At that time, plerixafor, a small-molecule bicyclam CXCR4 antagonist, was the only CXCR4 inhibitor approved by the FDA in association with G-CSF for autologous stem cell mobilization in patients with non-Hodgkin’s lymphoma and multiple myeloma (MM) [78,79]. This evidence concerns the gene CXCR4 and plasma cell myeloma.