ACTH Antagonists

Current and Emerging Pharmacological Therapies for Cushing's Disease

Cushing's Disease (CD), hypercortisolism due to pituitary ACTH secreting neuroendocrine neoplasm, is associated with increased morbidity and, if untreated, mortality in about half of the affected individuals. Consequently, the timely initiation of effective treatment is mandatory. Neurosurgery is the first line and the only potentially curative treatment; however, 30% of patients will have persistent disease post-surgery. Furthermore, a small percentage of those initially controlled will develop hypercortisolism during long-term follow- up. Therefore, patients with persistent or recurrent disease, as well as those considered non-eligible for surgery, will need a second-line therapeutic approach, i.e., pharmacotherapy. Radiation therapy is reserved as a third-line therapeutic option due to its slower onset of action and its unfavorable profile regarding complications. During the past few years, the understanding of molecular mechanisms implicated in the physiology of the hypothalamus-pituitary-adrenal axis has evolved, and new therapeutic targets for CD have emerged. In the present review, currently available treatments, compounds currently tested in ongoing clinical trials, and interesting, potentially new targets emerging from unraveling molecular mechanisms involved in the pathophysiology of Cushing's disease are discussed.

Effects of ACTH6-9-Pro-Gly-Pro Peptide on the Levels of Pro- and Anti-Inflammatory Cytokines in Wistar Rats under Conditions of Chronic Restraint Stress

We evaluated the effect of ACTH_6-9-Pro-Gly-Pro (ACTH_6-9-PGP) peptide on the serum levels of pro- and anti-inflammatory cytokines in experimental animals under conditions of chronic restraint stress. Stress exposure over 2 weeks led to an increase in the levels of IL-1β, IL-6, and IFNγ in rats. Daily intraperitoneal injection of ACTH_6-9-PGP in a dose of 5 μg/kg before stress exposure significantly decreased the levels of IL-6 and IFNγ by 4.8 and 49.3% respectively. Administration of the peptide in a dose of 50 μg/kg decreased the levels of IL-1β and IFNγ by 51.2 and 39.7%, respectively. However, no changes in the cytokine levels were observed after injection of the peptide in a dose of 500 μg/kg. Thus, ACTH_6-9-PGP administered in doses of 5 and 50 μg/kg prevented the stress-induced changes in the levels of pro- and inflammatory cytokines.

An evaluation of pharmacological options for Cushing's disease: what are the state-of-the-art options?

INTRODUCTION

Untreated Cushing's syndrome (CS) is associated with significant morbidity and mortality. Cortisol normalization is a key goal to treatment. Pituitary surgery remains the first-line approach for Cushing's disease, but sometimes it is impracticable, unsuccessful, or complicated by recurrence. Medical therapy has been historically considered a palliative. However, in the latest years, interest on this topic has grown due to both the availability of new drugs and the reevaluation of the old, commonly used drugs in clinical practice.

AREAS COVERED

In this article, we will discuss the current options and future directions of medical therapy for CS, aiming at fitting best patients' features. An extensive literature search regarding already approved and investigational principles was conducted (PubMed, ClinicalTrials.gov. Available drugs include inhibitors of ACTH secretion, steroidogenesis inhibitors, and glucocorticoid receptor antagonists; drugs acting at different levels can be also combined in uncontrolled patients.

EXPERT OPINION

Since there is still no standardized pharmacological approach and the superiority of one drug over another has not been established yet in the absence of comparative studies, each time clinicians' choices should be patient-tailored. Age, gender, tumor features, severity of hypercortisolism, comorbidities/complications, rapidity of action, side effects, drug-drug interactions, contraindications, availability, patients' preferences, and costs should be all considered.

ACTH(6-9)-Pro-Gly-Pro ameliorates anxiety-like and depressive-like behaviour and gut mucosal microbiota composition in rats under conditions of chronic restraint stress

