Inclusion Criteria:

1. Patients with histologically confirmed diagnosis of GBM

2. Availability of pre-treatment GBM tissue to determine the activation status of MGMT
gene is not mandatory but strongly recommended

3. Patients must have received radiation and TMZ for 6 weeks followed by 6 months of
TMZ. Randomization should be performed within the 6 weeks after the last
chemotherapy.

4. A brain MRI with or without a PET-Scan-methionine must be performed before enrolment.

5. Age ≥ 18 years

6. Karnofsky Performance status ≥ 60

7. Normal haematological functions: ANC ≥ 1.5 x 109cells/l, platelets ≥ 100 x 109
cells/l

8. Normal liver function: total bilirubin < 1.5 x ULN, alkaline phosphatase and
transaminases (ASAT/ALAT) < 2.5 times the upper limit of the normal range

9. Serum creatinine < 1.5 x ULN

10. Clinically normal cardiac function without history of ischemic heart disease in the
past 12 months. Absence of cardiac insufficiency NYHA grade III and IV, instable
angina, arrhythmia

11. No previous or current malignancy (except treated basal or squamous cell skin
carcinoma, cervix cancer or in situ carcinoma of the breast).

12. All patients (male and female) with reproductive potential must use effective
contraception. Females must have a negative serum pregnancy test at entry to study.

13. Signed informed consent from the patient or legal representative must be obtained.

Exclusion Criteria:

All non inclusion criteria