The PPAR-gamma activator rosiglitazone fails to lower plasma ACTH levels in patients with Nelson's syndrome

Innovative tumour targeting therapeutics in Cushing's disease

Cushing's disease (CD) is the most frequent form of endogenous hypercortisolism. Management of this devastating condition relies on pituitary surgery, while effective pharmacological treatment mainly focus on periphery targeting pharmaceuticals. Approved tumour-targeting drugs are limited to dopamine agonists and somatostatin analogues with frequently low efficacy and substantial side effects. Discoveries on the genetics and pathophysiology of corticotroph tumorigenesis brought forward new potential pharmacological targets. Compounds such as retinoic acid although promising in preclinical studies, are not as efficient in the clinic. Others, such as, silibinin, gefitinib and roscovitine are effective in preclinical models, but their efficacy and safety still needs to be determined in patients with CD.

Management of Nelson’s Syndrome

Nelson’s syndrome is a potentially severe condition that may develop in patients with Cushing’s disease treated with bilateral adrenalectomy. Its management can be challenging. Pituitary surgery followed or not by radiotherapy offers the most optimal tumour control, whilst pituitary irradiation alone needs to be considered in cases requiring intervention and are poor surgical candidates. Observation is an option for patients with small lesions, not causing mass effects to vital adjacent structures but close follow-up is required for a timely detection of corticotroph tumour progression and for further treatment if required. To date, no medical therapy has been consistently proven to be effective in Nelson’s syndrome. Pharmacotherapy, however, should be considered when other management approaches have failed. A subset of patients with Nelson’s syndrome may develop further tumour growth after primary treatment, and, in some cases, a truly aggressive tumour behaviour can be demonstrated. In the absence of evidence-based guidance, the management of these cases is individualized and tailored to previously offered treatments. Temozolomide has been used in patients with aggressive Nelson’s with no consistent results. Development of tumour-targeted therapeutic agents are an unmet need for the management of aggressive cases of Nelson’s syndrome.

Corticotroph tumor progression after bilateral adrenalectomy (Nelson's syndrome): systematic review and expert consensus recommendations

BACKGROUND

Corticotroph tumor progression (CTP) leading to Nelson's syndrome (NS) is a severe and difficult-to-treat complication subsequent to bilateral adrenalectomy (BADX) for Cushing's disease. Its characteristics are not well described, and consensus recommendations for diagnosis and treatment are missing.

METHODS

A systematic literature search was performed focusing on clinical studies and case series (≥5 patients). Definition, cumulative incidence, treatment and long-term outcomes of CTP/NS after BADX were analyzed using descriptive statistics. The results were presented and discussed at an interdisciplinary consensus workshop attended by international pituitary experts in Munich on October 28, 2018.

RESULTS

Data covered definition and cumulative incidence (34 studies, 1275 patients), surgical outcome (12 studies, 187 patients), outcome of radiation therapy (21 studies, 273 patients), and medical therapy (15 studies, 72 patients).

CONCLUSIONS

We endorse the definition of CTP-BADX/NS as radiological progression or new detection of a pituitary tumor on thin-section MRI. We recommend surveillance by MRI after 3 months and every 12 months for the first 3 years after BADX. Subsequently, we suggest clinical evaluation every 12 months and MRI at increasing intervals every 2-4 years (depending on ACTH and clinical parameters). We recommend pituitary surgery as first-line therapy in patients with CTP-BADX/NS. Surgery should be performed before extrasellar expansion of the tumor to obtain complete and long-term remission. Conventional radiotherapy or stereotactic radiosurgery should be utilized as second-line treatment for remnant tumor tissue showing extrasellar extension.

Rapid response of Nelson's syndrome to pasireotide in radiotherapy-naive patient

BACKGROUND

Nelson's syndrome is a well-described complication following bilateral adrenalectomy for management of Cushing's disease. There is no consensus on optimal management of Nelson's syndrome, characterized by the triad of pituitary corticotroph adenoma growth, elevated serum adrenocorticotropic hormone, and skin hyperpigmentation. Medical therapy with a variety of drug classes have been studied. One potentially promising drug already approved for Cushing's disease is pasireotide, a somatostatin analog with affinity for multiple somatostatin receptors, including subtype 5, the most highly expressed receptor on corticotroph tumors.

CASE PRESENTATION

A 24-year-old female was diagnosed with Cushing's disease with initial ACTH levels around 700-800 pg/mL. She underwent transsphenoidal surgery without remission, followed by bilateral adrenalectomy. Over the subsequent 3 years, the patient developed skin hyperpigmentation, recurrent elevations of ACTH, and tumor recurrence requiring two additional transsphenoidal surgeries. After her third transsphenoidal resection, ACTH normalized, no residual tumor was seen on radiology, and the patient's skin hyperpigmentation improved. She then had an uncomplicated full-term pregnancy, during which ACTH levels remained within normal limits. One month after delivery, ACTH levels began rising to a peak at 5,935 pg/mL. Imaging revealed two new bilateral pituitary adenomas, measuring 14 mm on the left, and 7 mm on the right. She was then started on pasireotide. After two months of therapy, ACTH decreased to 609 pg/mL, and repeat pituitary MRI showed interval decrease in size of both pituitary adenomas to 13 mm on the left and 6 mm on the right.

