Prilenia Enrolls First Patients Into its PROOF-HD Phase 3 Clinical Trial for Huntington’s Disease in the United States

  • PROOF-HD is designed to replicate previous findings of pridopidine demonstrating maintenance of functional capacity in early Huntington’s Disease patients
  • Conducted in collaboration with the Huntington Study Group, a world leader in clinical research for HD
  • If successful, PROOF-HD could lead to the registration of pridopidine, one of the few oral drugs currently in clinical development for the treatment of HD

NAARDEN, Netherlands–(BUSINESS WIRE)–Prilenia Therapeutics B.V., a clinical stage biotech company focused on developing novel treatments for neurodegenerative and neurodevelopmental disorders, today announces the enrollment of the first patients in the U.S. into PROOF-HD, a global phase 3 clinical trial for Huntington’s Disease (HD). The study is being conducted in collaboration with the Huntington Study Group (HSG).

Pridopidine Outcome On Function in Huntington’s Disease (PROOF-HD) is a randomized, double-blind, placebo-controlled, phase 3 study evaluating the efficacy and safety of pridopidine 45mg bid in patients with early stage HD. The study will enroll 480 participants aged 25 or older with a clinical diagnosis of adult-onset HD at approximately 60 study centers in the U.S., Canada and Europe. The treatment period will last up to 78 weeks and there will be an optional open-label extension.

The study is designed to replicate previous findings that demonstrated pridopidine’s effect in maintaining functional capacity in patients with early HD. The trial treatment dose (45mg bid) has a favorable safety profile based on over 1,000 patient years in previous HD trials.

Andrew Feigin, MD, North American Principal Investigator for the PROOF-HD Phase 3 Trial, said: “Huntington’s Disease is a serious condition with no known treatments that slow functional decline. A successful result would be a major advance in our ability to treat HD. I look forward to working with the Prilenia team as we push forward with patient recruitment.”

Michael R. Hayden, CEO of Prilenia and world-renowned scientist in Huntington’s Disease research, commented: “The design of the PROOF-HD study is based on strong scientific and clinical data, including in vivo target engagement for the selected dose, prior clinical efficacy results and extensive long-term safety data in our target population,” He added: “Enrolling our first patients is a significant milestone that brings hope to others suffering from this devastating disease.”

Pridopidine is a first in class small molecule developed by Prilenia for the treatment of neurodegenerative disorders such as HD and Amyotrophic Lateral Sclerosis (ALS). Pridopidine is a highly selective Sigma-1 receptor (S1R) agonist. It binds and activates the S1R, a protein that is expressed at high levels within the brain and regulates key cellular pathways, commonly impaired in neurodegeneration.

Further details of the trial can be found here:


Notes to Editors

About Prilenia (

Prilenia is a clinical stage biotech startup founded in 2018 with the purpose of improving the lives of patients and their families by developing treatments for neurodegenerative and neurodevelopmental disorders. Prilenia raised $ 82.5 million thus far and is backed by a group of well-respected investors: Talisman, Forbion, Morningside and Sectoral. The Company is based in Naarden, the Netherlands, Herzliya, Israel and Boston, MA in the U.S.

About Pridopidine

Prilenia’s lead asset is Pridopidine, a first-in-class drug candidate with an established safety profile and therapeutic potential in several neurodegenerative diseases affecting adults and children. The highly selective S1R agonist was acquired from Teva in 2018.

Pridopidine’s favorable safety profile has been established in clinical trials in >1300 study participants, exposed to various doses for a total of ~1300 patient years.

Pridopidine for Huntington’s Disease

HD is a fatal, inherited, neurodegenerative disorder. Every offspring of an HD patient has a 50% chance of inheriting the gene. Usually starting at around 40 years of age, HD patients suffer from movement disorder, progressive functional and cognitive decline, psychiatric disturbances and behavioral symptoms. Following diagnosis, functional, motor and cognitive functions decline steadily, ultimately leading to immobility, dementia and premature death.

Pridopidine has demonstrated maintenance of functional capacity in HD patients, as measured by Total Functional Capacity (TFC), in a clinical trial. This effect was most prominent in early stage HD patients (HD1 and HD2), who showed functional benefit from pridopidine 45 mg, taken twice a day.

There is extensive preclinical evidence that further supports pridopidine’s potential beneficial effect in HD. The therapeutic effect has been shown to be mediated exquisitely by the sigma-1 receptor (S1R) using multiple deletion and antagonist models.

Prilenia has an orphan drug designation for pridopidine for the treatment of HD in both the US and Europe.


PROOF-HD is a Phase 3, randomized, double-blind, placebo-controlled study evaluating the efficacy and safety of pridopidine in patients with early stage of Huntington’s Disease. The purpose of the study is to evaluate the effect of pridopidine 45mg bid on functional capacity, as well as on motor and behavioral features.

For more information about PROOF-HD, including inquiries regarding participation, please visit the study’s website:

About Huntington Study Group Clinical Research

Founded in 1993 in Rochester, NY, the Huntington Study Group (HSG) is a not-for-profit organization comprised of the world’s first and largest collaborative network of experts in Huntington’s Disease. HSG Clinical Research, Inc. is a wholly-owned for-profit subsidiary of the HSG, conducts clinical trials to benefit the HSG and its mission of seeking treatments that make a difference for those affected by HD. There are 700 credentialed HD experts at more than 120 HSG credentialed research sites worldwide. The HSG also offers educational services like CME4HD™ for healthcare professionals and care providers on treating patients with HD. For more information, visit


For further information, please contact:

Prilenia Therapeutics
Michael Hayden, CEO

Limor Ben Har, COO


Instinctif Partners
Melanie Toyne-Sewell / Agnes Stephens / Siobhan Sanford

T: +44 (0) 207 457 2020


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