Macroprolactinoma associated with Cushing's disease, successfully treated with cabergoline

Case report: Complete restoration of the HPA axis function in Cushing's disease with drug treatment

This report describes a rare case of a 20-year-old man with an ACTH- and prolactin-secreting invasive pituitary macroadenoma causing hyperprolactinemia and Cushing's disease. He was later found to have an AIP mutation. Treatment with cabergoline (1.5 mg weekly) normalized prolactin concentrations and induced a major shrinkage of the adenoma. Not only was urinary free cortisol normalized for more than 14 years, but also the treatment induced normal hypothalamo-pituitary-adrenal (HPA) axis function as illustrated by the reappearance of a normal cortisol/ACTH circadian rhythm, cortisol suppression to dexamethasone, and disappearance of the excessive and aberrant responses to CRH and desmopressin, respectively. This case is the first description of complete restoration of the physiological characteristics of the HPA axis by a medication during the treatment of Cushing's disease. Although exceptional, it illustrates that drugs targeting the pituitary adenoma can bring true complete remission of Cushing's disease.

Pathogenesis, clinical features, and treatment of plurihormonal pituitary adenoma

Plurihormonal pituitary adenoma (PPA) is a type of pituitary tumor capable of producing two or more hormones and usually presents as an aggressive, large adenoma. As yet, its pathogenesis remains unclear. This is the first study to systematically summarize the underlying pathogenesis of PPA. The pathogenesis is related to plurihormonal primordial stem cells, co-transcription factors, hormone co-expression, differential gene expression, and cell transdifferentiation. We conducted a literature review of PPA and analyzed its clinical characteristics. We found that the average age of patients with PPA was approximately 40 years, and most showed only one clinical symptom. The most common manifestation was acromegaly. Currently, PPA is treated with surgical resection. However, recent studies suggest that immunotherapy may be a potentially effective treatment.

Dopamine agonist-responsive Cushing’s disease

A 47-year-old Caucasian man was referred to our clinic with a severe clinical and biochemical phenotype of endogenous hypercortisolism for further evaluation and treatment. In addition to confirming adrenocorticotropic hormone (ACTH)-dependent Cushing’s syndrome, we found left temporal hemianopsia, massively increased prolactin, increased growth hormone/insulin-like growth factor 1 values, hypogonadotropic hypogonadism and central hypothyroidism. As the cause of these abnormalities we revealed an invasive macroadenoma of the pituitary secreting ACTH, prolactin and growth hormone, resulting not only in a clinically predominant picture of Cushing’s syndrome but also causing hypogonadotropic hypogonadism and central hypothyroidism. The patient responded surprisingly well to dopamine agonist treatment leading not only to normalisation of prolactin levels but also to clinical and biochemical remission of Cushing’s syndrome. Tumour size decreased successively in follow-up MRI scans. Despite lacking immunohistochemical analysis of tumour tissue, we assume plurihormonal secretion of ACTH, prolactin and growth hormone from pituitary macroadenoma, which fortunately responded well to dopamine agonist treatment.

An unusual case of Cushing's syndrome due to bihormonal ACTH-prolactin secreting pituitary macroadenoma with rapid response to cabergoline

A 23-year-old man presenting with florid Cushing's syndrome was found to have high plasma ACTH and very high serum prolactin. Pituitary MRI showed a large invasive macroadenoma. Low-dose cabergoline promptly suppressed both ACTH and prolactin levels within 2 weeks, with unexpected clinical and biochemical hypocortisolism requiring hydrocortisone replacement. Secondary hypogonadism was reversed. Clinical and biochemical remission of his Cushing's syndrome together with significant shrinkage of his macroadenoma has been maintained for 1 year on cabergoline 0.5 mg twice weekly. Reduction in pituitary tumour volume and brisk fall in serum prolactin in response to low-dose cabergoline is regularly observed in patients with macroprolactinomas, but the concurrent fall in the plasma ACTH level and hypocortisolism was a pleasant surprise. We assume that he most likely has a single bihormonal adenoma that is enriched with dopamine-2 receptors.

