Osilodrostat para el síndrome de Cushing endógeno / Osilodrostat for Cushing's syndrome endogenous

INTRODUCCIÓN: El síndrome de Cushing endógeno es un trastorno endocrino severo y multiorgánico causado por la hiperproducción de cortisol por parte de las glándulas adrenales. Las manifestaciones clínicas más habituales incluyen síndrome metabólico, resistencia a la insulina, obesidad visceral, diabetes, hipertensión, dislipemia, osteoporosis, cambios en la piel, daños en el sistema inmune (aumento del riesgo de infecciones), trastornos neuropsiquiátricos, hipogonadismo, desórdenes menstruales en mujeres y un estado de hipercoagulabilidad. Debido a las complicaciones metabólicas y cardiovasculares asociadas, los pacientes mal controlados o sin tratamiento presentan un incremento en la mortalidad. El manejo terapéutico puede incluir cirugía hipofisaria o suprarrenal, tratamiento médico y/o radioterapia. La cirugía es la terapia de elección, cualquiera que sea la causa de base, y que consiste en la resección quirúrgica del tumor subyacente, excepto en los pacientes que presenten un carcinoma suprarrenal metastásico o cuya enfermedad sea de origen desconocido. La segunda línea terapéutica es la irradiación sobre la hipófisis, la suprarrenalectomía bilateral y el tratamiento farmacológico (inhibidores de la enzima adrenal, etomidato, antagonistas de los receptores de glucocorticoides). Algunos de los fármacos mencionados no tienen autorización de comercialización del país aún. TECNOLOGÍA: Osilodrostat (Isturisa®) es un inhibidor de la 11ß-hidroxilasa (CYP11B1), enzima responsable de la etapa final de la biosíntesis de cortisol en la glándula suprarrenal. OBJETIVO: El objetivo del presente informe es evaluar rápidamente los parámetros de eficacia, seguridad, costos y recomendaciones disponibles acerca del empleo de osilodrostat para el tratamiento de adultos con síndrome de Cushing endógeno. MÉTODOS: Se realizó una búsqueda bibliográfica en las principales bases de datos tales como PUBMED, LILACS, BRISA, COCHRANE, SCIELO, EMBASE, TRIPDATABASE como así también en sociedades científicas, agencias reguladoras, financiadores de salud y agencias de evaluación de tecnologías sanitarias. Se priorizó la inclusión de revisiones sistemáticas, ensayos clínicos controlados aleatorizados, evaluación de tecnología sanitaria y guías de práctica clínica de alta calidad metodológica. En PubMed se utilizó la estrategia de búsqueda que se detalla en el Anexo I. La fecha de búsqueda de información fue hasta el 19 de octubre de 2022. Para la búsqueda en Pubmed se utilizó la siguiente estrategia de búsqueda: (osilodrostat [Supplementary Concept] OR Isturisa [tiab] OR LCI699 [tiab]) AND ("Cushing Syndrome" [MESH] OR "Cushing Syndrome" [tiab] OR Hypercortisolism [tiab]). RECOMENDACIONES: No se hallaron guías de práctica clínica actualizadas en Argentina que mencionen la tecnología en la indicación evaluada. Un consenso de expertos internacional publicado en 2021 menciona la utilización de osilodrostat como una opción terapéutica junto con otros inhibidores de la esteroidogénesis como el ketoconzol, etomidato, mitotano, metirapona, (estos últimos tres no se encuentran disponibles en nuestro país) o pasireotida, mifepristona. En España se ha emitido resolución de financiación de osilodrostat para el tratamiento del síndrome de Cushing endógeno en adultos, limitando su utilización al tratamiento tras fracaso o contraindicación a otras alternativas farmacológicas. No se hallaron documentos referentes al uso de osilodrostat en la indicación especificada por parte de otras entidades de evaluación de tecnologías sanitarias a nivel mundial como Instituto Nacional para la Excelencia en Salud y Atención (del inglés, National Institute for Health and Care Excellence) de Reino Unido y la Agencia Canadiense de Medicamentos y Tecnologías en Salud (del inglés, Canadian Agency for Drugs & Technologies in Health). CONCLUSIONES: La evidencia que sustenta la aprobación de comercialización de osilodrostat por parte de las agencias regulatorias relevadas para el tratamiento de personas adultas con síndrome de Cushing endógeno con enfermedad recurrente o persistente, se basa en ensayos clínicos frente a placebo con un bajo número de pacientes y corto seguimiento. El cuerpo de la evidencia mostraría que el uso de osilodrostat podría normalizar los valores de cortisol libre urinario y mejorar la calidad de vida de forma importante frente a placebo al mediano plazo. Sin embargo, estos estudios mostrarían una elevada incidencia de eventos adversos y de discontinuación del tratamiento por eventos adversos. La seguridad y eficacia frente a otras opciones terapéuticas disponibles no pudo ser establecida debido a que solo se hallaron estudios que comparan osilodrostat contra placebo. Las agencias regulatorias relevadas han autorizado recientemente la comercialización, junto con la designación de medicamento huérfano y vigilancia adicional. No se hallaron guías de práctica clínica actualizadas en Argentina que mencionen la tecnología en la indicación evaluada, mientras que una recomendación internacional la menciona como una opción entre otras alternativas. Agencias de Reino Unido y Canadá no hay evaluado su cobertura hasta el momento, y en España su cobertura se haya limitada al tratamiento del síndrome de Cushing endógeno que ha fracasado o tiene contraindicación a otras alternativas farmacológicas. No se hallaron evaluaciones económicas publicadas, aunque el costo del fármaco es muy elevado.

