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IONS' Rare Neurological Disease Drug Meets Late-Stage Study Goal

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Key Takeaways

  • Ionis' phase III study showed zilganersen stabilized gait speed in Alexander disease patients.
  • The drug demonstrated favorable safety and consistent benefit across secondary measures.
  • Ionis plans an FDA filing in Q1 2026 as it expands its wholly owned medicine portfolio.

Ionis Pharmaceuticals (IONS - Free Report) announced positive topline results from a pivotal phase III study evaluating its investigational RNA-targeted therapy zilganersen for treating a rare neurological condition called Alexander disease (AxD).

The study met its primary endpoint — patients who received a 50 mg dose of zilganersen achieved a statistically significant and clinically meaningful stabilization in gait speed compared with control. Ionis noted that the mean difference between the two groups was 33.3%, which was measured using the 10-Meter Walk Test (10MWT). Treatment with the drug also demonstrated a favorable safety and tolerability profile.

Though Ionis did not disclose whether key secondary endpoints were statistically significant, it reported that treatment with zilganersen showed a ‘consistent benefit’ across these measures, indicating evidence of slowed disease progression, stabilization or improvement.

Ionis to Seek FDA Nod for Zilganersen Soon

Per Ionis, the above results make zilganersen the first investigational medicine to show a positive disease-modifying impact in AxD.

AxD is a rare neurological disease that affects a type of cell in the brain called astrocytes, which play multiple roles in the brain to support neurons and oligodendrocytes. People living with this condition experience cognitive dysfunction and progressive neurologic deterioration, including difficulty swallowing and the inability to control muscles for large movements. There are currently no disease-modifying medicines approved for AxD patients.

Based on the pivotal study results, Ionis plans to submit a regulatory filing with the FDA for zilganersen in AxD next year in Q1.

If approved, zilganersen will become the third wholly-owned drug for the company, alongside Tryngolza (for familial chylomicronemia syndrome [FCS]) and Dawnzera (for hereditary angioedema [HAE]), both of which gained approval in the last 12 months. These commercial launches are part of Ionis' broad strategy to deliver a steady flow of wholly-owned medicines to patients and reduce reliance on collaboration partners for revenue.

IONS Stock Performance

Year to date, shares of Ionis have soared nearly 76% compared with the industry’s 12% growth.

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Ionis Boasts a Diverse Revenue Stream

Ionis has collaborations with leading drugmakers/biotech companies, such as AstraZeneca (AZN - Free Report) , Biogen (BIIB - Free Report) , GSK plc (GSK - Free Report) and Novartis. These deals provide the company with funds in the form of license fees, upfront and milestone payments to invest in the development of its wholly owned pipeline.

Ionis earns commercial revenues in the form of royalty payments on net sales of Spinraza, approved in the United States to treat spinal muscular atrophy (SMA) worldwide. The company licensed this drug to Biogen, which is responsible for its commercialization. Ionis and Biogen also market Qalsody, which was approved by the FDA in April 2023 for amyotrophic lateral sclerosis (ALS) caused by superoxide dismutase 1 mutations.

AstraZeneca, Novartis and GSK are its partners for Wainua, pelacarsen and bepirovirsen, respectively. The FDA approved Wainua in December 2023 to treat adults with polyneuropathy caused by hereditary transthyretin-mediated amyloidosis (ATTRv-PN) in the United States. The drug recently obtained approval in the EU for a similar indication and will be marketed under the name Wainzua.

While the GSK-partnered drug is being developed in two late-stage studies for chronic hepatitis B, the Novartis-partnered drug is in a late-stage study for patients with cardiovascular disease due to elevated Lp(a) levels. Data from all these studies are expected in 2026.

Based on funds received from the above partners, Ionis is expanding the portfolio of its wholly-owned medications. Apart from zilganersen, other wholly-owned candidates include ulefnersen (for ALS) and ION582 (for Angelman syndrome), which are also being evaluated in late-stage studies.

IONS’ Zacks Rank

Ionis currently carries a Zacks Rank #3 (Hold). You can see the complete list of today’s Zacks #1 Rank (Strong Buy) stocks here.

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