Design and Characterization of a Novel Intravitreal Dual-Transgene Genetic Medicine for Neovascular Retinopathies

Intravitreal delivery of therapeutic transgenes to the retina via engineered viral vectors can provide sustained local concentrations of therapeutic proteins and thus potentially reduce the treatment burden and improve long-term vision outcomes for patients with neovascular (wet) age-related macular degeneration (AMD), diabetic macular edema (DME), and diabetic retinopathy.

We performed directed evolution in nonhuman primates (NHP) to invent an adeno-associated viral (AAV) variant (R100) with the capacity to cross vitreoretinal barriers and transduce all regions and layers of the retina following intravitreal injection. We then engineered 4D-150, an R100-based genetic medicine carrying 2 therapeutic transgenes: a codon-optimized sequence encoding aflibercept, a recombinant protein that inhibits VEGF-A, VEGF-B, and PlGF, and a microRNA sequence that inhibits expression of VEGF-C. Transduction, transgene expression, and biological activity were characterized in human retinal cells in vitro and in NHPs.

R100 demonstrated superior retinal cell transduction in vitro and in vivo compared to AAV2, a commonly used wild-type AAV serotype in retinal gene therapies. Transduction of human retinal pigment epithelial cells in vitro by 4D-150 resulted in dose-dependent transgene expression and corresponding reductions in VEGF-A and VEGF-C. Intravitreal administration of 4D-150 to NHPs was well tolerated and led to robust retinal expression of both transgenes. In a primate model of laser-induced choroidal neovascularization, 4D-150 completely prevented clinically relevant angiogenic lesions at all tested doses.

These findings support further development of 4D-150. Clinical trials are underway to establish the safety and efficacy of 4D-150 in individuals with wet AMD and DME.