Novel Minimally-Invasive Episcleral Brachytherapy for the Treatment of Neovascular Age-Related Macular Degeneration (nAMD): Results of a Twelve Month Prospective Phase I Safety and Tolerability Evaluation

Abstract

 

Purpose

 

To evaluate the safety and feasibility of a novel episcleral brachytherapy device (SMD-1) for nAMD. Although anti-VEGF treatments have revolutionised the management of nAMD, they fail to significantly improve vision in the majority of patients, with some patients demonstrating no response to treatment. As neovascular regression is not achieved, many patients will likely require lifelong and often frequent invasive intravitreal injections. Radiation has multiple angiostatic properties which could address these issues, and has recently been evaluated using both vitrectomy and stereotactic external beam delivery methods. These approaches, however, are either invasive with predictable adverse effects or necessitate large complex expensive devices. A locally-delivered non-penetrating brachytherapy approach could overcome these limitations

 

Methods

 

6 patients received 24Gy radiation over 5.5 minutes directly to the macular CNV by positioning the SMD-1 brachytherapy probe adjacent to the macular sclera via a subtenon retrobulbar approach. The probe was then removed. Patients also received concomitant anti-VEGF injections with further readministration as-needed. Adverse effects and changes in BCVA and macular thickness were evaluated monthly

 

Results

 

The procedure was readily performed and was well tolerated with no serious adverse effects. At 3 months, all patients experienced increases in BCVA (mean +19 ETDRS letters). By 12 months, 3 patients continued to demonstrate improved or stabilised BCVA (mean +7 letters), 2 of whom required no further anti-VEGF injections during follow-up. All patients demonstrated reduced macular thickness compared with baseline. Three patients demonstrated reductions in BCVA

 

Conclusions

 

This prospective study supports the safety and tolerability of this novel device, and its further evaluation in planned larger phase I/II trials

 

 

The SMD-1 Episcleral Brachytherapy for nAMD Device

 

Keywords: 412 age-related macular degeneration • 671 radiation therapy • 466 clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials