TAS-116 is a novel small molecule inhibitor of HSP90 with Ki values of 34.7 nmol/L and 21.3 nmol/L for HSP90α and HSP90β, respectively. It does not inhibit other ATPases such as HSP70 (IC50 >200 μmol/L).
In a mouse model with human xenograft tumors, oral administration of TAS-116 induced tumor shrinkage accompanied by depletion of HSP90. In a rat model, TAS-116 was more distributed in subcutaneously xenografted NCI-H1975 non-small cell lung cancer tumors than in the retina. TAS-116 was also active in orthotopically transplanted NCI-H1975 lung tumors.