Hypersecretion of ACTH and PRL from pituitary adenoma in MEN1, adequately managed by medical therapy

Summary

A 54-year-old man had gastrinoma, parathyroid hyperplasia and pituitary tumor. His family history indicated that he might have multiple endocrine neoplasia type 1 (MEN1). MEN1 gene analysis revealed a heterozygous germline mutation (Gly156Arg). Therefore, we diagnosed him with MEN1. Endocrinological tests revealed that his serum prolactin (PRL) and plasma adrenocorticotropic hormone (ACTH) levels were elevated to 1699 ng/mL and 125 pg/mL respectively. Immunohistochemical analysis of the resected pancreatic tumors revealed that the tumors did not express ACTH. Overnight 0.5 and 8 mg dexamethasone suppression tests indicated that his pituitary tumor was a PRL-ACTH-producing plurihormonal tumor. Before transsphenoidal surgery, cabergoline was initiated. Despite no decrease in the volume of the pituitary tumor, PRL and ACTH levels decreased to 37.8 ng/mL and 57.6 pg/mL respectively. Owing to the emergence of metastatic gastrinoma in the liver, octreotide was initiated. After that, PRL and ACTH levels further decreased to 5.1 ng/mL and 19.7 pg/mL respectively. He died from liver dysfunction, and an autopsy of the pituitary tumor was performed. In the autopsy study, histopathological and immunohistochemical (IHC) analysis showed that the tumor was single adenoma and the cells were positive for ACTH, growth hormone (GH), luteinizing hormone (LH) and PRL. RT-PCR analysis showed that the tumor expressed mRNA encoding all anterior pituitary hormones, pituitary transcription factor excluding estrogen receptor (ER) β, somatostatin receptor (SSTR) 2, SSTR5 and dopamine receptor D (D2R). PRL-ACTH-producing tumor is a very rare type of pituitary tumor, and treatment with cabergoline and octreotide may be useful for controlling hormone levels secreted from a plurihormonal pituitary adenoma, as seen in this case of MEN1.

Learning points:

Cabergoline for Cushing's disease: a large retrospective multicenter study

OBJECTIVE

The efficacy of cabergoline in Cushing's disease (CD) is controversial. The aim of this study was to assess the efficacy and tolerability of cabergoline in a large contemporary cohort of patients with CD.

DESIGN

We conducted a retrospective multicenter study from thirteen French and Belgian university hospitals.

METHODS

Sixty-two patients with CD received cabergoline monotherapy or add-on therapy. Symptom score, biological markers of hypercortisolism and adverse effects were recorded.

RESULTS

Twenty-one (40%) of 53 patients who received cabergoline monotherapy had normal urinary free cortisol (UFC) values within 12 months (complete responders), and five of these patients developed corticotropic insufficiency. The fall in UFC was associated with significant reductions in midnight cortisol and plasma ACTH, and with clinical improvement. Compared to other patients, complete responders had similar median baseline UFC (2.0 vs 2.5xULN) and plasma prolactin concentrations but received lower doses of cabergoline (1.5 vs 3.5 mg/week, P < 0.05). During long-term treatment (>12 months), cabergoline was withdrawn in 28% of complete responders because of treatment escape or intolerance. Overall, sustained control of hypercortisolism was obtained in 23% of patients for 32.5 months (19-105). Nine patients on steroidogenesis inhibitors received cabergoline add-on therapy for 19 months (1-240). Hypercortisolism was controlled in 56% of these patients during the first year of treatment with cabergoline at 1.0 mg/week (0.5-3.5).

CONCLUSIONS

About 20-25% of CD patients are good responders to cabergoline therapy allowing long-term control of hypercortisolism at relatively low dosages and with acceptable tolerability. No single parameter, including the baseline UFC and prolactin levels, predicted the response to cabergoline.

Concomitant Cushing's Disease and Marked Hyperprolactinemia: Response to a Dopamine Receptor Agonist

A 38-year-old woman was admitted to our hospital because of amenorrhea, multiple bone fractures, and a Cushingoid appearance. Endocrinological investigations revealed that she had co-existing Cushing's disease and prolactinoma, with a serum level of prolactin (PRL) at 1,480 ng/mL, corticotropin (ACTH) at 81.3 pg/mL, and cortisol at 16.6 μg/dL. Due to the lack of indication for transsphenoidal surgery, cabergoline monotherapy was initiated. A 6-month course of treatment resulted in only subtle amelioration of hypercortisolism, while hyperprolactinemia was dramatically improved. In 5 cases of bihormonal (ACTH/PRL) pituitary macroadenoma reported in the English literature, 2 were initially treated with dopaminergic agonists with substantial effectiveness for both PRL and ACTH. We herein report an extremely rare case of bihormonal macroadenoma in which only PRL was responsive to treatment.

