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In development

Pridopidine

Also known as Nurzigma (proposed EU brand name, Huntington's disease)

Bottom line

No benefit overall in its only completed ALS trial. A small after-the-fact subgroup of early, fast-progressing patients did better, which could be chance; the Phase 3 PREVAiLS trial is testing exactly that group, with results expected in early 2028.

Pridopidine is a twice-daily pill that switches on a protective protein inside nerve cells called the sigma-1 receptor. In the HEALEY ALS Platform Trial it did not slow ALS: it missed its main goal and all key secondary goals. In an after-the-fact look at a small group of people early in their disease who were getting worse quickly, it seemed to do better. A 500-person Phase 3 trial (PREVAiLS) is now testing that group, with results expected in early 2028.

Information checked 5 Nov 2026

Evidence: Hints only

Studies: 1 mixed · 1 running

Controlled trials missed their main goal. Some measures or subgroups looked better, which needs confirming.

No benefit overall; hint in small post-hoc subgroup

5.2 points less decline over 24 weeks in a post-hoc group of 34 people, on the 48-point ALSFRS-R

How we decide the overall verdict: How to read this site.

At a glance

CompanyPrilenia Therapeutics (with Ferrer)Explanation and sources

Prilenia is a private biotech based in the Netherlands and Massachusetts, and pridopidine is its main drug, also being developed for Huntington's disease. The Spanish drug company Ferrer is its partner for Europe and some other markets and co-sponsors the ALS Phase 3 trial. Prilenia keeps the rights in North America and Asia.

Sources

  1. Pridopidine Pivotal Phase 3 ALS Study Unveiled at NEALS 2025 Annual MeetingPrilenia Therapeutics · 6 Oct 2025 · Company press release
  2. Pridopidine Phase 3 Study to Evaluate Efficacy and Safety in ALS (PREVAiLS, NCT07322003)ClinicalTrials.gov · Trial registry
How it worksSwitches on a protein that helps nerve cells cope with stressSigma-1 receptor (S1R) agonistExplanation and sources

The sigma-1 receptor is a protein that sits where the cell's protein factory meets its power plants (mitochondria). Turning it on is thought to help nerve cells handle stress, keep their energy supply working and clear damaged material. Most of this evidence comes from lab and animal studies.

Sources

  1. Pridopidine, a Potent and Selective Therapeutic Sigma-1 Receptor (S1R) Agonist for Treating Neurodegenerative DiseasesPharmaceuticals (MDPI) · Peer-reviewed paper
  2. Pridopidine Pivotal Phase 3 ALS Study Unveiled at NEALS 2025 Annual MeetingPrilenia Therapeutics · 6 Oct 2025 · Company press release
StagePhase 3Phase 3 PREVAiLS enrolling, ~60% of 500 peopleExplanation and sources

PREVAiLS started in March 2026 and is planned across up to 60 ALS centres in 13 countries. In late October 2026 the companies said it was about 60% enrolled and expected to finish enrolling in the first quarter of 2027. Pridopidine has never been filed for approval in ALS anywhere. Its only marketing application, in Europe for Huntington's disease, received a negative EMA opinion in July 2025 and was withdrawn in November 2025.

Sources

  1. Prilenia and Ferrer Announce First Participant Enrolled in the PREVAiLS Phase 3 Study of Pridopidine in ALSPrilenia Therapeutics · 30 Mar 2026 · Company press release
  2. Prilenia and Ferrer to Share New Pridopidine Data and PREVAiLS Study Updates at the NEALS Consortium 2026 Annual MeetingPrilenia Therapeutics · 28 Oct 2026 · Company press release
  3. Pridopidine Phase 3 Study to Evaluate Efficacy and Safety in ALS (PREVAiLS, NCT07322003)ClinicalTrials.gov · Trial registry
  4. Nurzigma (pridopidine) - withdrawn applicationEuropean Medicines Agency · 14 Nov 2025 · Regulator
Best reported effectNo benefit overall; hint in small post-hoc subgroup5.2 points less decline over 24 weeks in a post-hoc group of 34 people, on the 48-point ALSFRS-RExplanation and sources

In the HEALEY ALS Platform Trial, pridopidine did not slow ALS compared with placebo in the full group of 162 people, on the main goal (function and survival combined) or on any key secondary goal, as published in JAMA in 2025. When researchers looked back at 34 people within 18 months of first symptoms, with definite or probable ALS and fast decline, those on pridopidine lost 7.5 ALSFRS-R points versus 12.7 on placebo, and some speech measures were better. Looking back at small subgroups can produce chance findings, which is why PREVAiLS is testing this group prospectively.

