This article is more than 5 years old. Information may no longer be current.
Pilot study on external source radiation offers new AMD treatment option
Larger clinical trials are still needed to validate efficacy and evaluate safety of the device.
Click Here to Manage Email Alerts
An external beam source radiation platform proved safe in a pilot study and also showed potential to reduce the monthly dosing burden of anti-VEGF therapy.
Distinct from previous external source radiation platforms, the IRay (Oraya Therapeutics) delivers a controlled burst of radiation to a predestined target on the macula through three sequential beams delivered through the pars plana. The device also employs a suction contact lens placed on the cornea to hold the eye in place during the procedure and computerized eye tracking that shuts down the treatment if significant eye movement is detected.
The engineering design provides a highly targeted, low-energy radiation burst to a target lesion with little impact on adjacent retinal tissue, Andrew A. Moshfeghi, MD, MBA, said in a presentation at Retina 2010. If later studies can prove the device to be safe and effective, radiation therapy in conjunction with anti-VEGF therapy may become a useful option for treating patients with proliferative angiogenesis, such as age-related macular degeneration.
According to Dr. Moshfeghi, laboratory and animal studies have shown that radiation halts dividing cells. While anti-VEGF therapy is currently the gold standard therapy for neovascularization, the monthly dosing requirement is burdensome. Researchers have been exploring adjunctive therapies that can enhance the activity of anti-VEGF therapy in hopes of reducing the number of required doses.
“Anything that can be done in terms of synergy to reduce the frequency of those injections, like application of radiation to the macula, could potentially be very helpful,” Dr. Moshfeghi said.
Pilot study results
In an initial analysis of 28 patients 12 months after the radiation treatment, patients required a mean 0.9 additional injections of Lucentis (ranibizumab, Genentech) after a baseline injection followed by a protocol-mandated follow-up injection at 1 month. In addition, 52% of patients required no additional ranibizumab injections in the 12 months of follow-up.
In the study, patients received radiation therapy from the IRay device in an office-based procedure in one of two dosing strengths, 16 Gy or 24 Gy. However, only data from the 16-Gy group were available at the time of the analysis, Dr. Moshfeghi said.
At 6 months, 96% of patients had lost fewer than 15 letters of vision, 81% gained at least one letter and 50% gained more than 15 letters of vision.
“Granted, it’s an open-label study with small numbers of patients, but nevertheless, there was an effect seen,” Dr. Moshfeghi said.
In subanalysis of treatment-naive vs. non-treatment-naive patients, effectiveness results were similar. At 6 months, there was a mean 9.7-letter gain among patients in the treatment-naive group and a mean 9.3-letter gain among patients in the non-treatment-naive group.
Significantly, Dr. Moshfeghi said, there were no device-related serious adverse events reported in the study; however, the study was too short to adequately assess the risk of radiation retinopathy. The most common mild adverse event reported in the study was asymptomatic, self-limited superficial keratopathy following application of the contact lens. In addition, one patient reported a mild, short-lasting headache after application of the lens.
A larger efficacy trial has already started enrolling patients in Europe, and there are plans to launch a pivotal trial this summer, Dr. Moshfeghi said. – by Bryan Bechtel
- Andrew A. Moshfeghi, MD, MBA, medical director at Bascom Palmer Eye Institute, can be reached at University of Miami Miller School of Medicine, 7101 Fairway Drive, Palm Beach Gardens, FL 33418, U.S.A.; +1-561-355-8608; fax: +1-561-355-8601; e-mail: amoshfeghi@med.miami.edu. Dr. Moshfeghi is a consultant and speaker for Genentech.