The US Food and Drug Administration granted an accelerated approval on 19 August for a new gene therapy for patients with an inherited disorder caused by the shortage of an enzyme needed to maintain stable blood sugar levels in the body. The therapy, Genglycos (pariglasgene brecaparvovec), is the first treatment to be authorised for the disorder – glycogen storage disease type la. Also called von Gierke disease, the disorder results in the build-up of glycogen, a complex sugar, in the body’s cells.
This can affect the ability of critical organs to function normally. The enzyme, glucose-6-phosphatase, normally releases glucose, the main source of energy for the body, from the liver and kidneys into the blood stream in order to help maintain stable blood sugar levels between meals. However the deficiency, caused by a genetic mutation, impairs this function.
Genglycos has been designed as a one-time therapy to deliver a functional copy of the G6PC gene to the liver with the goal of restoring normal enzyme function. It is delivered in a recombinant adeno-associated virus vector. The agency based the accelerated approval on a clinical trial using cornstarch as a surrogate endpoint.
The trial showed that patients treated with the therapy were able to achieve a statistically significant mean reduction in daily cornstarch intake of 31% compared to a placebo. “The reduced reliance on cornstarch, experienced by patients in our clinical studies, demonstrates this gene therapy’s ability to establish the normal breakdown of glycogen to produce glucose during fasting or episodes of metabolic stress,” said Eric Crombez, chief medical officer of Ultragenyx Pharmaceutical Inc, the developer. The FDA requires companies with an accelerated approval for a product to provide further clinical data in order to receive a full approval.
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