Alexion report new data from two open-label, Phase II studies of asfotase alfa in pediatric patients

In this analysis, survival in patients with HPP at high risk of death who were treated with asfotase alfa for up to five years was significantly improved (89% vs. 27%, p<0.0001) compared with untreated historical control patients.

These late-breaking results were presented today at the American Society for Bone and Mineral Research (ASBMR) 2014 Annual Meeting in Houston, where researchers also presented new data from the ongoing open-label extension phases of two Phase 2 clinical studies in which sustained gains in physical function and reductions in disability and pain were observed in pediatric patients receiving asfotase alfa treatment for up to three years.2,3

HPP is a genetic, chronic and progressive ultra-rare metabolic disease that can lead to progressive damage to multiple vital organs, destruction and deformity of bones and premature death.4-8 Asfotase alfa is an investigational enzyme replacement therapy for the treatment of HPP.

"Pediatric patients with severe HPP face a high risk of death as well as significant challenges related to respiratory function, growth, development and physical function," said Martin Mackay, Ph.D., Executive Vice President and Global Head of R&D at Alexion.

"Survival was significantly improved among severely affected infants and children with HPP treated with asfotase alfa compared with a historical control of untreated patients, which is an important finding for the HPP community who currently has no approved treatment options."

In an oral session today, researchers reported that treatment with asfotase alfa significantly improved survival in pediatric patients (ages =5 years at enrollment) with severe HPP.1 Over the five-year analysis period, 89% (33/37) of patients treated with asfotase alfa survived compared with 27% (13/48) of untreated historical control patients. Invasive ventilator-free survival was also significantly improved in treated patients (p<0.0001); 83% (21/25) of treated patients required no invasive ventilation and survived, compared with 25% (12/48) of historical control patients.

These results were from an integrated analysis of survival from two multicenter, open-label, ongoing Phase 2 studies of patients with HPP who were treated with asfotase alfa, compared with data from a retrospective natural history study of untreated historical controls, matched for age and disease severity. Findings from the retrospective natural history study were previously reported at the Pediatric Academic Societies (PAS) meeting in May 2014.

Patients in the asfotase alfa trials were five years of age or younger at enrollment and had been diagnosed with HPP prior to six months of age. Included in the survival analysis were patients who had one or more of the following signs of severe HPP: rachitic chest, history of respiratory distress, or Vitamin B6-responsive seizures. Median duration of treatment was two years, with patients treated for up to five years.