Swedish biopharmaceutical company Hansa Biopharma (STO:HNSA) and Genethon, a developer of gene therapies for rare diseases, on Tuesday announced the start of a Phase 2 clinical trial to evaluate the efficacy and safety of GNT-0003, a gene therapy for Crigler-Najjar syndrome, in patients with pre-existing anti-AAV antibodies.

The trial will involve pre-treating patients with imlifidase, Hansa's antibody-cleaving enzyme therapy, to reduce the neutralising antibody levels against AAV vectors. This innovative approach may enable patients with pre-existing antibodies to access life-changing gene therapy treatments.

GNT-0003 has shown promising results in earlier clinical trials and has received PRIME designation from the European Medicines Agency. If successful, this gene therapy could provide a significant therapeutic advance for patients with Crigler-Najjar syndrome.