Phase 2 Trial of RGX-314 in Adults With Center Involved - Diabetic Macular Edema (CI - DME)

Inclusion Criteria: * Type I or Type II diabetes mellitus with center involving diabetic macular edema with previous treatment * HbA1c ≤12% * BCVA in study eye 78 to 25 ETDRS letters (\~20/32 to 20/320) at screening * Decreased visual acuity attributable primarily due to CI - DME * Demonstrate clinical response to aflibercept injection in the study eye * Provide written informed consent Exclusion Criteria: * Women of childbearing potential * Neovascularization in the study eye from a cause other than DR * Evidence in the study eye of optic nerve pallor on clinical examination * History of pan retinal photocoagulation in the study eye * Any concurrent ocular condition in the study eye other than CI-DME that could require surgical intervention within 6 months or any condition in the study eye that may increase the risk to the participant, require either medical or surgical intervention during the study to prevent or treat vision loss, or interfere with the study procedures or assessments * Presence of an implant in the study eye at screening (excluding intraocular lens) * Any condition in the investigator's opinion that could limit VA improvement in the study eye * Active or history of glaucoma, steroid response, or ocular hypertension * Any prior intravitreal steroid injection in the study eye within 6 months prior to screening, administration in the study eye of Ozudrex® within 12 months prior to screening, or administration in the study eye if Iluven® within 36 months prior to screening * Diabetic macular edema diagnosis ≥ 7 years * History of chronic renal failure requiring dialysis or kidney transplant * Participation in any other gene therapy study or receipt of any investigational product within 30 days prior to enrollment or 5 half-lives of the investigational product, whichever is longer, or any plans to use an investigational product within 6 months following enrollment Note: Other inclusion/exclusion criteria apply