Efficacy and Safety of Asfotase Alfa in Infants and Young Children with Hypophosphatasia: A Phase 2 Open-Label Study

Abstract

Long-term data on enzyme replacement treatment of hypophosphatasia (HPP) are limited. Objective: To evaluate efficacy and safety of asfotase alfa in patients aged #5 years with HPP followed for up to 6 years. Design: Phase 2 open-label study (July 2010 to September 2016). Setting: Twenty-two sites; 12 countries. Participants: Sixty-nine patients [median (range) age: 16.0 (0.02 to 72) months] with severe HPP and sign/symptom onset before age 6 months. Intervention: Asfotase alfa 2 mg/kg three times/week or 1 mg/kg six times/week subcutaneously. Main Outcome Measures: Primary efficacy measure: Radiographic Global Impression of Change (RGI-C) score [23 (severe worsening) to 13 (complete/near-complete healing)]. Additional outcome measures: respiratory status, growth, and safety. Post hoc analysis: characteristics of radiographic responders vs nonresponders at Year 1 (RGI-C: 12 vs ,12).