Crigler-Najjar syndrome (CN) is a rare recessive disorder caused by mutations in the uridine diphosphate glucuronosyltransferase 1A1(UGT1A1) gene. CN is a life-threatening disease with no cure which constitutes a severe burden for the patients, their families, and the society. CureCN has the objective of developing a curative gene therapy for CN syndrome based on liver gene transfer with and adeno-associated virus (AAV) vector expressing the UGT1A1 transgene. Additional goals of CureCN are to develop strategies to allow for vector re-administration and to address the issue of pre-existing anti-AAV neutralizing antibodies (NAbs), which prevent large proportion of seropositive patients from receiving AAV mediated gene therapy. Proof-of-concept studies of AAV8-UGT1A1 gene transfer provide a strong rationale for the safety and efficacy of gene therapy for CN. CureCN proposes to carry out an open-label, multicenter clinical trial of AAV8-UGT1A1 gene transfer to prove the safety and efficacy of the therapy in severe CN patients, and file for marketing authorization in Europe at the end of the study. CureCN will also produce enabling data for the clinical translation of a groundbreaking immunomodulatory strategy to allow for vector administration. Additionally, a technology for the selective removal of anti-AAV NAbs from the bloodstream of seropositive patients will be developed. The goal of these studies is to ultimately allow all CN patients to access AAV8-UGT1A1 gene therapy. CureCN is a patient-driven initiative that gathers top clinicians and scientists; it also includes small medium enterprises in its partners, to foster economic growth and valorization of intellectual property. CureCN sets itself in the ambitious goal set by the IRDiRC by 2020 by developing a curative treatment for CN syndrome. Importantly, it validates technologies that will broaden the scope of gene therapy, thus will have an impact on the development of treatments for several other rare diseases.

Major current hurdles for wide clinical use of AAV vectors are attributable primarily to: (i) host elimination by both immune and non-immune sequestering mechanisms – such neutralization by host antibody responses critically limits the possibility of repeated AAV delivery; (ii) AAVs are prevalent in the environment and hence a large proportion of the population carry AAV antibodies (up to 80%)– this pre-existing immunity renders AAV unable to infect target cells forcing substantial patient cohorts to be excluded from clinical trials. The current proposal is founded on compelling track record in the field and brings together a ‘best-with-best’ multidisciplinary team of international leading academic and EFPIA partners with complimentary expertise in gene therapy, immunology, chemistry, engineering, biotechnology, drug safety, viral vector production, regulatory and clinical trials. The overall goal is to analyse the currently available clinical data and then design preclinical and clinical studies to fill the knowledge gaps in advanced therapies development. Our main aims are to: 1) Develop improved model systems for predicting product immunogenicity in humans. This will be achieved by generating human and NHP 3D hepatic models; 2) Enhance our understanding of gene/cell therapy drug metabolism inside a host of cell types. The plan is to define metabolism of the therapeutic vector genome in different cell types to understand whether rates of degradation, episomal maintenance, or integration, and metabolic stress induced by AAV vector transgene expression vary from cell to cell. We will then adopt strategies to mitigate the loss of vector genomes and improve persistence; 3) Use diverse clinical expertise to establish the clinical factors around pre-existing immunity limiting patient access to advanced therapies therapy; 4) Engage regulators to ensure that the concepts and the data generated through this IMI programme will fill the gaps and support furture trials.