A critical component in designing an agent that will cross the protective blood brain barrier (BBB) is that the agent must be readily transported intracerebrally, does not produce local irritation/neurotoxicity and is not recycled back into the general circulation. After IV administration DM-CHOC-PEN readily penetrates the BBB, is not a substrate for the transporter protein P-glycoprotein (P-gp) and has shown anticancer activity in CNS tumors. The effective transport of DM-CHOC-PEN into CNS tumors in adults without neurotoxic behavioral alterations and associated events supports the drug's use in combination with radiation in the treatment of CNS tumors. The observed responses noted in adults with metastatic cancers involving the CNS and cerebellum treated with DM-CHOC-PEN is encouraging. Thus, the drug's unique properties and lack of toxicities noted in the adult studies merits the Phase I trial proposed here in combination with radiation.