Lifelong Correction of Hereditary Tyrosinemia Type 1 and Other Monogenic Liver Diseases using Liver-specific Hydrodynamic Gene Delivery through the Biliary System

PROJECT SUMMARY Hereditary tyrosinemia type 1 (HT1) is an autosomal recessive Inborn Error of Metabolism (IEM), characterized by the inability to metabolize tyrosine and caused by the deficiency in fumarylacetoacetate hydrolase (FAH) enzyme. The liver is central to IEMs, including HT1. Acute HT1 causes severe liver dysfunction and death, if left

untreated. Chronic HT1 leads to liver fibrosis and hepatocellular carcinoma (HCC). Early and life-long pharma- cological treatment with nitisinone (NTBC) can minimize liver damage. However, due to residual cellular toxicity that accumulates over years, HT1 patients on nitisinone remain at risk of cirrhosis, HCC, and liver failure and

experience progressive neurocognitive decline. Liver transplants remain the only curative therapy for HT1. Liver-directed gene therapy, in which the defective gene is replaced with a functional isoform, has the potential to replace risky liver transplants and costly life-long pharmacological treatment. HydroGene has developed a

non-viral gene delivery to the liver for affordable and safe gene therapy that can meet all the requirements for successful HT1 therapy. Unlike the Lentiviral method, which suffers from low efficacy of liver delivery, safety issues related to systemic immunotoxicity, and expensive manufacturing that limits its scalability, HydroGene

has developed a routine method of efficient hydrodynamic delivery of non-viral DNA specifically to hepatocytes via the biliary system. Because the method of gene delivery is based on a routine endoscopic clinical procedure that can be performed in under 30 min and has minimal complications, it is ideal for translation to clinics. In

addition, the method can deliver non-immunogenic naked DNA that is cheap to manufacture and can be easily tailored to different rare diseases. Therefore, the HydroGene liver gene therapy is suitable to be translated to clinics for cost-effective life-long correction of HT1 and other rare monogenetic liver diseases.

In this Fast-Track application, the objective is to demonstrate the clinically relevant efficacy of using hydrody- namic gene delivery for the treatment of HT1. One of the key features of HT1, and many other rare genetic liver disorders, is continuous liver damage and injury, causing excessive cell death. As a result, corrected hepato-

cytes have a survival advantage and will repopulate the damaged liver, but only if the corrective gene is trans- ferred into both daughter cells. Thus, to cure HT1, it is essential for the FAH gene to be integrated into the host genome. To this end, the focus of Phase 1 is to optimize the vector system for safe genome integration and

efficient cure in a HT1 mouse model. All the data obtained in Phase 1 is directly translatable to studies in a large animal proposed in Phase 2. The focus of Phase 2 is to determine the exact vector composition and regimen for interruption/tapering treatment with nitisinone in the most clinically relevant large animal HT1 model. The final

product of this proposal is a clear path toward clinical translation of hydrodynamic delivery of an integrating vector system to treat HT1 patients and beyond, to many other inborn errors of metabolism and liver diseases.