Phase 3, double-blind, placebo-controlled crossover RCT of oral levacetylleucine (N-acetyl-L-leucine) vs. placebo over two consecutive 12-week periods in 73 patients aged ≥4 years with genetically confirmed ataxia-telangiectasia, across 10 hospitals in 6 countries.
Levacetylleucine reduced SARA total score by −1.92 points (SD 2.81) vs. −0.14 (SD 2.38) for placebo; linear mixed model treatment effect −1.88 (95% CI −2.70 to −1.06; p<0.0001). Adverse events were fewer on levacetylleucine (54 events in 29 patients) than placebo (75 events in 25 patients); no drug-related serious adverse events or deaths occurred.
- Short 12-week treatment periods; long-term disease-modifying effects remain unconfirmed pending open-label extension data. - Patients <4 years, asymptomatic patients, and those with advanced disease were excluded, limiting generalizability. - 75% of participants were White/European or North American; limited ethnic diversity.
Levacetylleucine is the first treatment to show a positive phase 3 result in ataxia-telangiectasia, with a SARA improvement exceeding the validated minimally important clinical difference of 1–1.5 points and a benign safety profile — clinicians should watch for regulatory submissions. Benefit was consistent across pediatric and adult subgroups, suggesting broad applicability if approved.
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