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# FDA Approves IONIS Drug Zanvastro for Alexander Disease
- URL: https://redfiled.com/fda-approves-ionis-drug-zanvastro-for-alexander-disease/
- Published: 2026-09-04T14:40:18.000Z
- Updated: 2026-09-04T15:34:59.000Z
- Description: Ionis wins first-ever approval for a disease-modifying Alexander disease therapy, plus a rare pediatric disease priority review voucher.
- Author: William Hayes
- Tags: IONS, Regulatory

**Ionis Pharmaceuticals (IONS)** said the U.S. Food and Drug Administration has approved **ZANVASTRO (zilganersen)** for the treatment of **Alexander disease (AxD)** in pediatric and adult patients. It is the **first and only disease-modifying treatment** for the ultra-rare, progressive and often fatal neurological disorder, where care until now has been limited to managing symptoms. Alongside the approval, the FDA granted Ionis a **Rare Pediatric Disease Priority Review Voucher**.

ZANVASTRO is an RNA-targeted medicine designed to reduce production of **glial fibrillary acidic protein (GFAP)**, the protein that accumulates toxically in astrocytes as a result of variants in the GFAP gene. The drug is given as a **50 mg intrathecal injection once per quarter**, and Ionis said it will be available in the U.S. **in the coming weeks**.

The approval rests on a global Phase 1-3 study (NCT04849741) that enrolled **54 participants aged 1.5 to 53 years across 13 sites in eight countries**, randomized **2:1** to drug or control for a 60-week double-blind period. In patients aged five and older, the 50 mg dose met the primary endpoint with a **statistically significant stabilization of gait speed on the 10-Meter Walk Test at Week 61 (least square mean difference 33.3%, p=0.041)**. Children aged two to four showed improvement on the **GMFM-88** motor measure versus control.

Safety was described as favorable, with most adverse events **mild or moderate** and serious treatment-emergent events occurring **less frequently** in the ZANVASTRO arm than in the control arm. The label carries a warning for **aseptic meningitis**, including one serious case that recurred in the open-label extension and required dose interruption and intravenous dexamethasone pretreatment. The most common adverse reactions at an incidence of at least 25% were **vomiting, back pain, cough, headache and post-lumbar puncture syndrome**.

AxD affects roughly **1 in 1 to 3 million people worldwide** and usually leads to death **14 to 25 years after symptom onset**. Chief executive **Brett Monia** called the approval a *transformative* moment and said it marks the company's *first independent launch from our industry-leading neurology pipeline* and its **second independent launch this year**.

Commercially, Ionis retains U.S. rights. In **June 2026** the company licensed zilganersen outside the U.S. to Italy's **Recordati**, with regulatory submissions in **Europe and Japan expected in 2027**. Ionis said it will support U.S. patients through its **Ionis Every Step** access program.

The approval adds to a neurology franchise that already includes **SPINRAZA, WAINUA and QALSODY**, with a clinical-stage portfolio of **12 investigational medicines, seven of them wholly owned**. Management will host a **webcast on Friday, Sept. 4 at 10:00 a.m. ET** to discuss the decision.

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