A water soluble, small-molecule prodrug containing the pan-PI3K/mTOR inhibitor LY294002/SF1101 conjugated to the RGD-containing tetra-peptide SF1174 with potential antineoplastic and antiangiogenic activities. The targeting peptide SF1174 moiety of pan-PI3K/mTOR inhibitor SF1126 selectively binds to cell surface integrins and, upon cell entry, the agent is hydrolyzed to the active drug SF1101; SF1101 selectively inhibits all isoforms of phosphoinositide-3-kinase (PI3K) and other members of the PI3K superfamily, such as the mammalian target of rapamycin (mTOR) and DNA-PK. By inhibiting the PI3K signaling pathway, this agent may inhibit tumor cell and tumor endothelial cell proliferation and survival. Integrins are transmembrane cell adhesion proteins expressed on the surfaces of endothelial and tumor cells.