STRENSIQ

What it is

Strensiq is supplied as a single-use vial containing 40 or 100 mg/mL of asfotase alfa rch. Asfotase alfa rch is a human recombinant tissue-nonspecific alkaline phosphatase (TNSALP) — Fc-deca-aspartate fusion protein with enzymatic activity, produced by recombinant DNA technology using mammalian Chinese Hamster Ovary (CHO) cell culture. It is a sterile, preservative-free, non-pyrogenic solution for injection supplied as a clear, slightly opalescent or opalescent, colourless to slightly yellow aqueous solution for subcutaneous injection.

Approved indications

— Enzyme replacement therapy in patients with paediatric-onset hypophosphatasia.

Dosing overview

The recommended dosage regimen is 2 mg/kg of body weight, administered subcutaneously 3 times per week, or 1 mg/kg of body weight administered 6 times per week. The maximum volume of subcutaneous injection is 1 mL per injection site. If more than 1 mL is required, the volume should be split equally between two or more syringes, and each injection administered using a separate site. Patients can self-inject only if they have been appropriately trained on administration procedures.

Key safety warnings

Hypersensitivity reactions have been reported in Strensiq-treated patients including signs and symptoms consistent with anaphylaxis, with signs and symptoms including difficulty breathing, choking sensation, periorbital oedema and dizziness. The reactions have occurred within minutes after subcutaneous administration of Strensiq. Hypersensitivity reactions have been observed as late as more than one year after treatment initiation. If severe hypersensitivity reaction occurs, immediate discontinuation of Strensiq treatment is recommended and appropriate medical treatment should be initiated, observing current medical standards for emergency treatment. Administration of Strensiq may result in local injection site reactions (including erythema, rash, discolouration, pruritus, pain, papule, nodule or atrophy), which have been generally assessed as non-serious, mild to moderate in severity and self-limiting. Localised lipodystrophy, including lipoatrophy and lipohypertrophy, has been reported at injection sites after several months in patients treated with Strensiq, and patients should be advised to follow proper injection technique and rotate injection sites. Adverse events of craniosynostosis, including worsening of pre-existing craniosynostosis, have been reported in HPP patients under 5 years of age, and periodic monitoring including fundoscopy for signs of papilloedema and prompt intervention for increased intracranial pressure is recommended in infantile-onset HPP patients below 5 years of age. Patients with HPP are at increased risk for developing ectopic calcifications, and ophthalmology examinations and renal ultrasounds are recommended at baseline and periodically during treatment to monitor for signs and symptoms of ophthalmic and renal ectopic calcifications and for changes in vision or renal function. Serum parathyroid hormone concentrations may increase in HPP patients administered Strensiq, most notably during the first 12 weeks of treatment, and it is recommended that serum parathyroid hormone and calcium be monitored in patients treated with Strensiq, with supplements of calcium and oral vitamin D possibly required.

Contraindications

Strensiq is contraindicated in patients with known hypersensitivity to asfotase alfa rch, Chinese hamster ovary cell proteins or to any of the excipients of this product. Severe and life-threatening hypersensitivity to the active substance or to any of the excipients if hypersensitivity is not controllable is also contraindicated.

Regulatory history

Strensiq was first registered on the ARTG on 14 January 2016, with five strength variants approved: 12 mg/0.30 mL, 18 mg/0.45 mL, 28 mg/0.70 mL, 40 mg/1.00 mL, and 80 mg/0.80 mL solution for injection vials.