A Phase 3 interventional study of Pridopidine and Placebo in Huntington Disease, sponsored by Prilenia. Recruiting at 66 sites in 12 countries. Open to participants aged 23 Years to 65 Years. Per ClinicalTrials.gov, last updated 2026-11-04.
Sponsored by Prilenia · Phase 3, Interventional, and Treatment
The goal of this clinical trial is to learn if pridopidine can slow the clinical decline of Huntington's Disease (HD) in adult participants. It will also inform about the safety of pridopidine.
The main questions the study aims to answer are:
Does pridopidine slow the overall worsening of HD over 1 year? Does pridopidine slow the worsening of specific aspects of HD over 1 year, namely the clinical progression, the ability to perform daily life activities (functional capacity), the mind's ability to process information (cognition), working of the muscles (motor function), and quality of life?
Researchers will compare the drug pridopidine to a placebo (a look-alike substance that contains no drug) to see if pridopidine works better than placebo to treat HD. During the first year of the study, participants will have the same chance to receive either pridopidine or placebo.
Participants will:
Take 1 pridopidine or placebo capsule twice daily for 12 months. Visit the clinic 6 times within 1 year for checkups and tests.
All participants who complete this 1-year placebo-controlled study period will roll over into an additional 2-year study period during which all participants will receive pridopidine treatment, including participants who had received placebo during the first year. During this additional 2-year treatment period participants will visit the clinic a total of 6 times for checkups and tests.
This Phase 3 study consists of two study periods, a randomized, double-blind, placebo-controlled 1-year study period and a 2-year open-label extension (OLE) period. The study assesses the effect of pridopidine 45 mg twice daily on HD in participants who are not using antidopaminergic medications (ADMs) at study start. Main objectives of the study will be to assess the effect of pridopidine on clinical progression of HD within 1 year and to evaluate the effect of pridopidine on functional capacity, cognition, motor function, quality of life (QoL), and speech in participants with HD within 1 year.
The target population in this study are adult participants (age 23-65, inclusive) with adult-onset HD (onset of signs and symptoms and a diagnosis ≥21 years of age). Eligible participants have not been using ADMs for at least 6 months prior to the screening visit. In case ADM treatment is deemed necessary by the treating physician during the study, specific ADMs and doses may be initiated. Female participants who are pregnant, planning to become pregnant or breastfeeding are not allowed to enter the study.
The treatment period will start with a 2-week titration period of once-daily treatment (1 capsule of pridopidine or placebo taken orally in the morning). From Day 15 onwards, all participants will take the study drug twice daily: in the morning and in the afternoon. Treatment will continue for an additional 50 weeks.
The placebo-controlled study period includes 6 in-clinic visits and 5 telephone visits (safety calls) during the 1-year treatment period.
The placebo-controlled study period will be followed by a 2-year OLE period. During the OLE period, all eligible participants will receive pridopidine. The OLE will consist of a 2-year treatment period, including an initial 2-week (re)titration period for all participants at pridopidine once daily and a maintenance period of 102 weeks with pridopidine twice daily. The blinding of the original treatment assignment will be maintained for all participants and study personnel during the OLE period.
A total of 6 in-clinic visits and 6 telephone visits (safety calls) are planned during the 2-year OLE period.
293 studies on the registry are indexed under Huntington Disease; 54 are open to participants now.
This study's planned enrollment of 400 is above the median of 40 across 207 interventional studies indexed under Huntington Disease.
Browse Huntington Disease studies →Prilenia is the lead sponsor of 9 studies on the registry; 2 are open to participants now.
Of its 5 completed or terminated interventional studies of FDA-regulated products, 5 (100%) have results posted.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
On an ECG, the QT interval is the time the heart’s lower chambers take to activate electrically and recover in each beat. QTc is that time adjusted for heart rate (QTcF by Fridericia’s formula, QTcB by Bazett’s). Some medicines lengthen it, and a long QTc can raise the risk of a dangerous heart rhythm.
The study may name a correction formula and a limit in milliseconds, often around 450–480.
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
QT and QTc
On an ECG, the QT interval is the time the heart’s lower chambers take to activate electrically and recover in each beat. QTc is that time adjusted for heart rate (QTcF by Fridericia’s formula, QTcB by Bazett’s). Some medicines lengthen it, and a long QTc can raise the risk of a dangerous heart rhythm.
The study may name a correction formula and a limit in milliseconds, often around 450–480.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer (malignancy)
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis B tests
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis C tests
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
During the titration period (2 weeks), pridopidine 45 mg capsules will be taken orally once daily (in the morning) for 2 weeks. Afterwards, pridopidine 45 mg capsules will be taken orally twice daily (in the morning and in the afternoon; 7-10 hours apart) for 50 weeks.
Drug: Pridopidine
During the titration period (2 weeks), matched placebo hard gelatin capsules will be taken once daily (in the morning) for 2 weeks. Afterwards, placebo capsules will be taken twice daily (in the morning and in the afternoon; 7-10 hours apart) for 50 weeks.
Drug: Placebo
Pridopidine hard gelatin capsule
Matched placebo hard gelatin capsule
Change in Composite Unified Huntington's Disease Rating Scale (cUHDRS)
cUHDRS is a combined score to assess disease progression in HD. It includes TFC, TMS, SDMT, and SWR: Total Functional Capacity (TFC) tests the capacity to maintain daily living, finances, care level, occupation. Higher score = better outcome. Best score=13. Worst score=0. Total Motor Score (TMS) assesses motor features (oculomotor, dysarthria, chorea, dystonia, gait, postural stability). Higher score = worse outcome. Best score=0. Worst score= 124. Stroop Word Reading (SWR) measures attention and mental flexibility. Participant reads names of colors printed in black ink. Scores reflect correct responses in 45 sec. Higher score = better outcome. Best score=100. Worst score=0. Symbol Digit Modalities Test (SDMT) tests psychomotor speed and working memory. Participant has 90 sec to match numbers with symbols. Scores = correct answers in 90 sec. Higher score = better outcome. Best score=120. Worst score=0. Total integrated cUHDRS scale range: -7.6 to 24.8. The higher, the better.
Time frame: Change from Baseline to Week 52
Change in Total Functional Capacity (TFC) score
Total Functional Capacity (TFC) tests the capacity to maintain domestic chores, activities of daily living, finances, care level, and occupation. Scores from 0 - 13. Higher score = better outcome.
Time frame: Change from Baseline to Week 52
Change in Quantitative Motor (Q-Motor) Finger Tapping Inter-Onset Interval (FT-IOI) mean
Quantitative (Q)-motor is a clinical assessment of fine motor skills that are crucial for daily activities. It is based on the application of pre-calibrated and temperature-controlled force transducers and 3-dimensional position sensors. Higher score = worse outcome.
Time frame: Change from Baseline to Week 52
Change in Stroop Word Reading (SWR) score
Stroop Word Reading (SWR) measures attention and mental flexibility. Participant reads names of colors printed in black ink. Scores reflect correct responses in 45 sec. Higher score = better outcome.
Time frame: Change from Baseline to Week 52
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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Studies of the drug tested here: Pridopidine
Prilenia