CXCR4 and leukemia: The synthetic cyclopeptide CXCR4 inhibitors, POL6326 (balixafortide), efficiently mobilized engrafted leukemia cells from their protective stromal microenvironment into the circulation in a murine leukemia model; it also displayed a strong synergy in combination with G-CSF, significantly reducing leukemia burden and prolonging animals’ survival [84].