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Angiogenesis, Exudation and Degeneration Meeting
February 14, 2013
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Durability of anti-VEGF regimen may increase with low-voltage X-ray irradiation

MIAMI — In previously treated wet age-related macular degeneration, low-voltage X-ray irradiation may increase the durability of a ranibizumab treatment regimen, a speaker said here.

Perspective from Elias Reichel, MD

In a study led by Darius M. Moshfeghi, MD, 19 patients were given a single treatment of noninvasive, externally delivered low-voltage X-ray irradiation. The 24-Gy dose was administered to patients with neovascular AMD who had been previously treated with intravitreal Lucentis (ranibizumab, Genentech).

Single-dose X-ray irradiation paired with intravitreal ranibizumab works especially well for patients who have fluid at baseline, have a greatest linear dimension of less than 4 mm, and who have minimal fibrosis, Moshfeghi said at Angiogenesis, Exudation, and Degeneration 2013.

The two modern radiation therapies are stereotactic X-ray irradiation and epimacular brachytherapy. According to Moshfeghi, stereotactic uses a robotic control system vs. a manual control, uses ocular tracking, is noninvasive vs. surgical, has a greater horizontal dose control, and has less vertical dosing stability.

Radiation therapy coupled with intravitreal ranibizumab also maintains visual acuity and decreases the amount of fluid seen on optical coherence tomography, Moshfeghi said.

Disclosure: Moshfeghi is a consultant for Oraya Therapeutics, Synergetics, Krypton Vision and Visunex Medical Systems, is on the advisory board for Genentech and Regeneron, and is part equity owner of Oraya Therapeutics, InSitu Therapeutics, Krypton Vision, Visunex Medical Systems, Convene LLC and Versavision LLC.

Perspective

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Elias Reichel, MD
Elias Reichel, MD

It appears that radiation delivered either by stereotactic x-ray (a noninvasive office procedure) or by epimacular brachytherapy (a surgical procedure) can reduce the frequency of anti-VEGF intravitreal injections for the treatment of choroidal neovascularization caused by AMD. Moshfeghi’s presentation showed that patients who were treated with stereotactic x-ray irradiation in conjunction with anti-VEGF injections maintained visual acuity that was associated with a reduction in fluid seen on OCT. We are learning that pericytes are critical in the process of developing neovascularization and can cause resistance to anti-VEGF drugs. Radiation is one way of reducing or eliminating pericytes, so there likely is a synergy in treating with radiation as an anti-pericyte modality in conjunction with anti-VEGFs that act to reduce neovascular permeability.

An alternative way of inhibiting pericyte development is with anti-platelet-derived growth factor drugs. We are going to be hearing a lot more about altering the pathobiology of pericytes as it relates to choroidal neovascularization — there is no doubt that treatments that stop these cells from growing will be critical to our success in treating choroidal neovascularization. Stereotactic X-ray irradiation is just one way of doing that.

Elias Reichel, MD
New England Eye Center, Tufts Medical Center
Vice Chair, Research and Education in Department of Ophthalmology; Director, Vitreoretinal Diseases and Surgery Service
Disclosures: Reichel is a consultant for Neovista and Ophthotech.