KDR and glioblastoma: Since then, additional efforts have been made with small molecule kinase inhibitors that target multiple receptors involved in angiogenesis in glioblastoma and other brain tumors such as PDGF-R, FGF-R, VEGF-R, etc. These molecules have been so far used in Phase I–III trials; however, all of them have also failed and they are actually inferior to Avastin [205].