Abstract
Purpose: :
Bevacizumab is a human monoclonal IgG1 antibody that blocks the action of vascular endothelial growth factor (VEGF). The off-label use of intravitreal bevacizumab in VEGF-mediated diseases, such as choroidal neovascularization, and proliferative diabetic retinopathy has been reported. The purpose of this study was to determine the level of VEGF and pigment epithelium-derived factor (PEDF), a potent inhibitor of angiogenesis, in the plasma of patients with proliferative diabetic retinopathy (PDR) before and after an intravitreal injection of bevacizumab.
Methods: :
Eleven eyes of 11 patients who received an intravitreal injection of bevacizumab (1.25 mg/0.05 ml) were studied. Patients were included if they had neovascular glaucoma or iris rubeosis with PDR or aggressive PDR. Samples of blood were collected just before the injection, and 1day, 7 days, and 1 month after the injection of bevacizumab. The concentrations of VEGF and PEDF in the plasma were measured by enzyme-linked immunosorbent assay (ELISA).
Results: :
The mean VEGF concentration before the injection was 109.2 ± 20.1 pg/ml (mean ± SEM, n=11). It was significantly reduced after one day to 9.7 ± 3.7 pg/ml, after seven days to 11.7 ± 2.4 pg/ml, and even after one month to 11.7 ± 2.7 pg/ml (P<0.001, P<0.05, P<0.05, respectively). The mean PEDF concentration before the injection was 7.2 ± 0.3 µg/ml. It was reduced after one day to 5.8 ± 0.4 µg/ml, after seven days to 5.9 ± 0.5 µg/ml, and after one month to 6.3 ± 0.6 µg/ml (P<0.001, P<0.05, P=0.085, respectively).
Conclusions: :
The significant decrease of the VEGF levels in the plasma after the intravitreal injection of bevacizumab indicates that bevacizumab may be absorbed by the intraocular blood vessels into the general blood circulation. The decreased levels of VEGF in the plasma may also affect the PEDF levels. Although general complications have been reported to be rare after an intravitreal injection of bevacizumab, we should carefully examine patients for systemic changes especially those with multiple injections of bevacizumab.
Keywords: diabetic retinopathy • vascular endothelial growth factor