Whyte MP, et al. - In this prespecified, end of study, 7 year follow-up of a single-arm, open-label, phase 2 trial, researchers evaluated the long-term tolerability of asfotase alfa (defined as the number of patients with one or more treatment-emergent adverse events) and skeletal manifestations correlated with hypophosphatasia, assessed using the Radiographic Global Impression of Change (RGI-C) scale (−3 indicating severe worsening, and +3 complete or near-complete healing). They also assessed respiratory support, growth, and cognitive and motor functions in this extension study. Study participants included children aged 3 years or younger with life-threatening perinatal or infantile hypophosphatasia from ten hospitals. Early, sustained improvements in skeletal mineralization were seen in patients with perinatal or infantile hypophosphatasia treated with asfotase alfa for up to 7 years. It also improved respiratory function, growth, and cognitive and motor function. Pyrexia, upper respiratory tract infection, craniosynostosis, and pneumonia were the most common adverse events. Serious adverse events linked with asfotase alfa occurred in three (27%) patients (severe chronic hepatitis,; moderate immediate post-injection reaction, and severe craniosynostosis with severe conductive deafness). Overall, they concluded that asfotase alfa was generally well tolerated.