Selection and preclinical validation of a lead candidate liver-directed AAV-FVIII expression cassette

DESCRIPTION provided by applicant The development of transformative therapeutics including the possibility of a cure though gene therapy continues to be the major research and development activity in the commercial hemophilia space For example there are several company sponsored ongoing clinical trials of recombinant adeno associated viral rAAV encoding coagulation factor IX FIX for the treatment of hemophilia A Furthermore as a result of these trials there now exists extensive safety and initial efficacy data for multiple rAAV FIX products However progress in the translation of this approach to hemophilia A has been hampered by significant hurdles including the size complexity immunogenicity instability and biosynthetic inefficiency of coagulation factor VIII FVIII in comparison to FIX Now through the identification of liver specific transcriptional regulatory modules LTRMs that are smaller tha existing enhancer promoters combinations and a liver enhanced codon optimization algorithm used to engineer the coagulation factor VIII FVIII transgene we have been able to design rAAV vectors encoding FVIII with genome sizes under nucleotides that have unprecedented potency The proposed milestones of the current project are to characterize and select a lead candidate LTRM optimized for FVIII mRNA and transgene product output rAAV vector manufacture yield and rAAV product consistency and to identify a lead candidate AAV FVIII transgene These proof of concept studies will be performed using the preclinical murine model of hemophilia A The data obtained should facilitate the selection and preclinical validation of a lead candidate liver directed AAV FVIII expression cassette combining these novel technologies exclusively available to Expression Therapeutics ET Therefore ET is in an opportunistic position to capitalize on the ongoing rAAV FIX hemophilia B clinical findings and incorporate preclinical Randamp D and clinical protocol development strategies into this high priority rAAV FVIII project This existing clinical gene therapy knowledge combined with our hemophilia A experience and innovative technologies should enable ET to overcome the major hurdles facing commercialization of liver directed rAAV FVIII therapy for hemophilia A PUBLIC HEALTH RELEVANCE The goal of this project is test new technologies developed initially for liver directed recombinant adeno associated viral vector gene therapy of hemophilia A Our group has developed both liver expression and size optimized transcription regulatory modules and a liver optimized coagulation factor VIII transgene that should overcome the existing barriers to rAAV based gene therapy of hemophilia A The preclinical data obtained from the proposed studies should facilitate the selection of a lead gene therapy vector candidate