Bevacizumab therapy normalizes the pathological intraocular environment beyond neutralizing VEGF

PURPOSE Vascular endothelial growth factor (VEGF) plays a key role in neovascularization by stimulating the proliferation and migration of vascular endothelial cells. The anti-VEGF therapy bevacizumab acts by binding to VEGF and preventing its effects. However, this linear interaction represents only a partial view of the pathobiology of neovascular diseases and the anti-VEGF treatment. To obtain an integrated view of the processes involved in VEGF-related ocular pathologies, we applied a systems approach and investigated whether intravitreal bevacizumab injections have a global effect in normalizing the ocular physiology perturbed by the disease. METHODS We analyzed 90 analytes representing various pathophysiological processes in aqueous humor. The samples were obtained from eight patients receiving intravitreal bevacizumab injections for various ocular VEGF-related conditions. The samples were obtained before and after the injection and were analyzed using microbead technology developed by Luminex xMAP. RESULTS Forty-three analytes were detected above the sensitivity of the assay both in pre- and post-injection samples. Of these, normal values of 41 analytes were known and these analytes were further analyzed. The detected analytes included relevant markers such as VEGF, C reactive protein, glutathione, and cytokines. We identified 24 markers that were perturbed more than 1.5 fold in diseased samples (pre-injection) compared to normal levels. The levels of perturbed analytes were compared in post-treatment samples. The results demonstrated an unequivocal trend toward normalization in post-treatment samples. CONCLUSIONS Our results show intraocular bevacizumab injections change the perturbed physiologic environment of the eye toward normalization. Its effects reached beyond neutralizing VEGF. The results also demonstrate that large-scale analysis of the aqueous, using a systems approach, could provide useful insight regarding ocular diseases, their pathophysiologies, and treatment responses.