San Diego, CA—Results from a pair of phase 3 clinical trials show that injection of an antivascular endothelial growth factor antibody fragment significantly and rapidly improves vision in patients with diabetes and macular degeneration. The improvements are sustained to 2 years, said David S. Boyer, MD, an ophthalmologist at Retina-Vitreous Associates, Beverly Hills, CA, during his presentation at the 2011 Scientific Sessions of the American Diabetes Association.
“The vision improvement occurred as soon as week 1, seemed to go up in both groups after 6 or 7 months—6 or 7 injections—and then stabilized over the entire 24-month period,” Dr Boyer said.
Diabetic retinopathy is the most common microvascular complication of diabetes, and increases with the duration of diabetes. About 10% of patients with diabetes develop diabetic macular edema. Swelling in the central retina accounts for most vision loss in diabetic retinopathy. Unfortunately, 93% of patients with diabetic retinopathy and 63% with vision-threatening diabetic retinopathy are unaware that they have any diabetic retinopathy, he said.
Laser photocoagulation has been the standard treatment for diabetic macular edema since 1985, but although stabilization in vision occurs after laser treatment, improvement in vision is uncommon, he said.
In 2 double-masked, phase 3 trials, the researchers studied the anti-VEGF antibody fragment ranibizumab in 366 patients with loss of vision (best-corrected visual acuity 20/40 to 20/320 on a Snellen chart) and diabetic macular edema on retinal imaging. The mean duration of diabetes in the randomized groups was 14.5 to 16.6 years. About 70% of patients had received some form of previous therapy, mostly laser photocoagulation. They were randomized to receive monthly ranibizumab (0.5 mg or 0.3 mg) or sham intraocular injections. Patients were eligible for rescue macular laser treatment starting at month 3: 72% of sham patients and 33% of ranibizumab recipients received laser rescue treatment.
The primary outcome—the proportion of patients gaining ≥15 standardized eye chart letters (≥3 lines) in best-corrected visual acuity at month 24—was 18.1% in the sham group, 44.8% in the ranibizumab 0.3-mg group, and 39.2% in the ranibizumab 0.5-mg group in study 1; and 12.3%, 33.6%, and 45.7%, respectively, in study 2.
The mean change in best visual acuity was +2.6 lines in the sham group, +12.5 lines in the ranibizumab 0.3-mg group, and +11.9 lines in the ranibizumab 0.5-mg group in study 1, and +2.3 lines, +10.9 lines, and +12.0 lines, respectively, in study 2.
From 54% to 62% of ranibizumab recipients achieved a Snellen acuity of 20/40 or better, compared with about one third of those receiving sham injections. An acuity of 20/40 or better is required in some states for driving privileges, he noted. Contrast sensitivity, retinal anatomy, and patient-reported function on the National Eye Institute Visual Function Questionnaire also improved significantly in the ranibizumab groups compared with the control group.
One third of those receiving active therapy had 2 or more steps of improvement on the Retinopathy Severity Scale, compared with 7% of those receiving sham injections.