The US Food and Drug Administration (FDA) has granted Orphan Drug designation to Harmony Bioscience’s pitolisant for the treatment of Prader-Willi syndrome.

FDA Orphan Drug designation incentivizes the advancement of promising therapies for rare diseases by providing tax credits for clinical development, waivers for user fees, and seven years of market exclusivity following drug approval. Approximately 15,000-20,000 people in the US are living with Prader-Willi syndrome, the majority experiencing behavioral symptoms and more than half with excessive daytime sleepiness.

“The decision to grant Orphan Drug designation to pitolisant indicates that it could be a promising treatment option for people living with Prader-Willi syndrome,” says Kumar Budur, MD, MS, chief medical officer at Harmony Biosciences, in a release. “This designation marks an important step forward in our PWS (Prader-Willi syndrome) development program, and we are eager to continue working with the FDA and the broader community of PWS patients and caregivers to address their high unmet medical needs.”

In the upcoming phase 3 registrational TEMPO study, Harmony will assess the safety and efficacy of pitolisant in treating excessive daytime sleepiness and behavioral disturbances in Prader-Willi syndrome. This global study, anticipated to begin in Q1 2024, will be a randomized, double-blind, placebo-controlled trial in patients 6 years and older with Prader-Willi syndrome.

“We are excited about our upcoming phase 3 TEMPO study and the progress we have made to broaden the clinical utility of pitolisant not just in PWS but other rare diseases as part of our life cycle management programs that, if successful, could potentially help over 100,000 patients,” adds Budur in a release. “On behalf of Harmony, I would like to thank all the patients and family members for participating in our clinical trials, as well as our investigators and site personnel for their commitment to advancing science.”