Longitudinal Treatment Patterns for Chorea in Patients with Huntington Disease: Data from Enroll-HD
Erin Furr-Stimming1, Daniel Claassen2, Ginny Sen3, Mallory Farrar3, Ericha Franey3, Chuck Yonan3, Dietrich Haubenberger3
1The University of Texas Health Science Center at Houston, 2Vanderbilt University Medical Center, 3Neurocrine Biosciences, Inc.

To determine longitudinal treatment patterns for chorea in individuals with Huntington disease (HD) using Enroll-HD Periodic Dataset 5.0.


Enroll-HD is a worldwide, prospective, observational study of individuals with (or at-risk for) HD. Previous analyses of Enroll-HD data suggest that chorea may be undertreated despite the availability of FDA-approved medications such as the vesicular monoamine transporter 2 [VMAT2] inhibitors and off-label medications such as antipsychotics and benzodiazepines.

Data were collected from Jun-2012 to Oct-2020 for North American patients (≥18 years) with Unified Huntington’s Disease Rating Scale (UHDRS) Diagnostic Confidence Level 4 at each study visit. Presence of chorea was defined as UHDRS Total Maximal Chorea ≥2. Medications intended for chorea (as indicated in the Enroll-HD Database) were categorized as follows: VMAT2 alone, antipsychotics alone, medications other than VMAT2 inhibitors or antipsychotics (Other), and 2+ different medications from previous 3 categories (Combination). 
Chorea was documented in 96.8% (2507/2590) of eligible patients and 96.5% (6678/6920) of visits. Medications for chorea were prescribed to 36.1% (906/2507) of patients with chorea, with first-line treatments as follows: VMAT2 inhibitors (49.9%), antipsychotics (27.5%), other medications (18.7%), and combination treatments (4.0%). Average treatment duration ranged from 28.8 (VMAT2) to 41.2 (antipsychotics) months. Of the 906 treated patients, 688 (75.9%) continued their first-line medication; 147 (16.2%) changed treatment, often to a combination therapy (e.g., VMAT2 inhibitor plus antipsychotic, with/without other medication [n=43]); and 71 (7.8%) discontinued treatment for >90 days (mean 1-2 years). 29.4% (64/218) of patients switched/discontinued their second-line therapy.

In this analysis of a natural history database, 36.1% of patients with chorea received medication intended for chorea. Patients generally continued their first-line treatment, but those who switched often received a combination therapy. Continued research is needed to better understand optimal treatment patterns for chorea in patients with HD.