Efficacy and safety of asfotase alfa in infants and young children with hypophosphatasia : a phase 2 open-label study

Context 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 [−3 (severe worsening) to +3 (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: ≥+2 vs
Most infants and young children with hypophosphatasia, treated with asfotase alfa, showed improved skeletal manifestations, respiratory function, and growth within 1 year, maintained up to 6 years.