A Clinical Study in Subjects With Huntington's Disease to Assess Efficacy and Safety of Three Oral Doses of Laquinimod

Inclusion Criteria:

- Documentation of prior positive genetic testing for HD, or a clinical diagnosis of
symptomatic HD

- Presence of 36-49 CAG repeats, inclusive, in the huntingtin gene based on centralized
CAG testing during screening.

- Male or female between 21-55 years of age, inclusive, with an onset of HD at or after
18 years of age

- Women of child-bearing potential (women who are not post menopausal or who have
undergone surgical sterilization) must practice an acceptable method of birth control
for 30 days before taking the study treatment, and 2 acceptable methods of birth
control during all study duration and until 30 days after the last dose of treatment
was administered.

- A sum of >5 points on the UHDRS TMS at the screening visit

- Able and willing to provide written informed consent prior to any study related
procedure being performed at the screening visit. Patients with a legal guardian
should be consented according to local requirements

- Willing to provide a blood sample at the screening visit

- Willing and able to take oral medication and able to comply with the study specific
procedures

- Ambulatory, being able to travel to the study centre, and judged by the investigator
as likely to be able to continue to travel for the duration of the study

- Availability and willingness of a caregiver, informant, or family member to provide
input at study visits. A caregiver is recommended to be someone who attends to the
patient at least 2 to 3 times per week for at least 3 hours per occasion, and the
suitability of the caregiver should be judged by the investigator

- For patients taking allowed antidepressant medication, the dosing of medication must
have been kept constant for at least 30 days before baseline and must be kept constant
during the study

- Additional criteria may apply, please contact the investigator for more
information

Exclusion Criteria:

- Use of immunosuppressive agents, or cytotoxic agents, including cyclophosphamide and
azatioprine within 12 months prior to screening

- Previous use of laquinimod

- Use of moderate/strong inhibitors of cytochrome P450 (CYP)3A4 within 2 weeks prior to
randomization

- Use of inducers of CYP3A4 within 2 weeks prior to randomization

- Pregnant or breastfeeding

- Subjects with a clinically significant or unstable medical or surgical condition that
may put the patient at risk when participating in the study or may influence the
results of the study or affect the patient's ability to take part in the study, as
determined by medical history, physical examinations, ECG, or laboratory tests. Such
conditions may include:

- A major cardiovascular event (e.g. myocardial infarction, acute coronary
syndrome, de-compensated congestive heart failure, pulmonary embolism, coronary
revascularization) that occurred during the past 6 months prior to randomization

- Any acute pulmonary disorder

- A central nervous system (CNS) disorder other than HD that may jeopardize the
subject's participation in the study, including such disorders that are
demonstrated on the baseline magnetic resonance imaging (MRI) (based on local
read)

- A gastrointestinal disorder that may affect the absorption of study medication

- Renal disease

- Cirrhotic patients with moderate or severe hepatic impairment

- Known human immunodeficiency virus (HIV) positive status. Patients will undergo
an HIV test at screening per local requirements, if applicable

- Any malignancies, excluding basal cell carcinoma, in the 5 years prior to
randomization

- Any clinically significant, abnormal, screening laboratory result which in the opinion
of the investigator, affects the patients' suitability for the study or puts the
patient at risk if he/she enters the study

- Unsuitable for MRI (e.g, claustrophobia, metal implants)

- Alcohol and/or drug abuse within the 6 months prior to screening, as defined by
Diagnostic and Statistical Manual of Mental Disorders - Fourth Edition Text Revision
(DSM IV TR) criteria for substance abuse

- Patients with active suicidal ideation during the past month as measured by a most
severe suicide ideation score of 4 (Active Suicidal Ideation with Some Intent to Act,
without Specific Plan) or 5 (Active Suicidal Ideation with Specific Plan and Intent)
on the baseline screening Columbia-Suicide Severity Rating Scale (C-SSRS) or subjects
who answer "Yes" on any of the 5 C-SSRS Suicidal Behavior Items (actual attempt,
interrupted attempt, aborted attempt, preparatory acts, or behavior) if the attempt or
acts were performed within 1 year of screening, or subjects who, in the opinion of the
investigator, present a serious risk of suicide

- Patients with known intracranial neoplasms, vascular malformations, or intracranial
hemorrhage

- Known drug hypersensitivity that would preclude administration of laquinimod or
placebo, such as hypersensitivity to mannitol, meglumine or sodium stearyl fumarate

- Swallowing difficulties that would preclude administration of laquinimod or placebo
capsules

- Treatment with any investigational product within 12 weeks of screening or patients
planning to participate in another clinical study assessing any investigational
product during the study.

- Patients in noninterventional and/or observational studies will not be excluded from
participating in this study

- Treatment with tetrabenazine within 30 days of the study baseline visit

- Treatment with antipsychotic medication within 30 days of the study baseline visit

- Additional criteria may apply, please contact the investigator for more
information