CHICAGO — The modified amino acid levacetylleucine (Aqneursa) significantly improved neurologic symptoms and was well tolerated in patients with ataxia-telangiectasia, a rare genetic disorder that causes progressive loss of coordination.

The results of the global phase 3 trial showed participants who received oral levacetylleucine had significantly greater improvement on the Scale for the Assessment and Rating of Ataxia (SARA) at 12 weeks compared to those who received placebo, meeting the study’s primary endpoint. 

They also had greater improvement on secondary measures of neurologic symptoms and everyday function. No treatment-related serious adverse events were reported in either treatment group.

“I think the take-away message for clinicians is that finally there is a therapy that improves this genetic ataxia,” Marc C. Patterson, MD, chief medical officer at IntraBio, Austin, Texas, told Medscape Medical News. 

Because there are currently no approved treatments for the condition, “this is huge for the community,” especially because of disappointing results from a recent phase 3 trial of another drug type, he added. 

The study results were presented in a late-breaking science session on April 19 at the American Academy of Neurology (AAN) 2026 Annual Meeting. 

Rare, Progressive Disorder 

Ataxia-telangiectasia is a rare cerebellar ataxia affecting approximately 1 in 40,000 to 100,000 people and typically begins in early childhood. The disease progresses and causes loss of coordination, dilated blood vessels, immune system deficiencies, and an increased risk for cancer.

Topline results released in January from the highly anticipated phase 3 NEAT study were disappointing, showing that dexamethasone sodium phosphate encapsulated in autologous erythrocytes failed to meet its primary and key secondary efficacy endpoints vs placebo in patients with the disease.

Patterson said levacetylleucine takes a different approach, targeting metabolic dysfunction and the lysosomal-mitochondrial axis while helping to restore cellular signaling.

The drug is currently approved in the US and the European Union for the treatment of adult and pediatric patients with neurologic manifestations of Niemann-Pick disease type C, another autosomal neurodegenerative disorder characterized by prominent cerebellar ataxia.

As in the phase 3 trial in Niemann-Pick disease type C that supported the drug’s approval, the current ataxia-telangiectasia phase 3 study used a randomized, placebo-controlled, double-blind crossover design followed by a long-term open-label extension. The trial was conducted at 11 sites across six countries. These included the US, the UK, Germany, Spain, Switzerland, and Slovakia. 

The researchers enrolled 73 patients between the ages of 4 and 50 years (64.5% < 18 years of age; 52% female) who weighed at least 33 lb at screening and had a genetically confirmed diagnosis of ataxia-telangiectasia.

All participants were randomly assigned to receive either oral levacetylleucine granules dissolved in water, orange juice, or almond milk at a total daily dose of 2-4 g (based on weight) or matching placebo.

Clinically Meaningful Results 

Results showed that the levacetylleucine group had a “statistically significant and clinically meaningful” -1.88 point improvement on the SARA after 12 weeks of treatment compared with the placebo group (-1.92 vs -0.14, respectively; P < .001), Patterson told meeting attendees. 

The active-treatment group also had greater improvement on two of the secondary endpoints: the International Cooperative Ataxia Rating Scale (-4.22 vs -1.69; P = .003) and the Investigator-rated Clinical Global Impressions of Improvement (-0.6 vs -0.2; P = .02). 

The frequency of adverse events were comparable between the treatment groups, with 29 participants having a total of 54 events in the levacetylleucine group compared to 25 participants having a total of 75 events in the placebo group. 

No serious adverse events or deaths occurred in either group, and no treatment-emergent adverse events exceeded a 10% incidence among patients receiving levacetylleucine.

These findings show the drug “was safe and well-tolerated, consistent with its established safety profile,” Patterson said. 

He added that the extension phase of the study is still ongoing and will hopefully provide long-term efficacy and safety findings. 

In March, the company submitted a supplemental new drug application to the FDA for the treatment of ataxia-telangiectasia. There are also plans to advance regulatory submissions to the European Medicines Agency and other regulatory authorities, Patterson noted. 

Growing Momentum 

The search for therapeutic options “has been in its infancy” for many rare diseases, session co-moderator Jorg Dietrich, MD, PhD, a neuro-oncologist at Mass General Brigham in Boston, told Medscape Medical News. 

“Seeing momentum in these areas is very encouraging, especially if there are medications and interventions that could be widely used around the globe,” added Dietrich, who was not involved with the research.

The other co-moderator, Marcelo Matiello, MD, also from Mass General Brigham and associate professor of neurology at Harvard Medical School, agreed that “it’s exciting” when phase 3 trials assess treatments for rare conditions.

“It’s a great opportunity to understand the biology and to see the results,” Matiello told Medscape Medical News. 

However, he noted that these patients often face delays in diagnosis in real-world settings, whereas “clinical trials are done in centers with a lot of expertise in that disease.” As a result, “it would be interesting to see how the drug would do in different settings,” Matiello said. 

The study was funded by IntraBio; Patterson is an employee of and has or had stock in the company. Dietrich and Matiello reported no relevant financial relationships.