Zanvastro Approved for Alexander Disease
On Sept. 3, 2026, the US Food and Drug Administration (FDA) approved Ionis Pharmaceuticals’ Zanvastro™ (zilganersen) injection for the treatment of Alexander disease in pediatric and adult patients. Zanvastro is an RNA-targeted antisense oligonucleotide designed to reduce production of the abnormal glial fibrillary acidic protein (GFAP) that drives disease progression. It is the first FDA-approved treatment and first disease-modifying therapy for Alexander disease, a rare, progressive neurologic disorder caused by mutations in the GFAP gene. Zanvastro is administered as a 50mg intrathecal injection every three months by a trained healthcare professional. Launch is expected in the coming weeks. Cost is not yet known. Here is the prescribing information.
At a Glance
- Brand Drug: Zanvastro™ (zilganersen)
- Manufacturer: Ionis Pharmaceuticals
- Date Approved: Sept. 3, 2026
- Indication: For the treatment of Alexander disease in pediatric and adult patients.
- Dosage Forms Available: 56mg/2.8mL (20mg/mL) in a single-dose vial
- Launch Date: In the coming weeks.
- Estimated Annual Cost: TBD
- FDA Designation: Breakthrough Therapy. Orphan Drug. Priority Review. Fast Track. Rare Pediatric Disease Voucher.
- Alexander disease is an ultra-rare, progressive leukodystrophy caused by mutations in the GFAP gene, resulting in progressive neurologic dysfunction.
- It is estimated to affect approximately 100 to 350 individuals in the United States.
- Symptoms may include progressive neurologic deterioration, including motor and cognitive dysfunction, loss of independence, impaired voluntary movement, swallowing dysfunction, airway-protection impairment, seizures, developmental delay, and spasticity.
- Prior to this approval, treatment options were limited to supportive care and symptom management.
- Approval was supported by data from 49 pediatric and adult patients treated with Zanvastro demonstrating significantly better walking speed at 61 weeks compared with untreated controls. Children aged 2 to 4 years showed improvement in motor function measures while control patients declined.
- Common adverse events reported with treatment included vomiting, back pain, cough, headache, and post-lumbar puncture syndrome. Cases of aseptic meningitis have also been reported.