Second Drug OK’d for Ultra-Rare Neurodegenerative Disease

The FDA gave the green light to levacetylleucine (Aqneursa) as a stand-alone treatment for Niemann-Pick disease type C (NPC), just days after approving the first drug for the ultra-rare genetic disease.

The oral suspension therapy is a modified amino acid indicated to treat neurological manifestations of NPC in adults and pediatric patients who weigh at least 33 lb (15 kg).

NPC is an inherited lysosomal condition caused by changes to the NPC1 or NPC2 gene, which affect the transport of cholesterol and other lipids within cells, leading to progressive neurological symptoms and organ dysfunction. On average, people with NPC only live to the age of 13, according to the FDA.

Until last week’s approval of arimoclomol (Miplyffa) in combination with the enzyme inhibitor miglustat, no treatment was specifically indicated for the disease.

“This is the second treatment the FDA has approved for NPC within the span of a week. Today’s action further underscores the agency’s commitment to support development of new treatments for rare diseases,” said Janet Maynard, MD, MHS, of FDA’s Center for Drug Evaluation and Research, in a statement. “This approval again demonstrates the FDA’s commitment to work with the scientific community to overcome the unique challenges that may arise with rare disease drug development.”

A two-period crossover study laid the groundwork for levacetylleucine’s approval, with benefit seen within 12 weeks. A total of 60 patients ages 4 and older with at least mild disease-related neurological symptoms were enrolled. Overall, 85% of patients were on miglustat as background treatment prior to and during the study.

The primary efficacy outcome was based on the functional Scale for Assessment and Rating of Ataxia (fSARA) score, which assessed gait, sitting, stance, and speech disturbance domains, with total scores ranging from 0 to 16 (higher scores indicate worse neurological status). Over the course of the study, the estimated mean fSARA score was 5.1 with levacetylleucine versus 5.6 with placebo (difference -0.4, 95% CI -0.7 to -0.2).

Common adverse events that occurred in 5% or more of patients (and at a greater rate than with placebo) included abdominal pain, dysphagia, upper respiratory tract infections, and vomiting.

Levacetylleucine’s mechanism of action in NPC is unknown.

According to the label, the 1 g individual dose packets of the drug should be mixed in 40 mL of water, orange juice, or almond milk when taken by mouth, or water only if given through a G-tube. The prescribing information also cautions against using hot liquid. It is administered orally up to three times daily with or without food, with the recommended dosage based on a patient’s weight.

There are no contraindications, but levacetylleucine should be avoided by pregnant patients due to potential embryo-fetal toxicity. It also shouldn’t be taken with N-acetyl-DL-leucine, N-acetyl-D-leucine, or P-glycoprotein transporter substrates.

Developer IntraBio said levacetylleucine is available now.

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