This is an open-label; pharmacokinetic and pharmacodynamic phase II study of AUY922 in patients with advanced GIST failed to or intolerance of imatinib and sunitinib therapy. AUY922 is a novel HSP90 inhibitor and will be administered at dose of 70 mg/m2 i.v. infusion on D1 every week. The Simon one sample two-stage minimax design was used with 15 suitable patients to be accrued to the first stage. If at least two patients meet our primary endpoint (complete response＋partial response＋stable disease≧4 months), an additional 10 patients would be recruited to the second stage. AUY922 would be considered active in this patient population, if there were more than 5 cases of non-progressive disease in the total cohort of 25 patients.