FDA grants Priority Review to efzimfotase alfa for patients with hypophosphatasia aged two and older

The U.S. Food and Drug Administration has accepted Alexion’s Biologics License Application for efzimfotase alfa and granted it Priority Review for the treatment of patients aged two years and older with hypophosphatasia, or HPP.

Alexion is AstraZeneca’s rare disease business. A regulatory decision is expected during the first half of 2027 under the Prescription Drug User Fee Act timeline.

If approved, efzimfotase alfa would become the first treatment designed to address skeletal abnormalities and functional impairments in patients with HPP regardless of when the disease first appeared.

The investigational treatment has also been developed for self administration once every two weeks.

HPP is a rare inherited metabolic disorder caused by insufficient activity of the enzyme alkaline phosphatase.

Reduced activity of this enzyme can disrupt bone mineralisation and the regulation of calcium and phosphate. People with the disease may also experience muscle weakness, neurological symptoms, widespread fatigue and pain.

Marc Dunoyer, Chief Executive Officer of Alexion, said the FDA Priority Review represents an important development for people affected by HPP and reflects the potential of efzimfotase alfa to improve treatment outcomes.

He said the therapy was developed using insights from patients and is intended to address both skeletal and functional manifestations of the disease.

Dunoyer also highlighted the treatment’s once every two week self administration schedule and said efzimfotase alfa produced annualised injection site reaction rates that were five times lower than those observed with Strensiq.

The regulatory application is supported by what Alexion describes as the largest Phase III clinical development programme conducted in HPP.

The programme consists of three studies named HICKORY, MULBERRY and CHESTNUT.

HICKORY is evaluating adolescents and adults aged 12 years and older who have not previously received Strensiq, also known as asfotase alfa.

MULBERRY enrolled children aged from two to under 12 years who had also not previously been treated with Strensiq.

CHESTNUT, meanwhile, is studying children who had already received treatment with Strensiq before entering the trial.

Across all three Phase III studies, efzimfotase alfa demonstrated a favourable safety profile and was generally well tolerated.

Findings from the MULBERRY and CHESTNUT trials were recently presented at the 12th International Conference on Children’s Bone Health.

Results from HICKORY are expected to be presented at the 2026 American Society for Bone and Mineral Research Annual Meeting.

Regulatory applications based on findings from HICKORY, MULBERRY and CHESTNUT are also being reviewed in Japan and additional markets.

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Related Topics and Keywords

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