Ultragenyx (RARE) Shares Plunge 45% Following Critical Drug Trial Failure

Key Takeaways

• Shares of Ultragenyx plummeted 45% during after-hours trading following apazunersen’s Phase 3 trial failure in treating Angelman syndrome
• The experimental treatment failed to achieve its primary goal and critical secondary measures in the Aspire clinical study
• Researchers observed no significant improvements between participants receiving the drug versus placebo
• The negative outcome raises serious concerns about the company’s parallel Aurora trial
• The biotech firm intends to reduce operating costs while focusing on its commercial portfolio, including newly approved Genglycos

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Shares of Ultragenyx Pharmaceutical (RARE) tumbled 45% during Wednesday’s extended trading session following disappointing news that its investigational therapy apazunersen failed to demonstrate efficacy in a Phase 3 clinical study for Angelman syndrome.

Ultragenyx Pharmaceutical Inc., RARE

The clinical study, designated Aspire, evaluated apazunersen’s ability to enhance cognitive function and developmental progress in pediatric patients diagnosed with this rare genetic disorder. The therapy failed to achieve its primary measure—improvement in Bayley-4 cognitive raw scores—and also missed the crucial secondary measure, net response using the Multidomain Responder Index (MDRI).

According to Ultragenyx, researchers found no statistically significant improvements between trial participants receiving apazunersen compared to those in the placebo arm. While the drug’s safety characteristics aligned with previous studies, this provided minimal reassurance to investors.

Chief Executive Officer Emil Kakkis expressed deep disappointment with the findings, especially considering the expectations of patients and their families. “We are disappointed for the global patient community who has invested so much in early-stage research,” he stated.

Angelman syndrome impacts approximately 1 in every 15,000 newborns and results from dysfunction in the UBE3A gene. The condition manifests through intellectual disability, epileptic seizures, and profound developmental challenges. To date, no disease-modifying therapies have received regulatory approval for this condition.

Implications for the Ongoing Aurora Trial

The disappointing Aspire findings cast significant uncertainty over Aurora, another ongoing clinical investigation evaluating apazunersen in Angelman syndrome patients with alternative genetic variations.

According to William Blair analyst Sami Corwin, successful completion of Aurora’s primary endpoint may not guarantee commercial success. The eligible patient population remains too limited to sustain a financially viable marketed product, Corwin explained.

The FDA had previously granted apazunersen several important regulatory designations, including Breakthrough Therapy and Orphan Drug classifications. These recognitions stemmed from encouraging early-phase clinical data, making the late-stage disappointment particularly surprising.

Ultragenyx announced plans to conduct a comprehensive review of the apazunersen development program to determine next steps. The organization also intends to implement cost-reduction measures while reevaluating its strategic priorities.

Company Pivots to Marketed Products

Notwithstanding this significant setback, Ultragenyx highlighted its expanding portfolio of approved treatments as a foundation for continued operations.

The biotech company secured FDA clearance for Genglycos just last month, marking a milestone as the inaugural gene therapy authorized for glycogen storage disease type Ia, commonly referred to as Von Gierke disease.

Additionally, the firm anticipates potential regulatory approval for UX111 in treating Sanfilippo syndrome and continues geographic expansion of currently marketed therapies. Kakkis emphasized that the organization maintains its trajectory toward achieving profitability by 2027.

The Aspire study enrolled participants with baseline patient characteristics similar to those in earlier Phase 2 investigations, making the contrasting results particularly puzzling and intensifying investor concerns.

Ultragenyx confirmed its commitment to supporting commercially available products while conducting a thorough reassessment of its development pipeline following the apazunersen trial failure.

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