Growth inhibition of the 9L glioma using polymers to release heparin and cortisone acetate

Abstract

Malignant gliomas are difficult to treat systemically because of exclusion of many chemotherapeutic agents by the blood brain barrier. Furthermore, as opposed to other neoplasms, malignant gliomas recur locally, at the site of original presentation. These tumors are remarkably vascular and hence may be more dependent on angiogenesis for continued growth than other tumors. The inhibition of tumor angiogenesis can control tumor growth by preventing the exponential vascular growth phase. We report the inhibition of the growth of the 9L glioma by the localized, controlled release of known angiogenesis inhibitors administered in a biodegradable polyanhydride polymer matrix. In the presence of heparin and cortisone and of cortisone alone there was a 4.5- and 2.3-fold reduction, respectively, in the growth of the 9L glioma. We compared these results to the inhibition of tumor neovascularization in the rabbit cornea by the localized delivery of the same agents. In the rabbit cornea model, the local release of heparin and cortisone and of cortisone alone resulted in a 2.5- and 2.0-fold reduction, respectively, in the angiogenesis response evoked by the VX2 carcinoma. This study introduces two new potential therapeutic modalities for the treatment of malignant gliomas: the use of the combination of heparin and cortisone as antineoplastic agents and the use of polymeric carriers for the local delivery of such agents in the central nervous system.