CONCLUSION

We report the protracted course of a young female with several recurrences of Nelson's syndrome following bilateral adrenalectomy and multiple transsphenoidal surgeries, who ultimately responded to pasireotide. Unique features of her case not described previously are the response to pasireotide in a radiotherapy-naive patient, as well as the rapid radiologic response to therapy. Her history illustrates the unresolved challenges of Nelson's syndrome and the continued need for additional studies to identify optimal management.

Tumor-Directed Therapeutic Targets in Cushing Disease

CONTEXT

The most frequent cause of endogenous hypercortisolism is Cushing disease (CD), a devastating condition associated with severe comorbidities and high mortality. Effective tumor-targeting therapeutics are limited.

DESIGN

Search in PubMed with key words "corticotroph" and "Cushing's disease" plus the name of the mentioned therapeutic agent and in associated references of the obtained papers. Additionally, potential therapeutics were obtained from ClinicalTrials.gov with a search for "Cushing disease."

RESULTS

At present, the tumor-targeted pharmacological therapy of CD is concentrated on dopamine agonists (cabergoline) and somatostatin analogs (pasireotide) with varying efficacy, escape from response, and considerable side effects. Preclinical studies on corticotroph pathophysiology have brought forward potential drugs such as retinoic acid, silibinin, and roscovitine, whose efficacy and safety remain to be determined.

CONCLUSIONS

For many patients with CD, effective tumor-targeted pharmacological therapy is still lacking. Coordinated efforts are pivotal in establishing efficacy and safety of novel therapeutics in this rare but devastating disease.

Characterizing and predicting the Nelson-Salassa syndrome

OBJECTIVE Nelson-Salassa syndrome (NSS) is a rare consequence of bilateral adrenalectomy (ADX) for refractory hypercortisolism due to Cushing disease (CD). Although classically defined by rapid growth of a large, invasive, adrenocorticotropin hormone (ACTH)-secreting pituitary tumor after bilateral ADX that causes cutaneous hyperpigmentation, visual disturbance, and high levels of ACTH, clinical experience suggests more variability. METHODS The authors conducted a retrospective chart review of all patients 18 years and older with a history of bilateral ADX for CD, adequate pituitary MRI, and at least 2 years of clinical follow-up. Statistical tests included Student's t-test, chi-square test, Fisher's exact test, multivariate analysis, and derived receiver operating characteristic curves. RESULTS Between 1956 and 2015, 302 patients underwent bilateral ADX for the treatment of hypercortisolism caused by CD; 88 had requisite imaging and follow-up (mean 16 years). Forty-seven patients (53%) had radiographic progression of pituitary disease and were diagnosed with NSS. Compared with patients who did not experience progression, those who developed NSS were significantly younger at the time of CD diagnosis (33 vs 44 years, p = 0.007) and at the time of bilateral ADX (35 vs 49 years, p = 0.007), had larger tumors at the time of CD diagnosis (6 mm vs 1 mm, p = 0.03), and were more likely to have undergone external-beam radiation therapy (EBRT, 43% vs 12%, p = 0.005). Among NSS patients, the mean tumor growth was 7 mm/yr (SE 6 mm/yr); the median tumor growth was 3 mm/yr. Prevalence of pathognomonic symptoms was low; the classic triad occurred in 9%, while hyperpigmentation without visual field deficit was observed in 23%, and 68% remained asymptomatic despite radiographic disease progression. NSS required treatment in 14 patients (30%). CONCLUSIONS NSS is a prevalent sequela of CD after bilateral ADX and affects more than 50% of patients. However, although radiological evidence of NSS is common, it is most often clinically indolent, with only a small minority of patients developing the more aggressive disease phenotype characterized by clinically meaningful symptoms and indications for treatment. Young age at the time of CD diagnosis or treatment with bilateral ADX, large tumor size at CD diagnosis, and EBRT are associated with progression to NSS and may be markers of aggressiveness.

