Harmony Biosciences Holdings, Inc. announced initiation of a Phase 2 clinical trial to evaluate the safety and efficacy of pitolisant for excessive daytime sleepiness and other non-muscular symptoms in adult patients with type 1 myotonic dystrophy. Myotonic dystrophy 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, which is the most common form of this disorder. This equates to about 160,000 people in the U.S. with the genetic defect for DM1. Estimates suggest there are 40,000 people currently diagnosed with DM1 in the U.S., with up to 90% of them reporting EDS and fatigue and over 60% of them experiencing cognitive dysfunction. The Phase 2 clinical trial is a randomized, double-blind, placebo-controlled study designed to assess the safety and efficacy of pitolisant in patients with DM1 ages 18 – 65 years. Approximately 135 patients will be randomized at baseline to low-dose pitolisant, high-dose pitolisant, or placebo in a 1:1:1 treatment ratio titrated over three weeks, followed by eight weeks of stable dosing. Patients who complete the randomized, controlled phase of the trial will be eligible to participate in an open-label extension phase to assess the long-term safety and effectiveness of pitolisant in patients with DM1. The primary objective of the trial is to evaluate the effect of pitolisant compared with placebo on EDS. Secondary objectives include assessments of fatigue, specific measures of cognitive function using validated computer-based assessments, and overall disease burden utilizing a disease-specific, patient-reported outcomes instrument for DM1. Topline results are anticipated from the Phase 2 trial in the second half of 2022. Pitolisant is marketed as WAKIX in the U.S. for the treatment of EDS or cataplexy in adult patients with narcolepsy.