In the initial phase I/II study using a small molecule CXCR4 antagonist as a chemosensitizing agent (NCT00512252), 52 patients with relapsed or refractory AML (rrAML) were administered plerixafor followed by Mitoxantrone + Etoposide + Cytarabine (MEC) chemotherapy for 5 days (77). The gene discussed is CXCR4; the disease is acute myeloid leukemia.