The effects of the peptide ACTH(6-9)-Pro-Gly-Pro at doses of 5; 50; 500 μg/kg on the Wistar rats' behaviour and gut mucosal microbiota composition under conditions of chronic immobilization stress (CRS) were studied. CRS increased anxiety-like and depressive-like behaviour, disturbances in locomotor activity and gut dysbiosis. Administration of ACTH(6-9)-Pro-Gly-Pro showed many phenotypic results. Peptide demonstrated anti-depressant activity at doses of 5 and 500 μg/kg by a decrease in the total immobile time in the FST. ACTH(6-9)-Pro-Gly-Pro administered at a dose of 50 μg/kg resulted in an anxiolytic effect which is shown by an increase in the time in the open arms of EPM (p < 0.05) and a decrease in the time in the closed arms (p < 0.05). Moreover, the peptide led to a decrease in alpha- and beta-diversity of the gut microbiota (p < 0.01). Correlation and linear regression analysis demonstrated central mechanisms of ACTH(6-9)-Pro-Gly-Pro anxiolytic activity and both central and peripheral ones in an anti-depressant effect. In this way, peptide ACTH(6-9)-Pro-Gly-Pro could prevent the development of behavioural disturbances and gut dysbiosis caused by chronic restraint stress.

Novel treatments for congenital adrenal hyperplasia

Patients with classic congenital adrenal hyperplasia due to 21-hydroxylase deficiency (21OHD) need life-long medical treatment to replace the lacking glucocorticoids and potentially lacking mineralocorticoids and to lower elevated adrenal androgens. Long-term complications are common, including gonadal dysfunction, infertility, and cardiovascular and metabolic co-morbidity with reduced quality of life. These complications can be attributed to the exposure of supraphysiological dosages of glucocorticoids and the longstanding exposure to elevated adrenal androgens. Development of novel therapies is necessary to address the chronic glucocorticoid overexposure, lack of circadian rhythm in glucocorticoid replacement, and inefficient glucocorticoid delivery with concomitant periods of hyperandrogenism. In this review we aim to give an overview about the current treatment regimens and its limitations and describe novel therapies especially evaluated for 21OHD patients.

Translational advances of melanocortin drugs: Integrating biology, chemistry and genetics

Melanocortin receptors have emerged as important targets with a very unusual versatility, as their widespread distribution on multiple tissues (e.g. skin, adrenal glands, brain, immune cells, exocrine glands) together with the variety of physiological processes they control (pigmentation, cortisol release, satiety mechanism, inflammation, secretions), place this family of receptors as genuine therapeutic targets for many disorders. This review focuses in the journey of the development of melanocortin receptors as therapeutic targets from the discovery of their existence in the early 1990 s to the approval of the first few drugs of this class. Two major areas of development characterise the current state of melanocortin drug development: their role in obesity, recently culminated with the approval of setmelanotide, and their potential for the treatment of chronic inflammatory and autoimmune diseases like rheumatoid arthritis, multiple sclerosis or fibrosis. The pro-resolving nature of these drugs offers the advantage of acting by mimicking the way our body naturally resolves inflammation, expecting fewer side effects and a more balanced (i.e. non-immunosuppressive) response from them. Here we also review the approaches followed for the design and development of novel compounds, the importance of the GPCR nature of these receptors in the process of drug development, therapeutic value, current challenges and successes, and the potential for the implementation of precision medicine approaches through the incorporation of genetics advances.

Effects of His-Phe-Arg-Trp-Pro-Gly-Pro peptide on free-radical oxidation processes in conditions of chronic restraint stress

Studying the effects of regulatory peptides on the stress-induced shifts in the bodily processes is of great fundamental and applied significance. Currently, a wide range of peptide neurotropic drugs, affecting the stress response development, are used in medicine, and new promising molecules are being studied. The study was aimed to assess the effects of the adrenocorticotropic hormone (ACTH) synthetic analog, ACTH(6-9)-Pro-Gly-Pro, administered at a dose of 5, 50 and 500 μg/kg, on the free-radical oxidation processes in Wistar rats, subjected to chronic restraint stress (CRS) during two weeks. Serum levels of 8-oxo-2'-deoxyguanosine (8-OHdG) and superoxide dismutase 3 (SOD3) were assessed by enzyme immunoassay, and the levels of thiobarbituric acid reactive substances (TBARS) were assessed by fluorimetric method. CRS lead to the significant increase in the 8-OHdG levels by 18.4% (p = 0.01) and the decrease in the SOD3 levels by 14.3% (p = 0.01), however, it had no effect on the levels of TBARS. ACTH(6-9)-Pro-Gly-Pro, administered at a dose of 5 and 50 μg/kg, significantly decreased the levels of 8-OHdG by 19.8% (p = 0.03) and 30% (p = 0.001), respectively. Thus, it was found that CRS resulted in oxidative stress in animals. ACTH(6-9)-Pro-Gly-Pro administration at a dose of 5 and 50 μg/kg inhibits the stress-induced free-radical oxidation processes.

