TAS-116, an oral selective HSP90α/β inhibitor, showed significant anti-tumour activities without detectable ocular toxicities in a rat model.37 A Phase 1 trial of TAS-116 in patients with solid tumours demonstrated that TAS-116 had an acceptable safety and preliminary anti-tumour activity.46 The present study provides evidence that TAS-116 shows activity against GIST cell line GIST T1 and EGFR-mutated lung cancer cells. This evidence concerns the gene HSP90AA1 and gastrointestinal stromal tumor.