Gimatecan® is Sigma-Tau Research's new, potent, oral Topoisomerase I inhibitor. Drugs in this class play a crucial role in destroying DNA replication in tumors. We are conducting this study to determine the Maximum Tolerated Dose of our compound. In addition, we plan to assess the drug's ability to affect the evolution of malignant gliomas, when given as a capsule, rather than by intravenous injection.