Prilenia Therapeutics’ amyotrophic lateral sclerosis (ALS) therapy pridopidine failed to meet its primary endpoint in a Phase II clinical trial, but the biotech is planning to initiate a Phase III study after pointing out notable findings.
In the Phase II HEALEY ALS platform trial (NCT04615923), pridopidine didn’t yield significant differences in primary or key secondary endpoints that measure disease progression as per the ALS Functional Rating Scale-Revised (ALSFRS-R), and mortality event rate, compared to the placebo.
The company had announced these topline results in February 2023, and at the time had hinted at a post-hoc analysis of patients with definitely or probably analysis—diagnoses for this condition—showing efficacy signals. As per the the latest update, patients with definite ALS, and less than 18 months duration on pridopidine experienced a slower disease progression.
A further analysis showed a 57% improvement in survival benefit for patients with definite or probable ALS early in the disease course. Pridopidine was well tolerated with no serious treatment-related adverse events, with a safety and tolerability profile similar to placebo and consistent with previous clinical studies.
Moreover, Prilenia Therapeutics reported improvements in certain speech-related measures such as speaking rate (p=0.028), articulation rate (p=0.013), phonation time (p=0.076), and articulatory precision (p=0.11), in the full group analysis. Detailed results from the study were presented at the 14th Annual California ALS Research Summit in Los Angeles, US, which was held on 19–20 January.
Despite missing key endpoints, given the overall results, the company aims to initiate a Phase III clinical trial in the second half of this year.
Pridopidine is an investigational small molecule drug targeting the sigma-1 receptor (S1R), produced in the brainstem and spinal cord. It acts as an S1R agonist, with a focus on brain regions linked to ALS pathology and symptoms such as bulbar function and speech.
ALS is a progressive neurodegenerative disorder causing the loss of motor neurons, leading to muscle weakness and paralysis. The bulbar region of the brain, crucial for speech and swallowing, is particularly affected. With only a few treatments approved, there is yet to be a cure for the condition.
In October 2023, the US National Institute of Health (NIH) announced plans to fund three clinical trials to investigate drugs for the treatment of ALS, including one by Prilenia and researchers at Massachusetts General Hospital for pridopidine.
In the announcement accompanying the data, Prilenia CEO and founder Michael Hayden said: “Based on the clinical data generated to date, pridopidine has the potential to become a meaningful treatment for ALS. We believe it is important for Prilenia to advance our clinical programme in ALS, and we are actively planning a single, global, pivotal Phase III clinical trial.”
