onasemnogene abeparvovec: clinical use

Prescribing considerations

• Confirm licensed genetic and clinical eligibility criteria and document baseline disease burden.
• Test anti-AAV9 antibodies before treatment; safety and efficacy with titres above the specified threshold are uncertain.
• Ensure hydration and nutritional status are satisfactory; postpone treatment during active or uncontrolled infection.
• Plan corticosteroid immunomodulation and coordinate vaccinations and seasonal RSV prevention.
• Benefit may be substantially reduced in advanced disease with profound weakness, respiratory failure, permanent ventilation or inability to swallow.

Contraindications and cautions

• Hypersensitivity to onasemnogene abeparvovec or any excipient.
• Use caution with pre-existing hepatic impairment, acute hepatic viral infection or exposure to hepatotoxic substances.

Monitoring

• Before treatment: clinical assessment, anti-AAV9 antibodies, liver tests, coagulation, creatinine, full blood count including platelets, and troponin I.
• After treatment: monitor liver function closely through the corticosteroid taper and subsequently as indicated.
• Monitor platelets closely during the early post-infusion period; promptly investigate thrombocytopenia for haemolysis and renal dysfunction.
• Monitor troponin I as clinically indicated and consider cardiac specialist input.
• Maintain vigilance for infection, infusion reactions, systemic immune responses and thrombotic microangiopathy.

Clinical pharmacology

A non-replicating recombinant AAV9 vector delivers a functional human SMN transgene. Vector DNA remains mainly episomal in transduced cell nuclei, supporting sustained SMN protein expression without correcting the inherited genomic mutation.

Formulation and product differences

• The selected UK product is a ready-to-use solution for intravenous infusion supplied in weight-tailored packs of vials.
• The solution is clear to slightly opaque and colourless to faint white.
• It is stored frozen, transferred to refrigerated storage on receipt, must not be refrozen after thawing and must not be mixed with other medicines.