RARE Stock Gains on FDA Nod for Rare Disease Gene Therapy Genglycos
Zacks Equity Research
Thu, August 20, 2026 at 7:46 PM GMT+5:30
5 min read
Shares of Ultragenyx PharmaceuticalRARE are rising in premarket trading today following the FDA’s accelerated approval of DTX-401, an AAV8 gene therapy for glycogen storage disease type Ia (GSDIa)
The therapy will be marketed in the United States as Genglycos (pariglasgene brecaparvovec-opnr) and is indicated to reduce daily cornstarch intake as an adjunct to nutritional management in adult and pediatric patients aged eight years and older with GSDIa. The approval makes Genglycos the first FDA-approved treatment designed to address the underlying cause of GSDIa and marks Ultragenyx’s first gene therapy approval and its fifth FDA approval overall
FDA Nod for RARE’s Genglycos Supported by Phase III Data
The accelerated approval of Ultragenyx’s Genglycos is supported by results from the 48-week phase III GlucoGene study, which enrolled 46 participants aged eight years and older. Treatment with the drug produced a statistically significant reduction in daily cornstarch requirements compared with placebo. Patients were subsequently crossed over to the alternate treatment and continued to be monitored in longer-term follow-up
Under the accelerated approval, Ultragenyx is required to provide additional safety and efficacy data through an enhanced GSDIa Disease Monitoring Program. The company will follow 50 commercially treated patients and 20 control patients for two years, while the broader monitoring program will continue to evaluate patients for up to 10 years. Continued approval for the indication may depend on confirmation of clinical benefit in post-marketing studies
Year to date, shares of Ultragenyx have gained 14.1% compared with the industry’s 7% growth
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RARE’s Genglycos May Ease the GSDIa Treatment Burden
GSDIa is an ultra-rare inherited metabolic disorder caused by pathogenic variants in the G6PC gene. These variants lead to a deficiency of glucose-6-phosphatase, an enzyme required for the release of glucose from stored glycogen and other metabolicduring fasting, including overnight, along with excess glycogen accumulation in the liver and other metabolic complications
The condition affects an estimated 1,500-2,500 patients in the United States and 6,000-8,000 globally within commercially accessible geographies. Existing management relies on strict, around-the-clock supplementation with raw cornstarch to help maintain blood glucose levels. Even with strict adherence, interruptions in treatment can expose patients to severe hypoglycemia, seizures and potentially life-threatening complications, making the disease particularly burdensome for patients and caregivers.
