Burden of Duchenne Muscular Dystrophy in Patients with Mutations Amenable to Exon 44 Skipping (DMD44)



Poster Number: 188


Dan Malone, PhD, University of Utah, Edward P Armstrong, PharmD, Strategic Therapeutics, Kathy Munoz, PhD, MPH, 520-400-8712, Mark Stahl, MD, PhD, Avidity Biosciences, Inc., Alissa Peters, Avidity Biosciences, Inc., Kelly DiTrapani, RN, BSN, BA, Avidity Biosciences, Inc., Craig McDonald, MD, University of California Davis Medical Center

Background: Duchenne muscular dystrophy with mutations amenable to exon 44 skipping (DMD44) is an ultra-rare condition with limited research related to the burden of the disease and its impact on participation in clinical studies. About 7% of skip-amenable DMD patients have DMD44, or ~900 patients in the US.

Objectives: The study’s objectives were to document the disease burden for DMD44 patients, time from symptom onset to diagnosis, and attributes important to quality of life.

Methods: A cross-sectional survey and focus group were conducted with 10 individuals with DMD44. Ambulatory and non-ambulatory English-speaking males with DMD44, age 7 years or older were recruited. Participants and their caregivers completed a survey, then participated in a focus group session to provide insights regarding responses to the survey. The online survey contained 56 questions regarding desirable attributes for new treatments, disease burden, resource utilization, and demographics.

Results: Ten individuals, 5 ambulatory and 5 non-ambulatory, participated. The age range was from 9 to 31 years. Eight participants (80%) were Caucasian, and 2 (20%) were Hispanic/Latino. Age at time of diagnosis ranged from 2 to 7 years. Four participants had symptoms for 3-6 months before diagnosis, and 2 participants were symptomatic for more than 18 months prior to diagnosis. When asked what attributes were most important for assessing new therapies, all respondents indicated stabilization of disease was more important than improving daily symptoms. The most desirable attribute for new treatments was slowing progression of muscle weakness, followed by improving cardiac function. Functional abilities important to all participants included the use of a joystick and computer keyboard, maintaining upper body strength, ability to self-feed, and ability to reposition at night.

Conclusion: The burden of DMD44 is significant. Slowing or preventing progression of disease is the most important attribute identified by patients and caregivers for new treatments.