Harmony Reports Positive Topline Data from Phase 2 Study in DM1

Rare Daily Staff

Harmony Biosciences reported positive topline results from its phase 2 signal detection study evaluating the safety and efficacy of pitolisant in adult patients with myotonic dystrophy type 1.

Harmony said the study demonstrated a clinically meaningful improvement on the primary efficacy endpoint, the change from baseline to the end of the double-blind period for excessive daytime sleepiness (EDS) as measured by the Daytime Sleepiness Scale (DSS). A clinically meaningful improvement was also demonstrated for fatigue, a secondary efficacy endpoint measured by the Fatigue Severity Scale (FSS). EDS and fatigue occur in up to 80-90 percent of patients with DM1 and impact daily functioning as much as muscular symptoms (myotonia and muscle weakness).

“These strong topline results add to the body of evidence supporting the effectiveness of pitolisant for improving EDS,” said Jeffrey Dayno, president and CEO of Harmony Biosciences. “In addition, a positive signal for pitolisant has been demonstrated for fatigue, suggesting it could be a potential new treatment option for this symptom as well.”

Myotonic dystrophy type 1 (DM1) is the most common form of adult-onset muscular dystrophy. It is a genetic disorder inherited in an autosomal-dominant pattern. Latest estimates suggest a prevalence of about one per 2,100 people with the genetic defect for DM1. Estimates suggest there are 40,000 people currently diagnosed with DM1 in the United States, with up to 90 percent of them reporting EDS and fatigue and more than 60 percent of them experiencing cognitive dysfunction.

Wakix (pitolisant) is a selective histamine 3 (H₃) receptor antagonist/inverse agonist. The mechanism of action of Wakix is unclear; however, its efficacy could be mediated through its activity at H₃ receptors, thereby increasing the synthesis and release of histamine, a wake promoting neurotransmitter. Wakix was designed and developed by Bioprojet. Harmony has an exclusive license from Bioprojet to develop, manufacture, and commercialize pitolisant in the United States.

Wakix, a first-in-class medication, is approved by the U.S. Food and Drug Administration for the treatment of excessive daytime sleepiness or cataplexy in adult patients with narcolepsy and has been commercially available in the United States since the fourth quarter of 2019. The FDA granted Wakix orphan drug designation for the treatment of narcolepsy in 2010, and breakthrough therapy designation for the treatment of cataplexy in 2018.

A clear and consistent dose-response was demonstrated with the higher dose pitolisant group showing a greater response than the lower dose group across the study endpoints.