Forty-five patients with relapsed AML were treated with the Mito-FLAG regimen consisting of mitoxantrone (7 mg/m2, day 1, 3 and 5), fludarabine (30 mg/m2, days 1–5), Ara-C (1 g/m2, over 3 h every 12 h, days 1–5) and G-CSF [5 μg/kg/day subcutaneously from day 0 until the white blood count (WBC) was >20×109/l]. The gene discussed is CSF3; the disease is acute myeloid leukemia.