Aug 19 (Reuters) – Ultragenyx Pharmaceutical said on Wednesday that its gene therapy became the first to receive the U.S. Food and Drug Administration’s approval to treat a rare metabolic disorder, sending its shares up 7.5% in after-hours trading.
The drug, branded as Genglycos, has been approved for glycogen storage disease type Ia (GSDIa), also known as Von Gierke disease, in adults and pediatric patients.
It is an ultra-rare genetic disorder that is caused due to deficiency of an enzyme that helps release glucose from the liver into the bloodstream. GSDIa affects 1,500 to 2,500 patients in the U.S., the company estimates.
The deficiency reduces the liver’s ability to control glucose levels and is associated with potentially life-threatening low blood sugar levels.
Day-to-day management of the condition requires a relentless regimen of raw cornstarch as an oral glucose replacement therapy.
Ultragenyx’s Genglycos addresses the underlying cause of the disorder by aiding the normal breakdown of glycogen to produce glucose, which helps in regulating blood sugar levels and reducing reliance on cornstarch.
The FDA’s approval marks a win for the company that has grappled with regulatory hurdles in its gene-therapy business. In July 2025, the regulator declined to approve its brain disorder gene therapy, seeking additional manufacturing-related information.
The regulator’s authorization is based on a 48-week late-stage trial that found patients treated with Genglycos showed a reduction in the cornstarch requirements compared to placebo.
Reducing cornstarch intake is, however, the surrogate endpoint, and the manufacturer must complete additional clinical trials to confirm Genglycos’s effectiveness, the FDA said.
The company said it has agreed to provide two years of safety and efficacy clinical data from patients.
Several experimental treatments for GSDIa are also in development, including those from Moderna and Beam Therapeutics, though the candidates remain in early stages of clinical testing.
Genglycos will be available through qualified treatment centers, the company said.
(Reporting by Padmanabhan Ananthan and Sneha S K in Bengaluru; Editing by Leroy Leo and Shinjini Ganguli)
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