FDA grants clearance to Prilenia and Ferrer’s Phase III ALS therapy trial

The US Food and Drug Administration (FDA) has granted clearance to Prilenia Therapeutics and Ferrer to commence a Phase III trial of pridopidine in individuals with rapidly progressive amyotrophic lateral sclerosis (ALS) at an early stage of disease.

This randomised, placebo-controlled trial will involve 500 participants, with recruitment at US trial sites expected to start in early 2026.

Expansion to Europe and other regions will follow after local regulatory approvals.

The PREVAiLS study will be carried out at up to 60 ALS treatment centres across Canada, the European Union (EU), the US, Israel and the UK.

The trial will focus on participants who have definite or probable ALS, as defined by the El Escorial Criteria, and are within 18 months of their first disease symptoms.

It will include a 48-week placebo-controlled double-blind phase, randomising patients in a 3:2 ratio to receive either pridopidine or placebo. This will be followed by a 48-week open-label extension phase.

Change from baseline in ALSFRS-R, adjusted for mortality at 48 weeks, is the primary goal of the trial.

Secondary and exploratory goals will assess speech, bulbar and respiratory function, quality of life, survival, patient-reported communication, and plasma biomarkers.

The PREVAiLS trial is based on subgroup analyses from the Phase II HEALEY ALS Platform trial, which included 284 participants with rapidly progressive ALS early in their disease course.

Of these, 120 participants are in the therapy arm, with 164 in the placebo arm. The analyses indicated potential improvements in disease progression, survival and speech for those taking pridopidine.

In the HEALEY ALS Platform trial, the subgroup taking pridopidine demonstrated a 32% overall progression slowing, a 62% slowing in worsening of respiratory function, and an 88% slower decline in dyspnoea at 24 weeks.

Deterioration in articulation and speaking rate was decreased by 93% and 70%, respectively.

Survival benefit was also observed, with a 57% improvement and median survival extended from 300 to 600, alongside a favourable safety profile.

Pridopidine is an orally administered selective sigma-1 receptor (S1R) agonist, taken at 45mg twice a day.

Prilenia Therapeutics’s chief regulatory and commercialisation officer Henk Schuring said: “The FDA’s clearance to start PREVAiLS is significant, providing an immediate opportunity to begin a pivotal Phase III study with the aim of bringing a promising, oral, well-tolerated new therapy to patients.”

Prilenia and Ferrer are planning to start a confirmatory trial in Huntington’s disease (HD), with recruitment expected to begin in the first half of 2026, to support discussions on global regulatory pathways.

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