Strategy for PDR

Protocol S demonstrates efficacy, but more information needed

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The Diabetic Retinopathy Clinical Research Network, Protocol S established intravitreal injection with ranibizumab 0.5mg (Lucentis, Novartis) as a new strategy for the management of proliferative diabetic retinopathy (PDR). However, application of the study results to clinical practice is challenging because there are many questions about pharmacotherapy for panretinal photocoagulation (PRP) that need to be answered, said Francisco J Rodriguez MD at WOC 2016 in Guadalajara, Mexico. “Ranibizumab will allow us to avoid complications of PRP, which include peripheral visual field loss, decreased visual acuity (VA), the development or worsening of diabetic macular oedema (DME), and severe visual loss in up to 10 per cent of patients. However, treatment selection for individual patients is influenced by a number of parameters, including long-term efficacy, predictors of response, potential side effects, convenience for the patient, the family and the physician, and most importantly cost, which introduces the payer as another player,” noted Dr Rodriguez, Scientific Director, Fundación Oftalmológica Nacional, and Chairman of the Department of Ophthalmology, Escuela de Medicina y Ciencias de la Salud, Universidad del Rosario, in Bogota, Colombia. “More time is needed to answer questions about the chronic use of anti-vascular endothelial growth factor (anti-VEGF) therapy for PDR and to determine what is the best long-term strategy. Perhaps it will be a combination of laser and pharmacotherapy,” he added. EMERGING DATA Protocol S was undertaken as emerging data from DME clinical trials showed that anti-VEGF treatment modulated the progression of DR. The study randomised 305 patients to prompt PRP completed at one to three sittings within eight weeks, or ranibizumab 0.5mg with four mandatory injections and continued as frequently as every four weeks. The primary outcome analysis of mean change in VA at two years showed ranibizumab was non-inferior to PRP. However, ranibizumab treatment offered some advantages. Compared with the PRP group, eyes assigned to the anti-VEGF injection group had superior mean VA over two years, better visual fields, decreased chance of vitrectomy, and less frequent development of DME. “We also know PRP has some advantages. Compared with anti-VEGF therapy, it is less expensive and carries no risks of endophthalmitis or systemic VEGF inhibition. Furthermore, the treatment typically is completed in just one or two visits, and it is often long-lasting,” Dr Rodriguez said. Looking ahead, Dr Rodriguez outlined several issues that need to be addressed for better guidance on the use of anti-VEGF therapy for PDR. “We need to know if the same outcomes are achieved when treating PDR with an 0.3mg dose of ranibizumab or other anti-VEGF agents,” he said. Francisco J Rodriguez: fjrodriguez@fon.org.co
Tags: proliferative diabetic retinopathy