Open-Label Rollover Study for Continuing Valbenazine Administration for the Treatment of Chorea Associated With Huntington Disease

Study Overview
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Brief Summary
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This is a Phase 3, open-label study to evaluate the long-term safety and tolerability of valbenazine, and to provide participants continued access to valbenazine for the treatment of chorea associated with Huntington disease.

Detailed Description
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After completion of Week 156/early termination visit, participants in the US will be given the option to continue into an extended maintenance period for up to 104 weeks and participants in Canada will have the option to participate in a separate open-label study (Study NBI-98854-HD3022).

Official Title
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Open-Label Rollover Study for Continuing Valbenazine Administration for the Treatment of Chorea Associated With Huntington Disease

Conditions
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Chorea, Huntington

Intervention / Treatment
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* Drug: Valbenazine


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Either #1 or #2 must be met for inclusion eligibility. Have participated in Study NBI-98854-HD3005 and a. Study drug dosing completion of Study NBI-98854-HD3005, as demonstrated by completed study drug dosing through the follow-up visit or early terminated Study NBI-98854-HD3005 for administrative reasons due to COVID-19 (for example, site closure related to COVID-19) Did not participate in Study NBI-98854-HD3005 and Have a clinical and genetic diagnosis of Huntington Disease (HD) with chorea Be able to walk, with or without the assistance of a person or device Be able to read and understand English and capable of providing consent to study participation or have a legally authorized representative providing consent and the participant providing assent Participants of childbearing potential must agree to use contraception consistently while participating in the study until 30 days after last dose of the study treatment Exclusion Criteria: Have difficulty swallowing Are currently pregnant or breastfeeding Have a known history of long QT syndrome, cardiac tachyarrhythmia, left bundle-branch block, atrioventricular (AV) block, uncontrolled bradyarrhythmia, or heart failure Have an unstable or serious medical or psychiatric illness Have a significant risk of suicidal behavior Have a history of substance dependence or substance (drug) or alcohol abuse, within 1 year of screening Have received gene therapy at any time Have received an investigational drug in a clinical study (other than valbenazine) within 30 days before the baseline visit or plan to use such investigational drug (other than valbenazine) during the study Have had a blood loss ≥550 mL or donated blood within 30 days before the baseline visit Have a history of severe hepatic impairment or history of protocol specified hematologic abnormalities during the course of the NBI-98854-HD3005 study Had a medically significant illness within 30 days before baseline, or any history of neuroleptic malignant syndrome Have a known hypersensitivity to any component of the formulation of valbenazine For participants who did not participate in NBI-98854-HD3005: have a history of VMAT2 inhibitor use within 30 days of baseline

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 75 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Valbenazine<br>Capsule, administered orally once daily. | Drug: Valbenazine<br>* vesicular monoamine transporter 2 (VMAT2) inhibitor<br>* Other names: NBI-98854;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Number of Participants with Treatment-Emergent Adverse Events (TEAEs) |  | Up to 262 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change from Baseline in the Unified Huntington's Disease Rating Scale (UHDRS) Total Maximal Chorea (TMC) Score | The TMC is part of the motor assessment of the UHDRS and measures chorea in 7 different body parts including the face, oral-buccal-lingual region, trunk and each limb independently. The TMC score is the sum of the individual scores and ranges from 0 to 28. A decrease in score indicates improvement in chorea. | Up to 262 weeks |