Nilotinib is a potent TKI that has been shown both in vitro and in vivo to inhibit the auto-phosphorylation and proliferation of cells transformed with activating mutations of KIT or platelet-derived growth factor receptor-alpha (PDGFRA) tyrosine kinases, which are the kinases that are the key oncogenic drivers in GIST [7]–[9]. Here, KIT is linked to gastrointestinal stromal tumor.