% indicating signal for clinical efficacy. In an exploratory analysis, the difference in response to mifepristone vs placebo in the subgroup with no lifetime history of traumatic brain injury (TBI) (7.0 [50.0%] vs 3.0 [27.3%]; difference, 22.7%) exceeded the efficacy margin at 4 weeks and was sustained at 12 weeks. In contrast, in veterans with PTSD and lifetime TBI, the response rate to mifepristone was lower than placebo at 12 weeks (7.4 [27.4%] vs 13.5 [48.3%]; difference, -20.9%). This study did not detect a signal for efficacy for mifepristone at 600 mg/d for 1 week in male veterans with chronic PTSD. Thus, this study does not support a phase 3 trial in this population. Future studies of mifepristone for the treatment of PTSD may be of interest in those without a history of TBI or in samples with a low base rate of lifetime head trauma. ClinicalTrials.gov Identifier: NCT01946685.

Glucocorticoid-driven mitochondrial damage stimulates Tau pathology.

Prolonged exposure to glucocorticoids, the main stress hormones, damages the brain and is a risk factor for depression and Alzheimer's disease. Two major drivers of glucocorticoid-related neurotoxicity are mitochondrial dysfunction and Tau pathology; however, the molecular/cellular mechanisms precipitating these events, and their causal relationship, remain unclear. Using cultured murine hippocampal neurons and 4-5-month-old mice treated with the synthetic glucocorticoid dexamethasone, we investigate the mechanisms underlying glucocorticoid-induced mitochondrial damage and Tau pathology. We find that glucocorticoids stimulate opening of the mitochondrial permeability transition pore via transcriptional upregulation of its activating component, cyclophilin D. Inhibition of cyclophilin D is protective against glucocorticoid-induced mitochondrial damage as well as Tau phosphorylation and oligomerization in cultured neurons. We further identify the mitochondrially-targeted compound mito-apocynin as an inhibitor of glucocorticoid-induced permeability transition pore opening, and show that this compound protects against mitochondrial dysfunction, Tau pathology, synaptic loss, and behavioural deficits induced by glucocorticoids in vivo. Finally, we demonstrate that mito-apocynin and the glucocorticoid receptor antagonist mifepristone rescue Tau pathology in cytoplasmic hybrid cells, an ex vivo Alzheimer's disease model wherein endogenous mitochondria are replaced with mitochondria from Alzheimer's subjects. These findings show that mitochondrial permeability transition pore opening is a precipitating factor in glucocorticoid-induced mitochondrial dysfunction, and that this event stimulates Tau pathogenesis. Our data also link glucocorticoids to mitochondrial dysfunction and Tau pathology in the context of Alzheimer's disease and suggest that mitochondria are promising therapeutic targets for mitigating stress- and Tau-related brain damage.

Genetically engineered human pituitary corticotroph tumor organoids exhibit divergent responses to glucocorticoid receptor modulators

Cushing's disease (CD) is a serious endocrine disorder attributed to an adrenocorticotropic hormone (ACTH)-secreting pituitary neuroendocrine tumor (PitNET) that that subsequently leads to chronic hypercortisolemia. PitNET regression has been reported following treatment with the investigational selective glucocorticoid receptor (GR) modulator relacorilant, but the mechanisms behind that effect remain unknown. Human PitNET organoid models were generated from induced human pluripotent stem cells (iPSCs) or fresh tissue obtained from CD patient PitNETs (hPITOs). Genetically engineered iPSC derived organoids were used to model the development of corticotroph PitNETs expressing USP48 (iPSCUSP48) or USP8 (iPSCUSP8) somatic mutations. Organoids were treated with the GR antagonist mifepristone or the GR modulator relacorilant with or without somatostatin receptor (SSTR) agonists pasireotide or octreotide. In iPSCUSP48 and iPSCUSP8 cultures, mifepristone induced a predominant expression of SSTR2 with a concomitant increase in ACTH secretion and tumor cell proliferation. Relacorilant predominantly induced SSTR5 expression and tumor cell apoptosis with minimal ACTH induction. Hedgehog signaling mediated the induction of SSTR2 and SSTR5 in response to mifepristone and relacorilant. Relacorilant sensitized PitNET organoid responsiveness to pasireotide. Therefore, our study identified the potential therapeutic use of relacorilant in combination with somatostatin analogs and demonstrated the advantages of relacorilant over mifepristone, supporting its further development for use in the treatment of Cushing's disease patients.

