KDR and fibrosarcoma: Conversely, other anti-angiogenic agents, including Axitinib (an anti VEGFR TKI), Sorafenib (a TKI targeting VEGFR2/3, platelet-derived growth factor receptor (PDGFR) and rapidly accelerated fibrosarcoma (RAF)/c-KIT), and Imatinib mesylate (a TKI targeting BCR-ABL, c-KIT, and PDGFR) failed to show clinical efficacy on MM [83–87].