4. Histologically confirmed initial diagnosis of primary glioblastoma multiforme (GBM) or gliosarcoma (GS), now recurrent. Patients with recurrent/progressive disease whose initial diagnostic pathology confirmed GBM or GS will not need re-biopsy. Patients with prior low-grade glioma or anaplastic glioma are eligible, if histologic assessment demonstrates transformation to GBM or GS.