Suppressing the Morning Cortisol Rise After Memory Reactivation at 4 A.M. enhances Episodic Memory Reconsolidation in Humans.

Evidence from animal and human research shows that established memories can undergo changes after reactivation through a process called reconsolidation. Alterations of the level of the stress hormone cortisol may provide a way to manipulate reconsolidation in humans. Here, in a double-blind, within-subject design, we reactivated a 3-d-old memory at 3:55 A.M. in sixteen men and four women, immediately followed by oral administration of metyrapone versus placebo, to examine whether metyrapone-induced suppression of the morning cortisol rise may influence reconsolidation processes during and after early morning sleep. Crucially, reactivation followed by cortisol suppression versus placebo resulted in enhanced memory for the reactivated episode tested 4 d after reactivation. This enhancement after cortisol suppression was specific for the reactivated episode versus a non-reactivated episode. These findings suggest that when reactivation of memories is immediately followed by suppression of cortisol levels during early morning sleep in humans, reconsolidation processes change in a way that leads to the strengthening of episodic memory traces.SIGNIFICANCE STATEMENT How can we change formed memories? Modulation of established memories has been long debated in cognitive neuroscience and remains a crucial question to address for basic and clinical research. Stress-hormone cortisol and sleep are strong candidates for changing consolidated memories. In this double-blind, placebo-controlled, within-subject pharmacological study, we investigate the role of cortisol on the modulation of reconsolidation of episodic memories in humans. Blocking cortisol synthesis (3 g metyrapone) during early morning sleep boosts memory for a reactivated but not for a non-reactivated story. This finding contributes to our understanding of the modulatory role of cortisol and its circadian variability on reconsolidation, and moreover can critically inform clinical interventions for the case of memory dysfunctions, and trauma and stress-related disorders.

Osilodrostat: First Approval.

Osilodrostat (Isturisa®) is an orally available small molecule 11ß-hydroxylase inhibitor that is being developed by Novartis for the treatment of Cushing's disease. Based on results from a pivotal phase III trial, osilodrostat was approved in the EU for use in the treatment of endogenous Cushing's syndrome in adults and is under regulatory review in the USA for the treatment of Cushing's disease. This article summarises the milestones in the development of osilodrostat leading to this first approval.

Physiological and drug-induced changes in blood levels of adrenal steroids and their precursors in cynomolgus monkeys: An application of steroid profiling by LC-MS/MS for evaluation of the adrenal toxicity.

