Angiogenesis mediated by VEGF constitutes a new target for anti-cancer therapy which has explored through different ways of intervention aiming at the blocking of the tumoral angiogenesis. In the present study, we developed the assays by which efficacies of anti-VEGF inhibitor candidates are evaluated at the various levels.

First, we developed two sandwich ELISAs using coated anti-VEGF Ab and soluble Flt-1 receptor fusion protein (sFlt-1/Fc). As low as 200 pg/ml of hVEGF diluted in human sera was detectable by these assays. In addition, we found that VEGF inhibitors (2 µg/ml of either anti-VEGF Ab or sFlt-1/Fc) completely block 5 ng/ml VEGF in these ELISAs. Subsequently, two bioassays, wound healing and HUVEC tube formation assays, revealed that anti-VEGF Ab (1 µg/ml) & sFlt-1/Fc Ab (1 µg/ml), or SU5416 (VEGFR tyrosine kinase inhibitor, 1 µM) prevents the activity of VEGF (1~10 ng/ml). Finally, secretion of MMP-9 by VEGF-stimulated macrophages was abolished by treatment of anti-VEGF Ab (1 µg/ml) in gelatin zymography.

ELISAs together with bioassays developed in this study are appropriate for evaluation of the efficacy of inhibitors of VEGF.