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.

Effectiveness of cabergoline in monotherapy and combined with ketoconazole in the management of Cushing's disease

The expression of dopamine receptor subtypes has been reported in corticotroph adenomas, and this finding support the possibility for medical treatment of Cushing's disease (CD) with dopamine agonists when conventional treatment has failed. The aim of this study was to evaluate the effectiveness of cabergoline (at doses of up 3 mg/week), alone or combined with relatively low doses of ketoconazole (up to 400 mg/day), in 12 patients with CD unsuccessfully treated by transsphenoidal surgery. After 6 months of cabergoline therapy, normalization of 24 h urinary free cortisol (UFC) levels occurred in three patients (25%) at doses ranging from 2-3 mg/week, whereas reductions ranging from 15.0 to 48.4% were found in the remaining. The addition of ketonocazole to the nine patients without an adequate response to cabergoline was able to normalize UFC excretion in six patients (66.7%) at doses of 200 mg/day (three patients), 300 mg/day (two patients) and 400 mg/day (one patient). In the remaining patients UFC levels did not normalize but a significant reduction ranging from to 44.4 to 51.7% was achieved. In two of the six responsive patients to combination therapy, the weekly dose of cabergoline could be later reduced from 3 to 2 mg. Our findings demonstrated that cabergoline monotherapy was able to reverse hypercortisolism in 25% of patients with CD unsuccessfully treated by surgery. Moreover, the addition of relatively low doses of ketoconazole led to normalization of UFC in about two-thirds of patients not achieving a full response to cabergoline.

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.

Cushing's Syndrome

Cushing's syndrome is a rare endocrine disease characterized by cortisol hypersecretion, induced mainly by a pituitary tumor (Cushing's disease) or, rarely, by an adrenal or an ectopic neuroendocine tumor. Cushing's syndrome is associated with severe morbidities and an increased mortality. The major systemic complications and the main cause of death are represented by cardiovascular disease. The prognosis of the disease is mainly affected by the difficulties in the diagnosis and treatment of the disease, which remain a considerable challenge.

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.

Control of pituitary adenoma cell proliferation by somatostatin analogs, dopamine agonists and novel chimeric compounds

The antisecretory effects of somatostatin (SRIH) and its analogs are widely recognized and provide the basis for treatment of hormonal hypersecretion in patients with pituitary adenomas, especially in the settings of acromegaly. Dopamine (DA) agonists have also been used for medical treatment of prolactin and/or GH hypersecretion, and recent evidence points to an even greater antisecretory effect for a chimeric molecule, having high affinity for both SRIH and DA receptors. Evidence for an antiproliferative effect of these compounds has also been provided. This review focuses on the antiproliferative effects of SRIH and its analogs, of DA and chimeric compounds on pituitary adenomas, and on the clinical consequences on tumor volume of pharmacological treatment of pituitary adenomas with these drugs.

Cushing's Syndrome: important issues in diagnosis and management

CONTEXT

The diagnosis, differential diagnosis, and treatment of Cushing's syndrome are challenging problems in clinical endocrinology. We focus on critical questions addressing screening for Cushing's syndrome, differentiation of Cushing's subtypes, and treatment options.

EVIDENCE ACQUISITION

Ovid's MEDLINE (1996 through April 2006) was used to search the general literature. We also relied on previously published reviews and a recent monograph and cite a mix of primary articles and recent reviews.

EVIDENCE SYNTHESIS

Although this article represents our opinion, it draws heavily on a recent consensus statement from experts in the field and a recent monograph on Cushing's syndrome.

CONCLUSIONS

We concluded that: 1) measurement of late-night or bedtime salivary cortisol is a useful approach to screen for Cushing's syndrome; 2) measurement of suppressed plasma ACTH by immunometric assay is useful to differentiate ACTH-dependent and -independent Cushing's syndrome; 3) inferior petrosal sinus sampling for ACTH should be performed in patients with ACTH-dependent hypercortisolism in whom a pituitary magnetic resonance imaging is normal or equivocal (in the absence of a pituitary ACTH gradient, prolactin levels should be measured to confirm the integrity of venous sampling); 4) computed tomography of the chest and abdomen and somatostatin receptor scintigraphy should be performed in patients with the occult ectopic ACTH syndrome; and 5) patients with Cushing's disease should be referred to a neurosurgeon with extensive experience operating on corticotroph microadenomas. Bilateral laparoscopic adrenalectomy should be considered in patients with Cushing's disease who fail therapies directed at the pituitary.