The adrenal gland is the most common toxicological target of drugs within the endocrine system, and inhibition of adrenal steroidogenesis can be fatal in humans. However, methods to evaluate the adrenal toxicity are limited. The aim of the present study was to verify the usefulness of simultaneous measurement of blood levels of multiple adrenal steroids, including precursors, as a method to evaluate drug effects on adrenal steroidogenesis in cynomolgus monkeys. With this aim, physiological and drug-induced changes in blood levels of adrenal steroids, including cortisol, aldosterone, androgen, and their precursors were examined. First, for physiological changes, intraday and interday changes in blood steroid levels were examined in male and female cynomolgus monkeys. The animals showed circadian changes in steroid levels that are similar to those in humans, while interday changes were relatively small in males. Next, using males, changes in blood steroid levels induced by ketoconazole and metyrapone were examined, which suppress adrenal steroidogenesis via inhibition of CYP enzymes. Consistent with rats and humans, both ketoconazole and metyrapone increased the deoxycorticosterone and deoxycortisol levels, probably via CYP11B1 inhibition, and the increase was observed earlier and with greater dynamic range than the changes in cortisol level. Changes in other steroid levels reflecting the drug mechanisms were also observed. In conclusion, this study showed that in cynomolgus monkeys, simultaneous measurement of blood levels of adrenal steroids, including precursors, can be a valuable method to sensitively evaluate drug effects on adrenal steroidogenesis and to investigate the underlying mechanisms.

Osilodrostat Is a Potential Novel Steroidogenesis Inhibitor for the Treatment of Cushing Syndrome: An In Vitro Study.

CONTEXT: Metyrapone and ketoconazole, frequently used steroidogenesis inhibitors for treatment of Cushing syndrome, can be associated with side effects and limited efficacy. Osilodrostat is a CYP11B1 and CYP11B2 inhibitor, with unknown effects on other steroidogenic enzymes. OBJECTIVE: To compare the effects of osilodrostat, metyrapone, and ketoconazole on adrenal steroidogenesis, and pituitary adenoma cells in vitro. METHODS: HAC15 cells, 17 primary human adrenocortical cell cultures, and pituitary adenoma cells were incubated with osilodrostat, metyrapone, or ketoconazole (0.01 to 10 µM). Cortisol and ACTH were measured using chemiluminescence immunoassays, and steroid profiles by liquid chromatography-mass spectrometry. RESULTS: In HAC15 cells, osilodrostat inhibited cortisol production more potently (IC50: 0.035 µM) than metyrapone (0.068 µM; P < 0.0001), and ketoconazole (0.621 µM; P < 0.0001). IC50 values of osilodrostat and metyrapone for basal cortisol production varied with a 25- and 18-fold difference, respectively, with comparable potency. Aldosterone production was inhibited more potently by osilodrostat vs metyrapone and ketoconazole. Osilodrostat and metyrapone treatment resulted in strong inhibition of corticosterone and cortisol, 11-deoxycortisol accumulation, and modest effects on adrenal androgens. No pituitary-directed effects of osilodrostat were observed. CONCLUSIONS: Under our study conditions, osilodrostat is a potent cortisol production inhibitor in human adrenocortical cells, comparable with metyrapone. All steroidogenesis inhibitors showed large variability in sensitivity between primary adrenocortical cultures. Osilodrostat might inhibit CYP11B1 and CYP11B2, in some conditions to a lesser extent CYP17A1 activity, and a proximal step in the steroidogenesis. Osilodrostat is a promising treatment option for Cushing syndrome, and in vivo differences with metyrapone are potentially driven by pharmacokinetic differences.

Identification of the fungicide epoxiconazole by virtual screening and biological assessment as inhibitor of human 11ß-hydroxylase and aldosterone synthase.

