Rhythm announced the U.S. Food and Drug Administration (FDA) has expanded a previously granted Breakthrough Therapy Designation (BTD) for setmelanotide, the company's novel melanocortin-4 receptor (MC4R) agonist. The expanded BTD is for the treatment of obesity associated with genetic defects upstream of the MC4 receptor in the leptin-melanocortin pathway (the MC4 pathway), which includes both pro-opiomelanocortin (POMC) and leptin receptor (LepR) deficiency obesity. The FDA had previously granted BTD to setmelanotide for the treatment of POMC deficiency obesity.

Rhythm is developing setmelanotide for the treatment of obesity caused by genetic deficiencies in the MC4 pathway, a key biological pathway in humans that regulates weight by increasing energy expenditure and reducing appetite. The company has completed positive Phase 2 clinical trials in both POMC deficiency obesity and LepR deficiency obesity in which patients treated with setmelanotide experienced significant weight loss and substantial reductions in hunger. Setmelanotide was well tolerated in these trials. Rhythm recently initiated a Phase 3 clinical trial of setmelanotide in POMC deficiency obesity.

"We are developing setmelanotide to restore lost function in upstream MC4 pathway disorders for which there are no approved therapies," Keith Gottesdiener, CEO of Rhythm said. "We are grateful to receive this expanded Breakthrough Therapy Designation, and we look forward to continuing to work closely with the FDA to bring this therapy to patients living with these life-threatening genetic disorders of obesity."

The FDA grants BTD to expedite the development and review of therapeutics to treat serious or life-threatening conditions for which preliminary clinical evidence indicates that the therapy may demonstrate substantial improvement on at least one clinically significant endpoint over existing therapies. This designation conveys all FDA Fast Track program features, such as eligibility for rolling new drug application (NDA) submissions and priority review (if supported by clinical data at the time of NDA). Additionally, this designation provides more intensive involvement of FDA staff in a proactive, collaborative, cross-disciplinary review process.