The presence of a highly selective blood-brain barrier (BBB) at the level of the brain capillary endothelium prevents chemotherapeutic agents from attaining therapeutic concentrations at the target site. RMP-7 is a synthetic bradykinin analog which specifically binds to B2 receptors expressed on the brain capillary endothelial cells and preferentially increases capillary permeability within CNS tumors. Carboplatin is an anticancer agent with preclinical and clinical antitumor activity against a variety of brain tumors. A pediatric phase I trial of the combination of RMP-7 and carboplatin will be conducted to determine the maximum tolerated dose of RMP-7 in children with refractory brain tumors.