Experiences with the use of asfotase alfa in three patients with childhood-onset hypophosphatasia.

Summary: Hypophosphatasia (HPP) is a rare inherited metabolic disorder characterized by deficient activity of serum alkaline phosphatase due to loss-of-function mutations in the ALPL gene. Diagnosis confirmation, management, and follow-up of HPP are challenging, and clinical guidance is scant due to the difficulty in gathering high-level evidence. Asfotase alfa is the first long-term enzyme replacement therapy indicated in patients with pediatric-onset HPP to treat the bone manifestations of the disease. In the absence of large clinical studies, sharing clinical observations is an important source of information and support for clinicians. This article presents three case studies. A woman affected by HPP with manifestations of the disease at pediatric age began asfotase alfa therapy at the age of 43 years, resulting in improvements in bone density and epilepsy management. A man diagnosed with HPP in childhood had a severely compromised quality of life. He experienced improvements in bone fragility, respiratory function, sleep quality, and physical function with asfotase alfa therapy. Finally, a woman with infantile-onset HPP, presenting with severe bone deformity, musculoskeletal pain, pseudofractures, and cardiovascular and neurological involvement, showed radiological and clinical improvements in bone health, reduced pain, and increased walking autonomy during asfotase alfa treatment. Learning points: Delayed diagnosis of HPP is common and can cause morbidity. Asfotase alfa significantly improves clinical outcomes in childhood-onset HPP, even when initiated in adulthood. Asfotase alfa therapy provides benefits beyond bone health. Monitoring treatment response requires a comprehensive clinical evaluation beyond DXA measurements. Real-world clinical experience is crucial for optimizing treatment strategies for HPP.