An orally bioavailable inhibitor of both phosphoinositide 3-kinase (PI3K) class I and pan histone deacetylase (HDAC) enzymes, with potential antineoplastic activity. Upon oral administration, CUDC-907 inhibits the activity of both PI3K class I isoforms and HDAC, thereby preventing the activation of the PI3K-AKT-mTOR signal transduction pathway that is often overactivated in many cancer cell types. This may prevent growth of PI3K and/or HDAC-expressing tumor cells. CUDC-907 shows an increased inhibition of tumor cell growth and induction of apoptosis when compared to inhibitors that target either PI3K or HDAC.