Mifepristone: is there a place in the treatment of Cushing's disease?

A machine learning-integrated stepwise method to discover novel anti-obesity phytochemicals that antagonize the glucocorticoid receptor

As a type of stress hormone, glucocorticoids (GCs) affect numerous physiological pathways by binding to the glucocorticoid receptor (GR) and regulating the transcription of various genes. However, when GCs are dysregulated, the resulting hypercortisolism may contribute to various metabolic disorders, including obesity. Thus, attempts have been made to discover potent GR antagonists that can reverse excess-GC-related metabolic diseases. Phytochemicals are a collection of valuable bioactive compounds that are known for their wide variety of chemotypes. Recently, various computational methods have been developed to obtain active phytochemicals that can modulate desired target proteins. In this study, we developed a workflow comprising two consecutive quantitative structure-activity relationship-based machine learning models to discover novel GR-antagonizing phytochemicals. These two models collectively identified 65 phytochemicals that bind to and antagonize GR. Of these, nine commercially available phytochemicals were validated for GR-antagonist and anti-obesity activities. In particular, we confirmed that demethylzeylasteral, a phytochemical of the Tripterygium wilfordii Radix, exhibits potent anti-obesity activity in vitro through GR antagonism.

Management of patients with persistent or recurrent Cushing's disease after initial pituitary surgery

INTRODUCTION

Treatment options for persistent and recurrent Cushing's disease (CD) include an individualized approach for repeat surgery, medical treatment, radiation therapy (RT), and bilateral adrenalectomy (BLA).

AREAS COVERED

In this expert opinion perspective, the authors review the latest treatment(s) for persistent/recurrent CD. A PubMed search was undertaken (English articles through May 2020) and relevant articles discussed. Repeat pituitary surgery should be considered in most patients with proven hypercortisolism; there is potential for cure with low risk of major complications. Medical therapy is valuable either alone, while awaiting the effects of RT, or in preparation for BLA. Medical therapy includes steroidogenesis inhibitors, agents that act at the pituitary or glucocorticoid receptor level, and novel agents in development. Radiation therapy has been used successfully to treat CD, but hypopituitarism risk and delayed efficacy (improved with radiosurgery) are major drawbacks. Laparoscopic BLA is safe and effective in patients with severe, difficult-to-manage hypercortisolism, but long-term follow-up is required as corticotroph tumor progression can develop.

EXPERT OPINION

Treatment of persistent/recurrent CD is challenging. Most patients require >1 therapy to achieve long-lasting remission. There is currently no ideal single treatment option that provides high and rapid efficacy, low adverse effects, and preserves normal pituitary-adrenal axis function.

Persistent Cushing's Disease after Transsphenoidal Surgery: Challenges and Solutions

Transsphenoidal surgery remains the primary treatment for Cushing's disease (CD). However, despite the vast improvements in pituitary surgery, successful treatment of CD remains a great challenge. Although selective transsphenoidal removal of the pituitary tumor is a safe and effective procedure, the disease persists in around 22% of CD patients due to incomplete tumor resection. The persistence of hypercortisolism after pituitary surgery may also be the consequence of a misdiagnosis, as can occur in case of ectopic ACTH secretion or pseudo-Cushing. Considering the elevated mortality and morbidity characterizing the disease, a multidisciplinary approach is needed to minimize potential pitfalls occurring during the diagnosis, avoid surgical failure and provide the best care in those patients who have undergone unsuccessful surgery. In this review, we analyze the factors that could predict remission or persistence of CD after pituitary surgery and revise the therapeutic options in case of surgical failure.

90 YEARS OF PROGESTERONE: Selective progesterone receptor modulators in gynaecological therapies

Abnormal uterine bleeding (AUB) is a chronic, debilitating and common condition affecting one in four women of reproductive age. Current treatments (conservative, medical and surgical) may be unsuitable, poorly tolerated or may result in loss of fertility. Selective progesterone receptor modulators (SPRMs) influence progesterone-regulated pathways, a hormone critical to female reproductive health and disease; therefore, SPRMs hold great potential in fulfilling an unmet need in managing gynaecological disorders. SPRMs in current clinical use include RU486 (mifepristone), which is licensed for pregnancy interruption, and CDB-2914 (ulipristal acetate), licensed for managing AUB in women with leiomyomas and in a higher dose as an emergency contraceptive. In this article, we explore the clinical journey of SPRMs and the need for further interrogation of this class of drugs with the ultimate goal of improving women's quality of life.

