Significant Treatment Gaps Found in People Diagnosed with Chorea Associated with Huntington Disease

Less than 40% of people diagnosed with chorea associated with Huntington disease (HD) received treatment, according to findings of a large observational study published in Neurology and Therapy. In addition, only ~50% of treated patients received first-line monotherapy with the vesicular monoamine transporter 2 (VMAT2) inhibitors approved by the Food and Drug Administration (FDA) for the treatment of chorea, while the rest received off-label treatments.

Researchers analyzed a large natural-history cohort of people diagnosed with HD derived from the Enroll-HD (NCT01574053) registry, with data collected from 2012 to 2020 in North America. A total of 2592 participants were included in the primary analysis set, of whom 96.8% had chorea (n=2507), as defined by a Total Maximal Chorea (TMC) scale score of ≥2 at baseline.

Analysis of medical records for these participants revealed the following:

• Only 906 (36.1%) of the participants with chorea received ≥1 prescription for the treatment of chorea.
• VMAT2 inhibitors were the most commonly prescribed first-line therapy (49.9%; n=452).
• Off-label medications were used as a first-line therapy to treat 50.1% (n=454) of participants with chorea.
• The most common off label first-line therapy were antipsychotic medications (27.7%; n=251), followed by other medications (18.5%; n=168) such as amantadine and clonazepam, and lastly, combination therapy (3.9%; n=35).

Most participants (76.0%; n=689) remained on their initially prescribed line of therapy, including 84.3% of those on VMAT2 inhibitors and 76.1% of those on antipsychotic medications. Most participants who progressed to a second-line therapy received combination therapy (73.3%), which usually included the addition of a second medication to their first-line therapy.

The study authors note the need for additional research to determine why patients with clinically meaningful chorea may not receive treatment. At the time of this study, the only medications with FDA approval indicated for the treatment of chorea associated with HD were tetrabenazine and Austedo (deutetrabenazine; Teva Neuroscience, Parsippany, NJ), both of which are VMAT2 inhibitors. As of 2023, Ingrezza (valbenazine; Neurocrine Biosciences, San Diego, CA), another VMAT2 inhibitor, was approved for the treatment of chorea associated with HD.

The study by Erin Furr Stimming, MD and colleagues was conducted with funding from Neurocrine Biosciences (San Diego, CA).