Ionis Pharma prices first FDA-approved treatment for Alexander disease at $285,000 per dose

Jenny Pearson, whose daughter joined Ionis' trial for Alexander disease, called the approval a "miracle" that offers families meaningful hope instead of being turned away.

Zanvastro is administered as an injection into the spinal canal every three months by a healthcare professional.

Oppenheimer analyst Jay Olson said the approval meaningfully de-risks Ionis' broader neurology pipeline, including obudanersen for Angelman syndrome, for which late-stage trial data are expected in the second half of 2027.

"We don't view the recent failure of Ultragenyx's RARE.O apazunersen in Angelman syndrome as negatively impacting the probability of success for obudanersen," Olson added.

Ionis said it will continue to study Zanvastro in an open-label extension trial.

Ionis expects peak sales for the therapy zilganersen, branded as Zanvastro, to exceed $100 million and said the drug will be available in the United States in the coming weeks.

In an early-to-late-stage study, Alexander disease patients who got a 50 mg dose of Zanvastro showed a statistically significant improvement in gait speed as assessed by a 10-meter walk test at 61 weeks.

Ionis Pharmaceuticals said on Friday it would price its newly approved therapy to treat Alexander disease at $285,000 per dose, a day after the U.S. FDA cleared the injectable drug, making it the first approved treatment for the genetic disorder in adults and children.