Nelson's syndrome: a review of the clinical manifestations, pathophysiology, and treatment strategies

Nelson's syndrome is a rare clinical manifestation that occurs in 8%-47% of patients as a complication of bilateral adrenalectomy, a procedure that is used to control hypercortisolism in patients with Cushing's disease. First described in 1958 by Dr. Don Nelson, the disease has since become associated with a clinical triad of hyperpigmentation, excessive adrenocorticotropin secretion, and a corticotroph adenoma. Even so, for the past several years the diagnostic criteria and management of Nelson's syndrome have been inadequately studied. The primary treatment for Nelson's syndrome is transsphenoidal surgery. Other stand-alone therapies, which in many cases have been used as adjuvant treatments with surgery, include radiotherapy, radiosurgery, and pharmacotherapy. Prophylactic radiotherapy at the time of bilateral adrenalectomy can prevent Nelson's syndrome (protective effect). The most promising pharmacological agents are temozolomide, octreotide, and pasireotide, but these agents are often administered after transsphenoidal surgery. In murine models, rosiglitazone has shown some efficacy, but these results have not yet been found in human studies. In this article, the authors review the clinical manifestations, pathophysiology, diagnostic criteria, and efficacy of multimodal treatment strategies for Nelson's syndrome.

Re-examining Nelson's syndrome

PURPOSE OF REVIEW

Nelson's syndrome is a rare complication that can occur during the course of management of Cushing's disease. This article summarizes the recent literature on the diagnosis, monitoring and treatment of this potentially life-threatening outcome.

RECENT FINDINGS

Nelson's syndrome, with rising adrenocorticotropin hormone levels and corticotroph tumor progression on diagnostic imaging, can develop following treatment of refractory Cushing's disease with total bilateral adrenalectomy with/without radiotherapy. However, data showing that radiotherapy prevents Nelson's syndrome is inconsistent. In addition to the treatment of Nelson's syndrome with neurosurgery with/without adjuvant radiotherapy, selective somatostatin analogs and dopamine agonists, as well as other novel agents, have been used with increasing frequency in treating cases of Nelson's syndrome with limited benefit. The risk-benefit profile of each of these therapies is still not completely understood.

SUMMARY

Consensus guidelines on the evaluation and management of Nelson's syndrome are lacking. This article highlights areas in the surveillance of Cushing's disease patients, and diagnostic criteria and treatment regimens for Nelson's syndrome that require further research and review by experts in the field.

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.

Ursolic acid suppresses growth and adrenocorticotrophic hormone secretion in AtT20 cells as a potential agent targeting adrenocorticotrophic hormone-producing pituitary adenoma

Adrenocorticotrophic hormone (ACTH)-producing pituitary adenoma leads to excess ACTH secretion, which is associated with significant mortality and impaired quality of life. Thus far, the first line therapy is the transphenoidal microsurgery. Considering the high recurrence rate and complications of surgery, novel agents, which directly target on pituitary ACTH-producing adenoma and suppress ACTH secretion are urgently required. In the present study, the effect of ursolic acid (UA) as a candidate agent targeting ACTH-producing AtT20 cells was investigated. It was demonstrated that UA inhibited the viability and induced apoptosis of AtT20 cells and decreased ACTH secretion. The process of apoptosis involved a decrease of the B cell lymphoma 2 (Bcl-2)/Bcl2-associated X protein ratio followed by a release of mitochondrial cytochrome c into the cytosol with subsequent activation of caspase-9, -3/7 and -8. The potential signaling pathway involved the activation of c-Jun N-terminal kinase (JNK) but not extracellular signal-regulated protein kinases1/2 and p38 mitogen-activated protein kinase. The JNK pathway participated in UA-induced mitochondrial apoptotic signaling transduction via increasing the phosphorylation and degradation of Bcl-2, which may be partly attenuated by the JNK inhibitor SP600125. In conclusion, the present study indicates that UA may be a promising candidate agent for the management of ACTH-producing pituitary adenoma.

Retinoic acid receptor-α up-regulates proopiomelanocortin gene expression in AtT20 corticotroph cells

Cushing's disease is a disorder caused by excessive ACTH secretion from a corticotroph tumor of the pituitary gland. Although its standard therapy is a transsphenoidal surgery, innovation of novel medical treatments for the disease is urgently necessary. Retinoic acid (RA) has been reported to suppress adrenocorticotropic hormone (ACTH) secretion in Cushing's disease. However, the role of RA receptor (RAR) in proopiomelanocortin (Pomc) gene expression remains uncertain. We here examined the involvement of RARα in Pomc regulation using AtT20 corticotroph cells. Surprisingly, a synthetic RARα agonist Am80 increased Pomc mRNA expression, CRH-induced ACTH secretion, and Pomc promoter activity. Small interfering RNA-mediated RARα-knockdown suppressed both basal and Am80-induced Pomc promoter activity. RARα-overexpression dose-dependently increased Pomc promoter activity. Pomc promoter mutation analysis revealed that both Tpit and NeuroD1 binding elements were responsible for the Am80-mediated effect. Am80 increased Tpit expression while RAR antagonist LE540 suppressed the increase. Tpit-overexpression increased Pomc promoter activity. Mammalian two-hybrid assay revealed that Am80 induced NeuroD1-RARα interaction. NeuroD1-overexpression enhanced the Am80-induced Pomc promoter activity, which was suppressed by NeuroD1 truncated mutant-overexpression. RARα thus positively regulates ACTH secretion/Pomc gene expression through interaction with NeuroD1 and Tpit expression increase. The present observation will be useful for the future development of the RA/retinoid-derived therapeutics of the disease.