Chronic administration of glucocorticoid receptor ligands increases anxiety-like behavior and selectively increase serotonin transporters in the ventral hippocampus

Organic cation transporter-3 (OCT3) is widely distributed in the brain with high expression in portions of the stress axis. These high capacity, polyspecific transporters function in monoamine clearance and are sensitive to the stress hormone corticosterone. In rats, withdrawal from chronic amphetamine increases OCT3 expression in specific limbic brain regions involved anxiety and stress responses, including the ventral hippocampus, central nucleus of amygdala (CeA) and dorsomedial hypothalamus. (DMH). Previous studies show that glucocorticoid receptor (GR) agonists increase OCT1 mRNA and OCT2 mRNA expression in non-neural tissues. Thus, we hypothesized that corticosterone increases OCT3 expression in the brain by activating GRs. Male Sprague-Dawley rats were pre-treated daily with the GR antagonist mifepristone (20 mg/kg; sc.) or vehicle followed 45 min later by injections of corticosterone or vehicle for 2 weeks. Corticosterone treatment significantly increased OCT3 expression in the ventral hippocampus and increased anxiety-like behavior. However, these effects were not blocked by mifepristone. Interestingly, treatment with mifepristone alone reduced plasma corticosterone levels and increased serotonin transporter and GR expression in the ventral hippocampus but did not significantly affect OCT3 expression or behavior. No treatment effects on OCT3, serotonin transporter or GR expression were observed in the DMH, CeA or dorsal hippocampus. Our findings suggest that corticosterone increases OCT3 expression in the ventral hippocampus by a mechanism independent of GRs, and that mifepristone and corticosterone can act in an independent manner to affect HPA axis-related physiological and behavioral parameters.

PMON165 Favorable Liver Safety Profile of the Selective Glucocorticoid Receptor Modulator Relacorilant in Healthy and Hepatically Impaired Adults and in Patients with Cushing Syndrome

Abstract Background Relacorilant is a highly selective glucocorticoid receptor (GR) modulator in development for the treatment of endogenous Cushing syndrome (CS). Unlike the FDA-approved GR antagonist mifepristone, relacorilant lacks affinity for the progesterone and other receptors. In a phase 2 study in patients with CS (NCT02804750, Pivonello et al, 2021), relacorilant provided clinically meaningful changes in a number of cortisol-excess-related comorbidities, including hypertension and hyperglycemia, without undesirable antiprogesterone effects or drug-induced hypokalemia. Currently, 4 clinical studies of relacorilant in patients with CS are ongoing: GRACE (NCT03697109), a phase 3 trial enrolling patients with endogenous CS of all etiologies; GRADIENT (NCT04308590), a phase 3 trial focusing on hypercortisolism due to adrenal adenomas or hyperplasia; a phase 2/3 long-term extension study (NCT03604198); and a phase 1b study in patients with adrenocortical carcinoma associated with glucocorticoid excess (NCT04373265). Here, we report safety results and liver function test (LFT) changes from open-label phase 1 and 2 studies of relacorilant in healthy and hepatically impaired adults and in adult patients with CS. Methods In a special population study, 9 subjects with moderate hepatic impairment (Child-Pugh Class B) and 9 matched controls with normal hepatic function received relacorilant (300 mg QD) for 10 days. In a phase 1 fixed-sequence drug-drug interaction study (NCT03512548), 28 healthy subjects received relacorilant (300 mg QD) for 10 days followed by 10 days of relacorilant (300 mg QD) combined with itraconazole (200 mg QD). Thirty-five patients with CS received relacorilant (100–400 mg QD) for up to 16 weeks in the phase 2 study. Results While relacorilant is eliminated primarily through the hepatic route, no apparent difference in relacorilant pharmacokinetics in subjects with moderate hepatic impairment vs matched controls was observed, with relacorilant exposures (as measured by area under the concentration-time curve [AUC] and maximum concentration [Cmax]) largely overlapping across both groups. In addition, reductions in LFTs were observed in this study. In healthy adults treated with relacorilant followed by relacorilant + itraconazole (an agent with reported liver toxicity), a similar trend toward reduced LFTs was seen throughout the study. In the phase 2 study in patients with CS, reductions in LFTs were also observed, including normalization of LFTs in some patients with abnormal values at baseline. Conclusions These results suggest that relacorilant has a favorable liver safety profile that includes a trend toward improved LFTs in volunteers and patients with normal and abnormal liver function. The findings of the hepatic impairment study support the use of relacorilant without dose adjustment in patients with moderate hepatic impairment. Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.

Peripheral glucocorticoid receptor antagonism by relacorilant with modest HPA axis disinhibition.

