Objective: To report efficacy and safety findings from the pivotal, Phase 3 trial evaluating levacetylleucine in children and adults with Ataxia-Telangiectasia (A-T).

Background: A-T is a rare, inherited cerebellar ataxia. Levacetylleucine (N-acetyl-L-leucine) is a modified amino acid that enters enzyme-controlled pathways to correct metabolic dysfunction and restore cellular communication. The Phase 3, randomized, double-blind, placebo-controlled trial (IB1001-303) evaluated the safety and efficacy of levacetylleucine in pediatric and adult individuals with A-T.

Method: IB1001-303 enrolled A-T participants aged ≥4 years across 10 multinational trial sites. The primary efficacy endpoint was the Scale for the Assessment and Rating of Ataxia (SARA). Secondary endpoints included Spinocerebellar Ataxia Function Index (SCAFI), International Cooperative Ataxia Rating Scale (ICARS), Neurology Quality of Life-Upper Extremity Function (NeuroQOL-UEF), Quality of Life (EQ-5D), and investigator, caregiver, and patient Clinical Global Impression of Improvement (CGI-I). Safety assessment included adverse event incidence and severity.

Results: Seventy-three participants aged 4 to 50 were enrolled; 47 pediatric (<18 years) and 26 adult participants (≥18 years). The primary endpoint was met; mean change in the SARA total score with levacetylleucine was -1.92 (SD=2.81) and -0.14 (SD=2.38) with placebo; Linear Mixed Model (LMM) treatment effect -1.88 (SE=0.41) (95% confidence interval [CI] -2.70, -1.06; P<0.001) after 12 weeks of treatment. The trial met key secondary endpoints, including ICARS (95% CI: -4.87, -0.81; P=0.003) and investigator’s CGI-I (95% CI -0.7, 0.0; P=0.02). Subgroup analyses showed improvement in neurological status across all demographics of participants i.e., age of neurological disease onset, disease severity, and others. The frequency of adverse events was similar between the two groups and no serious adverse events or deaths occurred in either group.

Conclusion: Levacetylleucine demonstrated a significant benefit versus placebo, clinically meaningful improvements in neurological manifestations of A-T, functioning, and quality of life, and a favorable benefit-risk profile for the treatment of A-T. Levacetylleucine was observed to be safe and well-tolerated, consistent with its established safety profile.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/positive-results-from-a-global-phase-3-trial-ib1001-303-evaluating-levacetylleucine-in-ataxia-telangiectasia/