RESUMO
The aim of this study was to investigate the anti-angiogenic, vascular-disrupting and anti-metastatic properties of vinflunine, the latest vinca alkaloid in phase III clinical development. The effects of vinflunine on in vitro endothelial cell functions relevant to the performance of an already formed vasculature and to the angiogenic process were evaluated. The in vivo anti-angiogenic properties of vinflunine were also investigated, as were its activity against a model of experimental metastasis. In vitro vinflunine induced a rapid change in the morphology of endothelial cells and disrupted the network of capillary-like structures, indicating potential vascular-disrupting activity. Furthermore, vinflunine showed anti-angiogenic properties, since it inhibited endothelial cell migration and the capacity of these cells to organise into a network of capillary-like structures. All these effects were observed under conditions that only marginally affect endothelial cell proliferation. In vivo, vinflunine inhibited bFGF-induced angiogenesis in Matrigel implants at doses 40-20-fold lower than its maximal therapeutic dose (MTD). Treatment of mice with vinflunine reduced the number of liver metastases induced by intrasplenic injection of LS174T cells, with significant effects also observed at low doses; i.e. 16-fold lower than the MTD. This study demonstrates that vinflunine expresses both vascular-disrupting and anti-angiogenic activities and induced marked effects against experimental metastases, all properties that support its ongoing clinical development.