What is Alexander disease—and how does the first-ever drug for it work?

Zanvastro is the first approved treatment aimed at the GFAP buildup that drives Alexander disease.

Alexander disease is a rare, progressive neurological disorder in which abnormal GFAP protein builds up in supporting brain cells and damages the nervous system. Zanvastro (zilganersen) is an antisense treatment designed to reduce production of that harmful protein; it is not an ordinary pill. A trained professional injects it into the spinal canal every three months.

In a 54-patient trial across 13 sites, walking speed after a little more than a year was significantly better than in untreated controls. The FDA approved it from infancy through adulthood, with US availability expected in coming weeks and Recordati holding rights outside the US. The approval grows from roughly three decades of Waisman Center research and an Ionis-led clinical program, but it is a treatment—not a cure—and individual risks and eligibility require a specialist.