Lungs and bone (marrow), organs of predilection for (primary/ metastatic) EWS, represent predominant CXCL12 sources Currently, after having demonstrated anti-tumor activity in pre-clinical and animal tumor models, several CXCR4 antagonists are being evaluated in clinical studies for treatment of patients with hematological and solid tumors. This evidence concerns the gene CXCL12 and neoplasm.