Modelling and Control of Corticotropin Permeation from Hydrogels across a Natural Membrane in the Presence of Albumin

(1) Background: Skin is a difficult barrier to overcome, especially for molecules with masses greater than 500 Da. It has been suggested that albumin may contribute to more effective penetration of many therapeutic substances. In this study, an attempt was made to use albumin in semi-solid formulations to increase the skin penetration of another peptide—corticotropin (ACTH). (2) Methods: Hydrogels were prepared at two concentrations: 15 mg/g and 20 mg/g corticotropin, then albumin was added to them in different stoichiometric ratios. The degree of ACTH release from hydrogels, both with and without albumin addition, was investigated. For selected hydrogels the process of corticotropin permeation through a model membrane, i.e., pig skin, was examined. (3) Results: The study of corticotropin release showed that the addition of albumin, depending on its amount, may delay or increase the release process. Similarly, a study of ACTH permeation through porcine skin showed that albumin can delay or increase and accelerate ACTH permeation. (4) Conclusions: Hydrogel, applicated on the skin surface, may prove to be a beneficial and convenient solution for patients. It is an innovative way of application ACTH that bypasses the gastrointestinal tract and may result in increased availability of the peptide and its efficacy.

Antistress Action of Melanocortin Derivatives Associated with Correction of Gene Expression Patterns in the Hippocampus of Male Rats Following Acute Stress

Natural melanocortins (MCs) have been used in the successful development of drugs with neuroprotective properties. Here, we studied the behavioral effects and molecular genetic mechanisms of two synthetic MC derivatives-ACTH(4-7)PGP (Semax) and ACTH(6-9)PGP under normal and acute restraint stress (ARS) conditions. Administration of Semax or ACTH(6-9)PGP (100 μg/kg) to rats 30 min before ARS attenuated ARS-induced behavioral alterations. Using high-throughput RNA sequencing (RNA-Seq), we identified 1359 differentially expressed genes (DEGs) in the hippocampus of vehicle-treated rats subjected to ARS, using a cutoff of >1.5 fold change and adjusted p-value (Padj) < 0.05, in samples collected 4.5 h after the ARS. Semax administration produced > 1500 DEGs, whereas ACTH(6-9)PGP administration led to <400 DEGs at 4.5 h after ARS. Nevertheless, ~250 overlapping DEGs were identified, and expression of these DEGs was changed unidirectionally by both peptides under ARS conditions. Modulation of the expression of genes associated with biogenesis, translation of RNA, DNA replication, and immune and nervous system function was produced by both peptides. Furthermore, both peptides upregulated the expression levels of many genes that displayed decreased expression after ARS, and vice versa, the MC peptides downregulated the expression levels of genes that were upregulated by ARS. Consequently, the antistress action of MC peptides may be associated with a correction of gene expression patterns that are disrupted during ARS.

ACTH 6-9-PGP improves memory consolidation processes in rats

Introduction: The His-Phe-Arg-Trp sequence corresponding to the 6-9th amino acid residue of the adrenocorticotropic hormone molecule (ACTH6-9) is the critical pharmacophore of all endogenous melanocortin receptor agonists. In order to effects prolongation it may be stabilized by the addition of the amino acid sequence Pro-Gly-Pro (PGP) to the C-terminus. The aim of this work was to study the effect of ACTH6-9-PGP (HFRWPGP) on the processes of memory consolidation in the model of passive avoidance conditioning in comparison with ACTH4-7-PGP effects.

Materials and methods: The study was carried out on the model of passive avoidance conditioning. The effects of ACTH6-9-PGP were studied after its intraperitoneal injection to male Wistar rats at doses of 0.5, 5, 50, 150, and 450 μg/kg 15 minutes before the experiment, whereas the effects of ACTH4-7-PGP– under the similar conditions at doses of 50, 150, and 450 μg/kg.

Results and discussion: It was found that ACTH6-9-PGP had a pronounced stimulating effect on the memory consolidation process in the dose range from 0.5 μg/kg to 150 μg/kg, significantly increasing the latent period of an animal entering the dark chamber. Administration of ACTH4-7-PGP led to an improvement in the consolidation processes of the acquired conditioned reflex at the doses of 50 μg/kg and 450 μg/kg.

