Ionis Receives U.S. FDA Breakthrough Therapy Designation for Zilganersen for Alexander Disease
Wednesday, December 03, 2025
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). AxD is a rare, progressive and often fatal neurological disorder that can gradually lead to loss of mobility, difficulties with walking, speech, swallowing and breathing. There are currently no approved disease-modifying therapies for this condition. The Breakthrough Therapy designation is intended to speed up the review of medicines for serious or life-threatening diseases where early clinical data shows a potential for significant improvement over existing treatments.
The FDA’s decision is based on topline results from a pivotal study of zilganersen involving both children and adults with AxD. In the trial, a 50 mg dose of zilganersen showed statistically significant and clinically meaningful stabilisation in the primary endpoint of gait speed, measured by the 10-Metre Walk Test at week 61, when compared with the control group. The medicine also displayed favourable safety and tolerability, along with consistent benefits across key secondary endpoints.
Ionis recently received another Breakthrough Therapy designation for its investigational therapy olezarsen in severe hypertriglyceridaemia. The company states that this progress highlights the potential impact of its innovation pipeline. Ionis plans to independently bring both medicines to patients in 2026 and expects its portfolio of marketed and late-stage investigational therapies to support future growth.
The company intends to submit a New Drug Application (NDA) for zilganersen to the FDA in the first quarter of 2026. Work is also underway to introduce an Expanded Access Programme (EAP) in the United States.
Source: businesswire.com