New developments in the medical treatment of Cushing's syndrome

Cushing's syndrome (CS) is a severe endocrine disorder characterized by chronic cortisol excess due to an ACTH-secreting pituitary adenoma, ectopic ACTH production, or a cortisol-producing adrenal neoplasia. Regardless of the underlying cause, untreated CS is associated with considerable morbidity and mortality. Surgery is the primary therapy for all causes of CS, but surgical failure and ineligibility of the patient to undergo surgery necessitate alternative treatment modalities. The role of medical therapy in CS has been limited because of lack of efficacy or intolerability. In recent years, however, new targets for medical therapy have been identified, both at the level of the pituitary gland (e.g. somatostatin, dopamine, and epidermal growth factor receptors) and the adrenal gland (ectopically expressed receptors in ACTH-independent macronodular adrenal hyperplasia). In this review, results of preclinical and clinical studies with drugs that exert their action through these molecular targets, as well as already established medical treatment options, will be discussed.

Temozolomide (Temodar®) and capecitabine (Xeloda®) treatment of an aggressive corticotroph pituitary tumor

Only rarely do corticotroph pituitary tumors become invasive leading to symptoms caused by compression of cranial nerves and other local structures. When aggressive pituitary neuroendocrine tumors do develop, conventional treatment options are of limited success. A 50-year-old man developed a giant invasive corticotroph pituitary tumor 2 years after initial presentation. His tumor and symptoms failed to respond to maximal surgical, radio-surgical, radiation and medical therapy and a bilateral adrenalectomy was done. He subsequently developed rapid growth of his tumor leading to multiple cranial nerve deficits. He was administered salvage chemotherapy with capecitabine and temozolomide (CAPTEM), a novel oral chemotherapy regimen developed at our institution for treatment of neuroendocrine tumors. After two cycles of CAPTEM, his tumor markedly decreased in size and ACTH levels fell by almost 90%. Despite further decreases in ACTH levels, his tumor recurred after 5 months with increased avidity on PET scan suggesting a transformation to a more aggressive phenotype. Temozolomide had been reported to be effective against other pituitary tumors and this case adds to this literature demonstrating its use along with capecitabine (CAPTEM) against a corticotroph tumor. Further evaluation of the CAPTEM regimen in patients with pituitary neuroendocrine tumors which fail to respond to classic treatments is warranted.

Nelson's syndrome

Nelson's syndrome is a potentially life-threatening condition that does not infrequently develop following total bilateral adrenalectomy (TBA) for the treatment of Cushing's disease. In this review article, we discuss some controversial aspects of Nelson's syndrome including diagnosis, predictive factors, aetiology, pathology and management based on data from the existing literature and the experience of our own tertiary centre. Definitive diagnostic criteria for Nelson's syndrome are lacking. We argue in favour of a new set of criteria. We propose that Nelson's syndrome should be diagnosed in any patient with prior TBA for the treatment of Cushing's disease and with at least one of the following criteria: i) an expanding pituitary mass lesion compared with pre-TBA images; ii) an elevated 0800 h plasma level of ACTH (>500 ng/l) in addition to progressive elevations of ACTH (a rise of >30%) on at least three consecutive occasions. Regarding predictive factors for the development of Nelson's syndrome post TBA, current evidence favours the presence of residual pituitary tumour on magnetic resonance imaging (MRI) post transsphenoidal surgery (TSS); an aggressive subtype of corticotrophinoma (based on MRI growth rapidity and histology of TSS samples); lack of prophylactic neoadjuvant pituitary radiotherapy at the time of TBA and a rapid rise of ACTH levels in year 1 post TBA. Finally, more studies are needed to assess the efficacy of therapeutic strategies in Nelson's syndrome, including the alkylating agent, temozolomide, which holds promise as a novel and effective therapeutic agent in the treatment of associated aggressive corticotroph tumours. It is timely to review these controversies and to suggest guidelines for future audit.

Nelson's syndrome: physiopathology, management and prognosis

A classical description of a postadrenalectomy syndrome in Cushing's disease, described in 1958 by Don Nelson, included a deep skin hyperpigmentation, presence of a large pituitary tumor, high plasma adrenocorticotropic hormone levels and visual field deficits. The main pathophysiological mechanism of Nelson's syndrome development is a loss of feedback control of hypercortisolemia on corticotroph as a consequence of the removal of hyperactive adrenal glands. Modern techniques of imaging, computed tomography and MRI, made early detection of pituitary tumor at the stage of microadenoma possible. Determinations of plasma adrenocorticotropic hormone concentration during replacement therapy are the next essential diagnostic element. Absolute temporal scotomas in visual field examination are an early sign of Nelson's syndrome. Sufficient hydrocortisone therapy is very important to avoid hypocortisolemia, which stimulates corticotroph cells. Methods of treatment include neurosurgery, radiation therapy and pharmacotherapy. Prognosis in Nelson's syndrome depends on the stage of the disease; it may be poor in invasive pituitary tumors.

