etranacogene dezaparvovec: clinical use

Prescribing considerations

• Initiation and administration require clinicians experienced in haemophilia or bleeding disorders and immediate facilities for managing infusion reactions.
• Confirm absence of factor IX inhibitors and assess neutralising anti-AAV5 antibodies.
• Complete baseline liver assessment, including transaminases, bilirubin, hepatitis B and C testing, ultrasound and fibrosis assessment.
• Review infection status, hepatic comorbidity, thromboembolic risk, immunocompromise and hepatotoxic exposures.
• Ensure vaccinations are current where possible and plan for potential corticosteroid use.
• Discuss contraception, semen and transplant-donation restrictions, the Patient Card and long-term follow-up.

Contraindications and cautions

• Hypersensitivity to etranacogene dezaparvovec or an excipient.
• Active acute infection or uncontrolled chronic infection.
• Known advanced hepatic fibrosis or cirrhosis.

Monitoring

• Monitor closely for infusion reactions during and after administration.
• Follow ALT with AST and creatine phosphokinase alongside factor IX activity; investigate rises and consider immune-mediated transaminitis.
• Use consistent factor IX assay methods where possible because one-stage and chromogenic assays give different results.
• Test for factor IX inhibitors if activity is inadequate or declines, or bleeding control is lost.
• Continue long-term liver-function and factor IX surveillance; consider liver ultrasound and alpha-fetoprotein monitoring when hepatocellular carcinoma risk factors are present.
• Record the product name and batch number and support enrolment in long-term follow-up.

Clinical pharmacology

A non-replicating recombinant AAV5 vector delivers a liver-specific, codon-optimised gene encoding the high-activity factor IX Padua variant. Vector DNA remains mainly episomal in hepatocytes, enabling factor IX expression; pre-existing anti-AAV5 antibodies may reduce expression.

Formulation and product differences

• Clear, colourless concentrate for intravenous infusion requiring dilution with sodium chloride solution.
• Supplied in single-use vials and contains genetically modified organisms.
• Contains sodium and is essentially potassium-free.
• The diluted product requires a dedicated peripheral intravenous line and must not share a line with other products.