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

  1. Shalini Kunasegaran1,2,
  2. Michael S Croxson1,
  3. Ian Holdaway1,
  4. Rinki Murphy1

+Author Affiliations


  1. 1Department of EndocrinologyAuckland District Health BoardAuckland, New Zealand

  2. 2Department of EndocrinologyWaitemata District Health BoardTakapuna, New Zealand
  1. Correspondence to Dr Shalini Kunasegaran, shal84@gmail.com
  • Accepted 13 July 2017
  • Published 7 August 2017

Summary

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

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.

From http://casereports.bmj.com/content/2017/bcr-2017-219921.short?rss=1

Medical Therapies in Cushing’s Syndrome

Chapter

The Hypothalamic-Pituitary-Adrenal Axis in Health and Disease

pp 165-179

Date: 03 December 2016

Medical Therapies in Cushing’s Syndrome

Abstract

Medical therapy has an important, albeit secondary, role in patients with Cushing’s syndrome. While medications are not currently used as definitive therapy of this condition, they can be very effective in controlling hypercortisolism in patients who fail surgery, those who are not surgical candidates, or those whose tumor location is unknown. Medical therapies can be particularly helpful to control hypercortisolism in patients with Cushing’s disease who underwent radiation therapy and are awaiting its salutary effects.

Currently available treatment options include several steroidogenesis inhibitors (ketoconazole, metyrapone, mitotane, etomidate), which block one or several steps in cortisol synthesis in the adrenal glands, centrally acting agents (cabergoline, pasireotide), which decrease ACTH secretion, and glucocorticoid receptor antagonists, which are represented by a single agent (mifepristone). With the exception of pasireotide and mifepristone, available agents are used “off-label” to manage hypercortisolism. Several other medications are at various stages of development and may offer additional options for the management of this serious condition.

As more potential molecular targets become known and our understanding of the pathogenesis of Cushing’s syndrome improves, it is anticipated that novel, rationally designed medical therapies may emerge. Clinical trials are needed to further investigate the relative risks and benefits of currently available and novel medical therapies and examine the potential role of combination therapy in the management of Cushing’s syndrome.

Keywords

Cabergoline, Etomidate, Ketoconazole, Levoketoconazole, Metyrapone, Mifepristone, Mitotane, Osilodrostat, Pasireotide, Pituitary adenoma

Scientists Find Potential Therapeutic Target for Cushing’s Disease

Scientists at the Salk Institute for Biological Studies have identified a protein that drives the formation of pituitary tumors in Cushing’s disease, a development that may give clinicians a therapeutic target to treat this potentially life-threatening disorder.

The protein, called TR4 (testicular orphan nuclear receptor 4), is one of the human body’s 48 nuclear receptors, a class of proteins found in cells that are responsible for sensing hormones and, in response, regulating the expression of specific genes. Using a genome scan, the Salk team discovered that TR4 regulates a gene that produces adrenocorticotropic hormone (ACTH), which is overproduced by pituitary tumors in Cushing’s disease (CD). The findings were published in the May 6, 2013 early online edition of Proceedings of the National Academy of Sciences.

The diagram shows how adrenocorticotropin hormone is secreted in Cushing's disease.

“We were surprised by the scan, as TR4 and ACTH were not known to be functionally linked,” says senior author Ronald M. Evans, a professor in Salk’s Gene Expression Laboratory and a lead researcher in the Institute’s Helmsley Center for Genomic Medicine. “TR4 is driving the growth and overexpression of ACTH. Targeting this pathway could therapeutically benefit treatment of CD.”

In their study, Evans and his colleagues discovered that forced overexpression of TR4 in both human and mouse cells increased production of ACTH, cellular proliferation and tumor invasion rates. All of these events were reversed when TR4 expression was reduced.

First described more than 80 years ago, Cushing’s disease is a rare disorder that is caused by pituitary tumors or excess growth of the pituitary gland located at the base of the brain. People with CD have too much ACTH, which stimulates the production and release of cortisol, a hormone that is normally produced during stressful situations.

While these pituitary tumors are almost always benign, they result in excess ACTH and cortisol secretion, which can result in various disabling symptoms, including diabetes, hypertension, osteoporosis, obesity and psychological disturbances. Surgical removal of the tumors is the first-line therapy, with remission rates of approximately 80 percent; however, the disease recurs in up to 25 percent of cases.

Drugs such as cabergoline, which is used to treat certain pituitary tumors, alone or in combination with ketoconazole, a drug normally used to treat fungal infections, have been shown to be effective in some patients with Cushing’s disease. More recently, mefipristone-best known as the abortion pill RU-486-was approved by the FDA to treat CD. Despite these advances in medical therapy, the Salk scientists say additional therapeutic approaches are needed for CD.