Drugs in the medical treatment of Cushing's syndrome

Cushing's syndrome is a complex endocrine condition with potential serious complications if untreated or inadequately treated. Transsphenoidal surgery with resection of a pituitary adenoma is successful in 75 - 80% of patients, but approximately 20 - 25% show persistence of Cushing's, and a similar proportion may experience recurrence within 2 - 4 years post-op. When surgery fails, medical treatment can temporarily suppress excessive cortisol production and ameliorate its clinical manifestations while more definitive therapy becomes effective. We describe pharmacological approaches to the treatment of Cushing's syndrome. Drugs used to suppress cortisol secretion are mostly inhibitors of steroidogenesis. Ketoconazole, fluconazole aminoglutethimide, metyrapone, mitotane and etomidate are in that category. Ketoconazole is in current use while other drugs, although mostly available in the past, continue to have a potential role either alone or in combination. Drugs that suppress adrenocorticotropic hormone (ACTH) secretion are less popular as standard treatment and include cyproheptadine, valproic acid, cabergoline, somatostatin analogs, PPAR-gamma agonists, vasopressin antagonists. Some of these drugs have been tested in limited clinical trials but there is potential therapeutic benefit in analogs with better specificity for the class of receptors present in ACTH-secreting tumors. A third category of drugs is glucocorticoid receptor antagonists. Mifepristone is currently being tested in clinical trials in patients with persistent or recurrent Cushing's disease and in patients with metastatic adrenal cortical carcinoma or ectopic ACTH syndrome not amenable to surgery. We also review replacement therapy after surgery and non-specific drugs to treat complications in patients with severe hypercortisol. The review provides a complete survey of the drugs used in the medical treatment of Cushing's, and new advances in the development of pituitary-active drugs as well as receptor blockers of glucocorticoid action. It also provides avenues for exploration of new drugs active on somatostatin, dopamine and vasopressin receptors. There are effective pharmacological agents capable of chronically reversing biochemical and clinical manifestations of hypercortisolemia in Cushing's syndrome but new drugs are needed with action at the pituitary level.

Pituitary-directed medical treatment of Cushing's disease

The treatment of Cushing's disease is very complex and represents a challenge for clinicians. Transphenoidal surgical excision of adrenocorticotropic hormone (ACTH)-secreting pituitary adenoma remains the treatment of choice but, unfortunately, the rate of cure at long-term follow-up is suboptimal and recurrences are high, even in the hands of skilled neurosurgeons. Other treatment options, such as bilateral adrenalectomy and pituitary radiotherapy, are currently in use but no treatment has proven fully satisfactory during the lengthy progress of this chronic and devastating disease. Nelson's syndrome and hypopituitarism are of particular concern as affected patients need lifelong hormone-replacement therapy and have notably increased mortality. Although medical treatment represents a second-line treatment option in patients with Cushing's disease, so far pharmacological therapy has been considered a transient and palliative treatment. Many drugs have been employed: they may act at the hypothalamic-pituitary level, decreasing ACTH secretion; at the adrenal level, inhibiting cortisol synthesis (steroidogenesis inhibitors); or at the peripheral level by competing with cortisol (glucocorticoid receptor antagonists). Recently, there has been renewed interest in the medical therapy of Cushing's disease and pituitary-directed drugs include old compounds commercially available for other diseases, such as cabergoline, and new promising compounds, such as pasireotide (SOM230) or retinoic acid. This review focuses on the tumor-directed pharmacological approaches for the management of Cushing's disease based on the recent identification of possibile targets at a pituitary level.

Treatment of pituitary-dependent Cushing's disease with the multireceptor ligand somatostatin analog pasireotide (SOM230): a multicenter, phase II trial

CONTEXT

There is currently no medical therapy for Cushing's disease that targets the pituitary adenoma. Availability of such a medical therapy would be a valuable therapeutic option for the management of this disorder.

OBJECTIVE

Our objective was to evaluate the short-term efficacy of the novel multireceptor ligand somatostatin analog pasireotide in patients with de novo, persistent, or recurrent Cushing's disease.

DESIGN

We conducted a phase II, proof-of-concept, open-label, single-arm, 15-d multicenter study.

PATIENTS

Thirty-nine patients with either de novo Cushing's disease who were candidates for pituitary surgery or with persistent or recurrent Cushing's disease after surgery without having received prior pituitary irradiation.

INTERVENTION

Patients self-administered sc pasireotide 600 microg twice daily for 15 d.

