An orally bioavailable inhibitor of the class I phosphoinositide 3-kinase (PI3K) alpha isoform with potential antineoplastic activity. PI3K alpha inhibitor MLN1117 selectively inhibits PI3K alpha kinase, including mutations of PIK3CA, in the PI3K/Akt/mTOR pathway, which may result in tumor cell apoptosis and growth inhibition in PI3K alpha-expressing tumor cells. By specifically targeting class I PI3K alpha, this agent may be more efficacious and less toxic than pan PI3K inhibitors. Dysregulation of the PI3K/Akt/mTOR pathway is frequently found in solid tumors and results in promoting tumor cell growth, survival, and resistance to chemotherapy and radiotherapy; PIK3CA, one of the most highly mutated oncogenes, encodes the p110-alpha catalytic subunit of the class I PI3K.