FLT1 and gastrointestinal stromal tumor: Sunitinib, targeting vascular endothelial growth factor receptor 1 (VEGFR1), VEGFR2, and VEGFR3, Fms-like tyrosine kinase-3 (FLT3), and the receptor encoded by the proto-oncogene RET, was approved as second line therapy in 2006 after showing improved time to progression compared with placebo in GIST patients previously treated with imatinib10.