Isturisa lowers cortisol levels in Cushing’s patients: Real-world study
Treatment was found to be effective in earlier clinical trials
Treatment with Isturisa (osilodrostat) was found to be effective for reducing cortisol levels in people with Cushing’s disease and other forms of Cushing’s syndrome, according to data from a real-world study.
The study, “Osilodrostat Treatment of Cushing Syndrome in Real-World Clinical Practice: Findings From the ILLUSTRATE study,” was published in the Journal of the Endocrine Society. The work was funded by Recordati Rare Diseases, the company that sells Isturisa.
Isturisa blocks enzyme involved in production of cortisol
Cushing’s syndrome encompasses a series of disorders driven by excessive levels of the hormone cortisol. Cushing’s disease is a specific form of the syndrome caused by a tumor in the brain’s pituitary gland.
Isturisa is an oral therapy designed to reduce cortisol levels by blocking the activity of an enzyme involved in its production. The therapy is approved in the U.S. for Cushing’s disease and other forms of Cushing’s syndrome in people for whom surgery isn’t an option or hasn’t been effective.
Clinical trials have shown that Isturisa is generally effective for reducing cortisol levels in Cushing’s patients. Scientists at Recordati and other institutions conducted an observational study to evaluate the efficacy of Isturisa when used in real-world clinical practice.
“Although prospective clinical trials are essential for demonstrating the efficacy and safety of drug therapies, they entail enrollment of selected patient populations and a tightly controlled research setting,” the scientists wrote. “Real-world observational studies, in which the drug is used according to physicians’ clinical practice, provide complementary and helpful information.”
The study included 34 people with Cushing’s disease, as well as eight individuals with other forms of Cushing’s syndrome. Patients were a mean age of 43.7 years, and about three-quarters were female. Prior to starting treatment with Isturisa, most patients had undergone surgery and/or tried other medications.
Most patients (64.3%) began treatment with Isturisa at the recommended starting dose of 2 mg twice daily. Many patients had their doses adjusted based on efficacy and side effects. Most (66.7%) ended up continuing with long-term treatment at the 2 mg twice-daily dose, but there was a lot of individual variation.
These findings “highlight the importance of selecting a starting dose and titration regimen according to each patient’s circumstances, clinical response, and tolerability, as the dose required to normalize cortisol levels varies between patients and does not appear to depend on baseline [pre-treatment] levels,” the researchers wrote.
Majority of patients’ cortisol levels within normal ranges after treatment
Before starting treatment with Isturisa, blood and/or urine cortisol levels were above the upper limit of normal for most patients. With Isturisa, median cortisol levels dropped below the upper limit of normal — in other words, the majority of patients had cortisol levels within normal ranges following treatment with Isturisa.
“In the subgroup of patients with Cushing disease, most of those with [elevated urine and blood cortisol levels] at baseline had their levels reduced to normal during treatment,” the scientists wrote.
Isturisa was generally tolerated well; the most common safety issues reported were fatigue, nausea, and swelling in the legs and feet. No unexpected safety problems were reported, and the therapy’s safety profile was consistent with what had been seen in clinical trials.
Overall, the results from this real-world study “are consistent with those from clinical trials and other real-world studies, showing that [Isturisa] was effective and well tolerated in patients with varying [types] and severities of [Cushing’s syndrome] when used by physicians in routine clinical practice,” the researchers wrote.
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