Bevacizumab, a monoclonal antibody against vascular endothelial growth factor (VEGF), is an antiangiogenic treatment currently proposed to recurrent high grade glioma patients. Unfortunately some patients fail to respond to this treatment and finding biological factors allowing the discrimination between potential responders and non responders would be very helpful. As the immune system plays a key role in angiogenesis induction and maintenance in cancer, it could serve as a surrogate marker of angiogenesis in cancer patients.

The purpose of this study is to determine the influence of bevacizumab treatment on circulating immune cells in high grade glioma patients and to search for a link between the variation of these cells and the response to treatment.

The following leucocyte subsets will be analyzed in whole blood before treatment and before cycles 3, 5 and 7:

• Classical, intermediate, nonclassical and Tie2 expressing monocytes.
• Regulatory T cells (Treg).
• Myeloid Derived Suppressor cells (MDSCs) The variation of the absolute numbers (or relative percentages) of the cells in the blood of patients will be correlated to the response to treatment assessed according to the RANO criteria.

Inclusion Criteria:

• Patients with histologically proved recurrent glioblastoma or anaplasic glioma,
• Tumor recurrence documented by MRI at least 3 months after the end of radiotherapy or chemotherapy.
• Patients for whom a treatment by bevacizumab is proposed by a multidisciplinary team staff.
• Age ≥ 18.
• Signed informed consent.
• Affiliation to a social security coverage

Exclusion Criteria:

• Known Hepatitis B or C or HIV.
• Inclusion in another clinical trial.
• Patient having received an anti-angiogenic therapy.
• Pregnant or breast-feeding woman.
• Person deprived of liberty or under guardianship or trusteeship or judicial protection
• Inability to give informed consent
• Person unable or unwilling to comply with the requirements of the protocol for geographical, social or psychological reasons.