An orally bioavailable, small molecule, non-polyglutamatable, antifolate quinazoline derivative thymidine synthetase inhibitor with potential antineoplastic activity. Plevitrexed is transported into the cell via the physiological reduced folate carrier (RFC) system. Intracellularly, this agent selectively binds to the folate binding site of thymidylate synthase and inhibits thymidine synthesis, which may result in DNA synthesis inhibition and apoptosis.