“Pituitary tumors are extremely difficult to control,” says Michael Downes, a senior staff scientist in the Gene Expression Laboratory and a co-author of the study. “To control them, you have to kill cells in the pituitary gland that are proliferating, which could prevent the production of a vital hormone.”

Previous studies have found that, by itself, TR4 is a natural target for other signaling molecules in the pituitary. Small-molecule inhibitors that have been developed for other cancers could be potentially applied to disrupt this signaling cascade. “Our discovery,” says Evans, a Howard Hughes Medical Institute investigator and holder of the March of Dimes Chair in Molecular and Developmental Biology, “might lead clinicians to an existing drug that could be used to treat Cushing’s disease.

Notes about this neurogenetics and Cushing’s disease research

Other researchers on the study were Li Du, Marvin Bergsneider, Leili Mirsadraei, Stephen H. Young, William H. Yong and Anthony P. Heaney of the David A. Geffen School of Medicine at the University of California, Los Angeles, and Johan W. Jonker of the University of Groningen.

The study was supported by the National Institutes of Health, the Leona M. and Harry B. Helmsley Charitable Trust, the Samuel Waxman Cancer Research Foundation, the Jonsson Comprehensive Cancer Center at UCLA, and Ipsen/Biomeasure.

Contact: Andy Hoang – Salk Institute
Source: Salk Institute press release
Image Source: The ACTH Cushing’s disease diagram is credited to NIDDK/NIH and is available in the public domain.
Original Research: Abstract for “Evidence for orphan nuclear receptor TR4 in the etiology of Cushing disease” by Li Du, Marvin Bergsneider, Leili Mirsadraei, Steven H. Young, Johan W. Jonker, Michael Downes, William H. Yong, Ronald M. Evans, and Anthony P. Heaney in Proceedings of the National Academy of Sciences. Published May 6 2013 doi: 10.1073/pnas.1306182110

From http://neurosciencenews.com/tr4-cushings-disease-acth-neurogenetics-120/

Interview May 7 with Kathy C, Pituitary Patient

My name is Kathy Casey. I am a 63 year old retired school nurse. I am married with two wonderful sons and a grandson. My husband and I live in the mountain town of Mt. Shasta in northern California. I have always been athletic.

In 1995, I was diagnosed with a pituitary tumor. At the time the only symptom I was aware of was a severe headache. I had a transphenoidal resection by Dr. Wilson at UCSF Medical Center followed by radiation therapy for 23 days. At the time they said they could not remove all of the tumor.

In 2008/2009. I exhibited symptoms of Cushing’s and my cortisol level was outrageous, and I had to be hospitalized initially for a potassium level of 2. I returned to UCSF and Dr. Anwar Sandeep operated . By removing part of the tumor. My Cushing symptoms resolved. However, he said that the tumor was not encapsulated and was invading the cavernous sinus and stella turcica so it was still not possible to remove it all.

I was OK until December 2013 when I began exhibiting the symptoms of Cushings. One of my 24 hr. urines was 14,000. I had to be hospitalized for a potassium level of 1.9. Dr. Heaney said he has never seen a cortisol level that high. This time I decided to go to the UCLA Pituitary Tumor and Endocrinology Program where they were more oriented to follow-up and treating this disorder. Dr. Bergsneider decided that surgery was not an option. He and Dr. Heaney decided radiation was not an option. So now I am being followed by Dr. Heaney to see if medication can help.

I am now on Cabergoline 0.5 mg three tabs twice a week and Signifor 0.9 mg subcutaneosly twice a day. I think they are alleviating some of the symptoms. However, the Signifor caused my blood sugar to rise, and I had to go on Metformin which is causing nausea to a point where I have a hard time eating.

Anyway, this whole situation is depressing and overwhelming. I am tryng to stay positive, but I wonder how it will turn out. I am fortunate to have a supportive and helpful husband.

I am interested in communicating with people who may be going through a similar experience and learning more about this rare condition.

Kathy will be interviewed May 7, 2014 in BlogTalkRadio

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No High-Quality Studies for Cushing’s Drugs

By Salynn Boyles, Contributing Writer, MedPage Today

Reviewed by Zalman S. Agus, MD; Emeritus Professor, Perelman School of Medicine at the University of Pennsylvania and Dorothy Caputo, MA, BSN, RN, Nurse Planner

There is a paucity of clinical trial data supporting the efficacy of most drugs used to treat Cushing’s disease, researchers reported.

Just one drug — pasireotide — has been evaluated in a randomized, double-blind trial, but even it was judged by the researchers to have only a ‘moderate’ level of evidence supporting its effectiveness and safety.

The review of the literature evaluating drug treatments for Cushing’s disease, a rare pituitary disorder, is the first to employ a rigorous systematic approach with strict, predefined inclusion criteria and formal analysis of the quality of evidence using an established standard, researcher Monica Gadelha, MD, PhD, of Brazil’s Federal University of Rio de Janeiro, and colleagues wrote in the journal Clinical Endocrinology.

