Sparrow Cleared to Start Phase 2 Trial of SPI-62 Early Next Year

Marisa Wexler, MS avatar

by Marisa Wexler, MS |

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Sparrow Pharmaceuticals is gearing up for the start of a Phase 2 trial that will assess the safety and effectiveness of the company’s experimental medicine SPI-62 in people with Cushing’s disease.

The U.S. Food and Drug Administration has cleared Sparrow’s investigational new drug application (IND), giving the company the green light to start testing the therapy in patients. Sparrow is planning to start enrolling participants in the trial early next year.

“With the clearance of this IND we are now well positioned to accelerate our plans to generate proof-of-concept for SPI-62 in multiple indications,” Robert Jacks, Sparrow’s CEO and president, said in a press release.

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Cushing’s disease is caused by a tumor in the brain’s pituitary gland. The tumor prompts the excess release of certain signaling molecules from the pituitary gland, which in turn causes the adrenal glands — a pair of organs located above the kidneys — to produce large amounts of a hormone called cortisol. High cortisol levels are ultimately responsible for the symptoms of Cushing’s.

SPI-62 is designed to block the activity of an enzyme called 11 beta-hydroxysteroid dehydrogenase type 1 (HSD-1). This enzyme normally converts an inactive form of cortisol, called cortisone, into the active form of the hormone.

According to Sparrow, blocking HSD-1 “would be the first new mechanism of action in decades to treat Cushing’s.” The company says that SPI-62 has been shown to block the enzyme’s activity in brain and fat tissue, and to lower cortisol levels in the liver — all three are key tissues affected by cortisol-driven health problems.

“Current treatments either have limited efficacy or serious side effects, so new therapeutic options are sorely needed for [Cushing’s],” Frank Czerwiec, MD, PhD, Sparrow’s chief medical officer, said.

“We are moving rapidly to initiate enrollment in this international clinical trial to study whether SPI-62 can represent an entirely new way to treat Cushing’s,” he added.

In addition to Cushing’s disease, Sparrow is planning to launch Phase 2 trials to test SPI-62 in two other conditions associated with excessive cortisol levels by mid-2022. These include autonomous cortisol secretion, a condition in which cortisol is produced excessively due to tumors or other adrenal gland abnormalities, and polymyalgia rheumatica (PMR), an inflammatory disorder.

People with PMR and other inflammatory diseases are often treated with glucocorticoids, which are medications that mimic the activity of cortisol. These medicines have powerful anti-inflammatory properties, but also can cause substantial side effects. The planned Phase 2 trial will test whether adding SPI-62 to glucocorticoid treatment could lessen its side effects, without significantly affecting efficacy.