This study showed that inhibition of the CXCL12/CXCR4 axis (i) is safe in brain tumor patients, (ii) leads to improved local control, (iii) may improve overall survival with an estimated median OS of 20.7 months, and (iv) shifts the pattern of recurrence towards an out-of-field pattern (58.8% out-of-field recurrences vs. 10% in a control group) [137]. This evidence concerns the gene CXCR4 and brain neoplasm.