Study results demonstrate that low-dose proton beam irradiation may enhance and extend the effects of anti-vascular endothelial growth factor (anti-VEGF) therapy for age-related macular degeneration.
A phase 1 / 2 study presented at the American Society of Retina Specialists (ASRS) Annual Meeting in Vancouver, British Columbia, in July, demonstrated that low-dose proton beam irradiation is not only safe, but it may enhance and extend the effects of anti-vascular endothelial growth factor (anti-VEGF) therapy for age-related macular degeneration.
Anti-VEGF treatment is the standard of care for age-related macular degeneration. Although the treatment is effective, the results tend to be temporary, requiring frequent visits to the doctor for repeat treatments. Arranging reliable transportation for these visits can be an obstacle for the elderly population that tends to suffer from macular degeneration.
“Anti-VEGF therapy is effective in preserving vision, but the therapeutic effect does not last,” author Susanna Park, MD, PhD, professor of ophthalmology at the University of California Davis, shared with MD Magazine®. “This is a problem not only for conducting our study but also for patients receiving anti-VEGF treatment for wet macular degeneration as part of the standard of care. This is why a sustained treatment would be important in this patient population.”
To this end, investigators at the University of California Davis Eye Center sought to determine whether or not adding low-dose proton beam irradiation to the initial treatment might preserve its effects, thus limiting these extra visits.
The team recruited 34 patients, 16 of which were included in the final analysis; some patients dropped out of the study, possibly due to the challenges of arranging repeated visits. The team randomized the participants into 3 groups: 1 group received anti-VEGF therapy and sham radiation, 1 received anti-VEGF therapy with 24GyE radiation, and 1 received anti-VEGF therapy with 16GyE radiation. Investigators followed up with participants for 2 years.
Investigators found that participants who received the 24GyE radiation needed significantly fewer anti-VEGF injections over the 2 years. Furthermore, those who received radiation had no adverse effects, no cases of severe vision loss, no cases of radiation-induced cataract progression, and no visually significant retinal vascular changes.
A trend emerged suggesting that groups that received the radiation also had less intra and sub-retinal fluid, but this finding was not significant.
“Intravitreal anti-VEGF therapy is an effective therapy to control vision loss associated with wet macular degeneration. However, the treatment effect does not last and needs to be repeated frequently in a majority of eyes. By combining the treatment with low-dose proton beam radiation, the therapeutic effects of intravitreal anti-VEGF may be sustained without major safety concerns,” said Park.
The study is awaiting publication, but the poster and summary presented at ASRS can be found on the ASRS website. The team is awaiting funding for a phase 3 trial, to determine if low-dose proton beam irradiation can help sustain the effects of anti-VEGF therapy in a large number of patients with age-related macular degeneration.