Levacetylleucine Meets Primary and Secondary End Points in Phase 3 Ataxia-Telangiectasia Study

Positive topline results from the pivotal phase 3 IB1001-303 trial (NCT06673056) showed that levacetylleucine (Aqneursa; IntraBio), which is a therapy approved for Niemann-Pick disease type C, met its primary end point and secondary end points by demonstrating statistically significant improvement in ataxia symptoms compared with placebo in patients with ataxia-telangiectasia (A-T). Based on these data, the company stated that it plans to advance regulatory submissions to the FDA and the European Medicines Agency, as well as other global regulatory authorities.¹

IB1001-303 is a phase 3, randomized, placebo-controlled, double-blind crossover phase study, followed by a long-term open-label extension assessing the efficacy, safety, and tolerability of levacetylleucine in pediatric and adult patients with A-T. At 12 weeks, findings showed that treatment with the agent was associated with statistically significant improvement on the primary end point, change in Scale for the Assessment and Rating of Ataxia (SARA) score, compared with placebo (−1.92 vs −0.14; between-group difference, −1.88; P<.001).

“This is a breakthrough for patients and families affected by Ataxia-Telangiectasia,” principal investigator Franziska Hoche, MD, assistant professor of neurology at Mass General Research Institute, said in a statement.¹“A-T is a rare and devastating disorder with no approved treatments. The results from the IB1001-303 trial, demonstrating levacetylleucine significantly improved patients’ neurological symptoms and everyday function, represent a major scientific and clinical milestone, and provide compelling evidence that levacetylleucine has a meaningful impact on A-T patients’ lives.”

The study also met its secondary end points, with levacetylleucine demonstrating statistically significant improvements compared with placebo on the International Cooperative Ataxia Rating Scale (mean change, −4.22 vs −1.69; P = .003) and the Investigator’s Clinical Global Impression of Improvement (mean change, −0.6 vs −0.2; P = .02). In addition, the company noted that levacetylleucine was generally well tolerated, and no drug-related serious adverse events were reported, which is consistent with its previously established safety profile.

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“These results mark a major turning point for the Ataxia-Telangiectasia community,” Brad Margus, Founder of the A-T Children’s Project, said in a statement.¹ “This offers real hope that families will soon have access to their first effective and safe treatment approved for A-T. We look forward to continuing to collaborate with IntraBio to help ensure levacetylleucine is rapidly approved by the FDA and made available for patients in our community, given their urgent need for effective, approved treatments.”

Additional context for the phase 3 evaluation of levacetylleucine was provided by late-breaking data presented at the 2025 International Congress of Parkinson’s Disease and Movement Disorders (MDS), held October 5-9, in Honolulu, Hawaii, from an extension of the phase 2 IB1001-203 trial (NCT03759678).² The phase 2 study enrolled patients aged 6 years or older with A-T, and participants who completed the initial trial were eligible to continue treatment in an extension phase. The extension cohort included 12 patients aged 6 to 36 years who remained on levacetylleucine following completion of the parent study.

In the extension phase, the primary end point was change in SARA score from baseline to the end of the first year of levacetylleucine treatment. Exploratory end points included changes in SARA score during a washout period and changes from baseline through the end of the second year of continued treatment. After 12 months of therapy, the mean change from baseline in SARA score was −2.25 points (SD, 3.16; 95% CI, −4.25 to −0.25; P = .031). During the subsequent washout period, participants (n = 11) experienced a mean increase of 1.36 points in SARA score (SD, 2.04; 95% CI, 0–2.73; P = .25). Seven patients completed an additional year of treatment following washout, with a mean SARA change of −0.33 points compared with the start of the extension phase.

REFERENCES
1. IntraBio Announces Positive Pivotal Trial Results of Levacetylleucine for the Treatment of Ataxia-Telangiectasia. News release. IntraBio. January 21, 2026. Accessed January 21, 2026. https://www.businesswire.com/news/home/20260121091020/en/IntraBio-Announces-Positive-Pivotal-Trial-Results-of-Levacetylleucine-for-the-Treatment-of-Ataxia-Telangiectasia
2. Patterson M, Zanrucha B, Raymond J, et al. N-acetyl-L-leucine: Findings from the Extension Phase of a Phase II Clinical Trial in Ataxia-Telangiectasia. Presented at: 2025 MDS Congress; October 5-9; Honolulu, Hawaii. LBA-4.