Macugen® was approved on December 12, 2004, for the treatment of neovascular (wet) ARMD. This novel treatment involves injection of an “aptamer” directly into the eye every 6 weeks. Results are comparable to Ocular Photodynamic Therapy with Visudyne®.

The excitement of Macugen®’s approval is not its clinical efficacy, but rather the vilification of a new approach to treat degenerative neovascular disease. This is the first human disease treated with an aptamer. An aptamer is an oligonucleotide (DNA or RNA), which binds proteins (e.g. VEGF) and neutralizes its ability to bind to cellular receptors. In this way, the pathway that leads to neovascular disease is chemically derailed. It is important to note that the results of the two modalities are comparable to each other. It may be that certain patients respond better to one treatment over the other.

The mainstay of treatment for wet ARMD has been OPDT (Ocular Photodynamic Therapy). Macugen® therapy will be clinically available in the next two weeks. We are all eager to see how Macugen® can alter our present regimen of treatments for ARMD.

Macugen® will probably not supplant PDT as the preferred treatment. Although outcomes are somewhat similar numerically, it is not clear if the patient profiles are necessarily comparable. Despite the initial excitement, there are a few concerns with intraocular delivery of Macugen®. The potential for the development of endophthalmitis (infection inside the eye) is most concerning. Initial reports sited rates as high as 2% although recent analysis has decreased this rate to just over 1%. The risk of endophthalmitis for intravitreal Kenalog injection (similar type of injection) is about 0.1%.

As there is no one refractive vision correction technique for every patient, different treatments for ARMD will find their niche, too. Macugen®, PDT and Kenalog will probably be used individually or together for the treatment of ARMD. It is too early to truly assess the safety profile for Macugen® and will take at least a year or two of widespread clinical use to determine the actual rate of infection with Macugen®. Visual results with Macugen® may not be any better than PDT. Macugen® has to be safe and more effective than PDT for retinal specialists to endorse its use.

Written by Randall V. Wong, M.D., Retinal-Specialist/Ophthalmologist, Fairfax, Virginia.

Randall V. Wong, M.D.

Source: TotalRetina.com

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