Medical Management of Cushing's Syndrome: Current and Emerging Treatments

Endogenous Cushing's syndrome is a chronic disease associated with increased morbidity and mortality if not appropriately treated. Recurrence and/or persistence of hypercortisolemia after surgical treatment, especially for Cushing's disease, are high, and long-term medical treatment is used to decrease cortisol levels and risk of metabolic comorbidities. Medical treatment is also often required while waiting for radiation effects to take place. In some cases, severe or life-threatening hypercortisolism must be urgently and medically treated, via intravenous medications or with combination therapy, before patients can undergo surgery. In the last decade, medical treatment has progressed from a few steroidogenesis inhibitors to three novel drug groups: new inhibitors for steroidogenic enzymes with possibly fewer side effects, pituitary-directed drugs that aim to inhibit the pathophysiological pathways of Cushing's disease, and glucocorticoid receptor antagonists that block cortisol's action. Understanding the pathophysiology of Cushing's syndrome has also led to the identification of potential targets that may decrease adrenocorticotrophic hormone and/or cortisol excess, and/or decrease tumor cell proliferation, and induce senescence or apoptosis. We provide here a review of current and near-future medical options to treat Cushing's syndrome, and discuss updates on clinical trials and the efficacy and safety of novel or in-development drugs, as well as future potential targets.

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.

Pituitary Diseases and Bone

Neuroendocrinology of bone is a new area of research based on the evidence that pituitary hormones may directly modulate bone remodeling and metabolism. Skeletal fragility associated with high risk of fractures is a common complication of several pituitary diseases such as hypopituitarism, Cushing disease, acromegaly, and hyperprolactinemia. As in other forms of secondary osteoporosis, pituitary diseases generally affect bone quality more than bone quantity, and fractures may occur even in the presence of normal or low-normal bone mineral density as measured by dual-energy X-ray absorptiometry, making difficult the prediction of fractures in these clinical settings. Treatment of pituitary hormone excess and deficiency generally improves skeletal health, although some patients remain at high risk of fractures, and treatment with bone-active drugs may become mandatory. The aim of this review is to discuss the physiological, pathophysiological, and clinical insights of bone involvement in pituitary diseases.

Diabetes in Cushing Disease

PURPOSE OF REVIEW

This review focuses on the pathophysiological and clinical aspects of diabetes mellitus occurring in patients with Cushing disease (CD).

RECENT FINDINGS

Insulin resistance and impairment in insulin secretion are both involved in the pathogenesis of glucocorticoid-induced diabetes. Correction of glucocorticoid excess does not always resolve abnormalities of glucose homeostasis, and correction of hyperglycaemia is specifically required. In fact, insulin resistance may persist even after correction of glucocorticoid excess and diabetes needs to be treated for long term. On the other hand, emerging drugs used in the treatment of CD, such as the novel somatostatin analog pasireotide, may have direct effects on glucose homeostasis regardless of control of cortisol excess. Diabetes mellitus is a frequent and early complication of CD with important diagnostic, prognostic and therapeutic implications. Specifically, diagnosis of CD in patients with diabetes may be difficult due to potential misinterpretation of markers of cortisol hypersecretion. Moreover, diabetes mellitus is often difficult to be controlled in CD requiring a careful and dedicated therapeutic approach. Finally, the coexistence of diabetes may influence the therapeutic decision making in CD, since drugs used in this setting may variably influence glucose homeostasis regardless of control of hypercortisolism.

Update on medical treatment for Cushing's disease

Cushing's disease (CD) is the most common cause of endogenous Cushing's syndrome (CS). The goal of treatment is to rapidly control cortisol excess and achieve long-term remission, to reverse the clinical features and reduce long-term complications associated with increased mortality. While pituitary surgery remains first line therapy, pituitary radiotherapy and bilateral adrenalectomy have traditionally been seen as second-line therapies for persistent hypercortisolism. Medical therapy is now recognized to play a key role in the control of cortisol excess. In this review, all currently available medical therapies are summarized, and novel medical therapies in phase 3 clinical trials, such as osilodrostat and levoketoconazole are discussed, with an emphasis on indications, efficacy and safety. Emerging data suggests increased efficacy and better tolerability with these novel therapies and combination treatment strategies, and potentially increases the therapeutic options for treatment of CD. New insights into the pathophysiology of CD are highlighted, along with potential therapeutic applications. Future treatments on the horizon such as R-roscovitine, retinoic acid, epidermal growth factor receptor inhibitors and somatostatin-dopamine chimeric compounds are also described, with a focus on potential clinical utility.

