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Avastin
January 2007

Many of the sight-threatening diseases encountered in the field of retina and vitreous are the result of abnormal blood vessel growth within or under the retina. Exudative (wet) macular degeneration, central and branch retinal vein occlusions, proliferative diabetic retinopathy, diabetic macular edema, pathologic myopia, histoplasmosis, and angoid streaks are a few examples. These processes are able to damage the back of the eye by growing new blood vessels where they do not belong. This phenomenon is responsible for the vision loss in these diseases. This blood vessel growth is powered and supported by a naturally occurring protein in the body known as vascular endothelial growth factor (VEGF). An overproduction of VEGF is found in these disease processes.

Recently, ophthalmic research has produced some exciting new medicines that render VEGF ineffective. These medicines act as an antibody to bind the VEGF and prohibit its ability to support new blood vessel growth. Currently, three anti-VEGF medicines are on the market. Macugen was the first product to be approved by the FDA and used in the eye. Macugen was shown to slow down the rate of vision loss in age-related macular degeneration (ARMD), but was not effective in restoring any of the vision that was previously lost. Its limitations are thought to be secondary to its selectivity of the VEGF 165 isoform. That is, it only inhibits part of the VEGF present in the eye. Newer medications, known as Avastin and Lucentis, inhibit all isoforms of VEGF and offer more promising results.

Avastin was not initially developed to treat eye diseases. It was first approved and used for the treatment of colon cancer. Its effectiveness stemmed from the fact that a growing cancer needed to produce VEGF to support its own blood supply. Based on this mechanism of action, ophthalmologists began using Avastin “off-label” to treat ARMD and similar conditions since research indicates that VEGF is one of the causes for the growth of the abnormal vessels that cause these conditions. Since its initial use in the Fall of 2005, retina specialists world-wide have had many great results from the use of Avasin. Avastin is now commonly used to treat exudative ARMD, proliferative diabetic retinopathy, central and branch retinal vein occlusion, diabetic macular edema, and cystoid macular edema secondary to vein occlusions. It has also been shown to assist in clearing vitreous hemorrhages from either diabetic retinopathy or vein occlusions. Numerous clinical trials are currently being undertaken to demonstrate these observed benefits.

Lucentis is a recently FDA approved medication for the treatment of exudative ARMD that is identical in function and similar in design to Avastin. Lucentis was shown in clinical trials to not only slow the decline of vision loss in ARMD, but to also provide up to three lines of improvement in 70% of patients receiving the injections. There is some speculation that once Avastin and Lucentis are compared head-to-head, that Avastin may have a longer lasting effect than Lucentis while maintaing the same effectiveness in terms of visual recovery. Lucentis is labeled by the FDA to be injected every 4 weeks, whereas Avastin may be spread out in 6-8 week intervals.

Avastin is a commonly used drug at Carolina Retina Center, P.A. and your physician may recommend it for your particular retinal condition. The goal of treatment is to prevent further loss of vision or even restore some of the vision previously lost. The mode of administration for Avastin is intravitrealy (that is, injected into the cavity of the eye). The number of injections will vary in every patient and in each disease process based on the individual response. Your physician will discuss all the potential risks and benefits of Avastin injection to allow you to make an informed decision.