Clinical experience with fludarabine in hemato-oncology

Fludarabine monophosphate (Fludara) is a purine analogue which entered clinical trials in 1982. Although inactive in solid tumors, Fludara has marked activity in indolent lymphoproliferative disorders. The exact mechanism of action of Fludara is uncertain. Fludara has been established as the most active single agent in chronic lymphocytic leukemia (CLL) in single arm and comparative clinical trials. The activity has been demonstrated in both previously treated and initially treated patients. Marked activity has been noted in patients with low grade lymphoma, in particular, those with a follicular morphology and in Waldenstrom's macroglobulinemia. Combinations of fludarabine with alkylating agents, anthracyclines, and anthraquinones have led to clinically useful combination approaches. The ability of fludarabine to modulate the levels of the triphosphate form of cytosine arabinoside (ara-C) in acute leukemia cells has led to the development of combinations of fludarabine and ara-C. These combinations have demonstrated marked activity in treatment of relapsed and previously untreated patients with acute myelogenous leukemia (AML) and myelodysplastic syndrome (MDS). The ability to modulate the activity of pyrimidines and to inhibit repair of DNA damage caused by alkylating agents, anthracyclines, and other DNA active drugs suggest that the future of fludarabine will be in combination approaches to modulate the activity of other agents. These activities may extend its role to use in solid tumors.