This is the most favourable result reported. See all key studies for the full picture.

Sources

  1. Pridopidine in Amyotrophic Lateral Sclerosis: The HEALEY ALS Platform TrialJAMA · 17 Feb 2025 · Peer-reviewed paper
  2. Prilenia Announces Topline Results for Pridopidine in Phase 2 ALS StudyPrilenia Therapeutics · Company press release
  3. Pridopidine for the Treatment of ALS - Results from the Phase 2 Healey ALS Platform Trial (S5.003)Neurology (AAN 2024 abstract) · 9 Apr 2024 · Conference presentation
  4. E105 PREVAiLS: a phase 3, randomized, double-blind, placebo-controlled study in ALSJournal of Neurology, Neurosurgery & Psychiatry (EHDN 2026 abstract) · Conference presentation
Who it's forDefinite or probable ALS within 18 months of first symptomsEarly stage · Pill, 45 mg twice dailyExplanation and sources

PREVAiLS only enrols adults with definite or probable ALS whose first symptoms began less than 18 months earlier, the group that seemed to benefit in HEALEY. People can stay on riluzole, edaravone or Nuedexta if their dose has been stable for at least four weeks.

Sources

  1. Pridopidine Phase 3 Study to Evaluate Efficacy and Safety in ALS (PREVAiLS, NCT07322003)ClinicalTrials.gov · Trial registry
What's nextPREVAiLS enrolment complete (Q1 2027); topline results Q1 2028Expected Q1 2027Explanation and sources

Prilenia and Ferrer said on 28 October 2026 that they expect to finish recruiting about 500 people in the first quarter of 2027 and report the main results in the first quarter of 2028.

Sources

  1. Prilenia and Ferrer to Share New Pridopidine Data and PREVAiLS Study Updates at the NEALS Consortium 2026 Annual MeetingPrilenia Therapeutics · 28 Oct 2026 · Company press release
Can I join?Phase 3 recruiting in USA, Canada, EU, UK and IsraelRecruiting nowExplanation and sources

PREVAiLS is recruiting. Participants have a 3 in 5 chance of getting pridopidine for the first 48 weeks, and everyone gets it for a further 48 weeks afterwards. An NIH-funded expanded access programme run by the Healey Center gave pridopidine to 200 people who could not join trials; it completed enrolment and ClinicalTrials.gov now lists it as no longer available.

Sources

  1. Pridopidine Phase 3 Study to Evaluate Efficacy and Safety in ALS (PREVAiLS, NCT07322003)ClinicalTrials.gov · Trial registry
  2. Expanded Access Protocol for Pridopidine in People With ALS (NCT06069934)ClinicalTrials.gov · Trial registry
  3. Pridopidine Pivotal Phase 3 ALS Study Unveiled at NEALS 2025 Annual MeetingPrilenia Therapeutics · 6 Oct 2025 · Company press release

Signal: Active

Signal measures how often, and how reliably, Prilenia Therapeutics (with Ferrer) tells the public about this drug. It says nothing about whether the drug works. A quiet company isn't necessarily a bad sign, but regular, on-time updates help patients plan.

Last company update28 Oct 2026 (8 days ago)40 / 40
Company updates in the last 12 months635 / 35
Promises kept1 of 1 on time25 / 25
Signal score100 / 100 · Active

Announced milestones

70 or more is Active, 45 or more is Steady, 20 or more is Quiet, below 20 is Silent. Full method.

Timeline

10 events, newest first. Company updates are marked; independent news and regulator decisions are shown too.

2026

  1. Press releaseFrom the companyPrilenia Therapeutics

    PREVAiLS about 60% enrolled; results expected Q1 2028

    At NEALS 2026 the companies showed a new look-back analysis of 36 HEALEY participants compared with historical data, and said enrolment should finish in Q1 2027 with results in Q1 2028.

  2. Press releaseFrom the companyPrilenia Therapeutics (via SV Health Investors)

    PREVAiLS design presented at EHDN congress

    Alongside EU authorisation of the Huntington's trial, the companies said they would present the PREVAiLS ALS trial design at the EHDN congress in Kraków.

