PTK6 and gastrointestinal stromal tumor: Among them, sunitinib, an indol-2-one multikinase inhibitor targeting VEGFR-1/2/3, PDGFRα/β, c-Kit, CSF1R, RET, and FLT3, is the second approved anti-angiogenic TKI, and was simultaneously approved for two distinct indications including RCC and imatinib-resistant gastrointestinal stromal tumor (GIST).158,159 The anilinoquinazoline derivative vandetanib inhibits the activities of EGFR, VEGFR-2/3, RET, BRK, TIE2, and EPH.