Clinical management of critically ill patients with Cushing's disease due to ACTH-secreting pituitary macroadenomas: effectiveness of presurgical treatment with pasireotide

The management of critically ill Cushing's disease (CD) patients is extremely challenging. Pasireotide is indicated for the treatment of CD patients when pituitary surgery is unfeasible or has not been curative, but no data are available about the use of this drug as pre-operative treatment in critically ill patients. We report the effects of presurgical pasireotide therapy in CD patients in whom hypercortisolism caused life-threatening hypokalemia, alkalosis, and cardio-respiratory complications precluding surgical approach. Clinical, biochemical, and radiological data of two critically ill patients with ACTH-secreting pituitary macroadenoma, before and during first-line presurgical pasireotide treatment (600 μg s.c. bid). During the first 21 days of treatment, pasireotide therapy induced a rapid, partial decrease of plasma ACTH, serum cortisol, and urinary free cortisol levels, with the consequent normalization of serum potassium concentration and arterial blood gases parameters, in both the patients. They did not experience unmanageable side effects and underwent endoscopic transsphenoidal surgery after 4 weeks of effective treatment. Pre-operative MRI evaluation did not show pituitary tumor shrinkage. Surgical cure of CD was obtained in the first patient, while debulking allowed the pharmacological control of hypercortisolism in the second case. We suggest that pasireotide can induce a rapid improvement of clinical and metabolic conditions in critically ill CD patients in whom surgical approach is considered hazardous and need to be delayed.

Surgical management of adrenocorticotropic hormone-secreting pituitary adenomas

Cushing's disease is defined as hypercortisolemia caused by secretion of adrenocorticotropic hormone from a pituitary adenoma. The diagnosis of Cushing's disease is based on clinical symptoms, laboratory and imaging findings. Once an adrenocorticotropic-hormone-secreting adenoma is found, the standard of care is transsphenoidal adenomectomy. MRI negative microadenomas and large, invasive macroadenomas provide a surgical and clinical challenge and are best handled at high volume centers. Multiple options exist for refractory disease or recurrence, including repeat surgery, radiosurgery and radiotherapy, medical management and bilateral adrenalectomy.

Chitosan-based nanoparticles for improved anticancer efficacy and bioavailability of mifepristone

In addition to its well-known abortifacient effect, mifepristone (MIF) has been used as an anticancer drug for various cancers in many studies with an in-depth understanding of the mechanism of action. However, application of MIF is limited by its poor water solubility and low oral bioavailability. In this work, we developed a drug delivery system based on chitosan nanoparticles (CNs) to improve its bioavailability and anticancer activity. The MIF-loaded chitosan nanoparticles (MCNs) were prepared by convenient ionic gelation techniques between chitosan (Cs) and tripolyphosphate (TPP). The preparation conditions, including Cs concentration, TPP concentration, Cs/MIF mass ratio, and pH value of the TPP solution, were optimized to gain better encapsulation efficiency (EE) and drug loading capacity (DL). MCNs prepared with the optimum conditions resulted in spherical particles with an average size of 200 nm. FTIR and XRD spectra verified that MIF was successfully encapsulated in CNs. The EE and DL of MCNs determined by HPLC were 86.6% and 43.3%, respectively. The in vitro release kinetics demonstrated that MIF was released from CNs in a sustained-release manner. Compared with free MIF, MCNs demonstrated increased anticancer activity in several cancer cell lines. Pharmacokinetic studies in male rats that were orally administered MCNs showed a 3.2-fold increase in the area under the curve from 0 to 24 h compared with free MIF. These results demonstrated that MCNs could be developed as a potential delivery system for MIF to improve its anticancer activity and bioavailability.

