Endocrine clinical update: where are we in the therapeutic management of pituitary-dependent hypercortisolism?

Up-to 5-year efficacy of pasireotide in a patient with Cushing's disease and pre-existing diabetes: literature review and clinical practice considerations

PURPOSE

Pasireotide is a multi-receptor-targeted somatostatin analogue approved in the EU and in the US for the treatment of adults with Cushing's disease (CD). Pasireotide has a safety profile similar to other somatostatin analogues with the exception of hyperglycemia. In this report and literature review, the current understanding of predicting a positive treatment response to pasireotide in CD and the management of diabetes mellitus (DM) during pasireotide treatment are discussed and analyzed.

CASE PRESENTATION

We report a case of a 55-year-old woman with CD and DM who benefitted from long-term pasireotide. The patient, who was enrolled in a phase III trial of the drug, showed early clinical improvements with pasireotide [900 μg subcutaneously twice daily (bid)] but was classified as a non-responder as urinary free cortisol (UFC) levels, were not normalized. Continuation of pasireotide for 12 months at an increased dose (1,200 μg bid) normalized UFC levels and restored cortisol rhythm. The initial deterioration in her blood glucose was managed with insulin and metformin; however, after 12 months' treatment with pasireotide her DM was well controlled with oral hypoglycemic agents. Five years later, the patient is still receiving pasireotide (300 μg bid) with no loss of clinical or biochemical efficacy and with continued glycemic control.

CONCLUSIONS

This case presentation indicates that uncontrolled UFC levels during the first few months of pasireotide treatment as well as worsening of glycemic control in patients with CD and DM are not always predictive of the efficacy and tolerability and appears to support the long-term continuation of pasireotide.

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.

Mifepristone, a glucocorticoid receptor antagonist, produces clinical and metabolic benefits in patients with Cushing's syndrome

CONTEXT

Cushing's syndrome (CS) is a disorder associated with significant morbidity and mortality due to prolonged exposure to high cortisol concentrations.

OBJECTIVE

Our objective was to evaluate the safety and efficacy of mifepristone, a glucocorticoid receptor antagonist, in endogenous CS.

DESIGN AND SETTING

We conducted a 24-wk multicenter, open-label trial after failed multimodality therapy at 14 U.S. academic medical centers and three private research centers.

PARTICIPANTS

Participants included 50 adults with endogenous CS associated with type 2 diabetes mellitus/impaired glucose tolerance (C-DM) or a diagnosis of hypertension alone (C-HT).

INTERVENTION

Mifepristone was administered at doses of 300-1200 mg daily.

MAIN OUTCOME MEASURES

We evaluated change in area under the curve for glucose on 2-h oral glucose test for C-DM and change in diastolic blood pressure from baseline to wk 24 for C-HT.

RESULTS

In the C-DM cohort, an area under the curve for glucose (AUC(glucose)) response was seen in 60% of patients (P < 0.0001). Mean ± sd glycated hemoglobin (HbA1c) decreased from 7.43 ± 1.52% to 6.29 ± 0.99% (P < 0.001); fasting plasma glucose decreased from 149.0 ± 75.7 mg/dl (8.3 ± 4.1 mmol/liter) to 104.7 ± 37.5 mg/dl (5.8 ± 2.1 mmol/liter, P < 0.03). In C-HT cohort, a diastolic blood pressure response was seen in 38% of patients (P < 0.05). Mean weight change was -5.7 ± 7.4% (P < 0.001) with waist circumference decrease of -6.78 ± 5.8 cm (P < 0.001) in women and -8.44 ± 5.9 cm (P < 0.001) in men. Overall, 87% (P < 0.0001) had significant improvement in clinical status. Insulin resistance, depression, cognition, and quality of life also improved. Common adverse events were fatigue, nausea, headache, low potassium, arthralgia, vomiting, edema, and endometrial thickening in women.

CONCLUSIONS

Mifepristone produced significant clinical and metabolic improvement in patients with CS with an acceptable risk-benefit profile during 6 months of treatment.

