Stable Human FIX Expression After 0.9G Intrauterine Gene Transfer of Self-complementary Adeno-associated Viral Vector 5 and 8 in Macaques

Citra NZ Mattar, Amit C Nathwani, Simon N Waddington, Niraja Dighe, Christine Kaeppel, Ali Nowrouzi, Jenny Mcintosh, Nuryanti B Johana, Bryan Ogden, Nicholas M Fisk, Andrew M Davidoff, Anna David, Donald Peebles, Marcus B Valentine, Jens-Uwe Appelt, Christof von Kalle, Manfred Schmidt, Arijit Biswas, Mahesh Choolani, Jerry KY Chan

Intrauterine gene transfer (IUGT) offers ontological advantages including immune naiveté mediating tolerance to the vector and transgenic products, and effecting a cure before development of irreversible pathology. Despite proof-of-principle in rodent models, expression efficacy with a therapeutic transgene has yet to be demonstrated in a preclinical nonhuman primate (NHP) model. We aimed to determine the efficacy of human Factor IX (hFIX) expression after adeno-associated-viral (AAV)-mediated IUGT in NHP. We injected 1.0-1.95 × 10(13) vector genomes (vg)/kg of self-complementary (sc) AAV5 and 8 with a LP1-driven hFIX transgene intravenously in 0.9G late gestation NHP fetuses, leading to widespread transduction with liver tropism. Liver-specific hFIX expression was stably maintained between 8 and 112% of normal activity in injected offspring followed up for 2-22 months. AAV8 induced higher hFIX expression (P = 0.005) and milder immune response than AAV5. Random hepatocellular integration was found with no hotspots. Transplacental spread led to low-level maternal tissue transduction, without evidence of immunotoxicity or germline transduction in maternal oocytes. A single intravenous injection of scAAV-LP1-hFIXco to NHP fetuses in late-gestation produced sustained clinically-relevant levels of hFIX with liver-specific expression and a non-neutralizing immune response. These data are encouraging for conditions where gene transfer has the potential to avert perinatal death and long-term irreversible sequelae.