Humans are constantly exposed to a multitude of environmental chemicals that may disturb endocrine functions. It is crucial to identify such chemicals and uncover their mode-of-action to avoid adverse health effects. 11ß-hydroxylase (CYP11B1) and aldosterone synthase (CYP11B2) catalyze the formation of cortisol and aldosterone, respectively, in the adrenal cortex. Disruption of their synthesis by exogenous chemicals can contribute to cardio-metabolic diseases, chronic kidney disease, osteoporosis, and immune-related disorders. This study applied in silico screening and in vitro evaluation for the discovery of xenobiotics inhibiting CYP11B1 and CYP11B2. Several databases comprising environmentally relevant pollutants, chemicals in body care products, food additives and drugs were virtually screened using CYP11B1 and CYP11B2 pharmacophore models. A first round of biological testing used hamster cells overexpressing human CYP11B1 or CYP11B2 to analyze 25 selected virtual hits. Three compounds inhibited CYP11B1 and CYP11B2 with IC50 values below 3 µM. The most potent inhibitor was epoxiconazole (IC50 value of 623 nM for CYP11B1 and 113 nM for CYP11B2, respectively); flurprimidol and ancymidol were moderate inhibitors. In a second round, these three compounds were tested in human adrenal H295R cells endogenously expressing CYP11B1 and CYP11B2, confirming the potent inhibition by epoxiconazole and the more moderate effects by flurprimidol and ancymidol. Thus, the in silico screening, prioritization of chemicals for initial biological tests and use of H295R cells to provide initial mechanistic information is a promising strategy to identify potential endocrine disruptors inhibiting corticosteroid synthesis. A critical assessment of human exposure levels and in vivo evaluation of potential corticosteroid disrupting effects by epoxiconazole is required.

Benzophenones as xanthone-open model CYP11B1 inhibitors potentially useful for promoting wound healing.

The inhibition of steroidogenic cytochrome P450 enzymes has been shown to play a central role in the management of life-threatening diseases such as cancer, and indeed potent inhibitors of CYP19 (aromatase) and CYP17 (17α hydroxylase/17,20 lyase) are currently used for the treatment of breast, ovarian and prostate cancer. In the last few decades CYP11B1 (11-ß-hydroxylase) and CYP11B2 (aldosterone synthase), key enzymes in the biosynthesis of cortisol and aldosterone, respectively, have been also investigated as targets for the identification of new potent and selective agents for the treatment of Cushing's syndrome, impaired wound healing and cardiovascular diseases. In an effort to improve activity and synthetic feasibility of our different series of xanthone-based CYP11B1 and CYP11B2 inhibitors, a small series of imidazolylmethylbenzophenone-based compounds, previously reported as CYP19 inhibitors, was also tested on these new targets, in order to explore the role of a more flexible scaffold for the inhibition of CYP11B1 and -B2 isoforms. Compound 3 proved to be very potent and selective towards CYP11B1, and was thus selected for further optimization via appropriate decoration of the scaffold, leading to new potent 4'-substituted derivatives. In this second series, 4 and 8, carrying a methoxy group and a phenyl ring, respectively, proved to be low-nanomolar inhibitors of CYP11B1, despite a slight decrease in selectivity against CYP11B2. Moreover, unlike the benzophenones of the first series, the 4'-substituted derivatives also proved to be selective for CYP11B enzymes, showing very weak inhibition of CYP19 and CYP17. Notably, the promising result of a preliminary scratch test performed on compound 8 confirmed the potential of this compound as a wound-healing promoter.

Hypokalaemic metabolic alkalosis, hypertension and diabetes: what is the link.

Two years after diagnosis of a metastatic neuroendocrine gastrin-secreting tumour and after several cycles of chemotherapy and peptide receptor radionuclide therapy, a 56-year-old woman presented with hypokalaemic metabolic alkalosis, hypertension, leg oedema and new-onset diabetes mellitus. Further investigations revealed renal potassium loss confirmed by a transtubular potassium gradient of 16, fully suppressed serum aldosterone, but instead highly elevated blood levels of morning cortisol and adrenocorticotropic hormone as well as increased urinary excretion of glucocorticoid and mineralocorticoid metabolites. Ruling out other causes, paraneoplastic hypercortisolism was diagnosed. Pharmacological inhibition of the steroid 11ß-hydroxylase with metyrapone resulted in complete resolution of metabolic alkalosis, hypokalaemia, hypertension, hyperglycaemia and leg oedema within 1 week.

A steady state system for in vitro evaluation of steroidogenic pathway dynamics: Application for CYP11B1, CYP11B2 and CYP17 inhibitors.

