Later on, the indolinone-derivative sunitinib with a broad spectrum activity targeting VEGFR, PDGFR, FGFR, KIT, and FLT3, was approved for the treatment of renal cell carcinoma, as well as second-line therapy in the imatinib-resistant gastrointestinal stromal tumor (GIST) [81]. Here, PDGFRB is linked to gastrointestinal stromal tumor.