MAIN OUTCOME MEASURE

Normalization of urinary free cortisol (UFC) levels after 15 d treatment was the main outcome measure.

RESULTS

Of the 29 patients in the primary efficacy analysis, 22 (76%) showed a reduction in UFC levels, of whom five (17%) had normal UFC levels (responders), after 15 d of treatment with pasireotide. Serum cortisol levels and plasma ACTH levels were also reduced. Steady-state plasma concentrations of pasireotide were achieved within 5 d of treatment. Responders appeared to have higher pasireotide exposure than nonresponders.

CONCLUSIONS

Pasireotide produced a decrease in UFC levels in 76% of patients with Cushing's disease during the treatment period of 15 d, with direct effects on ACTH release. These results suggest that pasireotide holds promise as an effective medical treatment for this disorder.

Nelson's Syndrome

Nelson's syndrome is a potentially severe complication of bilateral adrenalectomy performed in the treatment of Cushing's disease, and its management remains difficult. Of all of the features of Nelson's syndrome, the one that causes most concern is the development of a locally aggressive pituitary tumour, which, unusually for pituitary disease, may occasionally cause death from the tumour itself. This feature is especially pertinent given the increasing use in Cushing's disease of laparoscopic bilateral adrenal surgery as a highly effective treatment modality to control cortisol-excess. Despite numerous studies and reports, there is no formal consensus of what defines Nelson's syndrome. Thus, some will define Nelson's syndrome according to the classical description with an evolving pituitary mass after bilateral adrenalectomy, whereas others will rely on increasing plasma ACTH levels, even in the absence of a clear pituitary mass lesion on MRI. These factors need to be borne in mind when considering the reports of Nelson's syndrome, as there is great heterogeneity, and it is likely that overall the modern 'Nelson's syndrome' represents a different disease entity from that of the last century. In the present paper, clinical and epidemiological features of Nelson's syndrome, as well as its treatment modalities, are reviewed.

Treatment of adrenocorticotropin-dependent Cushing's syndrome: a consensus statement

OBJECTIVE

Our objective was to evaluate the published literature and reach a consensus on the treatment of patients with ACTH-dependent Cushing's syndrome, because there is no recent consensus on the management of this rare disorder.

PARTICIPANTS

Thirty-two leading endocrinologists, clinicians, and neurosurgeons with specific expertise in the management of ACTH-dependent Cushing's syndrome representing nine countries were chosen to address 1) criteria for cure and remission of this disorder, 2) surgical treatment of Cushing's disease, 3) therapeutic options in the event of persistent disease after transsphenoidal surgery, 4) medical therapy of Cushing's disease, and 5) management of ectopic ACTH syndrome, Nelson's syndrome, and special patient populations.

EVIDENCE

Participants presented published scientific data, which formed the basis of the recommendations. Opinion shared by a majority of experts was used where strong evidence was lacking.

CONSENSUS PROCESS

Participants met for 2 d, during which there were four chaired sessions of presentations, followed by general discussion where a consensus was reached. The consensus statement was prepared by a steering committee and was then reviewed by all authors, with suggestions incorporated if agreed upon by the majority.

CONCLUSIONS

ACTH-dependent Cushing's syndrome is a heterogeneous disorder requiring a multidisciplinary and individualized approach to patient management. Generally, the treatment of choice for ACTH-dependent Cushing's syndrome is curative surgery with selective pituitary or ectopic corticotroph tumor resection. Second-line treatments include more radical surgery, radiation therapy (for Cushing's disease), medical therapy, and bilateral adrenalectomy. Because of the significant morbidity of Cushing's syndrome, early diagnosis and prompt therapy are warranted.

Nelson syndrome: comprehensive review of pathophysiology, diagnosis, and management

Nelson syndrome (NS) is a rare clinical manifestation of an enlarging pituitary adenoma that can occur following bilateral adrenal gland removal performed for the treatment of Cushing disease. It is characterized by excess adreno-corticotropin secretion and hyperpigmentation of the skin and mucus membranes. The authors present a comprehensive review of the pathophysiology, diagnosis, and management of NS. Corticotroph adenomas in NS remain challenging tumors that can lead to significant rates of morbidity and mortality. A better understanding of the natural history of NS, advances in neurophysiology and neuroimaging, and growing experience with surgical intervention and radiation have expanded the repertoire of treatments. Currently available treatments include surgical, radiation, and medical therapy. Although the primary treatment for each tumor type may vary, it is important to consider all of the available options and select the one that is most appropriate for the individual case, particularly in cases of lesions resistant to intervention.

