FDA Approves Levacetylleucine to Treat Ataxia in Adult, Pediatric Patients With A-T

The FDA approved levacetylleucine (Aqneursea; IntraBio Inc) to treat ataxia in adult and pediatric patients with ataxia-telangiectasia (A-T) who weigh at least 15 kg. Previously, levacetylleucine was approved in 2024 to treat the neurological manifestations of Niemann-Pick disease type C in adults and pediatric patients weighing at least 15 kg.^1,2

What is Ataxia-Telangiectasia?

A-T is a rare, autosomal recessive neurodegenerative disorder caused by mutations in the ATM gene. It primarily affects the nervous system, causing progressive loss of muscle control and coordination (known as ataxia) that typically begins in early childhood. The disease also causes small, dilated blood vessels (or telangiectasias), immune deficiencies, and an elevated risk of cancer.^1,3

A-T affects an estimated 1 in 40,000 to 100,000 people worldwide. Currently, there is no cure for disease, and treatment options for neurological symptoms are limited to supportive care. Life expectancy varies with symptom severity; however, many patients survive into early adulthood.^1,3

Clinical Data Supporting Levacetylleucine’s Approval

The new indication’s approval was supported by findings from a randomized, double-blind, placebo-controlled, 2-period crossover phase 3 clinical trial (NCT06673056).⁴ A total of 73 patients aged 4 years and older with genetically confirmed A-T were enrolled, of whom 47 (64%) were younger than 18 years, and 26 (36%) were 18 years or older. The participants were randomly assigned to receive levacetylleucine followed by placebo (n = 36) or placebo followed by levacetylleucine (n = 37) across two 12-week treatment periods. Dosing was weight-based, with patients 35 kg or heavier receiving 4 g per day in 3 divided doses.^1,4,5

The primary end point assessed change in the Scale for Assessment and Rating of Ataxia (SARA), a modified tool that evaluates gait, sitting, stance, and speech disturbance on a 0-to-16 scale, with lower scores indicating better neurological status.^1,4,5 Findings from this clinical trial were published in The Lancet Neurology.⁵

Levacetylleucine Shows Significant, Clinically Meaningful Improvement in Functioning

According to the trial data, patients scored significantly better on the SARA while taking levacetylleucine compared with placebo. Specifically, patients in these respective groups demonstrated mean changes −1.92 and −0.14 (treatment effect −1.88; 95% CI, −2.70 to −1.06; P < .0001), a difference that investigators noted exceeded published thresholds for clinically meaningful change. Secondary end points, including the International Cooperative Ataxia Rating Scale and Clinical Global Impression of Improvement, also favored levacetylleucine. Investigators reported that improvements were consistent across age groups, sex, and disease severity, and that patients lost their gains after crossing over to placebo, consistent with the drug’s expected pharmacologic action.⁵

Levacetylleucine was safe and well-tolerated, the study authors reported. The most common adverse events (AEs) among patients with A-T were falls, skin lacerations, and urinary tract infections.^1,5 Two patients had 3 treatment-emergent AEs that were consdiered to be related to levacetylleucine (diarrhea and eczema, which were mild; and insomnia, which was moderate). These events were all transient. Importantly, there were no study drug-related serious AEs or deaths that occurred in either group.⁵

According to an FDA news release announcing its approval, levacetylleucine carries no contraindications, though animal data suggest a potential for fetal harm. Concomitant use with N-acetyl-DL-leucine should be avoided, and it is recommended that patients on P-glycoprotein substrates should be monitored more closely.¹

REFERENCES

1. FDA Approves Therapy to Treat Ataxia in Patients with Ataxia-Telangiectasia, a Rare Genetic Disorder. News release. FDA. September 18, 2026. Accessed September 18, 2026. https://www.fda.gov/drugs/news-events-human-drugs/fda-approves-therapy-treat-ataxia-patients-ataxia-telangiectasia-rare-genetic-disorder

2. Halpern L. Levacetylleucine Receives FDA Approval as Stand-Alone Therapy for Niemann-Pick Disease Type C. Pharmacy Times. September 26, 2024. Accessed September 18, 2026. https://www.pharmacytimes.com/view/levacetylleucine-receives-fda-approval-as-stand-alone-therapy-for-niemann-pick-disease-type-c

3. Ataxia-telangiectasia. Cleveland Clinic. Updated July 6, 2022. Accessed September 18, 2026. https://my.clevelandclinic.org/health/diseases/23415-ataxia-telangiectasia

4. A Pivotal Study of N-Acetyl-L-Leucine on Ataxia-Telangiectasia (A-T). ClinicalTrials.gov identifier: NCT06673056. Updated July 3, 2025. Accessed September 18, 2026. https://clinicaltrials.gov/study/NCT06673056

5. Martakis K, Bremova-Ertl T, Bolton C, et al. Safety and efficacy of levacetylleucine in ataxia-telangiectasia: a phase 3, randomised, double-blind, placebo-controlled crossover trial. Lancet Neurol. 2026;25(7):633–644. doi:10.1016/S1474-4422(26)00158-4