Taselisib (GDC-0032) is a potent, selective inhibitor of PIK3CA (PI3Kα) with Ki of 0.29 nM and pAkt IC50 of 4 nM, 31-fold selective over PI3Kβ. Taselisib (GDC-0032) maintains biochemical selectivity over the non-class I PI3Ks, with IC50 values for PI3K-C2 beta and hVPS34 measuring 292 and 374 nM, respectively. Taselisib (GDC-0032) achieves a 1000-fold selectivity against a panel of potential off-targets. Taselisib (GDC-0032) potently inhibits cell proliferation of MCF7-neo/HER2 cells with IC50 of 25 nM. Taselisib (GDC-0032) (2.8 mg/kg) resulted in a similar decrease in Akt phosphorylation (59%). Taselisib (GDC-0032) orally at 1.4, 2.8, 5.8, 11.25, or 22.5 mg/kg resulted in dose-dependent increase in TGI (19%, 76%, 95%, 103%, and 123%, respectively) and tumor regressions in the MCF7-neo/Her2 xenograft model grown in nude mice.
