A66

A66 is a novel small molecule inhibitor of PI3K p110α with IC50 values of 32, 30 and 43 nM for p110α, p110α/E545K and p110α/H1047R. A66, showing the S-enantiomer to be a highly specific and selective p110α inhibitor. The responsive cell lines all harboured H1047R mutations in PIK3CA and have high levels of p110α and class-Ia PI3K activity. A66 is more than 100 fold less active against the other class-I PI 3-kinase isoforms and had not inhibitory activity against 200 protein kinases when tested at 10 micromolar. This makes it the most selective and specific p110α inhibitor available for research purposes.