(Addison’s Disease & Cushing’s Syndrome)
Novel and Emerging Therapies
Given the side effects of currently available medications and the burden of repeated laboratory testing necessary to monitor hormone levels, scientists are trying to find novel treatment approaches for adrenal disorders that may be more effective and have an acceptable range of side effects (Pozza 2012).
It is believed that the adrenal cortex contains dormant adrenal stem cells, which are specialized cells that can multiply and differentiate to replenish all cell types that make up the adrenal gland (Kim 2009). Further in-depth studies are needed to provide insights into the biology of these stem cells and to characterize their role in adrenal diseases before they can be utilized as a treatment option (Simon 2012).
At the time of this writing, one in-depth study is underway in the United Kingdom. Since cells of the adrenal cortex are sensitive to ACTH levels in the blood, investigators are exploring the possibility of stimulating adrenal cortex stem cells with ACTH, to push them to differentiate into steroid-producing cells. The assessment of serum cortisol levels after an ACTH stimulation test will be the main criterion to check if functioning adrenal cortical cells have been generated or not (ClincalTrials.gov NCT01371526). If successful, this trial could open the doors to a new treatment option for conditions, such as autoimmune Addison’s disease, in which the adrenal glands do not secrete adequate amount of hormones but have not lost their ability to respond to ACTH stimulation.
A new drug called pasireotide
has shown promising results in reducing cortisol levels in Cushing’s disease. This drug is similar in structure and function to the naturally-occurring hormone somatostatin, which has been suggested as a therapeutic target for pituitary-dependent Cushing’s disease, following a study revealing that adrenal cortex tumor cells have sites to which somatostatins can bind to prevent the release of ACTH (van der Hoek 2004). Results of a clinical trial examining the use of pasireotide in Cushing’s disease were published in the New England Journal of Medicine
in March 2012. The drug was administered for 12 months to 162 people with Cushing’s disease who were divided into 2 groups receiving either 600 or 900 mcg of the drug by subcutaneous injection twice daily. In both groups, the levels of free cortisol in the urine decreased by approximately 50% by the second month of treatment and remained stable. The levels of cortisol in the serum and saliva also decreased. In addition, the overall symptoms of Cushing’s disease diminished (Colao 2012).