Disorders featuring dysregulated adrenal steroidogenesis, such as primary aldosteronism, can benefit from targeted therapies. The aldosterone and cortisol producing enzymes, aldosterone synthase (CYP11B2) and 11-beta-hydroxylase (CYP11B1), share 93% homology requiring selective drugs for pharmacological treatment. Herein, we introduce an effective in vitro assay for evaluation of steroidogenic enzyme kinetics based on intracellular flux calculations. H295RA cells were cultured in chambers under constant medium flow. Four hourly samples were collected (control samples), followed by collections over an additional four hours after treatment with fadrozole (10 nM), metyrapone (10 µM), SI_191 (5 nM), a novel CYP11B2 inhibitor or SI_254 (100 nM), a newly synthesized 17-alpha-hydroxylase/17,20-lyase inhibitor. Mass spectrometric measurements of multiple steroids combined with linear system computational modeling facilitated calculation of intracellular fluxes and changes in rate constants at different steroidogenic pathway steps, enabling selectivity of drugs for those steps to be evaluated. While treatment with fadrozole, metyrapone and SI_191 all reduced fluxes of aldosterone, corticosterone and cortisol production, treatment with SI_254 led to increased flux through the mineralocorticoid pathway and reduced production of steroids downstream of 17-alpha-hydroxylase/17,20-lyase. Drug-induced decreases in rate constants revealed higher selectivity of SI_191 compared to other drugs for CYP11B2 over CYP11B1, this reflecting additional inhibitory actions of SI_191 on catalytic steps of CYP11B2 downstream from the initial 11-beta-hydroxlase step. By culturing cells under perfusion the described system provides a realistic model for simple and rapid calculations of intracellular fluxes and changes in rate constants, thereby offering a robust procedure for investigating drug or other effects at specific steps of steroidogenesis.

Structure of human cortisol-producing cytochrome P450 11B1 bound to the breast cancer drug fadrozole provides insights for drug design.

Human cytochrome P450 11B1 (CYP11B1) is responsible for the final step generating the steroid hormone cortisol, which controls stress and immune responses and glucose homeostasis. CYP11B1 is a promising drug target to manage Cushing's disease, a disorder arising from excessive cortisol production. However, the design of selective inhibitors has been hampered because structural information for CYP11B1 is unavailable and the enzyme has high amino acid sequence identity (93%) to a closely related enzyme, the aldosterone-producing CYP11B2. Here we report the X-ray crystal structure of human CYP11B1 (at 2.1 Å resolution) in complex with fadrozole, a racemic compound normally used to treat breast cancer by inhibiting estrogen-producing CYP19A1. Comparison of fadrozole-bound CYP11B1 with fadrozole-bound CYP11B2 revealed that despite conservation of the active-site residues, the overall structures and active sites had structural rearrangements consistent with distinct protein functions and inhibition. Whereas fadrozole binds to both CYP11B enzymes by coordinating the heme iron, CYP11B2 binds to the R enantiomer of fadrozole, and CYP11B1 binds to the S enantiomer, each with distinct orientations and interactions. These results provide insights into the cross-reactivity of drugs across multiple steroidogenic cytochrome P450 enzymes, provide a structural basis for understanding human steroidogenesis, and pave the way for the design of more selective inhibitors of each human CYP11B enzyme.

Drug design strategies for Cushing's syndrome.

INTRODUCTION: Cushing's syndrome (CS) is a metabolic disorder caused by chronic hypercortisolism. CS is associated with cardiovascular, metabolic, skeletal and psychological dysfunctions and can be fatal if left untreated. The first-line treatment for all forms of CS is a surgery. However, medical therapy has to be chosen if surgical resection is not an option or is deemed ineffective. Currently available therapeutics are either not selective and have side effects or are only available as an injection (pasireotide). Areas covered: The authors discuss the recent drug developments for the medical treatment of CS through two validated molecular targets. Specifically, the authors look at selective inhibitors of CYP11B1 that reduce cortisol production by inhibiting steroid 11beta-hydroxylase and glucocorticoid receptor (GR) antagonists that interrupt cortisol-mediating transcriptional regulation of related genes. Expert opinion: Patients with CS have limited treatment options; indeed, there is an unmet need for new compounds that target CYP11B1 selectively versus several steroidogenic enzymes and/or GR-signaling pathways. The complexity of steroid biosynthesis and signaling requires the application of structure-based drug discovery techniques that use molecular targets and highly similar off-targets. Significant differences in steroidogenesis between humans and other species necessitates caution over the choice of in vivo model for the preclinical evaluation of future potential compounds.

