Regenxbio Presents Positive Interim Data From Phase 2 ALTITUDE Trial of RGX-314 for Treatment of Diabetic Retinopathy Using Suprachoroidal Delivery

Regenxbio announced additional positive interim data from the ongoing phase 2 ALTITUDE trial of RGX-314 for the treatment of diabetic retinopathy (DR) without center-involved diabetic macular edema (CI-DME) using in-office suprachoroidal delivery. The data is being presented at the Angiogenesis, Exudation, and Degeneration 2022 conference by Michael A. Klufas, MD, Retina Service, Wills Eye Hospital, Assistant Professor of Ophthalmology, Thomas Jefferson University. RGX-314 is being investigated as a potential one-time gene therapy for the treatment of wet age-related macular degeneration (AMD) and DR.

We are pleased to see that RGX-314 continues to be well tolerated at 6 months following a one-time, in-office injection, with nearly 50 percent of patients dosed with RGX-314 in Cohort 1 demonstrating a clinically meaningful improvement from baseline," said Steve Pakola, MD, Chief Medical Officer of Regenxbio. "We are continuing to enroll patients in Cohorts 2 and 3 and look forward to sharing additional updates from this trial"

"I am encouraged by the clinical improvement of disease severity observed in the ALTITUDE trial of RGX-314," said Dr. Klufas. "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."  

Study Design and Safety Update from Phase II ALTITUDE Trial of RGX-314 for the Treatment of DR Using Suprachoroidal Delivery

ALTITUDE is a multicenter, open-label, randomized, controlled dose-escalation trial evaluating the efficacy, safety and tolerability of suprachoroidal delivery of RGX-314 using the SCS Microinjector in patients with a DR diagnosis of moderately severe or severe nonproliferative 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 2.5x10¹¹ 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 5x10¹¹ GC/eye versus observational control at a 3:1 ratio. 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. Patients in this trial do not receive prophylactic immune suppressive corticosteroid therapy before or after administration of RGX-314.

As of January 18, 2022, RGX-314 was reported to be well tolerated in Cohort 1. Two serious adverse events were reported in two patients, both of which were not considered drug-related. Among patients in Cohort 1 dosed with RGX-314, no intraocular inflammation was observed. As previously reported, one patient experienced a mild case of episcleritis that resolved with topical corticosteroids. Common ocular treatment emergent adverse events in the study eye through 6 months were not considered drug-related and were predominantly mild. These included conjunctival hemorrhage and conjunctival hyperemia. 

Summary of Data for Cohort 1 at Six Months

At 6 months, of the 15 patients dosed with RGX-314 in Cohort 1, seven patients (47%) demonstrated a two-step or greater improvement from baseline on the Early Treatment Diabetic Retinopathy Study-Diabetic Retinopathy Severity Scale (DRSS), the study's primary endpoint, compared to zero of the five patients (0%) in the observational control group. One patient (7%) dosed with RGX-314 continues to demonstrate a four-step improvement. The percentage of Cohort 1 patients dosed with RGX-314 achieving at least two-step improvement at six months in RGX-314 treated eyes (47%) increased from the previously reported 3-month results (33%). A 2-step improvement in DRSS has been accepted as a pivotal endpoint by the FDA for DR clinical trials.

In the 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 of RGX-314. 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. 

At 6 months after administration of RGX-314, Cohort 1 patients demonstrated stable mean change in BCVA of +0.3 letters compared to baseline, while five patients in the observational control arm demonstrated stable mean change in BCVA of -2.0 letters compared to baseline.

Data presented today is available on the "Presentations and Publications" section of the Regenxbio website at www.regenxbio.com.

About RGX-314

Regenxbio is investigating RGX-314 in collaboration with AbbVie as a potential one-time treatment for wet AMD, diabetic retinopathy, and other chronic retinal conditions. RGX-314 includes the NAV AAV8 vector containing a gene encoding for a monoclonal antibody fragment designed to inhibit vascular endothelial growth factor (VEGF). RGX-314 is believed to inhibit the VEGF pathway by which new, leaky blood vessels grow and contribute to the accumulation of fluid in the retina.

Two separate routes of administration of RGX-314 to the eye are being evaluated, including a standardized subretinal delivery procedure as well as delivery to the suprachoroidal space. REGENXBIO has licensed certain exclusive rights to the SCS Microinjector from Clearside Biomedical, Inc. to deliver gene therapy treatments to the suprachoroidal space of the eye.