Dexpramipexole is ineffective in two models of ALS related neurodegeneration

Area of Science:

• Neuroscience
• Drug Discovery
• Genetics

Background:

• Amyotrophic lateral sclerosis (ALS) presents limited therapeutic options.
• Dexpramipexole (RPPX) has been investigated in human ALS clinical trials.
• Understanding neurodegenerative mechanisms in ALS is critical for developing effective treatments.

Purpose of the Study:

• To evaluate the efficacy of dexpramipexole (RPPX) in preclinical models of ALS.
• To assess RPPX's impact on motor neuron survival in SOD1G93A mice and TDP43-transfected rat cortical neurons.
• To determine if RPPX warrants further investigation for ALS treatment.

Main Methods:

• Efficacy screening in SOD1G93A mice, assessing neuromotor disease progression and survival.
• High-content neuronal survival screening in primary rat cortical neurons transfected with wild-type or mutant human TDP43.
• Exposure of test systems to RPPX levels consistent with human Phase II clinical trials.

Main Results:

• RPPX did not affect disease progression or survival in SOD1G93A mice.
• A marginal, statistically significant improvement in one neuronal survival indicator was observed in TDP43-transfected neurons at 10 µM RPPX.
• The observed effects were minimal and did not demonstrate robust therapeutic potential.

Conclusions:

• RPPX demonstrated no significant efficacy in preclinical models representing SOD1- and TDP43-mediated ALS.
• The findings do not support further clinical investigation of RPPX for amyotrophic lateral sclerosis.
• Current preclinical data suggest RPPX is not a promising candidate for ALS therapy.