First Treatment for Rare Alexander Disease Approved by FDA

The first treatment for Alexander disease, a rare genetic disorder, has been approved in the United States. It opens a new option for patients and families who had no treatment options for years.

On the 4th (local time), the U.S. Food and Drug Administration (FDA) announced that it had approved Ionis Pharmaceuticals’ Alexander disease treatment, Zenvastro (ingredient: zilganersen). It is the first treatment for Alexander disease.

Dr. Emily Freilich, director of the Division of Neurology at the FDA’s Center for Drug Evaluation and Research, called the approval “a milestone that provides the first treatment targeting the underlying cause of this disease.”

Alexander disease is an ultra-rare disorder in which mutations in the GFAP gene cause toxic proteins to accumulate in astrocytes, the brain’s support cells, gradually impairing motor and cognitive function. Zilganersen is an antisense oligonucleotide (ASO) that binds to the messenger ribonucleic acid (mRNA) produced by the mutated GFAP gene, preventing protein accumulation.

Ionis conducted phase 1-3 clinical trials of zilganersen in collaboration with the FDA beginning in 2021, and met the primary endpoint of improved motor function last fall, Fierce Pharma reported.

Ionis CEO Brett Monia described the approval as “the first standalone launch achieved in our neurology pipeline.”

Miles Minter, an analyst at William Blair, called it “a groundbreaking achievement,” saying that “for patients and families living with this devastating disease, it creates an option where there was nothing.”

Ionis plans to expand into rare pediatric diseases following the approval. A phase 3 trial for Angelman syndrome is underway, and the company is also developing treatments for Pelizaeus-Merzbacher disease, MECP2 duplication syndrome and Dravet syndrome.

Analyst Minter said Ionis has the potential to grow into a larger biotechnology company “beyond its reputation as a research and development powerhouse,” supported by royalty revenue and collaboration sales.