KIT and gastrointestinal stromal tumor: Because the above-mentioned in vitro, in vivo and clinical data indicated complementary activity of sunitinib and regorafenib against the most common KIT imatinib-resistance secondary mutations (Fig. 3), we hypothesised that combined treatment with sunitinib and regorafenib might suppress a broad range of resistant subclones in GIST patients progressing on imatinib.