Psychosomatic aspects of Cushing's syndrome

There has been growing interest in the psychosocial aspects of Cushing's syndrome, such as the role of life stress as a pathogenetic factor, the association with affective disorders, and the presence of residual symptoms after treatment. Interestingly, a temporal relationship between stressful life events and disease onset is relevant only to pituitary-dependent Cushing's disease, and not to the pituitary-independent forms. A number of psychiatric and psychological disturbances may be associated with the active hypercortisolemic state, regardless of its etiology. Within the high frequency of mood disorders (about 60%), major depression is the most common complication. Other psychopathological aspects include mania, anxiety disorders, psychological symptoms (demoralization, irritable mood, somatization) and cognitive impairment. Cognitive symptoms are associated with brain abnormalities (mainly loss of brain volume). Quality of life may be seriously compromised during both active and post-treatment phases. Long-standing hypercortisolism may imply a degree of irreversibility of the pathological process. Recovery, thus, may be delayed and be influenced by highly individualized affective responses. Outcomes of Cushing's syndrome treatment are not fully satisfactory. Within its great complexity, a conceptual shift from a merely biomedical care to a psychosomatic consideration of the person and his/her quality of life appears to be necessary to improve effectiveness. It is time to translate the research evidence that has accumulated into clinical practice initiatives. To patients who show persistence or even worsening of psychological distress upon adequate endocrine treatment psychiatric/psychological interventions should be readily available. Applying interdisciplinary expertise and addressing the needs for rehabilitation would markedly improve final outcome.

Should we evaluate for cardiovascular disease in patients with Cushing's syndrome?

Current evidence indicates a strong association between Cushing's syndrome, characterized by a cluster of systemic complications and increased cardiovascular risk. The biological link is cortisol overproduction, which influences various pathogenetic processes leading to cardiovascular damage, a main cause of increased mortality. Anthropometric and biochemical profile (including fasting glucose, lipids, potassium and coagulation parameters), clinical blood pressure measurement and electrocardiogram should be routinely carried out. Oral glucose tolerance test, 24-h ambulatory blood pressure monitoring, echocardiography and carotid ultrasound are recommended for further evaluation. Search for cardiac and vascular damage, according to specialist's advice, is mandatory in complicated hypertension or diabetes, as part of a comprehensive assessment. A combination of treatments directed against the aetiology of hypercortisolism and aimed at controlling cardiovascular risk factors, is required in this complex condition.

New treatment guidelines on Cushing's disease

It is important to treat patients with Cushing's disease as rapidly as possible to limit its long-term mortality and morbidity. Selective transphenoidal pituitary adenomectomy 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 expert neurosurgeons. Treatment options for persistent or relapsed disease include repeat trasphenoidal pituitary surgery, radiotherapy or bilateral adrenalectomy. Medical treatment, a second-line treatment option, may have either a primary or adjunctive role if the patient cannot safely undergo surgery, if surgery fails, or if the tumor recurs. Cabergoline and pasireotide (SOM230), two pituitary tumor-directed drugs, are the most exciting news in the human pharmacological approach. However, the use of these drugs in clinical practice and their real impact in the management of patients is yet to be determined. The treatment of patients with Cushing's disease is complex and requires a multidisciplinary and individualized approach to patient management using cost-benefit analyses.

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 Cushing's disease with ketoconazole]

Cushing's disease (CD), which is caused fundamentally by a pituitary microadenoma, is a rare endocrine disease in the paediatric age and which is associated with significant morbidity. The current treatment of choice for CD is trans-sphenoidal selective adenomectomy resulting in long-term remission rates. Pharmacological management of CD is directed at decreasing adrenal steroid secretion. Ketoconazole inhibits adrenal enzyme activity and decreases cortisol secretion. Our patient is a girl of 13 years and eight months of age with CD. The clinical manifestations were obesity, decrease in growth rate, Cushingoid phenotype, headache and arterial hypertension. The hormone determinations showed elevated values of UFC and ACTH. The circadian rhythm cortisol and ACTH and the short and long dexamethasone tests of provide definitive diagnosis of CD. The cranial MRI with gadolinium suggests the presence of microadenoma in the right pituitary lobe. The diagnosis is confirmed after performing a selective catheterisation of the inferior petrosal sinuses with CRH stimulus. While waiting for trans-sphenoidal surgery, the treatment with ketoconazole (200mg/24h) controlled the hypercortisolism. After the surgical procedure, the patient received replacement therapy with hydrocortisone for 1 month. At the present time, the patient, without fulfilling the post surgery cure criteria, has been 2 and a half years in clinical and hormonal remission.