Application of --cultured Primary Hepatocytes to Evaluate Species Translatability and AAV Transduction Mechanisms of Action

Recombinant adeno-associated virus (AAV) is an effective platform for therapeutic gene transfer; however, tissue-tropism differences between species are a challenge for successful translation of preclinical results to humans. We evaluated the use of primary hepatocyte cultures to predict liver-directed AAV expression in different species. We assessed whether AAV transduction assays in cultured primary hepatocytes from mice, nonhuman primates (NHPs), and humans could model liver-directed AAV expression of valoctocogene roxaparvovec (AAV5-hFVIII-SQ), an experimental gene therapy for hemophilia A with a hepatocyte-selective promoter. Relative levels of DNA and RNA in hepatocytes grown correlated with liver transduction across species. Expression in NHP hepatocytes more closely reflected expression in human hepatocytes than in mouse hepatocytes. We used this hepatocyte culture model to assess transduction efficacy of a novel liver-directed AAV capsid across species and identified which of 3 different canine factor VIII vectors produced the most transgene expression. Results were confirmed . Further, we determined mechanisms mediating inhibition of AAV5-hFVIII-SQ expression by concomitant isotretinoin using primary human hepatocytes. These studies support using primary hepatocyte models to predict species translatability of liver-directed AAV gene therapy and improve mechanistic understanding of drug-drug interactions.