This is a Phase III study comparing Imatinib mesylate and hydroxyurea combination therapy with hydroxyurea monotherapy in patients with temozolomide resistant progressive glioblastoma.

Inclusion Criteria:

• Signed informed consent prior to initiation of any study procedure.
• Patients >= 18 years of age.
• Histological confirmed diagnosis of glioblastoma multiforme / astrocytoma World Health Organization (WHO) grade IV by a reference pathologist
• Eastern Cooperative Oncology Group (ECOG) Performance Status of 0, 1 or 2.
• Adequate hepatic, renal and bone marrow function as defined by the following: total bilirubin < 1.5 x Upper Limit of Normal (ULN), ALT and AST < 2.5 x ULN, creatinine < 1.5 x ULN, absolute neutrophil count > 1.5 x109/L, platelets > 100 x109/L and hemoglobin > 10 g/dL.
• Female patients of childbearing potential with a negative pregnancy test within 7 days of initiation of study drug dosing. Postmenopausal women must be amenorrheic for at least 12 months to be considered of non-childbearing potential. Male and female patients of reproductive potential who agree to employ an effective barrier method of birth control throughout the study, and for up to 3 months following discontinuation of study drug.
• Life expectancy of >3 months.
• MRI available every 6 weeks for disease management
• No intercerebral inflammation
• Irradiation therapy 54 to 62 gy finished or less according to national standard
• Chemotherapy at least 1 temozolomide containing regimen finished, no established chemotherapy regiment available and progression under chemotherapy or in between 6 months following the last chemotherapy.
• Leucocytes > 2.500/µl, to be controlled once a week
• Thrombocytes > 80.000/µl, to be controlled once a week
• Ensured compliance
• Patients who had a second or third resection after disease progression cannot be included earlier than 2 weeks following the resection. MRI should be performed not later than 72 h post operation. If patients are to be included later than 4 weeks after the resection, a new baseline MRI must be performed.

Exclusion Criteria:

• Female patients who are pregnant or breast-feeding.
• Patients who have been treated with any investigational agent(s) within 28 days of the first day of administration of study drug.
• Patients with uncontrolled medical disease such as diabetes mellitus, thyroid dysfunction, neuropsychiatric disorders, infection, angina or Grade 3 or 4 cardiac problems as defined by the New York Heart Association Criteria.
• Patients with other malignant disorders.
• Patient with acute or known chronic liver disease (i.e., chronic active hepatitis, cirrhosis).
• Patients who are known to be HIV positive (no specific tests are required for confirmation of eligibility).
• Expected incompliance according to treatment, treatment diary and examination schedule
• Not confirmed histological diagnosis glioblastoma multiforme/astrocytoma WHO grade IV
• Other drugs with potential cytostatic main or side effect
• No or inadequate chemotherapy or irradiation therapy
• Patients without hematological recovery after previous chemotherapy who have been treated with Chemotherapy within 28 days of the first day of administration of study drug.

Other protocol-specific inclusion /exclusion criteria may apply.