Glucocorticoid stress hormones are produced in response to hypothalamic-pituitary-adrenal (HPA) axis activation. Glucocorticoids are essential for physiology and exert numerous actions via binding to the glucocorticoid receptor (GR). Relacorilant is a highly selective GR antagonist currently undergoing a phase 3 clinical evaluation for the treatment of endogenous Cushing's syndrome. It was found that increases in serum adrenocorticotropic hormone (ACTH) and cortisol concentrations after relacorilant treatment were substantially less than the increases typically observed with mifepristone, but it is unclear what underlies these differences. In this study, we set out to further preclinically characterize relacorilant in comparison to the classical but non-selective GR antagonist mifepristone. In human HEK-293 cells, relacorilant potently antagonized dexamethasone- and cortisol-induced GR signaling, and in human peripheral blood mononuclear cells, relacorilant largely prevented the anti-inflammatory effects of dexamethasone. In mice, relacorilant treatment prevented hyperinsulinemia and immunosuppression caused by increased corticosterone exposure. Relacorilant treatment reduced the expression of classical GR target genes in peripheral tissues but not in the brain. In mice, relacorilant induced a modest disinhibition of the HPA axis as compared to mifepristone. In line with this, in mouse pituitary cells, relacorilant was generally less potent than mifepristone in regulating Pomc mRNA and ACTH release. This contrast between relacorilant and mifepristone is possibly due to the distinct transcriptional coregulator recruitment by the GR. In conclusion, relacorilant is thus an efficacious peripheral GR antagonist in mice with only modest disinhibition of the HPA axis, and the distinct properties of relacorilant endorse the potential of selective GR antagonist treatment for endogenous Cushing's syndrome.

RF01 | PMON168 Hedgehog-Induced Somatostatin Receptor Expression is Inhibited by the Activation of the Glucocorticoid Receptor Signaling Pathway in Human Pituitary Adenoma Organoids

Abstract Background Cushing's disease (CD) is an endocrine disorder caused by an ACTH-secreting pituitary adenoma that is associated with increased morbidity and mortality. Because somatostatin inhibits pituitary ACTH secretion, the somatostatin receptor subtypes (SSTR) 2 and 5 have been targets of medical therapies for CD. The SSTR5 is most consistently and strongly expressed in corticotroph pituitary tumors but the SSTR dynamics in CD during treatment and responses to cortisol level changes are far from being understood. Studies in adult stomach demonstrated that the Hedgehog (Hh) signaling pathway is critical for the regulation of somatostatin and SSTR signaling. While Hh signaling is known to be essential during the embryonic development of the pituitary and in the adult gland, the mechanism by which Hh signaling regulates SSTR expression in CD is unknown. Hypothesis Activation of glucocorticoid receptor (NR3C1, GR) results in the inhibition of Hh transcription factor GLI1 leading to reduced SSTR expression. Methods We developed a human pituitary adenoma organoid model (hPITOiPSC) from induced pluripotent stem cells treated with the glucocorticoid receptor (GR) antagonist mifepristone, and co-treated them with or without SSTR agonists pasireotide or octreotide. In a separate series of experiments, the role of Hh transcription factor GLI1 was identified using hPITOiPSC treated with mifepristone with or without GANT61 (GLI inhibitor) or ketoconazole (Smoothened, SMO inhibitor). CRISPR-Cas9 gene editing of hPITOiPSC pituitary organoids were used to model the development of pituitary corticotroph adenomas in the presence of BRAF, USP48 and USP8 mutations. Human pituitary adenoma tissue harvested fresh during pituitary surgery was used to generate pituitary corticotroph subtype adenoma organoids (hPITOs). Dose responses using standard of care drugs were performed using the hPITOs. Results 1) At baseline SSTR2 was abundantly expressed within hPITOiPSC. Mifepristone induced significant increases in ACTH secretion and POMC expression that correlated with induced SSTR2 and 5. Mifepristone-induced SSTR2 and 5 expression was significantly inhibited in the presence of GANT61, whereas SMO inhibitor ketoconazole had a minimal effect on mifepristone-induced SSTR2/5, POMC expression and ACTH secretion. Dexamethasone alone significantly inhibited both GLI1 and SSTR2 and 5. 2) While pituitary organoids that were differentiated from control iPSCs (iPSCCtrl) expressed all major hormone-producing cell lineages, there was a significant increase in ACTH expression with loss of PIT1, GH, FSH, LH and PRL in iPCSs expressing mutated BRAF, USP48 and USP8. Organoids expressing a mutation in BRAF had significantly higher SSTR2 expression levels compared to controls. 3) HPITOs generated from pituitary adenomas of CD patients showed differential organoid responses to pasireotide, mifepristone, and ketoconazole. Conclusion Within pituitary adenomas, the SSTR is a transcriptional target of Gli1, and this response is blocked by the activation of the GR. These data form the basis of combination therapy for CD with mifepristone and pasireotide. Presentation: Saturday, June 11, 2022 1:37 p.m. - 1:42 p.m., Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.

