First FDA-Approved GSDIa Gene Therapy Could Change Treatment

Ultragenyx Pharmaceutical’s gene therapy Genglycos has received U.S. FDA approval for glycogen storage disease type Ia (GSDIa).

The gene therapy is the first FDA-approved treatment for the rare metabolic disorder. GSDIa, also known as Von Gierke disease, affects about 1,500 to 2,500 people in the U.S.

The inherited disorder is caused by a deficiency of an enzyme needed to release glucose from the liver. This can lead to dangerous drops in blood sugar.

Genglycos is designed to address the underlying cause of the disease. It helps the body break down glycogen and produce glucose. This could reduce patients’ dependence on raw cornstarch to control blood sugar.

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How does Genglycos change GSDIa treatment?

People with GSDIa often need frequent doses of raw cornstarch throughout the day. The regimen helps maintain blood glucose levels and prevent severe hypoglycemia. The FDA approval is based on results from a 48-week Phase 3 trial. Patients treated with Genglycos needed less cornstarch than those who received placebo.

Earlier Phase 3 results showed a 41.3 percent average reduction in daily cornstarch intake among treated patients. The placebo group recorded a 10.3 percent reduction.

Key findings included:

• All patients receiving DTX401 reduced their cornstarch intake.
• 68 percent achieved at least a 30 percent reduction.
• 37 percent achieved at least a 50 percent reduction.
• Patients also needed fewer cornstarch doses each day.
• Glucose control remained comparable to placebo.

What does the FDA approval mean for patients?

The FDA granted accelerated approval to Genglycos for adults and children aged eight years and older with GSDIa. However, the approval comes with additional requirements. The reduction in cornstarch use is considered a surrogate endpoint. Ultragenyx must conduct further trials to confirm the treatment’s long-term benefits.

The company has agreed to provide two years of additional safety and efficacy data. Patients from the treatment program will also be followed for longer-term outcomes. Genglycos will have a U.S. list price of $2.7 million per patient. Ultragenyx expects the treatment to reach qualified centers within 30 to 60 days.

The approval also marks an important milestone for Ultragenyx. Genglycos is the company’s first FDA-approved gene therapy and its fifth FDA approval overall. Other companies are also studying treatments for GSDIa. Moderna and Beam Therapeutics have explored early-stage approaches for the disorder. However, their candidates remain in earlier clinical development.