AMD drugs continue to redefine treatment strategies

In addition to the marked advances in treatments for age-related macular degeneration (AMD) seen with bevacizumab (Avastin, Genentech) and ranibizumab (Lucentis, Genentech), studies are ongoing that will hone physician skills in dealing with the disease, said Ron Adelman, MD, MPH, Department of Ophthalmology and Visual Science, Yale University School of Medicine, New Haven, CT, United States.

Dr. Adelman provided physicians with an overview of the newest AMD drugs.

The Complications of AMD Treatment Trials (CATT), which just began, will compare the benefits of bevacizumab with those of ranibizumab head to head.

The Vascular Endothelial Growth Factor (VEGF)-Trap-Eye Study conducted in animals showed that one injection of VEGF Trap (Regeneron Pharmaceuticals) resulted in rapid reversal of leaking. The phase II study in which wet AMD was treated indicated that an intravitreal injection of 2 mg every 4 weeks resulted in an average gain of more than 10 letters after 12 weeks of treatment.

The CLEAR-IT 2 interim results showed that repeated intravitreal VEGF-Trap is safe in 78 patients who completed 12 weeks of follow-up. The results showed significant decreases in retinal thickness and significant improvements in visual acuity. The phase III study will begin later in 2007.

Anecortave acetate (Retaane, Alcon Laboratories) administered as a posterior juxtascleral injection works on endothelial cell activation and stops angiogenesis. A comparison of anecortave acetate with photodynamic therapy (Visudyne, Novartis) showed that the two drugs are similar in efficacy but anecortave acetate did not pass the test of non-inferiority to PDT. Another study is ongoing to determine if anecortave acetate may be helpful in preventing dry AMD from becoming wet AMD; results are not yet available.

Interferon RNA (Sirna) also has potential in treating AMD. Following injection, the RNA enters the cells, and affects the production of proteins in the eye. The results of phase 1 testing are similar to results with ranibizumab, according to Dr. Adelman.

A new technology, i.e., intravitreal Icon targeted PDT, targets abnormal blood vessels and preserves normal blood vessels. The technology selectively targeted abnormal blood vessels and resulted in regression of the treated vessels in rats.

"This technology should improve the efficacy of other medications by selective targeting," Dr. Adelman stated.