New Confirmatory “PRECISE-HD” study of Pridopidine in HD ready to start recruitment in June

Date of release: 07/07/2026

Dear HD Community,

We would like to share an update on the confirmatory PRECISE-HD study (Pridopidine Phase 3 Study to Establish Clinical Impact and Safety in Huntington’s Disease (HD)), a global clinical study evaluating the investigational medicine pridopidine in people living with Huntington’s disease. The study has now been listed on www.clinicaltrials.gov (NCT07609108).

Incorporating past study learnings, extensive input from the patient and research communities, and advice from regulatory authorities, PRECISE-HD is intended to collect important data on the efficacy and safety of pridopidine and is designed to generate robust data to further support regulatory evaluation. Site initiation is underway, and recruitment is expected to commence at the first sites in the US in June 2026, followed by sites in other countries on a rolling basis later in the year.

What is the PRECISE-HD study?

Currently, there are no approved treatments to slow or stop HD from progressing.

PRECISE-HD is a confirmatory Phase 3 clinical study evaluating the efficacy and safety of the investigational medicine pridopidine (taken as an oral capsule twice a day) in people living with HD. The study design was informed by previous research, input from the HD community, and discussions with regulatory authorities.

The study plans to enroll 400 people living with HD, from early to mid-stage disease (defined as Total Functional Capacity (TFC) score of 7-13), and a Total Motor Score (TMS) of ≥20, meaning people who have experienced motor changes or impact on independent functioning. This population is intended to enable the appropriate assessment of any potential effect of the therapy on disease progression in comparison to placebo.

PRECISE-HD will consist of two sequential stages:

Stage 1 — Placebo-controlled (52 weeks): Participants receive either pridopidine or placebo (half receiving pridopidine and half placebo). Neither participants nor their doctors will know which they are receiving.

Stage 2 — Open-label extension (104 weeks): All (eligible) participants, regardless of the treatment received during Stage 1, will be assigned to receive pridopidine for two years, allowing researchers to assess longer-term effects over up to three years in total.

The study will evaluate a range of HD-related outcomes, with the primary endpoint being the change from baseline to Week 52 in the combined Unified Huntington’s Disease Rating Scale (cUHDRS) score. Several other endpoints, including function, motor, cognition, speech and quality of life, will be also measured, along with the safety and tolerability of pridopidine.

The study is planned to be conducted at up to 75 study sites globally, including in the US, EU, UK and Canada. Recruitment is expected to commence at the first sites in the US in June 2026, followed by sites in other countries on a rolling basis later in the year.

People who would like more information about PRECISE-HD can speak with their neurologist or HD specialist. They may also contact their local HD patient advocacy organization for additional guidance and support. Eligibility, study procedures, and any potential risks and benefits will be explained by the study team at the investigational sites during the informed consent process.

What is pridopidine?

Pridopidine is an investigational medicine, and its safety and efficacy have not been established, participants may or may not benefit from taking part in this study.

It exerts its effect by activating a protein in the brain called the sigma-1 receptor (S1R) and is often referred to as an S1R agonist. S1R has been shown to play a role in stimulating multiple neuroprotective pathways impaired in neurodegenerative diseases, such as HD. The clinical effects of pridopidine on HD progression will be evaluated in this study.

To date, more than 1,600 people have received pridopidine in clinical studies — the majority from HD trials — with some participants on active treatment for up to seven years. Across these studies, pridopidine has shown a generally favorable safety and tolerability profileⁱ.

Who is sponsoring the PRECISE-HD study

PRECISE-HD is being undertaken by Prilenia and Ferrer, who are co-developing pridopidine in partnership. Prilenia is a private biopharmaceutical company driven by an unwavering commitment to scientific excellence and accelerating progress for people affected by Huntington’s disease (HD), amyotrophic lateral sclerosis (ALS) and other neurodegenerative disorders. Ferrer is a B Corp-certified international pharmaceutical company that uses business to fight for social justice and offers transformative solutions for life-threatening diseases in more than one hundred countries with a growing focus on rare neurological disorders.

Prilenia and Ferrer are also studying pridopidine in a Phase 3 study in ALS.

For more information on the companies, please visit www.prilenia.com or www.ferrer.com.

For more information on PRECISE-HD, visit www.clinicaltrials.gov (NCT07609108) and a PRECISE-HD study website (www.precisehdtrial.com) will be launched soon.

⚠ Important Note
Pridopidine is an investigational medicine and is not approved for use by any regulatory authority. Its safety and efficacy have not yet been established. This update is for informational purposes only and does not constitute medical advice. Please speak with your healthcare provider before making any decisions about treatment or participation in a clinical study.

Press release