Photoreceptor and vision protective effects of astragaloside IV in mice model with light-evoked retinal damage

Cone cell-enriched macular degeneration is a major cause of functional vision deterioration. Astragaloside IV (Asg IV), an active triterpenoid saponin component with properties of anti-oxidative and anti-apoptotic damage, which benefit retinal tissue and capillaries. But, the nutraceutical therapeutic effects on functional vision have not been fully evaluated. In this study, mice were administrated to high-intensity light exposure after either receiving a vehicle or Asg IV (0.05, 0.5, and 50 mg/kg, BID). During this time, their spatial-visual performance, visual acuity (VA), and visual contrast sensitivity function (VCSF) were measured using the behavioral optomotor reflex method. Morphological changes in the retina were determined by histological examination. High energy light-evoked visual damage was confirmed by the loss in structural tissue integrity in the retina accompanied by a decline in both VA and VCSF, whereas the retina tissue exhibited loss of cone cell density and severe cone-specific opsin misplacement. In contrast, prophylactic oral Asg IV (0.5, and 50 mg/kg, BID)-treated exerted protective and improvement effects against light-evoked deterioration of functional vision. Asg IV treatment significantly improved the thresholds of VA and VCSF. In particular, Asg IV (50 mg/kg, BID) modulated and increased the survival of the photoreceptors, especially the cone cells, which targeted and enhanced the high spatial frequency-characterized VCSF. In contrast, the cellular protective effect of Asg IV (50 mg/kg, BID) on photoreceptors was significantly reversed by synchronous injection of a glucocorticoid receptor (GR) antagonist (mifepristone). This study demonstrated the major neuroretina-protective effect and functional vision-improving effect of Asg IV in vivo.

Protective effects of glucocorticoid receptor antagonist Mifepristone on fear memory extinction impairment in a rat model of PTSD

IntroductionCentral glucocorticoid receptor (GR) has been found to play an important role in the interpretation of cognitive abnormalities of posttraumatic stress disorder (PTSD), particularly focused on the extinction failure of fear memory. Potential of using GR antagonist as a pharmacological agent to prevent PTSD-related fear memory disruption is worth investigating.ObjectivesWe aimed to examine whether GR antagonist Mifepristone (RU486) administered before single prolonged stress (SPS) can prevent rats from fear memory extinction impairment.MethodsIn the present study, SPS was employed in rats to induce a rodent model of PTSD. 60 minutes before SPS, RU486 (20 mg/kg) was administered by intraperitoneal injection. Seven days after SPS, rats received a protocol of behavioral testing to measure their abilities of specific fear memory (by a cue-dependent fear conditioning paradigm) and nonspecific spatial memory (by T-maze). Neurochemically, we measured plasma corticosterone with or without dexamethasone suppression, activation ratio of GR and levels of norepinephrine, dopamine, and serotonin in amygdala, paraventricular nucleus, dorsal and ventral hippocampus.ResultsOur results found that RU486 exerted protective effects on SPS-induced fear extinction impairment. Corticosterone of SPS-RU486 rats was less suppressed by dexamethasone. GR became less activated in dorsal hippocampus of SPS-RU486 rats.ConclusionsThe findings supported the utility of GR antagonism in preventing the development of PTSD.DisclosureNo significant relationships.

Stress axis programming generates long-term effects on cognitive abilities in a cooperative breeder.

The ability to flexibly adjust behaviour to social and non-social challenges is important for successfully navigating variable environments. Social competence, i.e. adaptive behavioural flexibility in the social domain, allows individuals to optimize their expression of social behaviour. Behavioural flexibility outside the social domain aids in coping with ecological challenges. However, it is unknown if social and non-social behavioural flexibility share common underlying cognitive mechanisms. Support for such shared mechanism would be provided if the same neural mechanisms in the brain affected social and non-social behavioural flexibility similarly. We used individuals of the cooperatively breeding fish Neolamprologus pulcher that had undergone early-life programming of the hypothalamic–pituitary–interrenal axis by exposure to (i) cortisol, (ii) the glucocorticoid receptor antagonist mifepristone, or (iii) control treatments, and where effects of stress-axis programming on social flexibility occurred. One year after the treatments, adults learned a colour discrimination task and subsequently, a reversal-learning task testing for behavioural flexibility. Early-life mifepristone treatment marginally enhanced learning performance, whereas cortisol treatment significantly reduced behavioural flexibility. Thus, early-life cortisol treatment reduced both social and non-social behavioural flexibility, suggesting a shared cognitive basis of behavioural flexibility. Further our findings imply that early-life stress programming affects the ability of organisms to flexibly cope with environmental stressors.