 This ClinicalTrials.gov record includes the results from two studies Novartis protocol IDs CSTI571H2201 and CSTI571H2202 which were conducted separately but reported together in a single clinical study report. Both studies were phase II, open-label, multicenter, single-arm studies that evaluated the efficacy of imatinib mesylate plus hydroxyurea in subjects with progressive glioblastoma multiforme. The studies were identical in design with two exceptions: Patients in study CSTI571H2201 received a dose of imatinib 600 mg once daily and were not allowed concomitant use of enzyme-inducing anticonvulsant drugs EIACDs; patients in study CSTI571H2202 received a dose of imatinib 500 mg twice daily and were allowed concomitant use of EIACDs. 