Alexion Pharmaceuticals has announced that researchers presented new data from an integrated analysis of survival from two open-label, Phase 2 studies of asfotase alfa in pediatric patients (ages ≤5 years at enrollment) with hypophosphatasia (HPP) compared with data from a retrospective natural history study of untreated historical control patients matched for age and disease severity. 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. In an oral session of the American Society for Bone and Mineral Research (ASBMR) 2014 Annual Meeting, 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.