Metyrapone treatment in Cushing's syndrome: a real-life study.

INTRODUCTION AND AIM: Medical treatment is increasingly used in patients with Cushing's syndrome (CS). Metyrapone (MET) is an inhibitor of 11ß-hydroxylase: retrospective studies reported a decrease of cortisol secretion in 50% of cases. We evaluated the effectiveness of MET in an observational study, considering the normalization of urinary-free cortisol (UFC) and late-night salivary cortisol (LNSC) levels. MATERIALS AND METHODS: We enrolled 31 patients with CS, treated with MET for at least 1 month (16 for primary treatment and 15 after surgical failure). A planned dose-titration regimen considering baseline UFC levels was adopted; MET dose was uptitrated until UFC normalization, surgery, or side effect occurrence. UFC and LNSC levels were routinely measured by liquid chromatography-tandem mass spectrometry. RESULTS: Patients were treated with a median dose of 1000 mg for 9 months. UFC and LNSC decreased quickly after the first month of treatment (-67 and -57% from baseline), with sustained UFC normalization up to 12 and 24 months (in 13 and 6 patients, respectively). UFC and LNSC normalized later (after 3-6 months) in patients with severe hypercortisolism (>5-fold baseline UFC). Regarding the last visit, 70 and 37% of patients normalized UFC and LNSC, respectively. Body weight reduction (-4 kg) was observed after UFC normalization. Severe side effects were not reported, half of the female patients complained of hirsutism, and blood pressure was not increased. CONCLUSIONS: MET therapy is a rapid-onset, long-term effective, and safe medical treatment in CS patients, achieving UFC normalization (in 70% of patients) more than cortisol rhythm recovery (in 37% of subjects).

CYP11B1 has no role in mitotane action and metabolism in adrenocortical carcinoma cells.

Mitotane is the reference drug for adrenocortical carcinoma (ACC) and the metabolic activation of the drug is considered as essential for its activity. The aim of this study was to assess the role of CYP11B1 on mitotane action and metabolism in H295R ACC cells to understand whether this enzyme may influence mitotane action. The simultaneous incubation with mitotane and metyrapone, an adrenolytic molecule targeting 11-beta-hydroxylase, did not influence mitotane-mediated cytotoxic effect and metabolism in H295R ACC cells. CYP11B1 silencing confirmed the lack of a significant metyrapone effect on mitotane action. The present findings do not support the view that CYP11B1 catalyzes a crucial step in the metabolic activation of mitotane and that CYP11B1 confers the adrenal specificity to mitotane.

Accelerated skin wound healing by selective 11ß-Hydroxylase (CYP11B1) inhibitors.

Previous studies have shown that inhibition of cortisol biosynthesis in skin leads to accelerated wound healing. Here, pyridylmethyl pyridine type 11ß-hydroxylase (CYP11B1) inhibitors were optimized for topical application to avoid systemic side effects. The resulting very potent, non-toxic CYP11B1 inhibitor 14 (IC50 = 0.8 nM) exhibited good selectivity over 11ß-HSD1, CYP17A1 and CYP19A1. The compound showed high stability toward human plasma (t1/2= > 150 min, as a substitute for wound fluid) and low stability toward HLS9 (t1/2 = 19 min) for rapid metabolic clearance after absorption. Compound 14 was able to accelerate wound healing in human skin.

Drifting of heme-coordinating group in imidazolylmethylxanthones leading to improved selective inhibition of CYP11B1.

An abnormal increase in glucocorticoid levels is responsible for pathological disorders affecting different organs and systems, and the selective inhibition of appropriate steroidogenic enzymes represents a validated strategy to restore their physiological levels. In continuing our studies on CYP11B inhibitors, in this paper a small series of 6-substituted 3-imidazolylmethylxanthones was designed and synthesized, according to the data acquired from previously reported series of derivatives and from a purposely-performed docking study. The new compounds proved to be potent inhibitors of CYP11B isoforms, being effective on CYP11B1 in the low nanomolar range and improving selectivity with respect to CYP11B2, compared to previously reported related compounds. These data further confirmed that a suitable mutual arrangement of the imidazolylmethyl pharmacophore and a properly selected substituent on the xanthone core allows a fine tuning of the activity towards the different CYPs and further corroborate the role of the xanthone scaffold as a privileged structure in this field.

