Use of fludarabine in the treatment of acute myeloid leukemia

Acute myeloid leukemia (AML) is a disease, which when left untreated, is invariably fatal. The disease is more common in elderly people, who also fare worse than younger patients with AML due to a higher rate of unfavorable prognostic factors, such as poor performance status, multiple comorbidities, reduced tolerance to treatment, 'unfavorable' chromosomal abnormalities and multidrug resistant protein-1 expression. While many patients achieve a complete remission, the rate of relapse is high and prognosis after relapse very poor. Promising results have been published in recent years using fludarabine-containing combination therapy for AML, most commonly fludarabine + cytarabine + granulocyte colony-stimulating factor (G-CSF) [FLAG], FLAG + mitoxantrone (FLANG), or FLAG + idarubicin (FLAG-Ida). Such combinations maximize favorable cytotoxic interactions between cytarabine and G-CSF, and between cytarabine and fludarabine. In small studies, such combinations used as second-line therapy have resulted in complete response (CR) rates of 36-59%. Early retrospective analyses suggested higher CR rates in patients with refractory AML than in those with relapsed AML, but this observation has not been confirmed in recent prospective trials. Fludarabine-containing combinations have also been evaluated as first-line therapy in high-risk patients and resulted in CR rates of 34-70%, with median survival from 7 to 16 months. The current large MRC randomized high-risk study will provide further data on the use of fludarabine-containing regimens in patients with poor prognosis AML. Further studies are investigating the use of fludarabine in combination with other agents, such as gemtuzumab ozogamicin and gemcitabine, in patients with AML.