CYH33, an orally active and highly selective PI3Kalpha inhibitor, demonstrates specificity with IC50 values of 5.9 nM for the alpha isoform, 598 nM for beta, 78.7 nM for delta, and 225 nM for gamma. It effectively inhibits Akt and ERK phosphorylation and induces substantial G1 phase arrest in breast cancer and non-small cell lung cancer (NSCLC) cells, showcasing potent activity against solid tumors.