[Enzyme replacement therapy for hypophosphatasia].

Hypophosphatasia is caused by abnormal tissue-nonspecific alkaline phosphatase (ALP), leading to impaired calcification in bone. Patients with severe hypophosphatasia have difficulties in respiratory function from early days after birth and the rate of lethality is extremely high. Enzyme replacement therapy using bone-targeting recombinant ALP, which has 10 aspartic acids in the C-terminal tail has developed. The efficacy of ERT was firstly observed in model mice of hypophosphatasia. In clinical trial including perinatal and infantile types of hypophosphatasia, efficacy and safety have been reported. Expanded clinical trial is underway and the results of the clinical trial might be reported by the end of the next year.