Data from the phase 3 trial of Pridopidine in Huntington's disease appear in Nature Medicine.

A joint press release from the companies Prilenia and Ferrer announced today the publication in Nature Medicine, one of the world's leading peer-reviewed medical journals, of the results of the phase 3 Proof-HD study, coordinated in Italy by Prof. Ferdinando Squitieri, Head of the Huntington's and Rare Disease Unit at the IRCCS Casa Sollievo della Sofferenza and Scientific Director of the Italian League for Huntington Research Foundation (LIRH).

The publication describes data demonstrating that treatment with pridopidine slowed clinical progression in patients with Huntington's disease who were not taking antidopaminergic drugs.

The article states that treatment with pridopidine slowed clinical progression and maintained function, cognition, and motor performance in the subgroup of patients with early-stage Huntington's disease who were not taking antidopaminergic drugs (ADMs). Antidopaminergic drugs can cause side effects that are indistinguishable from disease progression and can negatively impact clinical outcome measures and confound treatment-related effects in a clinical trial.

The PROOF-HD study did not meet its overall primary and secondary endpoints for the entire study population, but only for this specific subgroup.

This randomized, double-blind, placebo-controlled study represents—to date—the first and only Phase 3 study in Huntington's disease to have shown improvements in all disease domains, while maintaining a good safety profile.

However, the EMA recently rejected the drug's marketing authorization application because the primary objective—clinical improvement in all patients, including those taking dopaminergic drugs—was not achieved. Therefore, Prilenia, together with its partner Ferrer, intends to plan a further confirmatory study to further support discussions on the regulatory approval process globally.

This important publication adds weight to the evidence supporting the sigma-1 receptor agonist approach and the development of pridopidine for the treatment of neurodegenerative diseases such as Huntington's disease and Amyotrophic Lateral Sclerosis.

"This is a long journey that began in 2007 and unfortunately, it still prevents us from having this drug commercially available," states Ferdinando Squitieri, co-author of the study. "Pridopidine could represent a valuable resource to combine with the innovative experimental therapies currently under development. The fact that antidopaminergic drugs mask the positive effect of Pridopidine raises questions about the inconsistencies in the clinical approach to Huntington's disease, which in Italy is still referred to as "chorea," even by specialists themselves."