Positive results for Alexion’s latest ultra rare treatment

Alexion Pharmaceuticals has announced promising data from the extension phases of two phase II studies of asfotase alfa, an investigational enzyme replacement therapy, in paediatric patients with ultra-rare disease hypophosphatasia (HPP).

Researchers observed sustained improvements in growth, strength and physical function in paediatric patients with HPP who were treated with asfotase alfa for up to three years.

HPP is a genetic, chronic and progressive metabolic disease that can lead to ongoing damage to multiple vital organs, destruction and deformity of bones, and premature death.

Data were presented in Ireland at the Annual European Society for Paediatric Endocrinology (ESPE) meeting. Speaking about the findings, lead researcher Nick Bishop, professor of paediatric bone disease at the Mellanby Centre for Bone Research, University of Sheffield said, “We also observed important improvements in gross motor, fine motor, and cognitive skills throughout the treatment period. These findings are meaningful given the developmental challenges and failure to thrive often associated with severe HPP.”

HPP is caused by mutations in the gene encoding an enzyme known as tissue non-specific alkaline phosphatase (TNSALP).

The genetic deficiency in HPP can affect people of all ages. Paediatric patients with HPP have a high mortality rate, with 73 per cent mortality reported in a natural history study at five years, primarily due to respiratory failure. Patients surviving to adolescence and adulthood typically have recurrent and non-healing fractures, debilitating weakness, severe pain and need wheelchairs or assistance walking.

Asfotase alfa is designed to address the underlying cause of HPP by aiming to restore the genetically defective metabolic process, thereby preventing or reversing the severe and potentially life-threatening complications of life-long dysregulated mineral metabolism.

In 2013, the US FDA granted Breakthrough Therapy designation for asfotase alfa. In April 2014, Alexion initiated the rolling submission of a Biologics Licence Application (BLA) for asfotase alfa as a treatment for patients with HPP with the FDA. In July 2014, the Marketing Authorisation Application (MAA) for asfotase alfa was granted accelerated assessment by the European Medicines Agency.

Last week, Japan’s Ministry of Health, Labour and Welfare (MHLW) granted orphan drug designation (ODD) to asfotase alfa for the treatment of patients with HPP.

Alexion has been in the news recently regarding the high price of another of its drugs for ultra-rare disorders, Soliris (eculizumab), used for patients with paroxysmal nocturnal haemoglobinuria (PNH) and atypical haemolytic uremic syndrome (aHUS).

Alexion is evaluating other potential indications for Soliris in severe and ultra-rare disorders beyond PNH and aHUS.

However, debate continues over the proportion of healthcare budgets being used to fund drugs which help relatively small numbers of people with very rare conditions.


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