The collaboration will, in a clinical study, evaluate the safety and efficacy of Hansa's antibody cleaving enzyme imlifidase as a pre-treatment prior to the administration of Genethon's gene therapy product candidate GNT-0003 in Crigler-Najjar syndrome in patients with pre-existing neutralizing antibodies (NAbs) to adeno-associated virus serotype 8 (AAV8). The presence of circulating NAbs today excludes patients from entering clinical studies with potentially curative gene therapy treatments and from future access to approved gene therapies.

Søren Tulstrup, President and CEO, Hansa Biopharma stated: "Genethon is a pioneer at the cutting-edge of research and development of gene therapies for rare diseases and we are thrilled to be collaborating with them.  This research collaboration further validates Hansa's commitment in gene therapy and underscores the important role that our antibody-cleaving enzyme technology can play in ensuring that even more patients can benefit from life-saving gene therapies".

GNT-0003 is currently being evaluated in a pivotal clinical study in France, Italy, and the Netherlands and has received PRIME (PRIority MEdicines) status from the EMA. Through the collaboration announced today, patients with Crigler-Najjar and pre-formed antibodies to AAV8 will be enrolled in a study with similar design where imlifidase is evaluated as a pre-treatment to enable gene therapy treatment with GNT-0003. The outcome of the ongoing clinical study of GNT-0003 could potentially form the basis for a MAA or BLA application in Europe or the US.

Crigler-Najjar is a genetic disease-causing bilirubin accumulation which leads to irreversible neurological damage manifested as muscle weakness, lethargy, deafness, mental retardation, and eye movement paralysis. Crigler-Najjar syndrome is an ultra-rare disease affecting less than one case per one million people per year.¹

Frédéric Revah, CEO, Genethon added: "Patients with pre-existing neutralizing antibodies against AAV vectors cannot today benefit from gene therapy. This collaboration with Hansa Biopharma is thus an important next step in the development of our gene therapy treatment for Crigler-Najjar syndrome,  Hansa Biopharma's proven enzyme technology coupled with its scientific expertise will help us advance the critical research we are conducting in Crigler-Najjar and could enable gene therapy treatment for patients who are today not eligible because of their immunological status".