Conclusion: The range of effective doses of ACTH6-9-PGP is lower than that of ACTH4-7-PGP, which indicates the greater activity of HFRWPGP sequence in relation to memory consolidation processes and allows considering this peptide as a promising molecule for creating nootropic pharmacological drugs.

Stress-Induced Alteration in Chloride Transporters in the Trigeminal Nerve May Explain the Comorbidity between Depression and Migraine

Migraine is frequently comorbid with depression and anxiety disorders. In the case of depression and panic disorder, the associations seem to be bidirectional. Stress (activation of the hypothalamic-pituitary-adrenal axis) is thought to be involved in increasing the attack frequency. In the current review, it is argued that elevated levels of cortisol increase the function of chloride-ion transporter NKCC1 and decrease the function of chloride-extruder KCC2 in the trigeminal nerve. This leads to a diminished inhibitory effect of gamma-aminobutyric acid (GABA) and an enhanced likelihood of a migraine attack. Since migraine attacks themselves are stressful, and since brain areas are activated that could contribute to panic, anxiety and depression, a number of self-sustaining circular processes could occur that would explain the bi-directionality of the associations. On the basis of this hypothesis, several novel therapeutic approaches to counter the pathological process can be proposed. These include inhibition of corticotrophin releasing factor by CRF1 receptor antagonists, blockade of adrenocorticotropic hormone (ACTH) at the MC2 receptor, and inhibition of the hyperactive NKCC1 chloride-transporter.

Development and Study of Semi-Solid Preparations Containing the Model Substance Corticotropin (ACTH): Convenience Application in Neurodegenerative Diseases

Corticotropin (ACTH, previously an adrenocorticotropic hormone) is used in the diagnosis and treatment of pituitary gland disorders, adrenal cortex disorders, and other diseases, including autoimmune polymyositis, systemic lupus erythematosus, rheumatoid arthritis, Crohn’s disease, and ulcerative colitis. So far, the ointment dosage form containing ACTH for use on the skin is unknown. Therefore, it seems appropriate to develop a semi-solid formulation with corticotropin. Emulsion ointments were prepared using an Unguator based on the cream base Lekobaza^® containing corticotropin in different concentrations, and then the physical and chemical parameters of the ointment formulations, such as pH, spreadability, rheological properties, and texture analysis, were evaluated. In addition, a USP apparatus 2 with enhancer cells was utilized to study the in vitro drug release characteristics of the selected formulations. All the ointments obtained were characterized by good spreadability and viscosity. An analysis of the ointment texture was performed and the dependence of the tested parameters on the ACTH content in the ointment was demonstrated. Examination of the structure of the ointment showed that a high concentration of ACTH increases the hardness and adhesiveness of the ointment. In turn, it adversely affects the cohesiveness and elasticity of the ointments tested. The results of the release study showed that ACTH is released the fastest from the formulation with the lowest concentration, while the slowest from the ointment with the highest concentration of ACTH.

Molecular determinants of ACTH receptor for ligand selectivity

The adrenocorticotropic hormone (ACTH) receptor, known as the melanocortin-2 receptor (MC2R), plays a key role in regulating adrenocortical function. ACTH receptor is a subtype of the melanocortin receptor family which is a member of the G-protein coupled receptor (GPCR) superfamily. ACTH receptor has unique characteristics among MCRs. α-MSH, β-MSH, γ-MSH and ACTH are agonists for MCRs but only ACTH is the agonist for ACTH receptor. In addition, the melanocortin receptor accessory protein (MRAP) is required for ACTH receptor expression at cell surface and function. In this review, we summarized the information available on the relationship between ACTH and ACTH receptor and provide the latest understanding of the molecular basis of the ACTH receptor responsible for ligand selectivity and function.

Changes in the nociceptive response to thermal stimulation in rats following administration of N-terminal analogs of the adrenocorticotropic hormone

Melanocortins (MCs) are an increasingly studied class of regulatory peptides exerting a wide range of biological effects. All naturally occurring MCs share a His-Phe-Arg-Trp fragment (HFRW) corresponding to the sequence of amino acid residues 6–9 of the adrenocorticotropic hormone (ACTH6-9), which is also a central active component of ACTH. Attaching the Pro-Gly-Pro (PGP) sequence to the C-end of the peptide extends the duration of the peptide’s effect. The aim of this study was to investigate the effects of ACTH6-9-PGP (HFRWPGP) on the spinal and supraspinal mechanisms involved in the nociceptive response in rats and to compare them to those of its structural analog ACTH4-7-PGP (MEHFPGP). ACTH6-9-PGP effects were studied following the intraperitoneal administration of the peptide at doses 0.5, 1.5, 5, 15, 50, 150, or 450 μg/kg 15 minutes before the hot plate and tail flick tests. ACTH4-7-PGP effects were studied under the same conditions at the following doses: 50, 150 and 450 μg/kg. We found that ACTH6-9-PGP administered intraperitoneally at 5 or 150 μg/kg induced a pronounced reduction in pain sensitivity 15 and 45 minutes after the injection (p = 0.04); this effect was implemented via supraspinal mechanisms. In the tail flick test, 150 μg/kg ACTH6-9-PGP increased pain sensitivity, with the participation of segmental spinal mechanisms (p = 0.04). ACTH4-7-PGP did not have any effect on the studied mechanisms of pain sensitivity. Thus, unlike ACTH4-7-PGP, ACTH6-9-PGP can both increase pain sensitivity and exert an analgesic effect.

Testicular Adrenal Rest Tumors: Current Insights on Prevalence, Characteristics, Origin, and Treatment

This review provides the reader with current insights on testicular adrenal rest tumors (TARTs), a complication in male patients with congenital adrenal hyperplasia (CAH). In recent studies, an overall TART prevalence of 40% (range, 14% to 89%) in classic patients with CAH is found. Reported differences are mainly caused by the method of detection and the selected patient population. Biochemically, histologically, and molecularly, TARTs exhibit particular adrenal characteristics and were therefore thought to originate from aberrant adrenal cells. More recently, TARTs have been found to also exhibit testicular characteristics. This has led to the hypothesis of pluripotent cells as the origin of TARTs. High concentrations of ACTH could cause hyperplasia of these pluripotent cells, as TARTs appear to be associated with poor hormonal control with concomitant elevated ACTH. Unfortunately, as yet there are no methods to prevent the development of TARTs, nor are there guidelines to treat patients with TARTs. Intensified glucocorticoid treatment could improve fertility status in some cases, although studies report contradicting results. TARTs can also lead to irreversible testicular damage, and therefore semen cryopreservation could be offered to patients with TARTs. Further research should focus on the etiology and pharmacological treatment to prevent TART development or to treat TARTs and improve the fertility status of patients with TARTs.

ACTH signalling and adrenal development: lessons from mouse models

The melanocortin-2-receptor (MC2R), also known as the ACTH receptor, is a critical component of the hypothalamic-pituitary-adrenal axis. The importance of MC2R in adrenal physiology is exemplified by the condition familial glucocorticoid deficiency (FGD), a potentially fatal disease characterised by isolated cortisol deficiency. MC2R mutations cause ~25% of cases. The discovery of a MC2R accessory protein MRAP, mutations of which account for ~20% of FGD, has provided insight into MC2R trafficking and signalling. MRAP is a single transmembrane domain accessory protein highly expressed in the adrenal gland and essential for MC2R expression and function. Mouse models helped elucidate the action of ACTH. The Mc2r-knockout (Mc2r - / - ) mice was the first mouse model developed to have adrenal insufficiency with deficiencies in glucocorticoid, mineralocorticoid and catecholamines. We recently reported the generation of the Mrap - / - mice which better mimics the human FGD phenotype with isolated glucocorticoid deficiency alone. The adrenal glands of adult Mrap - / - mice were grossly dysmorphic with a thickened capsule, deranged zonation and deranged WNT4/beta-catenin and sonic hedgehog (SHH) pathway signalling. Collectively, these mouse models of FGD highlight the importance of ACTH and MRAP in adrenal progenitor cell regulation, cortex maintenance and zonation.

Small cell lung cancer starting with diabetes mellitus: Two case reports and literature review

BACKGROUND

Small-cell lung cancer (SCLC) is a type of fatal tumor that is increasing in prevalence. While these are unpleasant facts to consider, it is vitally important to be informed, and it is important to catch the disease early. Typically, lung cancer does not show severe clinical symptoms in the early stage. Once lung cancer has progressed, patients might present with classical symptoms of respiratory system dysfunction. Thus, the prognosis of SCLC is closely related to the early diagnosis of the disease. Ectopic adrenocorticotropic hormone (ACTH) syndrome (EAS) is related to cancer occurrence, especially for SCLC with the presence of Cushing's syndrome, which is dependent on markedly elevated ACTH and cortisol levels.

