Study Exploring Safety, Pharmacokinetic and Pharmacodynamic of BN82451 in Male Huntington's Disease Patients

The purpose of this study is to evaluate the safety, tolerability, pharmacokinetics and pharmacodynamics of BN82451B versus placebo after oral administration twice daily (bid) for 28 days in patients with Huntington's Disease (HD).


Eligibility Criteria:
Inclusion Criteria:

* Male subjects 20 to 70 years old (inclusive).
* Provision of written informed consent prior to any study related procedures. In this study consent may be provided by the legal guardian or carer.
* Confirmed symptomatic Huntington's Disease diagnosed based on clinical features (i.e. Diagnostic Confidence Level equal to 4) and presence of at least 36 cytosine adenine guanine (CAG) repeats in the Huntington gene as documented by a copy of a previous genetic test report.
* Unified Huntington's Disease Rated Scale-Total Motor Score (UDHRS-TMS) greater than or equal to 15.
* Ambulatory.
* UDHRS-Total Functional Capacity (TFC) greater than or equal to 3 (i.e. Shoulson \& Fahn Scale stages 1-3 inclusive.
* Subjects on antipsychotic, antidepressant, anxiolytic and hypnotic therapy must have been on stable treatment 4 weeks prior to study drug start and during the study period.
* Able to swallow study medication.
* Able to perform Q-Motor tests.
* If his partner is at risk of pregnancy, the subject agrees to use a condom or be abstinent for 14 days after the last intake of study drug.

Exclusion Criteria:

* Juvenile forms of Huntington's Disease.
* Any form of chorea other than Huntington's Disease.
* History of seizure, epilepsy or other convulsive disorder, with the exception of febrile seizures in childhood.
* History of conditions susceptible to induce seizures such as severe traumatic brain injury, brain tumours, stroke.
* History of neurosurgical procedure.
* Current evidence or history (within 1 year of Baseline) of psychosis, hallucinations or delusions, including major depression with psychotic features, as defined in the Diagnostic and Statistical Manual, Fourth Edition, Text Revision (DSM-IV-TR). Patients currently experiencing mild depression, or moderate depression which is adequately and appropriately treated in the judgement of the investigator, can participate if depression is not expected to interfere with study participation.
* History of drug and/or alcohol abuse as per the DSM IV-TR criteria within 12 months prior to Baseline.
* At imminent risk of self harm based on investigator's clinical judgment, with a "yes" answer on item 4 or 5 on the Columbia-Suicide Severity Rating Scale (CSSRS) questionnaire.
* Mini Mental State Exam (MMSE) total score less than or equal to 23.
* Used any investigational drugs within 30 days prior to Screening or 5 half lives, whichever is the longest.
* Known allergy/sensitivity to the study drugs or their excipients.
* A severe or ongoing unstable medical condition (e.g. cardiac, hepatic, renal, metabolic or endocrine).
* Any clinically significant condition which, in the opinion of the investigator, would interfere with the trial evaluations or optimal participation in the trial.
* Any significant laboratory results which, in the investigator's opinion, would not be compatible with study participation or represent a risk for subjects while in the study.
* History of malignant disease within the 5 years prior to Screening (with the exception of basal cell and squamous cell carcinomas of the skin that have been completely excised, in situ prostate cancer with a normal prostate specific antigen).
* An estimated Creatinine Clearance (CrCl) of less than 60 mL/minute (using the Cockcroft-Gault formula).
* Alanine Aminotransferase (ALT)/Aspartate Aminotransferase (AST) values greater than or equal to 2 times the Upper Limit of Normal range (ULN) or both GGT and ALT values greater than three times the ULN.
* Known history of hepatitis B or C or Human Immunodeficiency Virus (HIV) or positive serology at Screening.
* Corrected QT interval using Bazett's correction (QTcB) greater than 450 ms or other clinically significant ECG findings.
* Receiving tetrabenazine within 4 weeks prior to Baseline.
* Taking the following prohibited medications/substances: Strong Cytochrome (CYP) 3A4 inhibitors and Strong CYP3A4 inducers (Wash out prior to Baseline 30 days or 5 half lives,whichever is the longest), CYP2B6 substrates, CYP1A2 substrates, CYP3A4 substrates, CYP2C19 substrates (assessed on a case by case basis)