Why MERLOT
Age-related macular degeneration (AMD) is the most common cause of visual loss in older adults in the developed world. The recently introduced anti-VEGF drugs for the treatment of subfoveal choroidal neovascularisation (CNV) secondary to wet AMD offer a greater than 90% chance that patients can maintain their vision, whereas without treatment vision would tend to decline. The main drawback of anti-VEGF therapy is that it is very expensive, and patients require regular injections into the eye for life, typically eight times in the first year, and approximately six per year thereafter.
A new, alternative treatment has been developed for treating CNV secondary to AMD that combines the well established vitrectomy procedure with the delivery of focal radiation treatment (epimacular brachytherapy*) to reduce or eliminate the new blood vessels that cause wet AMD. Preliminary studies using this device have been promising, with 93% of patients maintaining vision and 37% getting an improvement, similar to anti-VEGF treatment, but without the need for such regular injections into the eye. To date, this device has mainly been offered to patients with newly diagnosed wet AMD, but it is proposed to also offer treatment to patients with established disease, to see if it can reduce or eliminate their need for regular eye injections. Although extremely encouraging, it is not possible to rely fully on the findings in untreated (treatment naive) patients, as prior therapy with ranibizumab doubtlessly modifies the disease process, and those that respond poorly to injections differ from the majority, suggesting differences in the underlying disease process. It is therefore necessary to study the subset of patients who continue to rely heavily on regular injections of anti-VEGF therapy to maintain control of their disease and maintain vision, if valid clinical conclusions are to be reached.
MERLOT is designed to demonstrate efficacy and safety of epimacular brachytherapy for the treatment of patients with subfoveal CNV secondary to wet AMD who have commenced anti-VEGF therapy, and who might benefit from a treatment that has the potential to reduce their reliance on regular intravitreal injections. Previous epimacular brachytherapy studies (NVI-068, NVI-111 and CABERNET) have targeted treatment naïve patients, but MERLOT aims to determine if previously treated patients (the largest group of patients with wet AMD), might also benefit from this device. If outcomes from this study are positive, epimacular brachytherapy may provide an important and viable alternative to on-going anti-VEGF injections in this otherwise resource intensive group of patients.
* Epimacular brachytherapy (VIDION® System) is manufactured by NeoVista Inc. in the US and distributed in the UK by Carleton Ltd