CASE SUMMARY

In the current report, we describe two middle-age patients who were originally diagnosed with diabetes mellitus with no classical symptoms of lung cancer. The patients were eventually diagnosed with SCLC, which was confirmed by bronchoscopic biopsy and histopathology. SCLC-associated diabetes was related to EAS, which was an endogenous ACTH-dependent form of Cushing’s syndrome with elevated ACTH and cortisol levels. Multiple organ metastases were found in Patient 1, while Patient 2 retained good health at 2 years follow-up. EAS symptoms including thyroid dysfunction, hypercortisolism and glucose intolerance were all resolved after anticancer treatment.

CONCLUSION

In conclusion, SCLC might start with diabetes mellitus and increased cortisol and hypokalemia or other EAS symptoms. These complex clinical features were the most significant factors to deteriorate a patient’s condition. Early diagnosis and treatment from clinicians were essential for the anti-cancer treatment for patients with SCLC.

Advances in the medical treatment of Cushing's syndrome

Cushing's syndrome is associated with multisystem morbidity and, when suboptimally treated, increased mortality. Medical therapy is an option for patients if surgery is not successful and can be classified into pituitary-directed drugs, steroid synthesis inhibitors, and glucocorticoid receptor antagonists. In the last decade there have been new developments in each drug category. Targeting dopamine and somatostatin receptors on corticotroph adenomas with cabergoline or pasireotide, or both, controls cortisol production in up to 40% of patients. Potential new targets in corticotroph adenomas include the epidermal growth factor receptor, cyclin-dependent kinases, and heat shock protein 90. Osilodrostat and levoketoconazole are new inhibitors of steroidogenesis and are currently being evaluated in multicentre trials. CORT125134 is a new selective glucocorticoid receptor antagonist under investigation. We summarise the drug therapies for various forms of Cushing's syndrome and focus on emerging drugs and drug targets that have the potential for new and effective tailor-made pharmacotherapy for patients with Cushing's syndrome.

Melanocortin 2 receptor antagonists in canine pituitary-dependent hypercortisolism: in vitro studies

Canine hypercortisolism is most often caused by an ACTH-secreting pituitary adenoma (pituitary-dependent hypercortisolism; PDH). An interesting target for a selective medical treatment of PDH would be the receptor for ACTH: the melanocortin 2 receptor (MC2R). In this study we investigated whether two peptide compounds, BIM-22776 (#776) and BIM-22A299 (#299), are effective MC2R antagonists in vitro. Their effects on cortisol production and mRNA expression of steroidogenic enzymes, MC2R and melanocortin 2 receptor accessory protein (MRAP) were evaluated in primary adrenocortical cell cultures (n = 8) of normal canine adrenal glands. Cortisol production stimulated by 50 nM ACTH was dose-dependently inhibited by #299 (inhibition 90.7 ± 2.3% at 5 μM) and by #776 (inhibition 38.0 ± 5.2% at 5 μM). The ACTH-stimulated mRNA expression of steroidogenic enzymes, MC2R and MRAP was significantly inhibited by both compounds, but most potently by #299. These results indicate that canine primary cell culture is a valuable in vitro system to test MC2R antagonists, and that these compounds, but especially #299, are effective MC2R antagonists in vitro. To determine its efficacy in vivo, further studies are warranted. Antagonism of the MC2R is a promising potential treatment approach in canine PDH.

Treating canine Cushing's syndrome: Current options and future prospects

Naturally occurring hypercortisolism, also known as Cushing's syndrome, is a common endocrine disorder in dogs that can be caused by an adenocorticotrophic hormone (ACTH)-producing pituitary adenoma (pituitary-dependent hypercortisolism, PDH; 80-85% of cases), or by an adrenocortical tumor (ACT; 15-20% of cases). To determine the optimal treatment strategy, differentiating between these two main causes is essential. Good treatment options are surgical removal of the causal tumor, i.e. hypophysectomy for PDH and adrenalectomy for an ACT, or radiotherapy in cases with PDH. Because these options are not without risks, not widely available and not suitable for every patient, pharmacotherapy is often used. In cases with PDH, the steroidogenesis inhibitor trilostane is most often used. In cases with an ACT, either trilostane or the adrenocorticolytic drug mitotane can be used. Although mostly effective, both treatments have disadvantages. This review discusses the current treatment options for canine hypercortisolism, and considers their mechanism of action, efficacy, adverse effects, and effect on survival. In addition, developments in both adrenal-targeting and pituitary-targeting drugs that have the potential to become future treatment options are discussed, as a more selective and preferably also tumor-targeted approach could have many advantages for both PDH and ACTs.

