Rhythm Pharmaceuticals, Inc., a global commercial-stage biopharmaceutical company focused on transforming the lives of patients living with rare neuroendocrine diseases, announced it has received orphan drug designation from Japan’s Ministry of Health, Labour and Welfare (MHLW) for setmelanotide as a treatment for acquired hypothalamic obesity.

Setmelanotide is a melanocortin-4 receptor (MC4R) agonist designed to treat hyperphagia and obesity. Rhythm is evaluating setmelanotide in a global Phase 3 trial in patients with acquired hypothalamic obesity, with topline data on track to be disclosed in the second quarter of 2025.

“Orphan drug designation points to the need for therapeutic options for people living with acquired hypothalamic obesity,” said Yann Mazabraud, Executive Vice President, Head of International at Rhythm Pharmaceuticals. “With this designation now in place in Japan, as well as in Europe, we believe we are well positioned to execute on our global strategy to bring patients with hypothalamic obesity the first-ever treatment targeting the underlying biology of this disease, pending success of our Phase 3 trial and subsequent regulatory filings.”

Acquired hypothalamic obesity is a disease characterized by accelerated and sustained change in weight trajectory caused by an injury to the hypothalamus, often accompanied by hyperphagia (pathological, insatiable hunger and impaired satiety accompanied by abnormal food-seeking behaviors) and/or decreased energy expenditure. Acquired hypothalamic obesity most frequently follows hypothalamic injury from the growth or surgical removal of craniopharyngioma, astrocytoma, or other rare brain tumors. Additional causes of injury may include traumatic brain injury, stroke, or inflammation due to infection.

“There is a significant unmet medical need in Japan for a safe and effective precision medicine for patients living with acquired hypothalamic obesity, said Prof. Arima, MD, PhD, Professor of the Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine. “Setmelanotide could provide new hope to these patients and their families.”

In Japan, drugs can be designated as orphan drugs if they treat diseases affecting fewer than 50,000 patients in Japan and there is a high medical need. Rhythm estimates there are 5,000 to 8,000 people living with acquired hypothalamic obesity in Japan, 5,000 to 10,000 people living with acquired hypothalamic obesity in the U.S., and 3,500 to 10,000 people living with acquired hypothalamic obesity in the E.U.