Lead Optimization Generates CYP11B1 Inhibitors of Pyridylmethyl Isoxazole Type with Improved Pharmacological Profile for the Treatment of Cushing's Disease.

Cushing's disease, characterized by elevated plasma cortisol levels, can be controlled by inhibition of 11ß-hydroxylase (CYP11B1). The previously identified selective and potent CYP11B1 inhibitor 5-((5-methylpyridin-3-yl)methyl)-2-phenylpyridine Ref 7 (IC50= 2 nM) exhibited promutagenic potential as well as very low oral bioavailability in rats (F = 2%) and was therefore modified to overcome these drawbacks. Successful lead optimization resulted in similarly potent and selective 5-((5-methoxypyridin-3-yl)methyl)-3-phenylisoxazole 25 (IC50 = 2 nM, 14-fold selectivity over CYP11B2), exhibiting a superior pharmacological profile with no mutagenic potential. Furthermore, compound 25 inhibited rat CYP11B1 (IC50 = 2 µM) and showed a high oral bioavailability (F = 50%) and sufficient plasma concentrations in rats, providing an excellent starting point for a proof-of-principle study.

Discovery of indazole aldosterone synthase (CYP11B2) inhibitors as potential treatments for hypertension.

We report the discovery and hit-to-lead optimization of a structurally novel indazole series of CYP11B2 inhibitors. Benchmark compound 34 from this series displays potent inhibition of CYP11B2, high selectivity versus related steroidal and hepatic CYP targets, and lead-like physical and pharmacokinetic properties. On the basis of these and other data, the indazole series was progressed to lead optimization for further refinement.

Prospective evaluation of a week one overnight metyrapone test with subsequent dynamic assessments of hypothalamic-pituitary-adrenal axis function after pituitary surgery.

OBJECTIVE: To determine whether an overnight metyrapone test (OMT) within the first week postpituitary surgery can definitively assess the hypothalamic-pituitary-adrenal (HPA) axis, compared with subsequent dynamic tests and glucocorticoid requirement at 6 months. DESIGN: Prospective study measuring morning cortisol levels on days 3 and 4 post-operatively, OMT day 5-7 and week 6, week 6 250 µg short Synacthen test (SST) and week 7 insulin tolerance test (ITT). PATIENTS AND MEASUREMENTS: Forty participants who underwent pituitary surgery at a single centre (Cushing's disease excluded) were followed for at least 6 months. 46% had pre-operative adrenal insufficiency. PRIMARY OUTCOME: week 1 OMT compared to glucocorticoid requirement at 6 months. SECONDARY OUTCOMES: the performance of ITT as a "definitive" test and all tests compared to glucocorticoid requirement at 6 months. RESULTS: Week 1 OMT showed concordance with ITT at week 7 of 78% and glucocorticoid requirement at 6 months of 81% respectively which was not significantly different from post-operative morning cortisol levels; 37% of participants with an abnormal OMT on day 6 had a normal OMT at week 6. All HPA axis tests showed similar concordance with glucocorticoid requirement at 6 months of 80%-85%. CONCLUSIONS: Overnight metyrapone test within the first week after pituitary surgery was no better than an early morning cortisol level at predicting glucocorticoid requirement at 6 months. OMT at week 6 demonstrated recovery of HPA axis in a substantial proportion of participants who failed earlier assessments; thus, definitive testing should be delayed until 6 weeks post-operatively.

Imidazopyridyl compounds as aldosterone synthase inhibitors.

The inhibition of aldosterone synthase (CYP11B2) may be an effective treatment of hypertension and heart failure, among other ailments. Previously reported benzimidazole CYP11B2 inhibitors led the way for bioisosteric imidazopyridines that are both potent and selective over CYP11B1.