New and emerging drug therapies for Cushing's disease

INTRODUCTION

Cushing's disease is a rare systemic and disabling disease due to oversecretion of adrenocorticotrophic hormone (ACTH) resulting in excess cortisol levels. Diagnosis and treatment are difficult; despite the availability of various pharmaceutical treatment options, there is an ongoing, unmet need for even more effective treatment.

AREAS COVERED

The present review aims at providing an overview of available drugs and presenting new developments. Focusing on the pituitary as a target, the review covers compounds targeting pituitary cell signaling or cell cycle control such as heat shock protein inhibitors (e.g. silibinin), histone deacetylase inhibitors (trichostatin A, vorinostat), kinase inhibitors (gefitinib, seliciclib), and others (such as triptolide, AT-101). Levoketoconazole and osilodrostat are in clinical testing and inhibit steroidogenesis. Blockade of ACTH receptor binding at the adrenal level is explained as a theoretical drug target. Inhibition of binding of the glucocorticoid receptor in the peripheral tissue plays a minor role due to its lack of biomonitoring options.

EXPERT OPINION

In our opinion, further research and drug development of pituitary-directed targets are necessary. Combination therapies may exert synergistic effects and allow for smaller and better tolerated doses, but more experience and data are needed to guide such treatment schemes.

Are Cushing's disease patients curable?

Treatment of Cushing's disease remains a challenge. Whereas pituitary surgery can "cure" the patient and restore a completely normal pituitary adrenal axis, there are immediate failures and late recurrences which ultimately require alternate therapeutic approaches. These are numerous, but so are their drawbacks, and all appear to be "default options". For the future, pituitary adenoma has to remain the "reasonable obsession" of efficient and optimistic therapists….

Melanocortins, Melanocortin Receptors and Multiple Sclerosis

The melanocortins and their receptors have been extensively investigated for their roles in the hypothalamo-pituitary-adrenal axis, but to a lesser extent in immune cells and in the nervous system outside the hypothalamic axis. This review discusses corticosteroid dependent and independent effects of melanocortins on the peripheral immune system, central nervous system (CNS) effects mediated through neuronal regulation of immune system function, and direct effects on endogenous cells in the CNS. We have focused on the expression and function of melanocortin receptors in oligodendroglia (OL), the myelin producing cells of the CNS, with the goal of identifying new therapeutic approaches to decrease CNS damage in multiple sclerosis as well as to promote repair. It is clear that melanocortin signaling through their receptors in the CNS has potential for neuroprotection and repair in diseases like MS. Effects of melanocortins on the immune system by direct effects on the circulating cells (lymphocytes and monocytes) and by signaling through CNS cells in regions lacking a mature blood brain barrier are clear. However, additional studies are needed to develop highly effective MCR targeted therapies that directly affect endogenous cells of the CNS, particularly OL, their progenitors and neurons.

MANAGEMENT OF ENDOCRINE DISEASE: Congenital adrenal hyperplasia due to 21-hydroxylase deficiency: update on the management of adult patients and prenatal treatment

Congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency is characterized by cortisol and in some cases aldosterone deficiency associated with androgen excess. Goals of treatment are to replace deficient hormones and control androgen excess, while avoiding the adverse effects of exogenous glucocorticoid. Over the last 5 years, cohorts of adults with CAH due to 21-hydroxylase deficiency from Europe and the United States have been described, allowing us to have a better knowledge of long-term complications of the disease and its treatment. Patients with CAH have increased mortality, morbidity and risk for infertility and metabolic disorders. These comorbidities are due in part to the drawbacks of the currently available glucocorticoid therapy. Consequently, novel therapies are being developed and studied in an attempt to improve patient outcomes. New management strategies in the care of pregnancies at risk for congenital adrenal hyperplasia using fetal sex determination and dexamethasone have also been described, but remain a subject of debate. We focused the present overview on the data published in the last 5 years, concentrating on studies dealing with cardiovascular risk, fertility, treatment and prenatal management in adults with classic CAH to provide the reader with an updated review on this rapidly evolving field of knowledge.