Predictive Role of Gene Polymorphisms Affecting Thrombin-Generation Pathway in Variable Efficacy of Photodynamic Therapy for Neovascular Age-Related Macular Degeneration

Abstract

Age-related macular degeneration (AMD) represents the leading cause of central blindness in developed countries. The majority of severe vision loss occurs in the neovascular form of AMD, generally characterized by the presence of choroidal neovascularization (CNV) beneath the fovea. Photodynamic therapy with verteporfin (PDT-V) and drugs acting against vascular endothelial growth factor are the most commonly employed treatments for AMD-related subfoveal CNV. The combined use of both these strategies is the most promising therapeutic approach towards this harmful disease. The therapeutic action of PDT-V depends to a photochemical perturbation of thrombo-coagulative processes within CNV. Predictive correlations between peculiar coagulation-balance gene polymorphisms and different levels of post-PDT-V benefit have been recently documented in Caucasian patients with neovascular AMD. Particularly, heterozygous A-allele carriers of factor V Leiden 1691 or prothrombin 20210 gene are characterized by a greater possibility to exhibit clinical benefit after PDT-V. Both mutations induce thrombophilia increasing the thrombin generation in plasma and, thus, they can consistently intensify the photothrombotic phase of the therapeutic CNV occlusion. In prospect, considering the different individual susceptibility to PDT-V, a preoperative assessment of the genotypic thrombophilic background could optimize the eligibility criteria of this intriguing treatment. This review summarizes some of the recent published patents on treatment of neovascular AMD, with a particular attention to PDT-V application in combined therapeutic modalities.