An Open Label-study to Compare the Efficacy of Aflibercept Monotherapy for Polypoidal Choroidal Vasculopathy

Overview

Polypoidal choroidal neovasculopathy (PCV) is a subtype of wet age related macula degeneration (AMD) occuring more commonly in the Asian population. Besides the phenotypic differences, PCV is thought to have a lesser response to anti VEGF therapy which is the mainstay of treatment for other typical wet AMD. Recent trial data suggest that a combination with photodynamic therapy may help in the visual and anatomical outcome of PCV, and emerging evidence shows favourable outcomes the newer anti VEGF agent, aflibercept 2mg monotherapy. These trials however, have assessed aflibercept in a strict 2mg every 8 weekly regime. In the clinical setting, a significant an unmet need in the management of PCV is a tailored treatment regime. Here we propose a treatment regimen based on disease activity for PCV with aflibercept mono therapy. A limitation of the 2q8 regime is that it is fixed and does not vary regardless of polyp closure or anatomical outcome at the first time point of assessment (month 3). We hypothesize that after the initial 3 monthly injections of aflibercept, about 50% of PCV will close and become quiescent, and in the remaining 50%, a further 3 monthly injections will increase overall polyp closure rate. After a loadings phase of either 3 or 6 months, all eyes will start on a treat and extend regime (T\&E), with a minimum period of 8 weeks and a maximum of 12 weeks between treatments with 2 week increments if PCV remains quiescent. The proposed study aims to evaluate the efficacy of a modified treat and extend regime based on disease activity with aflibercept monotherapy for PCV.

Age related macular degeneration (AMD) is one of the leading causes of blindness worldwide. In its exudative or wet form, choroidal neovascularization (CNV) causes an exudative maculopathy resulting in sudden loss of vision with severe effects on patients' quality of life.1,2 Intra vitreal injections of anti-vascular endothelial growth factor agents (anti-VEGF) agents have become the mainstay of treatment for AMD CNV and have been shown to have favorable outcomes in most AMD CNV subtypes.3,4 In the Asian population however, a particular subtype called polypoidal choroidal vasculopathy (PCV), which affects about 50% of exudative maculopathy, has been shown to have less favorable response to anti-VEGF therapy.5,6 The EVEREST trial, a randomized controlled trial which compares the efficacy of photodynamic therapy (PDT) with or without ranibizumab for treatment of PCV showed that PDT with or without anti VEGF improved polyp closure rate on angiographic assessment but this trial did not take into account vision as a primary end point.7 PDT appears work through its effects on choroidal vasculature, hence making it relevant to PCV which is increasingly thought to be a condition on the pachychoroid spectrum.8 PDT however, as a treatment modality presents several disadvantages. Firstly, PCV often presents as a widely distributed lesion, making it difficult to treat, with a single beam of PDT. Secondly, PDT is limited in its ability to treat lesions in the peripapillary area as there is risk of damage to the optic nerve. Thirdly, features commonly associated with PCV such as a large pigment epithelial detachment (PED) or extensive submacular hemorrhages are not usually suitable for PDT. Fourthly, there is a risk of long-term choroidal atrophy especially if repeated treatments are administered.8,9 There is emerging evidence for the use of aflibercept monotherapy in PCV. Reports range from small case series and retrospective studies to larger prospective studies. Recent data from the PLANET study showed that monotherapy of aflibercept resulted in similar letter gains in visual acuity as compared to combination treatment with PDT at 1 year. Polyp closure rate was also similar between the two groups at 38.9% with monotherapy and 44.8% with combination therapy. The VAULT and APOLLO studies suggest vision and anatomical improvements with 66-72% polyp closure in 1 year.10 These trials however, use a fixed dosing regimen (3 monthly loading doses of 2mg aflibercept followed by fixed dosing every 8 weeks (2q8) totaling 7 injections in 1 year). In addition to resolution of subretinal fluid, recent studies using the novel OCT-angiography (OCT-A) to evaluate choroidal vasculature suggests re-modelling of choroidal vasculature may also be an important therapeutic effect. We reported more prominent reduction in choroidal vessel calibre after combination treatment with PDT and bevacizumab compared to bevacizumab monotherapy. The effect of Aflibercept on choroidal vasculature has been less well studied. Some evidence however, suggested aflibercept may have more profound effect on choroidal vasculature with the reducing choroidal thickness than ranibizumab or bevacizumab. A significant unmet need in the management of PCV with anti VEGF monotherapy is a practical way of treating patients in the real world setting that maximizes efficacy with minimal number of visits and injections. Clinical trial regimes follow a rigid treatment algorithm that aim to maximize response. In the clinical setting, these regimes are impractical in "real world" patients. Regular intensive course of treatment involves lengthy visits which include consultation time, clinical examination, retinal imaging, and often an intra vitreal injection. In clinical practice this often result in treatment fatigue and in a co-payment healthcare environment in Singapore, may also result in significant financial burden to the patient and society. While aflibercept affords an 8 weekly treatment regime which is better than other monthly anti VEGF therapy regimes, trial regimes still do not take into account individual patients' disease patterns. This study aims to take disease activity into account to tailor treatment regimes specific for patients. In addition, it aims to provide insight into the outcomes of patients on a more clinically relevant treat and extend (T\&E) regime which changes the treatment tempo in relation to disease activity.