Ionis' rare neurological disorder drug shows promise in clinical trial

Sept 22 (Reuters) - Ionis Pharmaceuticals' IONS.O experimental drug improved walking ability in patients with a rare progressive and often fatal neurological condition, the company said on Monday, meeting the main goal in an early-to-late-stage study.

Shares of the company were up about 3% in premarket trading.

In the 54-patient study, those who received the 50 mg dose of zilganersen showed a statistically significant improvement in gait speed as assessed by a 10-meter walk test, an assessment of functional mobility, at 61 weeks.

Ionis was testing the drug in patients with Alexander disease, a disorder that damages brain cells and causes problems with movement, speech, and swallowing, often starting in early childhood.

According to National Institutes of Health, the condition affects fewer than 1,000 people in the United States and has no approved treatments.

Zilganersen works by blocking the production of a harmful brain protein, GFAP, which builds up abnormally in the brain due to a genetic mutation and contributes to the disease.

The clinical results are a "monumental step forward in advancing a potential treatment for Alexander disease," said Ionis CEO Brett Monia.

Ionis plans to submit a marketing application to the U.S. Food and Drug Administration in the first quarter of 2026.

The full results from the study will be presented at an upcoming medical conference.