Pharmacological management of Cushing's syndrome: an update

The treatment of choice for Cushing's syndrome remains surgical. The role for medical therapy is twofold. Firstly it is used to control hypercortisolaemia prior to surgery to optimize patient's preoperative state and secondly, it is used where surgery has failed and radiotherapy has not taken effect. The main drugs used inhibit steroidogenesis and include metyrapone, ketoconazole, and mitotane. Drugs targeting the hypothalamic-pituitary axis have been investigated but their roles in clinical practice remain limited although PPAR-gamma agonist and somatostatin analogue som-230 (pasireotide) need further investigation. The only drug acting at the periphery targeting the glucocorticoid receptor remains Mifepristone (RU486). The management of Cushing syndrome may well involve combination therapy acting at different pathways of hypercortisolaemia but monitoring of therapy will remain a challenge.

Advances in medical treatment of Cushing's disease

It is well known that transphenoidal surgery is the first line of treatment for Cushing's disease (CD). In case of recurrence, pituitary irradiation or adrenalectomy are usually performed; however, the morbidity due to these procedures is not negligible. For this reason, there is still a strong need for medical therapy, although there are only a few controlled data on this field. A variety of compounds are invaluable complementary tools in the management of this serious condition for which no treatment has yet been proven fully satisfactory. Pharmacological treatment could be employed by using neuromodulatory drugs (i.e., serotonin antagonists, dopamine, and GABA agonists) active only in a few cases of hypothalamic-pituitary-dependent CD. New approaches at the pituitary tumor level involve the potential use of other compounds (e.g., PPAR-γ agonists and retinoic acid). Exciting news in treating CD includes the recent availability of new multiligand somatostatin analogues. This review focuses on the new potential pharmacologic approaches for the management of CD based on the recent identification of possible targets and/or pathogenetic mechanisms.

Prise en charge du syndrome de Nelson: données actuelles

PURPOSE

Nelson's syndrome is a severe complication of bilateral adrenalectomy performed in the treatment of some Cushing's diseases, and its management remains difficult. Trough the observation of a patient suffering from a severe form of Nelson's syndrome for more than 10 years, the authors review the literature and discuss the main current therapeutic possibilities.

CURRENT KNOWLEDGE AND KEY POINTS

Many molecules have been used with variable results. In our observation cabergoline at 2 mg per week seems to be efficient after a 3 and a half years follow-up, in accordance with some recent publications. More than bromocriptine, this dopamine agonist provides interesting prospects for this disease's management. Moreover, if the conventional treatments as valproic acid or cyproheptadine are not very efficient, somatostatin analogs seem to be of some therapeutic interest.

FUTURE PROSPECTS AND PROJECTS

New molecules are currently evaluated, but studies are difficult to conduct because of the low disease prevalence. Tumour receptors analysis undoubtedly constitutes an attractive way to find new therapeutic targets.

Peroxisome proliferator-activated receptor gamma in the human pituitary gland: expression and splicing pattern in adenomas versus normal pituitary

Pituitary adenomas are slow-growing tumours arising within the pituitary gland. If secreting, they give rise to well-known syndromes such as Cushing's disease or acromegaly; when hormonally inactive, they come to clinical attention often with local mass effects or pituitary deficiency. Peroxisome proliferator-activated receptor gamma (PPARgamma), a nuclear hormone receptor with a key role in fat and glucose metabolism, but also involved in several neoplasia, has recently been detected in pituitary adenomas. In the present study, we evaluated the occurrence and splicing profile of PPARgamma in 43 cases of pituitary adenoma of different subtypes and compared it to 12 normal pituitary glands. By real-time polymerase chain reaction, PPARgamma was expressed as much in adrenocorticotrophic hormone (ACTH)-secreting and ACTH-silent adenomas as in controls, with a moderate underexpression in somatotrophinomas and prolactinomas and overexpression in 54% of nonfunctioning pituitary adenomas (NFPA). There was no apparent qualitative change in the splicing profile of pathological pituitary glands, nor was the presence of specific isoforms with dominant negative effects against PPARgamma detected. Western blotting revealed similar expression levels in the different subgroups of pituitary adenomas and normal glands. Immunohistochemistry confirmed PPARgamma expression in approximately one-half of analysed samples. The intra- and intergroup differences observed in pituitary adenomas may represent new elements in the process of understanding the different clinical responses of Cushing's and Nelson patients to PPARgamma-ligand treatment. Moreover, the higher level of PPARgamma expression detected in the NFPA subgroup may suggest its possible role as a molecular target in these pituitary adenomas, paving the way for investigations on the effectiveness of treatment with thiazolidinediones in such patients.

Ineffectiveness of rosiglitazone therapy in Nelson's syndrome

BACKGROUND

Peroxisome proliferator-activated receptor (PPAR)-gamma agonists have been proposed as therapy to lower plasma ACTH in Cushing's disease. Cyclical secretion of ACTH may, however, explain some of the responses seen. Patients with Nelson's syndrome have persistently high levels of ACTH and may be a better model for examining new therapies to elevated ACTH levels.

OBJECTIVE

The objective of the study was to assess whether high-dose rosiglitazone therapy reduces circulating ACTH levels in Nelson's syndrome, a model of ACTH hypersecretion for which no established medical therapy exists.

