Epiretinal brachytherapy system, bevacizumab combo promising for age-related macular degeneration

April 15, 2008

A feasibility study of a novel beta radiation epiretinal brachytherapy system for age-related macular degeneration produced favorable 1-year results. The radiation was administered in combination with bevacizumab in two study arms. Patients had a mean improvement in visual acuity of 13.1 lines.

Key Points

New Orleans-Results were favorable in a 1-year feasibility study of a novel beta radiation epiretinal brachytherapy system (Epi-Rad 90, NeoVista Inc.) used in combination with intravitreal bevacizumab (Avastin, Genentech) to treat patients with age-related macular degeneration (AMD). Nearly half of the patients gained 3 lines of visual acuity (VA), and adverse events related to the procedure were minimal, said Jeffrey S. Heier, MD.

He reported results of a study of the ophthalmic system, an intraocular device that delivers and directs radiation to the choroidal vascular bed of the retina, here at the American Academy of Ophthalmology annual meeting. Local delivery of radiation permits selective treatment of the lesion while minimizing neurosensory degeneration due to secondary radiation, said Dr. Heier, a vitreoretinal specialist in private practice at Ophthalmic Consultants of Boston.

Radiation previously has been evaluated as a therapeutic option for AMD with varying degrees of success, he said. "Ionizing radiation is strongly anti-angiogenic, anti-inflammatory, and anti-fibrotic, all important characteristics for the treatment of macular degeneration. In addition, synergism with radiation and other pharmacotherapeutic approaches has been demonstrated, such as that seen with bevacizumab and radiation for colon cancer."

"This enables you to deliver a large dose of radiation with less damage to the surrounding or contiguous tissues," Dr. Heier said. "Also, 24 Gy can be delivered with an exposure of 3 to 5 minutes."

The procedure is performed on an outpatient basis with the patient under local anesthesia. Following a core vitrectomy, controlled focal radiation is delivered to a target area approximately 5.5 mm in diameter. There is minimal radiation exposure to the surgeon, staff, or patient, Dr. Heier said, adding that the effective dose to the entire body is comparable to 15 minutes of sun exposure.

The trial of selective epiretinal brachytherapy with bevacizumab for the treatment of choroidal neovascularization (CNV) was conducted at two centers in Brazil and one in Mexico. Eligibility requirements were active, subfoveal CNV secondary to AMD in the study eye, no history of previous treatment, VA of 20/40 to 20/320, and lesion size ≤12 Macular Photocoagulation Study disc areas. The trial enrolled 34 patients, 22 female and 12 male; the mean age at entry into the study was 72 years.

Occult lesions were the most common, found in 17 (50%) of study eyes, followed by predominantly classic lesions in 10 eyes (29%) and minimally classic lesions in seven eyes (21%).

Patients were randomly assigned to one of two groups. One group received a 1.25-mg bevacizumab injection 10 days prior to strontium treatment and another injection 1 month following treatment. Patients in the second group received the bevacizumab injection at the same time as the strontium treatment as well as 1 month after. From that time on, patients were followed monthly; additional bevacizumab injections could be given as needed at the discretion of the investigator, based on evidence of lesion activity.

1-year data

Dr. Heier presented 1-year data for 27 of the 34 patients in the ongoing study. One of the significant findings was that only five patients (of 27 for whom the 12-month timepoint had been reached) had received additional bevacizumab injections. Four subjects received one additional injection, and one patient received two additional injections.

"This means that 85% of the patients received no additional therapy after the delivery of radiation and the two [bevacizumab] injections," Dr. Heier said.

VA results were similar in the two patient groups. At 12 months, the mean change in VA was 13.1 ETDRS letters (n = 27). A rapid increase in vision was seen in the first 3 months and maintained over time, with a slight decline from the peak level.