Sparrow Pharmaceuticals Announces Completion of Phase 2 Trial and FDA Orphan Drug Designation of Clofutriben for Endogenous Cushing’s Syndrome

Portland, Oregon, October 28, 2024 — Sparrow Pharmaceuticals a clinical-stage biopharmaceutical company developing novel, targeted therapies to address unmet needs in both endocrinology and immunology, today announced that the Phase 2 RESCUE trial of clofutriben, a potent and selective HSD-1 inhibitor, for the treatment of endogenous Cushing’s syndrome is complete. All eligible patients who completed the trial elected to continue treatment with clofutriben in an open label extension (OLE) protocol. The promising results observed to date have catalyzed planning for the next phase of development to begin next year. In addition, Sparrow announced that clofutriben has been granted Orphan Drug Designation by the US Food and Drug Administration (FDA) for the treatment of endogenous Cushing’s syndrome.

The RESCUE trial was a randomized, placebo-controlled trial of clofutriben for ACTH-dependent endogenous Cushing’s syndrome, a rare disease caused by a tumor that leads to hypersecretion of cortisol. HSD-1 inhibition with clofutriben lowers intracellular cortisol in key tissues where excess cortisol causes toxicity, thereby potentially reducing morbidity from cortisol excess. “HSD-1 inhibition with clofutriben is a completely novel approach to the treatment of endogenous Cushing’s syndrome that may overcome many of the serious problems with current therapies, including major safety, tolerability, and complexity issues such as the risk of adrenal insufficiency and adrenal crisis,” commented Sparrow Chief Medical Officer Frank Czerwiec, MD, PhD. “One of the most encouraging observations is that, given the option to continue clofutriben or switch to another treatment at the end of the trial, patients chose to continue clofutriben in the OLE. We are working closely with our medical, scientific, and patient advisors on plans to present these data and on designs for our next phase of clinical trials to startup next year.”

Sparrow also announced that clofutriben has been granted Orphan Drug Designation (ODD) by the FDA for the treatment of endogenous Cushing’s syndrome. “ODD qualifies sponsors for incentives including tax credits for qualified clinical trials, exemption from user fees, and a potential seven years of market exclusivity after NDA approval,” added Jamie MacPherson, PharmD, Sparrow’s SVP of Regulatory Affairs and Quality. “We are pleased that the FDA has recognized the potential for clofutriben to treat this devastating disease.”

Clofutriben is a potent and selective HSD-1 inhibitor that is in clinical testing for endogenous Cushing’s syndrome (EnCS) and autonomous cortisol secretion (ACS), a milder and more prevalent, yet still serious, form of hypercortisolism than EnCS. HSD-1 is an intracellular enzyme that activates glucocorticoids in target tissues in which glucocorticoids such as cortisol are associated with morbidity including liver, adipose, brain, bone, muscle, and skin. Additionally, clofutriben in combination with the glucocorticoid medicine prednisolone is in Phase 2 clinical trials for the treatment of immunological disorders, beginning with polymyalgia rheumatica (PMR), a prevalent autoimmune disease that mainly affects people over 50. Clofutriben co-administration is intended to reduce the side effects of prednisolone while maintaining its immune suppressive and anti-inflammatory benefits, thereby unlocking the potential of a class of medicines that has been limited in utility for more than 75 years by severe toxicity.