Abstract
Cereport® is a nine amino acid peptide with greater selectivity for the B2 bradykinin receptor and a longer plasma half-life than bradykinin. In tissue culture conditions, Cereport initiates typical bradykinin-like second messenger systems, including increases in intracellular calcium and phosphatidylinositol turnover. Electron microscopy studies demonstrated that intra-venous Cereport increased permeability of the blood-brain barrier (BBB) by disengaging the tight junctions of the endothelial cells that comprise the BBB. Autoradiographic studies in rat models of glioma further demonstrated that intra-venous or intra-arterial Cereport increases the uptake of radiolabeled tracers and chemotherapeutic agents into the tumor. These effects are dose-related and relatively selective for the tumor and the brain surrounding the tumor. The increase in permeability occurs rapidly but is transient, with restoration of the BBB occurring within 2-5 minutes following cessation of infusion. Survival studies in rodent models of both gliomas and metastatic tumors in the brain demonstrate that the enhanced uptake observed with the combination of Cereport and water-soluble chemotherapeutics enhances survival to a greater extent than achieved with chemotherapy alone. Preliminary clinical trials in human glioma patients confirm that Cereport safely permeabilizes the blood-brain tumor barrier to increase delivery of agents such as carboplatin to tumors without the toxic risks typically associated with dose escalation. Finally, the recent demonstration that Cereport enhances drug delivery to solid peripheral tumors and increases the delivery of drugs across the healthy BBB, permitting responses to drugs that would otherwise not have occurred, broadens the potential uses of Cereport in oncology, psychiatry and neurology.
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