Anchor
FDA approves first Alexander disease treatment, Ionis's Zanvastro
New CapabilitiesApproval is Ionis's first independent neurology launch, validating its rare disease pipeline
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Overview
Updated 1 hour agoJenny Pearson's daughter Elise had her first seizure at 16 months. A scan a year later showed white splotches on her frontal lobe, and a genetic test confirmed Alexander disease, a rare progressive neurological disorder with no treatment.
On September 3, 2026, the FDA approved the first treatment for that disease. Zanvastro (zilganersen), made by Ionis Pharmaceuticals, reduces production of the abnormal protein that drives Alexander disease, and marks Ionis's first independent neurology launch.
Why it matters
For the roughly 1 in a million people with Alexander disease, there is now a treatment that slows the disease's progression.
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Key Indicators
$285,000
Price per dose
Zanvastro is priced at $285,000 per intrathecal injection, about $1.14 million per year at four doses.
33.3%
Gait speed difference vs control
Patients treated with Zanvastro showed 33.3% better walking speed at 61 weeks than untreated controls (p=0.041).
54
Participants in pivotal study
The global Phase 1-3 study enrolled 54 patients aged 1.5 to 53 years across 13 sites in eight countries.
2
Independent launches in 2026
Ionis launched Tryngolza in June and Zanvastro in September, its first two drugs commercialized without a partner.
Related Media
Brett P. Monia, PhD - Chief Executive Officer at Ionis Pharmaceuticals, Inc. | LinkedIn
Elise's Corner - Alexander Disease | AXD -
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FDA Approves First Therapy for Alexander Disease | 2026
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People Involved
Organizations Involved
Ionis Pharmaceuticals
Biopharmaceutical company
Developer of Zanvastro, now launching independently
RNA-targeted drug developer based in Carlsbad, California.
U.S. Food and Drug Administration
Federal regulatory agency
Approved Zanvastro
The U.S. agency that approves drugs and medical devices.
Recordati
Pharmaceutical company
Holds ex-US rights to zilganersen
Italian pharmaceutical company focused on specialty and rare diseases.
Timeline
1949 September 2026
7 events
Latest: Today
Tap a bar to jump to that date
-
Fierce Biotech publishes feature
Today MediaFeature on the approval opens with the story of patient Elise Pearson.
-
FDA approves Zanvastro
RegulatoryFirst approved treatment for Alexander disease, for pediatric and adult patients.
-
Tryngolza approved
RegulatoryIonis's first independent launch, for severe hypertriglyceridemia.
-
Recordati license agreement
BusinessRecordati obtains ex-US rights to zilganersen, plans Europe and Japan submissions in 2027.
-
Pivotal study begins
Clinical trialPhase 1-3 study (NCT04849741) begins enrolling patients with Alexander disease.
-
GFAP gene identified as cause
Medical discoveryMutations in the GFAP gene identified as the cause of Alexander disease.
-
Alexander disease first described
Medical discoveryW. Stewart Alexander first described the disease that would bear his name.
Historical Context
3 moments from history that rhyme with this story — and how they unfolded.
1998-2026
Antisense oligonucleotides come of age (1998-2026)
The first antisense drug, fomivirsen, was approved in 1998 but failed commercially. The field struggled for two decades before a wave of approvals for rare diseases, including Spinraza, Tryngolza, and now Zanvastro.
Then
Early antisense drugs failed commercially, nearly killing the field.
Now
The platform now underpins multiple approved drugs for rare diseases.
Why this matters now
Zanvastro is the latest validation of a platform Ionis has spent three decades developing.
December 2016
Spinraza for spinal muscular atrophy (2016)
Ionis developed nusinersen, an antisense oligonucleotide delivered intrathecally, for spinal muscular atrophy. It was the first treatment for SMA and became a blockbuster, with Biogen commercializing it.
Then
Approved by FDA in December 2016, became standard of care for SMA.
Now
Proved antisense oligonucleotides could treat neurological diseases, generating billions in revenue.
Why this matters now
Same company, same modality, same delivery route. Zanvastro is the second intrathecal antisense drug from Ionis to reach approval.
September 2016
Exondys 51 for Duchenne muscular dystrophy (2016)
Sarepta Therapeutics won FDA approval for eteplirsen, an antisense oligonucleotide for Duchenne muscular dystrophy, despite a tiny trial and a surrogate endpoint. The approval was controversial.
Then
Approved via accelerated pathway, became a commercial success.
Now
Showed FDA willingness to approve ultra-rare disease drugs with limited data.
Why this matters now
Demonstrates the regulatory path for ultra-rare disease drugs with small trials, similar to Zanvastro's 54-patient study.