Alexion snags latest 'breakthrough' coup with PhIII rare-disease drug

The FDA has added another regulatory coup for Alexion's ($ALXN) late-stage program for asfotase alfa, an enzyme replacement therapy for extremely rare cases of a metabolic disease known as hypophosphatasia. Already handed an orphan drug designation alongside fast-track status, the agency has added the highly sought after "breakthrough drug" designation for the therapy, which could further shave some time off the development schedule. 

Alexion--which has been cheered and jeered for its success marketing Soliris, the most expensive drug in the world--acquired the therapy in a $1.08 billion deal to buy Enobia at the beginning of 2012, paying $610 million in cash and offering $470 million in milestones to buy the biotech. The bulk of that money was paid for asfotase alfa, which had already demonstrated positive mid-stage data ahead of the buyout.

The FDA has been rapidly adding to its roster of breakthrough drugs, demonstrating a clear preference for experienced and successful drug developers with late-stage oncology and rare-disease treatments. It's still early days for this designation, but the agency has been signaling that it's willing to open its doors to drug development teams which have won the designation, potentially carving out a shortcut to an approval.

"The FDA's Breakthrough Therapy designation for perinatal-, infantile- and juvenile-onset HPP recognizes the severe, debilitating and life-threatening nature of the disease, the clear unmet medical need of patients, and the clinical evidence collected to date on asfotase alfa," said Martin Mackay, Alexion's R&D chief. "Asfotase alfa is a highly innovative therapeutic candidate with the potential to transform the lives of patients with HPP who currently have no treatment options and often receive only palliative care for this life-threatening disease."

Mackay joined Alexion just days ago. He was recently squeezed out of the top R&D job at AstraZeneca ($AZN).

Hypophosphatasia is a disorder brought on by a metabolic disaster. Patients with HPP can't produce an enzyme needed to maintain phosphate levels in metabolites required for normal bone formation as well as brain and muscle function. Asfotase alfa is a recombinant protein designed to address the genetic deficiency, according to Alexion, preventing or reversing the impact of dysregulated calcium and phosphate metabolism.

- here's the press release

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