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

NIH: An Open-Label Study of The Safety, Pharmacokinetics and Pharmacodynamics of Mifepristone in Children With Refractory Cushing’s Disease

This study is currently recruiting participants.

Summary

Number 13-CH-0170
Sponsoring Institute National Institute of Child Health and Human Development (NICHD)
Recruitment Detail Type: Participants currently recruited/enrolled
Gender: Male & Female
Min Age: 6
Max Age: 17
Referral Letter Required No
Population Exclusion(s) None
Special Instructions Currently Not Provided
Keywords Child;
Cushing Syndrome;
Metabolism;
Mifepristone;
Pharmacokinetic-Pharmacodynamic
Recruitment Keyword(s) None
Condition(s) Cushing’s Syndrome;
Cushing Syndrome
Investigational Drug(s) Mifepristone
Investigational Device(s) None
Intervention(s) Drug: mifepristone
Supporting Site National Institute of Child Health and Human Development

Background:

– There are currently no approved therapies for children with Cushing’s disease who are not cured by surgery alone. A drug called mifepristone has been approved to treat adults with Cushing’s syndrome and elevated blood glucose caused by Cushing’s. The drug is marketed under the name Korlym(Registered Trademark). The study drug may have a different effect on a child’s body than an adult’s, so researchers want to know how much of the drug to give children and what effect it will have. They want to learn if mifepristone improves Cushing’s disease in children as it does in adults. They also want to know about the drug’s side effects in children.

Objectives:

– To study the effect of a medication called mifepristone in children with Cushing’s disease that has not been helped by pituitary surgery.

Eligibility:

– Children ages 6 to 17 with active Cushing’s disease following pituitary surgery and who have a body weight higher than expected for their height and age.

Design:

– Participants will be screened for up to 8 weeks with a physical exam, medical history, and medical tests including blood tests and X-rays.

– Participants will take tablets of the study drug each day for 12 weeks.

– Participants will stay at the clinic for 4 nights at the beginning of the study. They will have three 1-day visits during the study. They will stay at the clinic the last 3 days of the study.

– At these visits, participants will be given several tests. In one test, a small wire is inserted under the skin of the belly and a small monitor is attached taped to the belly. In another, the participant drinks a liquid and blood samples are taken.

– Follow-up visits will occur 4 weeks and 12 weeks after the study ends.

–Back to Top–

Eligibility

INCLUSION CRITERIAPatients who are eligible for enrollment must meet the following eligibility criteria:

– Males and females 6-17 years at informed consent

– Active Cushing’s disease as demonstrated by the following:

–24 hour Urinary Free Cortisol greater than the upper limit of normal for age on two urine collections during screening and

— midnight serum cortisol > 4.4 mcg/dL (mean of two determinations on a single day at 2330 and 2400 during screening)

– Previous trans-sphenoidal surgery (TSS) for ACTH secreting pituitary tumor at least 3 months prior to screening

– Increased body weight defined by BMI Z-score of 1.5 or above

– Able to provide consent/assent

– Able to swallow study drug tablets (not crushed or split)

– Willing to use non-hormonal method of contraception in patients of reproductive potential

– Primary health care provider in home location

EXCLUSION CRITERIA:

– Hypercortisolism not due to Cushing’s disease.

– Type 1 diabetes mellitus

– HbA1c geater than or equal to 9.5% at Screening

– Body weight < 25 kg

– Use of certain medications that are CYP3A substrates with narrow therapeutic ranges, such as simvastatin, lovastatin, cyclosporine, dihydroergotamine, ergotamine, fentanyl, pimozide, quinidine, sirolimus, and tacrolimus during the 4 weeks prior to starting study drug. Use of these medications is also prohibited until 2 weeks after end of dosing.

– Use of certain medications that are strong CYP3A inhibitors such as itraconazole, nefazodone, ritonavir, nelfinavir, indinavir, atazanavir, amprenavir, fosamprenavir, boceprevir, clarithromycin, conivaptan, lopinavir, mibefradil, posaconazole, saquinavir, telaprevir, telithromycin, and voriconazole during the 2 weeks prior to starting study drug.

Use of these medications is also prohibited until 2 weeks after end of dosing. Grapefruit and grapefruit juice are prohibited during this time frame.

– Use of certain medications that are strong inducers on CYP3A such as rifampin, rifabutin, rifapentin, phenobarbital, phenytoin, carbamazepine, St. John’s wort during the 2 weeks prior to starting study drug. Use of these medications is also prohibited until 2 weeks after end of dosing.

– Use of medications used to treat hypercortisolism from the duration indicated below prior to Day 1. Use of the medications is also prohibited until after the end of study 4 week follow up visit.

–steroidogenesis inhibitors such as ketoconazole, metyrapone: 4 weeks

–cabergoline, bromocriptine, somatostatin analogs such as octreotide, lanreotide, pasireotide long acting formulations: 8 weeks (immediate release formulations: 2 weeks)

–mitotane: 8 weeks

– Use of systemic glucocorticoid medications beginning 1 month prior to screening or anticipated use of these medications except for the treatment of adrenal insufficiency. Use of glucocorticoid medications is prohibited during the study until after the end of study 4 week study visit.

– Inflammatory, rheumatological, proliferative or other disorder(s) that would be anticipated to worsen with glucocorticoid blockade (e.g. inflammatory bowel disease, rheumatoid arthritis, psoriasis, etc.).

– Uncontrolled hypo- or hyperthyroidism.

– Uncorrected hypokalemia (< 3.5 mEq/L). The screening period may be used to correct hypokalemia prior to starting study drug. Use of potassium and/or mineralocorticoid antagonists is permitted during the study.

– QTc geater than or equal to 450 msec on Screening electrocardiogram

– Unexplained vaginal bleeding in females and/or any history of endometrial pathology.

– Positive pregnancy test in females.

From http://clinicalstudies.info.nih.gov/cgi/detail.cgi?A_2013-CH-0170.html

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