LAUSR

2546Background: TAS-116 is an oral non-ansamycin, non-purine, and non-resorcinol highly selective inhibitor of HSP90α/β. The objective of this FIH study was to determine the MTD and investigate the safety, tolerability, PK, PD (HSP70 protein levels in PBMCs), and antitumor activity of TAS-116. Methods: The study is being conducted in Japan and the UK. Patients with advanced solid tumors received escalating doses of TAS-116 once daily (QD) with an accelerated titration design. After the MTD was determined, safety and tolerability of 5 days on / 2 days off per week administration (QDx5) at the MTD in QD was explored. In parallel, the MTD with every other day administration (QOD) was evaluated by using a 3 + 3 design. Results: As of 20 September 2016, 52 patients were enrolled. TAS-116 was evaluated at doses of 4.8 to 150.5 mg/m2/day in the QD schedule and doses of 107.5 to 295.0 mg/m2/day in the QOD schedule. The MTD was 107.5 mg/m2/day with QD and 210.7 mg/m2/day with QOD. QDx5 at the MTD in QD using a fla...