• To assess the clinical efficacy (symptomatic and long-term) of N-acetyl-L-Leucine on symptoms of ataxia, functioning, and quality of life for patients with NPC. To evaluate the safety and tolerability of N-acetyl-L-leucine at 4 g/day in patients with NPC aged ≥4 years and older. Extension Phase Only: Characterize the pharmacokinetics of N-acetyl-L-leucine in NPC patients.

Niemann-Pick disease type C (NPC) is a rare autosomal recessive neurodegenerative lysosomal disease characterized by multiple symptoms such as cerebellar ataxia and cognitive decline. The modified amino acid N-acetyl-leucine has been associated with positive symptomatic and neuroprotective, disease-modifying effects in various studies, including animal models of NPC, observational clinical case studies, and a multinational, rater-blinded Phase IIb clinical trial.

This multinational double-blind randomized placebo-controlled crossover Phase III study enrolls patients with a genetically confirmed diagnosis of NPC patients aged 4 years and older across 16 trial sites (NCT05163288). Patients are assessed during a baseline period and then randomized (1:1) to one of two treatment sequences: IB1001 followed by placebo or vice versa. Each sequence consists of a 12-week treatment period. The primary efficacy endpoint is based on the Scale for the Assessment and Rating of Ataxia, and secondary outcomes include cerebellar functional rating scales, clinical global impression, and quality of life assessments. The Parent Study is followed by the 1-year Extension Phase. 

Given the lack of global symptomatic or disease-modifying therapies for NPC and other lysosomal diseases there is an urgent need for effective and well-tolerated drug treatments. This clinical trial was designed through a collaboration between National Regulatory Agencies, leading Clinical Experts, Patient Organizations, and the industry Sponsor.