  3. Press releaseFrom the companyPrilenia Therapeutics

    Confirmatory Huntington's disease trial PRECISE-HD starts

    The companies began a 400-person Huntington's study. The release also noted the ALS Phase 3 trial was recruiting.

  4. Press releaseFrom the companyFerrer

    First European participant enrolled in PREVAiLS

    Ferrer announced the first participant in Europe, at University Medical Center Utrecht in the Netherlands.

  5. Press releaseFrom the companyPrilenia Therapeutics

    First participant enrolled in PREVAiLS

    The first person joined the Phase 3 trial at Mass General Brigham in Boston, with up to 60 centres in 13 countries planned.

2025

  1. Press releaseFrom the companyPrilenia Therapeutics

    FDA clears the PREVAiLS Phase 3 trial

    The FDA allowed the 500-person Phase 3 trial in early, rapidly progressing ALS to begin, with US recruitment planned for early 2026.

  2. RegulatoryEuropean Medicines Agency

    Prilenia withdraws its EU application in Huntington's disease

    Prilenia withdrew the application before the EMA's re-examination finished, saying it needs more clinical data. It said ALS trials and compassionate use were not affected.

  3. Press releaseFrom the companyPrilenia Therapeutics

    Phase 3 ALS trial design unveiled at NEALS 2025

    Prilenia and Ferrer presented the planned 48-week Phase 3 trial in early, fast-progressing ALS and said enrolment should start in January 2026.

  4. Press releaseFrom the companyFerrer

    Prilenia and Ferrer respond to the negative EMA opinion

    The companies said they were disappointed and planned a new Huntington's study plus a global pivotal Phase 3 study in ALS.

  5. RegulatoryEuropean Medicines Agency

    EMA recommends refusing pridopidine for Huntington's disease

    Europe's medicines committee found the studies did not show pridopidine works in early Huntington's disease. This was not an ALS application, but it is the only time pridopidine has been reviewed for approval.

All sources for this page

  1. Pridopidine Phase 3 Study to Evaluate Efficacy and Safety in ALS (PREVAiLS, NCT07322003)ClinicalTrials.gov · Trial registry
  2. Expanded Access Protocol for Pridopidine in People With ALS (NCT06069934)ClinicalTrials.gov · Trial registry
  3. Pridopidine, a Potent and Selective Therapeutic Sigma-1 Receptor (S1R) Agonist for Treating Neurodegenerative DiseasesPharmaceuticals (MDPI) · Peer-reviewed paper
  4. Four regimens fail endpoints simultaneously in HEALEY ALS trialClinical Trials Arena · News
  5. E105 PREVAiLS: a phase 3, randomized, double-blind, placebo-controlled study in ALSJournal of Neurology, Neurosurgery & Psychiatry (EHDN 2026 abstract) · Conference presentation
  6. Pridopidine Pivotal Phase 3 ALS Study Unveiled at NEALS 2025 Annual MeetingPrilenia Therapeutics · 6 Oct 2025 · Company press release
  7. Prilenia and Ferrer Announce FDA Clearance to Start the PREVAiLS Pivotal Phase 3 Study with Pridopidine in ALSPrilenia Therapeutics · 11 Dec 2025 · Company press release
  8. Prilenia and Ferrer Announce First Participant Enrolled in the PREVAiLS Phase 3 Study of Pridopidine in ALSPrilenia Therapeutics · 30 Mar 2026 · Company press release
  9. Prilenia and Ferrer to Share New Pridopidine Data and PREVAiLS Study Updates at the NEALS Consortium 2026 Annual MeetingPrilenia Therapeutics · 28 Oct 2026 · Company press release
  10. Pridopidine in Amyotrophic Lateral Sclerosis: The HEALEY ALS Platform TrialJAMA · 17 Feb 2025 · Peer-reviewed paper
  11. Prilenia Announces Topline Results for Pridopidine in Phase 2 ALS StudyPrilenia Therapeutics · Company press release
  12. Pridopidine for the Treatment of ALS - Results from the Phase 2 Healey ALS Platform Trial (S5.003)Neurology (AAN 2024 abstract) · 9 Apr 2024 · Conference presentation
  13. Researchers See Path Forward for Pridopidine Despite Missing HEALEY EndpointsThe ALS Association · Patient organisation
  14. Nurzigma (pridopidine) - withdrawn applicationEuropean Medicines Agency · 14 Nov 2025 · Regulator