PDGFRA and gastrointestinal stromal tumor: To date, sunitinib, an inhibitor of multiple receptor tyrosine kinases including KIT, PDGFRA, vascular endothelial growth factor receptor (VEGFR), and fms-related tyrosine kinase 3 (FLT3), is used as a second-line treatment providing clinical benefit in patients with imatinib-resistant GIST for a limited time period (Judson and Demetri, 2007).