Pharmacologic Management of Cushing Syndrome

The successful treatment of Cushing syndrome depends on specific therapy directed against the etiology of hypercortisolism. In addition to surgical procedures, various drugs have been employed in the management of this difficult disease. Compounds with neuromodulatory properties have been effective in only a limited number of cases of hypothalamic-pituitary-dependent Cushing disease, the most common form of Cushing syndrome. These agents include serotonin antagonists (cyproheptadine, ketanserin, ritanserin), dopamine agonists (bromocriptine, cabergoline), GABA agonists (valproic acid [sodium valproate]), and somatostatin analogs (octreotide). Interesting new avenues at the pituitary level involve the potential use of thiazolidinedione compounds, such as rosiglitazone, and of retinoic acid, which are ligands of different nuclear hormone receptors involved in hypothalamic-pituitary regulation. The most exciting news, however, in the pharmacologic approach to Cushing syndrome refers to the adrenal corticotropin (adrenocorticotropic hormone; ACTH)-independent forms, in which aberrant adrenal receptors, through the binding of their respective ligands, could lead to chronic cortisol overproduction. They include receptors for gastric inhibitory peptide (GIP), beta-adrenergic agonists, luteinizing hormone (LH)/human chorionic gonadotropin, serotonin (5-HT(4) receptor), vasopressin (V(1) receptor), and angiotensin II (AT(1) receptor). In GIP-dependent Cushing syndrome, the most frequent subtype of ACTH-independent macronodular adrenal hyperplasia associated with the presence of aberrant adrenocortical hormone receptors described so far, octreotide administration before each meal showed clinical efficacy only in the first few months, probably because of somatostatin receptor downregulation in GIP-secreting cells. Long-term medical treatments with propranolol and the gonadotropin-releasing hormone analog leuprorelin (leuprolide acetate) were effective in patients with catecholamine-dependent and LH-dependent Cushing syndrome, respectively. The oral vasopressin V(1) receptor antagonist OPC-21268 and the angiotensin II (AT(1)) receptor antagonist candesartan cilexetil were also able to decrease cortisol levels during the few days of administration of the drugs in patients with specific receptor abnormalities. These adrenal forms of Cushing syndrome are rare, and clinical data are scarce. Moreover, the real clinical significance of aberrant hormone receptors is still under investigation, as is the possibility of avoiding surgery by pharmacologic manipulation. Patients in whom these intriguing syndromes are suspected require detailed investigation protocols, which should be carried out in specialized centers. While awaiting further developments, the use of traditional medical treatment at the adrenal level with adrenal steroid inhibitors is still valuable in several instances.

Effect of cabergoline treatment on Cushing's disease caused by aberrant adrenocorticotropin-secreting macroadenoma

The present case involves a 47-yr-old woman with Cushing's disease due to pituitary macroadenoma. The patient had suffered from hypertension and obesity for two yr. Her serum cortisol levels were moderately elevated throughout the observation period, and dexamethasone failed to suppress the cortisol secretion. Plasma ACTH levels were markedly high (>100 pg/ml) and did not respond to CRH provocation. Gel filtration analysis of the patient's plasma detected the existence of big ACTH molecules, which eluted with a peak of authentic 1-39 ACTH. Cranial magnetic resonance imaging (MRI) revealed a 3 cm pituitary tumor occupying the sellar region and right cavernous sinus with diffuse enhancement by gadolinium. The pituitary mass was removed by transsphenoidal surgery, and was pathologically identified as compatible to ACTH-producing pituitary adenoma by immunohistochemistry. RT-PCR analysis of total cellular RNA extracted from the resected adenoma revealed a relatively high expression level of dopamine D2 receptor (D2R) mRNA. Therefore, a long-acting D2R agonist, cabergoline (0.25 to 0.5 mg/week), was administered for the remnant adenoma, which gradually reduced ACTH levels in 90 days. In addition, cranial MRI exhibited shrinkage of the remnant pituitary mass after a 6-month treatment with cabergoline. This case demonstrates the efficacy of cabergoline to treat Cushing's disease caused by pituitary macroadenoma secreting aberrant ACTH molecules.