Biosimilars in diabetic macular edema: Promise, progress, and pitfalls

Diabetic macular edema (DME) is a common microvascular complication of diabetes and a major cause of vision impairment. Intravitreal vascular endothelial growth factor (VEGF) inhibitors remain the gold standard for its management. However, the high cost and limited accessibility of reference anti-VEGF agents have driven growing interest in biosimilars-biologic therapies designed to match the efficacy, safety, and immunogenicity of their reference products. Following the expiration of patents for agents such as aflibercept and ranibizumab, several biosimilars have been developed, approved, and introduced into clinical practice. Evidence from real-world studies-including RE-ENACT2 (REal-life assessmENt of safety And effeCTiveness of Razumab) and REAR-RD2 (REal-world observational study to evaluate the risk factors in the management of REtinal Diseases-2)-as well as randomized clinical trials such as INSIGHT and CT-P42 has demonstrated clinical equivalence between these biosimilars and their reference anti-VEGF counterparts in the treatment of DME. This article provides an updated overview of the current evidence base, recent advances in regulatory pathways, and ongoing challenges in integrating biosimilars into routine DME management.