Gliomas are a heterogeneous group of tumors that display histologic similarities to glia, which include astrocytes, ependymal cells and oligodendrocytes. The annual incidence of malignant gliomas is approximately 3-4 cases per 100,000 people in Europe and each year more than 2000 new cases are diagnosed in Germany (Cancer in Germany 2003-2004 Incidence and Trends, Robert Koch Institute, update 2009). The most malignant form, glioblastoma multiforme (GBM, figure 1), is one of the most aggressive and lethal forms of cancer. The median age of patients at the time of diagnosis is 64 years in the case of GBM . The World Health Organization (WHO) classifies gliomas on the basis of histologic features into four prognostic grades: grade I (benign) to grade IV (malign). Glioblastomas (WHO grade IV) can be separated into two main subtypes on the basis of biologic and genetic differences – primary and secondary glioblastomas. Despite their genetic differences, primary and secondary glioblastomas are morphologically indistinguishable. Standard treatment for newly diagnosed glioblastoma is neurosurgical debulking followed by radiotherapy and temozolomide (TMZ) with additional maintenance TMZ. At the time of disease recurrence, few treatment options are available.