The Treatment of Cushing's Disease

Cushing's disease (CD), or pituitary-dependent Cushing's syndrome, is a severe endocrine disease caused by a corticotroph pituitary tumor and associated with increased morbidity and mortality. The first-line treatment for CD is pituitary surgery, which is followed by disease remission in around 78% and relapse in around 13% of patients during the 10-year period after surgery, so that nearly one third of patients experience in the long-term a failure of surgery and require an additional second-line treatment. Patients with persistent or recurrent CD require additional treatments, including pituitary radiotherapy, adrenal surgery, and/or medical therapy. Pituitary radiotherapy is effective in controlling cortisol excess in a large percentage of patients, but it is associated with a considerable risk of hypopituitarism. Adrenal surgery is followed by a rapid and definitive control of cortisol excess in nearly all patients, but it induces adrenal insufficiency. Medical therapy has recently acquired a more important role compared to the past, due to the recent employment of novel compounds able to control cortisol secretion or action. Currently, medical therapy is used as a presurgical treatment, particularly for severe disease; or as postsurgical treatment, in cases of failure or incomplete surgical tumor resection; or as bridging therapy before, during, and after radiotherapy while waiting for disease control; or, in selected cases, as primary therapy, mainly when surgery is not an option. The adrenal-directed drug ketoconazole is the most commonly used drug, mainly because of its rapid action, whereas the glucocorticoid receptor antagonist, mifepristone, is highly effective in controlling clinical comorbidities, mainly glucose intolerance, thus being a useful treatment for CD when it is associated with diabetes mellitus. Pituitary-directed drugs have the advantage of acting at the site responsible for CD, the pituitary tumor. Among this group of drugs, the dopamine agonist cabergoline and the somatostatin analog pasireotide result in disease remission in a consistent subgroup of patients with CD. Recently, pasireotide has been approved for the treatment of CD when surgery has failed or when surgery is not an option, and mifepristone has been approved for the treatment of Cushing's syndrome when associated with impairment of glucose metabolism in case of the lack of a surgical indication. Recent experience suggests that the combination of different drugs may be able to control cortisol excess in a great majority of patients with CD.

Medical combination therapies in Cushing's disease

INTRODUCTION

There has been growing interest on medical therapy for the management of Cushing's disease (CD), particularly in cases of persistent or recurrent hypercortisolism. Ketoconazole, an inhibitor of adrenal steroidogenesis, is the most widely used drug, whereas cabergoline and pasireotide are the most promising centrally acting agents. The main purpose of this review article is to highlight the options of medical treatment for CD, with a special emphasis on combination therapies, a topic that has only been addressed by a limited number of studies.

CONCLUSIONS

According to the results of these studies, combination therapies involving medications with additive or synergistic effects on ACTH and cortisol secretion seem quite attractive as they yield higher probability of longterm control of the hypercortisolism at lower doses, a lower incidence of side-effects, and possibly a lower rate of treatment escapes. Currently, ketoconazole, cabergoline, and pasireotide are the best drugs to be prescribed in combination.

Medical treatment of Cushing disease: new targets, new hope

This article provides an update on current medical therapies for the treatment of Cushing disease. This information will be of value in determining patients' suitability for certain medical treatments. An approach of combining drugs from the same or different classes could potentially increase the number of patients in whom Cushing can be controlled while minimizing adverse effects, although larger studies are needed. Successful clinical management of patients with Cushing disease remains a challenge.

Ectopic ACTH-secreting pituitary adenomas within the sphenoid sinus

Ectopic pituitary adenomas are defined by the presence of adenomatous pituitary tissue outside the sella and distinctly separate from the pituitary gland. Ectopic ACTH-secreting pituitary adenomas (EAPAs) are a rare cause of Cushing's syndrome. Detecting these radiologically can prove difficult, in part, due to their typically small size and unpredictable anatomical location. In ACTH-dependent Cushing's syndrome, if, despite comprehensive testing, the source of excess ACTH remains occult (including negative work up for ectopic ACTH syndrome) thought should be given to the possibility of the patient harboring an EAPA. In most cases, ectopic ACTH pituitary adenomas within the sphenoid sinus will manifest with symptoms of hormonal excess, have an obvious sphenoid sinus mass on pre-operative imaging and will demonstrate resolution of hypercortisolism after surgical excision if located and removed. Twenty cases of EAPAs have been reported in the literature to date. This paper will review the current literature on all previously reported EAPAs within the sphenoid sinus in addition to the current case.

Adrenocorticotropin responsiveness to acute octreotide administration is not affected by mifepristone premedication in patients with Cushing's disease

Octreotide (OCT) is ineffective in patients with Cushing's disease (CD) due to the cortisol-induced down-regulation of somatostatin receptor subtype 2 which was shown to be reversible in vitro by using anti-glucocorticoid mifepristone. This study aimed to verify, in vivo, if mifepristone can modulate response to acute OCT administration in patients with CD. Three men and two postmenopausal women (age 52.5 ± 2 years) with CD were enrolled in the study. OCT (100 μg, s.c.) was administered alone on the first day (OCT-only), and it was then given after mifepristone administration (2 × 200 mg, p.os, 12 and 1 h before OCT), 3 days later (OCT-mif). ACTH and cortisol levels were measured before OCT administration and every 60 min thereafter for 6 h. Baseline ACTH and cortisol values, nadir values and percentage decrements (Δn) were compared during both tests. Mean ACTH-Δn did not differ significantly during the two tests. Both tests induced a <30 % decrease in plasma ACTH in three patients (#1, 2 and 3) and a >50 % decrease in the other two cases (#4 and 5). Cortisol decreased in patients #4 and 5, during both tests. ACTH-Δn did not correlate with morning cortisol nor with urinary free cortisol values. Patients #4 and 5 with the highest ACTH-Δn had the lowest cortisol values after 1 mg of dexamethasone. Brief mifepristone pre-treatment does not modify ACTH and cortisol response to acute OCT administration in CD. However, OCT seems to be more effective in patients with partially preserved cortisol inhibitory feedback.

