A randomised, double-masked phase III/IV study of the efficacy and safety of Avastin？ (Bevacizumab) intravitreal injections compared to standard therapy in subjects with choroidal neovascularisation secondary to age-related macular degeneration: clinical trial design

The Avastin？ (bevacizumab) for choroidal neovascularisation (ABC) trial is a double-masked randomised controlled trial comparing intravitreal bevacizumab injections to standard therapy in the treatment of nAMD. Patients are randomised to intravitreal bevacizumab or standard therapy available at the time of trial initiation (verteporfin photodynamic therapy, intravitreal pegaptanib or sham treatment). Ranibizumab treatment was not included in the control arm as it had not been licensed for use at the start of recruitment for this trial. The primary outcome is the proportion of patients gaining ≥ 15 letters of visual acuity at 1 year and secondary outcomes include the proportion of patients with stable vision and mean visual acuity change.The ABC Trial is the first double-masked randomised control trial to investigate the efficacy and safety of intravitreal bevacizumab in the treatment of nAMD. This trial fully recruited in November 2007 and results should be available in early 2009. Important design issues for this clinical trial include (a) defining the control group (b) use of gain in vision as primary efficacy end-point and (c) use of pro re nata treatment using intravitreal bevacizumab rather than continuous therapy.Current controlled trials ISRCTN83325075Age-related macular degeneration (AMD) is the leading cause of visual loss in patients over the age of 50 years in Europe and North America [1]. There are 2 forms of the disease with dry AMD and wet AMD (neovascular or exudative AMD). Neovascular age-related macular degeneration (nAMD) is characterised by choroidal neovascularisation (CNV) and is responsible for 75% of visual loss due to AMD despite only accounting for 25% of all cases [2].Historically the prognosis for patients with subfoveal nAMD has been poor with the established treatment of verteporfin photodynamic therapy (PDT) only showing modest efficacy in reducing visual loss in patients with well-defined (predominantly classic or classic no occult) su