Ionis Pharmaceuticals Secures FDA Orphan Drug Designation For Rare Epilepsy Treatment

• Orphan Drug Designation provides benefits such as tax credits and potentially seven years of market exclusivity if the drug is approved.
• The company is currently studying the treatment, called ION337, in the Phase 1/2 Ascend trial.
• Ionis recently got FDA approval for Zanvastro, a treatment for Alexander disease

Ionis Pharmaceuticals (IONS) was on investors’ radar on Thursday after the biotech firm received Orphan Drug Designation from the U.S. Food and Drug Administration for an experimental treatment targeting Dravet syndrome, a rare genetic disorder that causes severe, recurring seizures.

IONS shares were down 0.8% at the time of writing, tracking the broader biotech selloff. The State Street SPDR S&P Biotech ETF (XBI) was down 1.5%.

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 ION337 Is Currently In A Phase 1/2 Trial

The treatment targets the SCN1A gene, which helps the brain produce a protein that controls electrical activity and prevents seizures.

Orphan Drug Designation supports the development of treatments for rare diseases and provides benefits such as tax credits and potentially seven years of market exclusivity if approved. However, this is a designation and not an approval.

The company is currently studying the treatment, called ION337, in the Phase 1/2 Ascend trial. In July, Ionis announced that it had dosed the first patient in the trial. The study is evaluating the drug's safety and tolerability in children aged 2 to 12, with repeated doses planned every six months.

Dravet syndrome typically begins in infancy and can cause developmental delays. The experimental drug already has a Fast Track designation. The FDA issues the label for drugs that may treat a serious disease with unmet medical needs.

Ionis’ Pipeline At A Glance

Ionis is also developing a drug called Obudanersen for Angelman syndrome, a rare genetic disorder that causes developmental delays, speech difficulties and seizures, and Ulefnersen for a rare inherited form of amyotrophic lateral sclerosis (ALS), a disease that progressively weakens muscles and affects movement, speech and breathing. It recently secured FDA approval for Zanvastro, a treatment for Alexander disease, another rare neurological disorder that affects movement, and speech.

Ionis held about $2.1 billion in cash, cash equivalents and short-term investments as of June 30, 2026.

Retail Is Bullish On IONS

Retail sentiment surrounding IONS on Stocktwits remained ‘bullish’ over the past 24 hours, amid ‘high’ message volumes.

The stock has been under heavy selling pressure so far in 2026, slumping nearly 45%.

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