Patients headed toward blindness because of diabetic macular edema showed substantial gains in visual acuity after two years of treatment with the angiogenesis inhibitor drug ranibizumab (Lucentis), its manufacturer said….
According to Roche, diabetic macular edema develops in up to 10% of diabetic patients, with about 75,000 new cases occurring annually. Laser surgery is the current standard of care.
In a phase III study called RISE, 45% of patients receiving monthly 0.3-mg intravitreal injections of ranibizumab gained at least 15 letters of best corrected visual acuity on a standard eye chart, compared with 18% of patients given sham injections, according to Roche, which markets ranibizumab and sponsored the trial.
Ranibizumab inhibits vascular endothelial growth factor (VEGF) to restrain the growth of new blood vessels, the root cause of diabetic retinopathy as well as “wet” age-related macular degeneration.
Patients in a third arm of the study, receiving 0.5 mg of ranibizumab monthly, had a response rate of 39%, Roche said. Mean acuity gains in the 377-patient trial were 12.5, 11.9, and 2.6 letters for the 0.3-mg, 0.5-mg, and sham injection groups, respectively.
Roche said improvements in the ranibizumab arms were detectable as soon as a week after the first dose.
Surrogate markers of efficacy were also improved with the drug, according to Roche. Mean decreases in central foveal thickness after two years were about twice as great in the active-treatment arms compared with sham injections.
Macular edema is the clinically relevant consequence of diabetic retinopathy. Abnormalities in the blood vessels serving the retina cause them to leak, which in turn leads to swelling of the retina’s light-sensing macula.
Roche said adverse effects were similar to those seen in previous ranibizumab studies. Those occurring more frequently in the active-treatment groups included conjunctival hemorrhage, eye pain, eye irritation, vitreous floaters, foreign body sensation in the eye, and increased intraocular pressure.
Roche said patients in RISE’s control group were offered treatment with ranibizumab after completing two years in the study. All patients choosing to remain in the study will be dosed monthly and followed for another year, with an open-label extension phase following that.
Not addressed in the study was whether the same acuity improvements are also possible with bevacizumab (Avastin), another VEGF inhibitor often used off-label to treat neovascular diseases in the eye. Bevacizumab is far less expensive than ranibizumab in ocular applications.
At least eight trials comparing the two drugs in wet age-related macular degeneration are currently under way, according to listings on the Clinicaltrials.gov website.
The study was presented at the Macula Society’s annual meeting in Boca Raton, Fla., March 2011