CXCL12 and glioblastoma: Adding OLA-PEG, a novel CXCL-12 inhibitor, to bevacizumab or B-20 (anti-VEGF agent) significantly improved the anti-tumor effect by reducing intratumoral CD68+ TAM accumulation and by increasing the survival of tumor-bearing mice in the orthotopic G12 human glioblastoma model [237].