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IONS Completes Enrollment in Pivotal Cohort of Angelman Syndrome Study

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Key Takeaways

  • IONS completed enrollment of 136 children in cohort 1 of the phase III REVEAL study for Angelman syndrome.
  • Ionis expects adult cohort enrollment to finish in Q3 2026, with top-line REVEAL data due in H2 2027.
  • IONS plans a late-stage CHAMPION study for additional Angelman syndrome genotypes before the end of 2026.

Ionis Pharmaceuticals (IONS - Free Report) announced that it has completed enrollment in cohort 1 of the phase III REVEAL study, which is evaluating its investigational drug, obudanersen (formerly ION582), for the treatment of Angelman syndrome (AS), a rare neurological disease.

The pivotal pediatric cohort has enrolled 136 participants aged two to less than 18 years with a confirmed clinical diagnosis of AS and genetic confirmation of either a UBE3A deletion or a UBE3A mutation. Completion of enrollment marks an important milestone as the company advances obudanersen toward potential regulatory submissions.

Alongside the pediatric cohort, Ionis is conducting an adult cohort (cohort 2) that includes patients aged 18 to less than 50 years with AS. Enrollment in this cohort is expected to be completed in the third quarter of 2026.

The company expects to report top-line data from the REVEAL study in the second half of 2027. Positive results could position obudanersen as one of the first disease-modifying treatment options for patients with Angelman syndrome.

AS is a rare neurogenetic disorder that affects around one in 21,000 people globally. The disease often presents in infancy, which leads to severe developmental challenges, including cognitive and motor impairments, speech loss, balance issues, seizures, anxiety and sleep disturbances, taking a severe toll on the quality of life.

IONS Stock Performance

Year to date, shares of Ionis have gained over 5% against the industry’s nearly 3% fall.

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Ionis Expands Obudanersen Program

Ionis is also preparing to launch another late-stage study, CHAMPION, which will evaluate obudanersen in patients with AS caused by uniparental disomy (UPD) or imprinting defect (ID) genotypes. The study is expected to begin before the end of 2026, further expanding the clinical development program.

Notably, Ionis’ long-time collaboration partner, Biogen (BIIB - Free Report) , opted not to license obudanersen last year. It did not disclose the reason for this decision.

Currently, no disease-modifying therapies are approved for treating AS. Another company developing a late-stage treatment for the disorder is Ultragenyx Pharmaceuticals (RARE - Free Report) , which expects to report phase III data for its investigational candidate later this year. The outcome of both programs could help shape the future treatment landscape for AS.

IONS’ Zacks Rank

Ionis currently has a Zacks Rank #4 (Sell). You can see the complete list of today’s Zacks #1 Rank (Strong Buy) stocks here.

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