PDGFRA and gastrointestinal stromal tumor: Furthermore, although the presence of PDGFRA D842V mutation is related to more indolent disease in primary resectable GIST [37], it is poor prognostic factor in advanced disease, as this mutation is insensitive to commonly used tyrosine kinase inhibitors (including imatinib and sunitinib) [33, 38] and is responsible for primary resistance to imatinib.