Ultragenyx completes enrollment for phase 3 Angelman syndrome study

NOVATO, Calif. - Ultragenyx Pharmaceutical Inc. (NASDAQ:RARE), a $2.58 billion market cap biotechnology company currently trading near its 52-week low of $25.81, announced Thursday it has completed enrollment for its Phase 3 Aspire study evaluating GTX-102 (apazunersen) as a treatment for Angelman syndrome, with approximately 129 participants ages four to 17. According to InvestingPro data, seven analysts have recently revised their earnings expectations upward for the upcoming period.

The study, which began enrollment in December 2024, reached full recruitment in just seven months. Participants all have a genetically confirmed diagnosis of full maternal UBE3A gene deletion, according to the company’s press release statement.

The randomized trial will evaluate GTX-102 administered via intrathecal injection against a sham comparator over 48 weeks. Patients in the treatment group will receive three monthly 8 mg loading doses followed by maintenance therapy up to 14 mg quarterly.

The primary endpoint will measure improvement in cognition using the Bayley-4 cognitive raw score, with a key secondary endpoint assessing response across five domains: cognition, receptive communication, behavior, gross motor function, and sleep.

Ultragenyx expects to complete the study in the second half of 2026 and plans to report topline data afterward.

"The accelerated enrollment of the Phase 3 Aspire study underscores the urgent need and strong desire for an effective treatment for these patients," said Eric Crombez, chief medical officer at Ultragenyx.

The company is also preparing to initiate the Aurora study of GTX-102 in additional ages and genotypes in the second half of 2025.

GTX-102 is an antisense oligonucleotide therapy designed to target and inhibit expression of UBE3A-AS to reactivate expression of the deficient protein in Angelman syndrome. The therapy has received multiple regulatory designations including Breakthrough Therapy and Fast Track from the FDA.

Angelman syndrome affects approximately 60,000 people in commercially accessible regions and currently has no approved therapies. Despite the significant market opportunity, investors should note that analysts don’t expect profitability this year, though the company maintains a healthy current ratio of 2.4, indicating strong short-term liquidity.

In other recent news, Ultragenyx Pharmaceutical Inc. reported several significant developments. Health Canada has approved the company’s Evkeeza (evinacumab) for treating infants as young as six months with homozygous familial hypercholesterolemia (HoFH), expanding its use from the initial approval for children aged five and older. Meanwhile, the U.S. Food and Drug Administration (FDA) issued a Complete Response Letter (CRL) for Ultragenyx’s Biologics License Application for UX111, a gene therapy for Sanfilippo syndrome type A. The FDA requested additional information and improvements related to chemistry, manufacturing, and controls, as well as observations from manufacturing facility inspections. Ultragenyx believes these issues pertain to facilities and processes rather than the product’s quality. Additionally, H.C. Wainwright initiated coverage on Ultragenyx with a Buy rating and set a price target of $80.00. The firm considers the stock an attractive opportunity despite a significant decline in its value this year. These updates underscore the company’s ongoing regulatory and market activities.

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