Managing Cushing's disease: the state of the art

Cushing's disease is a rare chronic disease caused by a pituitary adenoma, which leads to excess secretion of adrenocorticotropic hormone (ACTH). The over-production of ACTH leads to hyperstimulation of the adrenal glands and a chronic excess of cortisol, resulting in the signs and symptoms of a severe clinical state (Cushing's syndrome) that leads to significant morbidity, negative impacts on the patient's quality of life, and, if untreated, increased mortality. The management of patients with Cushing's disease is complicated by the heterogeneity of the condition, with signs and symptoms that overlap with those of other diseases, and high subclinical incidence rates. Controversies surrounding the tests used for screening and identifying patients with Cushing's disease add to the challenge of patient management. Surgical intervention to remove the adenoma is the first-line treatment for patients with Cushing's disease, but medical therapies are useful in patients who relapse or are unsuitable for surgery. The recent introduction of pasireotide, the first pituitary-directed medical therapy, expands the number of treatment options available for patients with Cushing's disease. This state-of-the-art review aims to provide an overview of the most recent scientific research and clinical information regarding Cushing's disease. Continuing research into improving the diagnosis and treatment of Cushing's disease will help to optimize patient management.

Molecular basis of pharmacological therapy in Cushing's disease

Cushing's disease (CD) is a severe endocrine condition caused by an adrenocorticotropin (ACTH)-producing pituitary adenoma that chronically stimulates adrenocortical cortisol production and with potentially serious complications if not or inadequately treated. Active CD may produce a fourfold increase in mortality and is associated with significant morbidities. Moreover, excess mortality risk may persist even after CD treatment. Although predictors of risk in treated CD are not fully understood, the importance of early recognition and adequate treatment is well established. Surgery with resection of a pituitary adenoma is still the first line therapy, being successful in about 60-70 % of patients; however, recurrence within 2-4 years may often occur. When surgery fails, medical treatment can reduce cortisol production and ameliorate clinical manifestations while more definitive therapy becomes effective. Compounds that target hypothalamic-pituitary axis, glucocorticoid synthesis or adrenocortical function are currently used to control the deleterious effects of chronic glucocorticoid excess. In this review we describe and analyze the molecular basis of the drugs targeting the disease at central level, suppressing ACTH secretion, as well as at peripheral level, acting as adrenal inhibitors, or glucocorticoid receptor antagonists. Understanding of the underlying molecular mechanisms in CD and of glucocorticoid biology should promote the development of new targeted and more successful therapies in the future. Indeed, most of the drugs discussed have been tested in limited clinical trials, but there is potential therapeutic benefit in compounds with better specificity for the class of receptors expressed by ACTH-secreting tumors. However, long-term follow-up with management of persistent comorbidities is needed even after successful treatment of CD.

Recent advances in the medical treatment of Cushing's disease

Cushing’s disease is a condition of hypercortisolism caused by an adrenocorticotropic hormone (ACTH)-secreting pituitary adenoma. While rare, it is associated with significant morbidity and mortality, which suggests that early and aggressive intervention is required. The primary, definitive therapy for patients with Cushing’s disease in the majority of patients is pituitary surgery, generally performed via a transsphenoidal approach. However, many patients will not achieve remission or they will have recurrences. The consequences of persistent hypercortisolism are severe and, as such, early identification of those patients at risk of treatment failure is exigent. Medical management of Cushing’s disease patients plays an important role in achieving long-term remission after failed transsphenoidal surgery, while awaiting effects of radiation or before surgery to decrease the hypercortisolemia and potentially reducing perioperative complications and improving outcome. Medical therapies include centrally acting agents, adrenal steroidogenesis inhibitors and glucocorticoid receptor blockers. Furthermore, several new agents are in clinical trials. To normalize the devastating disease effects of hypercortisolemia, it is paramount that successful patient disease management includes individualized, multidisciplinary care, with close collaboration between endocrinologists, neurosurgeons, radiation oncologists, and general surgeons. This commentary will focus on recent advances in the medical treatment of Cushing’s, with a focus on newly approved ACTH modulators and glucocorticoid receptor blockers.