3 The technology

3.1 Asfotase alfa (Strensiq, Alexion Pharma UK) is a targeted enzyme replacement therapy designed to restore the regulation of metabolic processes in the bones and teeth, and to reduce complications of dysregulated bone mineral metabolism. Asfotase alfa is administered by subcutaneous injection.

3.2 Asfotase alfa has a marketing authorisation under exceptional circumstances in the UK 'for long-term enzyme replacement therapy in patients with paediatric-onset hypophosphatasia to treat the bone manifestations of the disease'. Treatment should be started by a physician experienced in the management of metabolic or bone disorders. The recommended dosage of asfotase alfa is 2 mg/kg 3 times per week, or 1 mg/kg 6 times per week. For full details of the recommended dosage regimens of asfotase alfa, see the summary of product characteristics.

3.3 The summary of product characteristics lists the following very common adverse reactions for asfotase alfa: contusion, erythema, headache, injection-site reactions, irritability, pain in extremity and pyrexia. For full details of adverse reactions and contraindications, see the summary of product characteristics.

3.4 Asfotase alfa is available in vials of 40 mg/ml and 100 mg/ml. The cost of asfotase alfa is £58.80 per mg (excluding VAT; company's evidence submission). The cost of 52 weeks of treatment, assuming an average weight of 19.3 kg, is £366,912 per patient (excluding VAT). The company has proposed that asfotase alfa will be made available under commercial terms agreed with NHS England (including a price offer, per-patient cost cap and other commercial terms). The details of the commercial terms are commercial in confidence.

  • National Institute for Health and Care Excellence (NICE)