DESIGN

The design was an open-label, prospective, nonrandomized study over 14 wk.

SETTING

The study was conducted at a university teaching hospital.

PATIENTS

Six patients with Nelson's syndrome participated in the study.

METHODS

Patients were assessed at -2, 0, 4, 8, and 12 wk. Rosiglitazone 12 mg/d was administered between 0 and 8 wk. PPAR-gamma immunoreactivity was assessed in pathological tissue.

OUTCOME MEASURE

Plasma ACTH was measured before (0830 h) and 120 min after morning dosing with hydrocortisone (HC).

RESULTS

One female withdrew prior to commencing therapy for personal reasons. There was no evidence that ACTH levels changed over time (P = 0.864). The average ACTH level was 1187 ng/liter (95% confidence interval 928-1446) for patients before the HC dose and 432 ng/liter (95% confidence interval 172-692) after the HC dose. PPAR-gamma immunoreactivity was positive in three ACTH-secreting tumors available.

CONCLUSIONS

Rosiglitazone 12 mg/d did not change circulating ACTH over time, despite PPAR-gamma receptor expression in the tumor tissue. However, this does not preclude the possibility that other patients may respond or that higher doses of rosiglitazone or more potent agonists might prove useful treatment.

PPAR-gamma expression in pituitary tumours and the functional activity of the glitazones: evidence that any anti-proliferative effect of the glitazones is independent of the PPAR-gamma receptor

OBJECTIVE

It has been reported that both normal pituitary and pituitary tumours express PPAR-gamma, a nuclear hormone receptor, the expression being more abundant in pituitary tumours, and that this is the basis for the reported antiproliferative effects of the thiazolidinedione, rosiglitazone, in animal models. However, the mechanisms for the responsivity to rosiglitazone have remained unclear.

DESIGN AND MEASUREMENTS

To investigate this further, 'real-time' PCR was used to assess PPAR-gamma mRNA expression, and Western blotting and immunohistochemistry to study its protein expression, in 46 human pituitary tumours and normal pituitary tissue. Cell proliferation of the GH3 pituitary cell line was assessed by [3H]-thymidine-incorporation after 48 h rosiglitazone and pioglitazone (10(-4) M- 10(-10) M) treatment alone, or rosiglitazone in combination with the PPAR-gamma antagonist GW9662.

RESULTS

PPAR-gamma mRNA and protein was found to be expressed in normal pituitary and was variably expressed in pituitary tumours, but were increased specifically in nonfunctioning pituitary adenomas. However, very little staining was observed with immunohistochemistry, with only occasional cell nuclei stained, and no difference was detectable between controls and tumours. Rosiglitazone at 10(-4) M and 10(-5) M concentrations inhibited cell proliferation (10(-4) M 14.0% +/- 1.5% and 10(-5) M 67% +/- 4%[mean +/- SEM]vs Control 100% +/- 3%, P < 0.0001) while lower concentrations showed no significant effect. Following withdrawal of rosiglitazone 10(-5) M, the cells fully recovered at a further 48 h, while lower doses showed a 'rebound' of stimulation. Pioglitazone was of similar potency to rosiglitazone in inhibiting proliferation. The PPAR-gamma antagonist did not show a significant reversal of the antiproliferative effect of rosiglitazone, and indeed suppressed proliferation on its own.

CONCLUSIONS

Our data suggest that the antiproliferative action of rosiglitazone is probably not via PPAR-gamma.

Clinical and biochemical stabilization of Nelson's syndrome with long-term low-dose cabergoline treatment

We report the results of long-term (6-year) treatment of Nelson's syndrome with the long-acting dopamine agonist, cabergoline, in a 55-year-old woman. The disease presented 26 years after bilateral adrenalectomy and radiation treatment for Cushing's disease, followed by glucocorticoid and mineralocorticoid replacement therapy. Signs of Nelson's syndrome included skin and mucosal hyperpigmentation accompanied by elevated plasma levels of adrenocorticotropic hormone (ACTH) (984 pmol/l; normal, 2.0-11.5 pmol/l). Magnetic resonance imaging of the pituitary demonstrated sellar enlargement with a 15 mm macroadenoma. The patient was initially treated with bromocriptine (10 mg/d) which had no effect on either ACTH level or tumor mass. Because of visual loss, transsphenoidal surgery was performed, with partial excision of the adenoma and chiasmal decompression, followed by radiosurgery. However, ACTH levels improved only temporarily, and then increased to previous levels. Therefore, cabergoline treatment (1.5 mg/week) was initiated. ACTH levels decreased dramatically from 1050 to 132 pmol/l, accompanied by clinical improvement. Repeated imaging studies demonstrated a stable residual pituitary tumor. This case demonstrates that long-term cabergoline treatment may be efficient in patients with Nelson's syndrome.