Gene therapy in neovascular age related macular degeneration: an update.

Neovascular age-related macular degeneration (NV-AMD) is a leading cause of preventable blindness in the elderly. Intravitreal injections of anti-VEGF agents are currently the treatment of choice for NV-AMD. However this treatment is burdensome and fosters non-compliance which leads to inferior visual outcomes. Gene therapy has emerged as a promising therapeutic option for NV-AMD that may improve these outcomes. Potential risks of gene therapy include a potential immune response that may be elicited by the vector, accidental activation of oncogenes or inactivation of tumor suppresor genes leading to malignant transformation via insertational mutagenesis and integration of the viral DNA inserts into the host's DNA. The main strategy of current gene therapy for NV-AMD has focused on delivering transgenes that express anti-angiogenic proteins that directly or indirectly inhibit the VEGF pathway. Ixoberogene soroparvovec, RGX-314 and 4D-150 are the leading NV-AMD genetic treatment programs. Pre-clinical models suggest that genome surgery with clustered regularly interspaced short palindromic repeats (CRISPR) may be another option in the future.