Posted on 5th December 2025

FDA Breakthrough Therapy designation for AxD investigational medicine

Ionis Pharmaceuticals has announced that the U.S. Food and Drug Administration (FDA) has granted Breakthrough Therapy designation to zilganersen for the treatment of Alexander disease (AxD).

“There are currently no approved disease-modifying treatments for AxD. Breakthrough Therapy designation is intended to expedite the review of medicines that treat a serious or life-threatening condition and have shown preliminary clinical evidence indicating the potential for substantial improvement over available therapies.”

“The FDA’s designation is supported by the topline results from the pivotal study of zilganersen in children and adults living with AxD.”

To read the full press release: Ionis receives U.S. FDA Breakthrough Therapy designation for zilganersen for Alexander disease (AxD) | Ionis Pharmaceuticals, Inc.