Development and Implementation of an ELISA to Detect “Anti- Ranibizumab” Immunity in Age-Related Macular Degeneration Patients

Abstract

Purpose: To determine if there is a correlation between the non-responsiveness of patients to ranibizumab and the presence of anti-ranibizumab antibodies in patients with exudative age-related macular degeneration (AMD). In order to achieve this we have developed an enzyme-linked immunosorbent assay (ELISA) to detect anti-ranibizumab antibodies in serum of patients who are responders and non-responders to ranibizumab.

Methods: The assay we developed uses a homogeneous biotin-dioxigenin based bridging ELISA format. Briefly, patient serum was simultaneously incubated with both a ranibizumab-biotin conjugate and a ranibizumab-dioxigenin conjugate. Following incubation this mixture was loaded into a streptavidin coated well and complexes of anti-ranibizumab antibodies with the biotin-dioxigenin conjugates was detected using a horseradish peroxidase-conjugated anti-dioxigenin antibody. Mice were immunised with ranibizumab to generate a positive control for this assay. A cohort of 48 AMD patients was recruited from the clinic at the Lions Eye Institute, Western Australia. The cohort included 8 patients participating in an anti-VEGF gene therapy study currently being conducted by our group. All patients had received multiple injections of ranibizumab prior to sampling of their serum.

Results: Mouse serum containing anti-ranibizumab antibodies was used to successfully validate this assay. While the mouse serum generated a robust response no anti-ranibizumab antibodies were detected in the 48 patient serum samples screened.

Conclusions: In this initial limited study we have found no correlation between patient responsiveness to ranibizumab and anti-ranibizumab antibodies. However, having successfully generated a robust assay capable of detecting anti-ranibizumab antibodies within sera this study will be expanded to 300 patients and will continue to include further patients from our anti-VEGF gene therapy study. A greater understanding of anti-ranibizumab antibodies will assist in the development of guidelines to match the treatment strategies to the responsiveness of patients.

Keywords: 412 age-related macular degeneration • 748 vascular endothelial growth factor