“This systematic review indicates that the majority of medical therapies currently used in the treatment of Cushing’s disease are supported by a low level of evidence,” the researchers wrote. “Further well-designed prospective studies of medications in Cushing’s disease would help to inform clinical practice further.”

Cushing’s disease is the most common form of endogenous Cushing’s syndrome, a hormonal disorder resulting from persistent exposure to abnormally high levels of the hormone cortisol. In the case of Cushing’s disease, the cortisol is secreted by a pituitary adenoma.

Prolonged exposure to high levels of cortisol raises the risk for diabetes mellitus, cardiovascular disease, osteoporosis and nephrolithiasis. Patients with persistent Cushing’s disease have a 3- to 5-fold higher mortality than the general population.

Surgery to remove the pituitary adenoma is the first-line treatment for Cushing’s disease in the U.S., and when the procedure is performed by an experienced surgeon, remission rates in patients with smaller tumors range from 65% to 90%. The long-term remission rate is lower, however, because many patients develop recurrent disease.

Several medical therapies are widely used to treat patients who are not candidates for surgery or who experience relapse following surgery.

Novartis Oncology’s somatostatin analog drug pasireotide (Signifor) became the only drug approved for this indication in December of last year. And the progesterone-blocking drug mifepristone, best known as the abortion pill once called RU-486, was approved in February of 2012 for the treatment of Cushing’s disease-associated hyperglycemia.

Other drugs — including metyrapone, mitotane, cabergoline, and ketoconazole — are also used off-label in the treatment of Cushing’s, and several have shown better response rates than pasireotide in small studies.

In their systematic review, Gadelha and colleagues identified 15 studies that included at least 10 adults with Cushing’s disease and reported treatment responses as the proportion of patients reaching a specified definition of response. Studies examining combinations of medications were excluded from the analysis, as were studies with indefinite diagnoses of Cushing’s disease.

For medications other than mifepristone, studies had to report the proportion of patients with normalized urinary free cortisol (UFC), midnight salivary cortisol or midnight serum cortisol.

The studies were scored according to the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system for rating quality of evidence.

Ten of the 15 included studies reported outcomes specifically for patients with Cushing’s disease and the remaining five included patients with other forms of Cushing’s syndrome.

The researchers reported that:

  • Pasireotide was the only treatment assessed in a randomized trial, and it was judged to have a ‘moderate’ level of evidence supporting its use. Response rates from three prospective studies of the drug ranged from 17% to 29%.
  • The remaining medications were supported by a ‘low’ or ‘very low’ level of evidence.
  • The highest response rates were reported in a small retrospective studies of metyrapone (75%, one study) and mitotane (72%, one study).
  • Response rates were 25% to 50% for cabergoline (four studies) and 45% for ketoconazole (one study).
  • Among studies that included patients with other forms of Cushing’s syndrome, response rates were 53% to 88% for ketoconazole (three studies), 70% for mitotane (one study), 57% for metyrapone (one study), and 38% to 60% for mifepristone (one study).

 

But the researchers urged caution in comparing the drugs, citing the variability in the study designs and patient selection endpoints, among other limitations in the research literature.

“The wide variation in the time-frames over which response to treatment was measured makes comparison a challenge,” they wrote. “Comparison of response rates reported in the included studies is also complicated by the variation in methodology used to assess response.”

They noted that well-designed clinical trials are needed to determine which drugs or drug combinations are most effective in the treatment of Cushing’s disease patients.

“Combinations of medical therapies with different modes of action might aid in optimizing the balance of efficacy and safety,” they wrote. “Investigational medications, such as bexarotene, LC1699 and retinoic acid, may help to expand the range of future therapeutic options.”

Maria Fleseriu, MD, who was not involved in the review, agreed that more drug treatments are needed. But she added that Cushing’s patients today have many more drug options than they did just a few years ago.

Fleseriu directs the Pituitary Center at Oregon Health & Science University, where she is an associate professor of medicine and endocrinology.

In a recently published analysis, Fleseriu wrote that pituitary-targeted medical therapies should soon play a more prominent role in treating Cushing’s disease, and may become first-line treatments when surgery fails or is contraindicated.

“We now have one drug approved for Cushing’s and another approved for diabetes symptoms associated with the disease,” she told MedPage Today. “We are moving forward, but we are not where we would like to be. Combination therapy is probably where we are heading, but further studies are needed.”

Financial support for this research was provided by Novartis Pharmaceuticals.

Researcher Monica Gadelha reports receiving speaker fees and participating on advisory boards for Novartis. Gadelha and co-author Leonardo Vieira Neto were investigators in Novartis’ clinical trials of pasireotide.

 

From http://www.medpagetoday.com/Endocrinology/GeneralEndocrinology/42043

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