Pimitespib (TAS-116)

Pimitespib (TAS-116) (CAS No.: 1260533-36-5) is a synthetic small molecule research probe in the molecular chaperone inhibitor class, primarily categorized as a selective ATP competitive inhibitor of cytosolic HSP90 isoforms HSP90 alpha and HSP90 beta, with reported binding activity in the nanomolar range and strong isoform preference over related heat shock proteins and other ATPases, including minimal activity against GRP94 and weak inhibition of HSP70 only at much higher micromolar levels. Functionally, this compound is used to investigate HSP90 dependent proteostasis networks and the stability of client proteins that regulate oncogenic signaling, stress adaptation, cell cycle progression, and survival pathways, including studies of MAPK and PI3K AKT axis associated client degradation after HSP90 blockade. In vitro, published profiling supports potent engagement of HSP90 alpha and HSP90 beta at nanomolar to low micromolar experimental concentrations depending on assay format and cellular context, making it suitable for mechanistic studies of chaperone dependency, resistance biology, and combination screening paradigms. In biomedical research workflows, Pimitespib is commonly applied in cultured cell systems and preclinical animal models to characterize pharmacodynamic modulation of heat shock response biology, client protein turnover, and pathway level response signatures, while dose levels and exposure conditions are selected according to specific experimental designs and research objectives. Relative to less selective chaperone inhibitors, it is also frequently described in preclinical literature as having a favorable nonclinical ocular safety profile, which supports its utility for sustained target biology interrogation in translational drug discovery research settings.