Preclinical Reproductive Safety and Germline Transmission Risk of Gene Therapy Following Intravenous or Intracerebroventricular Administration in Mice

Topic:

Pre-Clinical Research

Poster Number: 186 M

Author(s):

Francis Tukov, DVM, PhD, DABT, Novartis Pharmaceuticals Corporation, Silvana Libertini, PhD, Novartis Biomedical Research, Tony del Rio, PhD, Novartis Biomedical Research, Keith Mansfield, DVM, Novartis Biomedical Research, Emily Meseck, DVM, Novartis Pharmaceuticals Corporation, Guanrong Huang, PhD, Novartis Biomedical Research, Jayson Chen, PhD, Novartis Pharmaceuticals Corporation, Cameron McElroy, MSc, PhD, Novartis Pharmaceuticals Corporation, Anthony M. DeLise, PhD, Novartis Pharmaceuticals Corporation

Background: Gene therapy offers significant potential for treating genetic disorders by addressing mutations at their source. For gene therapies aimed at populations with reproductive potential, understanding the risk of germline transmission, reproductive toxicity, and possible impact on fertility and embryofetal development is essential.
Objectives: Onasemnogene abeparvovec (OA), a recombinant adeno-associated virus 9 for treatment of spinal muscular atrophy (SMA), was assessed in mice. For germline transmission studies, neonatal mice received a single intravenous (IV) or intracerebroventricular (ICV) OA injection (1.1×10^14 vg/kg) on Postnatal Day 1, and gonads were analyzed up to 24 weeks after treatment. For fertility and embryonic development (FEED) studies, approximately 25 mice/sex/group were administered a single IV dose of either vehicle control, 1.1×10^13 vg/kg OA, or 1.1×10^14 vg/kg OA up to 4 weeks prior to cohabitation with undosed mates. For the embryo-fetal development (EFD) study, three groups of approximately 25 time-mated female mice/group received the same doses as for the FEED study via IV injection on Gestational Day 6.
Results: In the germline transmission studies, low levels of OA vector DNA were detected by droplet digital PCR (ddPCR) in homogenated ovarian and testicular tissues. In situ hybridization (ISH) showed viral nucleic acids in sparse testicular and ovarian non-germline cells. Vector DNA was not detected in spermatozoa (ddPCR) nor in oocytes (ISH). In FEED studies, no adverse effects on survival, fertility, mating, or embryonic development were observed in mates or offspring of dosed animals. OA administration to pregnant mice did not affect embryofetal development. Vector DNA was not detected in the fetuses from the FEED or EFD studies.
Conclusions: These nonclinical investigations indicate that OA administration (IV or ICV) poses negligible risk of germline transmission, impaired fertility, or embryofetal toxicity at clinically relevant doses, supporting its safe clinical use for patients with SMA of reproductive potential.