REGENXBIO Inc. (Nasdaq: RGNX), a clinical-stage biotechnology company, based in Rockville, Maryland, has reported positive interim data from an ongoing Phase II “ALTITUDE” trial of a gene therapy treatment (RGX-314) for diabetic retinopathy (DR) patients, without centre-involved diabetic macular edema (CI-DME) and using in-office suprachoroidal delivery. According to their study interim results, 47% of patients treated with RGX-314 had a ≥2 step improvement from baseline on the ETDRS-DRSS at six months, compared to 0% of patients in an observational control cohort. The in-office suprachoroidal delivery of the treatment, 15 patients in their first cohort were to be well tolerated and with no drug-related serious adverse events at six months and no intraocular inflammation observed.
RGX-314 is being developed for diabetic retinopathy using an AAV8 vector encoding an antibody fragment designed to inhibit vascular endothelial growth factor (VEGF). According to the company, two separate routes of administration of RGX-314 use a standardized subretinal delivery procedure as well as delivery to the suprachoroidal space. A microinjector medical device from Clearside Biomedical, Inc. is aimed to deliver gene therapy treatment to the suprachoroidal space of the eye. The current dose-escalation trial, evaluating the efficacy, safety and tolerability of suprachoroidal delivery of RGX-314, is conducted in patients with a DR diagnosis of moderately severe or severe non-proliferative diabetic retinopathy (NPDR), or mild proliferative diabetic retinopathy (PDR). Twenty patients in cohort 1 were randomized to receive RGX-314 at a dose level of 2.5×1011 genomic copies per eye (GC/eye), versus observational control at a 3:1 ratio. Cohort 2 will include 20 patients randomized to receive RGX-314 at an increased dose level of 5×1011 GC/eye, versus observational control at a 3:1 ratio. Finally, cohort 3 is designed to evaluate RGX-314 at the same dose level as cohort 2 in 20 patients, who are neutralizing antibody (NAb) positive. Enrollment is ongoing in cohorts 2 and 3 and patients in this trial do not receive prophylactic immune suppressive corticosteroid therapy before or after administration of RGX-314.
As highlighted, following six months, 15 patients were dosed with RGX-314 in cohort 1 and seven(7) patients (47%) demonstrated a two-step or greater improvement from baseline on the ETDRS-Diabetic Retinopathy Severity Scale (DRSS), using the study’s primary endpoint, compared to zero of the five patients (0%) in the observational control group. In further detail, one patient (7%) dosed with RGX-314 continues to demonstrate a four-step improvement. In seven patients who had NPDR (DR severity level 47-53) at baseline, 57% of patients demonstrated a two-step or greater improvement from baseline DRSS at six months after administration. In the eight patients who had PDR (DR severity level ≥ 61) at baseline, 38% of patients demonstrated a two-step or greater improvement at six months after administration of RGX-314. In commenting on the interim results, Dr. Michael A. Klufas, M.D., Assistant Professor of Ophthalmology, Thomas Jefferson University, stated, “I am encouraged by the clinical improvement of disease severity observed in the ALTITUDE trial of RGX-314. Globally, DR is the leading cause of blindness in working-age adults, and these patients are in need of new treatment options. I look forward to the further investigation of RGX-314 as a potentially compelling treatment option for patients with DR.”