Lack of effect of bromocriptine on ACTH levels in patients with bilateral adrenalectomy for pituitary-dependent Cushing's syndrome

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.

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.

Limited value of cabergoline in Cushing's disease: a prospective study of a 6-week treatment in 20 patients

CONTEXT AND OBJECTIVE

The role of cabergoline in Cushing's disease (CD) remains controversial. The experience is limited to case reports and few open studies that report the effects determined after ≥1 month of treatment. In prolactinomas and dopamine-responsive GH-secreting tumours, effects of cabergoline are seen within days or weeks. Here, we searched for short-term effects of cabergoline in CD.

DESIGN

Twenty patients (19 naïve and one recurrent) were included in a prospective study. Cabergoline was administered in increasing doses of 0.5-5 mg/week over 6 weeks.

METHODS

Urinary free cortisol (UFC) 24 h, morning cortisol and ACTH, and salivary cortisol at 0800, 1600 and 2300 h were determined once weekly throughout. Diurnal curves (six samples) of serum cortisol were measured at start and end.

RESULTS

At study end, the median cabergoline dose was 5 mg, range 2.5-5 mg/week. The prolactin levels, markers of compliance, were suppressed in all patients. During the treatment, hypercortisolism varied, gradual and dose-dependent reductions were not seen. Five patients had a >50% decrease of UFC, three had a >50% rise of UFC. Salivary cortisol at 2300 h showed a congruent >50% change with UFC in two of the five cases with decreased UFC, and in one of the three cases with increased UFC. One patient with decreases in both UFC and 2300 h salivary cortisol also had a reduction in diurnal serum cortisol during the course of the study.

CONCLUSIONS

Cabergoline seems to be of little value in the management of CD. Only one patient had a response-like pattern. Given the known variability of disease activity in CD, this might represent a chance finding.

Nelson’s Syndrome: Complete Remission with Cabergoline but Not with Bromocriptine or Cyproheptadine Treatment

A woman affected by Cushing's disease underwent bilateral adrenalectomy followed by radiotherapy of the hypothalamic-pituitary area when she was 18 years old. Thereafter, she used hydrocortisone acetate replacement therapy (35.5 mg divided into two daily doses). At the age of 26 years, the patient exhibited the clinical signs of the Nelson's syndrome, i.e. skin and gingival hyperpigmentation accompanied by amenorrhea, and elevated ACTH plasma levels (2,850 pg/ml, normal range 15-80 pg/ml). The magnetic resonance imaging (MRI) analysis of the sellar region evidenced a pituitary macroadenoma, measuring 14 x 13 mm. The patient was initially treated with cyproheptadine hydrochloride (12 mg/day) for 18 months. There was a partial improvement of the symptoms, with a reduction of the ACTH plasma levels to 112 pg/ml, but without any modification of the tumor mass. Due to sleepiness and weight gain, the cyproheptadine treatment was interrupted and substituted by a cabergoline (0.5 mg twice a week) therapy. Soon after cabergoline was applied an improvement of the clinical symptoms and signs was observed such as a regression of the tumor mass and the normalization of the ACTH plasma titers (38 pg/ml). Later, cabergoline was substituted by bromocriptine (7.5 mg/day) and the plasma levels of ACTH increased again (247 pg/ml), and headache and cutaneous hyperpigmentation were recorded. When cabergoline was reintroduced there was a clinical improvement and normalization of ACTH plasma levels (64 pg/ml). The MRI analysis of the sella region demonstrated a complete remission of the pituitary adenoma. The results obtained show for the first time that a long-term treatment with cabergoline also brings about a complete remission of Nelson's syndrome in the presence of a pituitary macroadenoma.

An acth-secreting pituitary tumour arising in a patient with congenital adrenal hyperplasia

The case reported is of a 46-year-old woman who had congenital adrenal hyperplasia due to a 21-hydroxylase deficiency, and in whom there was the development of an ACTH secreting pituitary tumour. The patient was untreated with glucocorticoids until the age of 32 years when she presented with infertility. She next presented with amenorrhoea at the age of 44 years when she was found to have an enlarged pituitary fossa. Despite treatment with bromocriptine and adequate doses of dexamethasone, the tumour enlarged and required operative treatment 1 year later. Before and after operation, plasma ACTH levels were between 300 and 400 ng/l, immunocytochemistry showed staining for ACTH and other structurally related pro-opiocortin peptides but for no other hormones, and the tumour secreted large amounts of ACTH in vitro. The report of this case is to our knowledge the first account of a feedback tumour in congenital adrenal hyperplasia and provides yet another reason why patients with this condition should be treated, and good control achieved.

Long term bromocriptine therapy in Cushing's disease

Recently, bromocriptine has been successfully introduced as medical therapy for the pituitary hypersecreting syndromes of hyperprolactinemia and acromegaly. Subsequently, an inhibitory effect on ACTH secretion was reported using bromocriptine in Cushing's disease. While most studies have focused on the acute response to bromocriptine, few have investigated the response to chronic therapy with this agent. In this report, we describe a patient with Cushing's disease in whom an acute inhibition of ACTH and cortisol was demonstrated following bromocriptine and in whom the long term administration of bromocriptine as the sole therapy produced a transient beneficial response. Further pharmacologic testing suggested this inhibitory effect on the hypothalamic-pituitary-adrenal axis was mediated through dopaminergic stimulation.

Direct effects of thyrotropin-releasing hormone, cyproheptadine, and dopamine on adrenocorticotropin secretion from human corticotroph adenoma cells in vitro

In an attempt to delineate the mechanism and the site of action of cyproheptadine and dopaminergic agonists as well as hormones including thyrotropin-releasing hormone (TRH) and hydrocortisone, the effects of these substances on ACTH secretion from corticotroph adenoma cells in culture were examined. Dispersed cells of pituitary adenomas obtained at surgery from four patients with Nelson's syndrome and one subject with Cushing's disease formed a monolayer and actively secreted ACTH into the medium. When TRH (0.1 microM) was added to the medium, a significant increase in ACTH secretion was demonstrated by adenoma cells from two patients who responded to TRH preoperatively. Moreover, a dose-response relationship between TRH concentrations and ACTH secretion was observed. Incubation of cells with cyproheptadine (1 or 0.1 microM) resulted in a significant decrease in ACTH release, and inhibited stimulation produced by TRH in one experiment. This effect of cyproheptadine was blocked when equimolar concentrations of serotonin was coincubated, whereas serotonin by itself did not affect ACTH secretion. Dopamine (0.1 microM) lowered ACTH accumulation in the medium, which was blocked by the addition of haloperidol. When hydrocortisone was added to the culture, dose-dependent suppression of ACTH secretion was demonstrated. TRH at an equimolar concentration reversed this effect, but, failed to overcome the inhibition induced by a higher concentration of hydrocortisone in cells from one adenoma studied. Cultured normal corticotrophs obtained from a patient with metastatic breast cancer, on the other hand, did not show any response to these substances, except for hydrocortisone. We suggest that TRH, cyproheptadine, dopamine affect ACTH secretion in patients with ACTH-producing pituitary adenomas by their direct action on the adenoma.