Gene therapy for inherited jaundice

This thesis describes experimental and clinical studies that bring adeno-associated virus (AAV)-mediated gene therapy for inherited jaundice a step closer toward clinical application. This may prevent the need of life-long phototherapy in patients suffering from Crigler-Najjar syndrome, caused by an enzyme deficiency impairing bilirubin metabolism. In addition, this technology may relieve symptoms and prevent the need of liver transplantation in patients suffering from progressive familial intrahepatic cholestasis, which results from a transport defect involved in bile formation. We show a high disease burden of Crigler-Najjar syndrome (CN) and regional differences in treatment outcome in the largest, worldwide patient cohort for this disease to date. In preparation of the clinical gene therapy trial for CN, the optimal production strategy of adeno-associated virus (AAV) vectors was validated and the subsequent toxicology and bio-distribution studies show to be safe and effective in the relevant animal models. Additionally, a quantitative in vitro assay to determine the potency of adeno-associated virus vectors was developed to assess vector quality, reducing assay time, costs and animal experiments. We found that the seroprevalence of anti-AAV neutralizing antibodies in CN patients is comparable with that in other populations and show that the negative effect of low antibody titers on liver transduction can be overcome by a favorable full-to-empty capsid ratio. Furthermore, liver-directed gene therapy results in long-term correction of progressive familial intrahepatic cholestasis type 3 (PFIC3) in a mouse model, encouraging translational studies for application in patients with PFIC3