Correlation of kinase genotypes and activity of sunitinib in imatinib failure gastrointestinal stromal tumor.

e20521 Background: Sunitinib, which targets KIT, PDGFR, VEGFR, has demonstrated efficacy in patients with GIST after they experience imatinib failure. A study from JCO reported GIST patients with exon 9 gene mutation or wild type had more benefit receiving sunitinib treatment. We analysed the impact of primary and secondary gene mutation on sunitinib treatment in Chinese GIST patients. Methods: We assessed the tumor response according to RECIST criterion in 31 patients with imatinib-resistant/intolerant GIST, and examined the Kit/PDGFRA mutation status by using tumor specimens obtained before or after prior imatinib therapy. Progression-free survival (PFS) was evaluated with Kaplan-Meier methods and log-rank tests. Results: Primary gene mutations examination were performed in all the patients and secondary gene mutations in nine patients. Primary gene mutations were identified in 77.4% GIST. 61.3% had exon 11 mutation, 12.9% had exon 9 mutation, 3.2% obtained exon 17 mutation, no PDGFR gene mutation was f...