Systemic counterregulatory response of angiopoietin-2 after aflibercept therapy for nAMD: a potential escape mechanism.

purposeTo analyse the effect of intravitreal aflibercept injections on systemic angiopoietin-2 (Ang2) and vascular endothelial growth factor (VEGF)-A levels in patients with neovascular age-related macular degeneration (nAMD).

methodsIn a prospective, randomized study, aflibercept (2.0 mg/50 µl) or ranibizumab (0.5 mg/50 µl) was administered intravitreally to 38 treatment-naive patients. Blood samples were taken before, 7 days after, and 28 days after the first intravitreal therapy. Cytokine levels were measured by enzyme-linked immunosorbent assay. Twenty-two age- and sex-matched individuals served as controls.

resultsAt baseline, there were no significant differences of systemic Ang2 and VEGF-A levels among the treatment and control groups. After intravitreal aflibercept administration, median (interquartile range: IQR) systemic Ang2 was significantly upregulated from 1819 pg/ml (1262-3099) to 2123 pg/ml (1441-3769; p = 0.011) 7 days after the drug injection and remained non-significantly elevated at 1944 pg/ml (1431-2546 pg/ml; p = 0.653) 28 days after the drug injection. Median (IQR) systemic VEGF-A levels were significantly reduced from 43 pg/ml (30-57) to 8 pg/ml (8-8; p < 0.0001) 7 days and 16 pg/ml (8-26; p = 0.001) 28 days after the injection in the aflibercept group. There were no significant effects on systemic VEGF-A and Ang2 levels in the ranibizumab group at any time point following the first injection.

conclusionIn this study, we report significant systemic upregulation of Ang2 after intravitreal aflibercept administration. This counterregulatory response may represent a potential escape mechanism from antiangiogenic therapy.