Acute Tumor Lysis Syndrome during Oral Fludarabine Treatment for Chronic Lymphocytic Leukemia. Role of Treatment with Rasburicase

INTRODUCTION: Oral fludarabine is the first oral formulation of a purine analogue available for clinical use which has produced encouraging results in patients with B-cell chronic lymphocytic leukemia (CLL). It has a similar tolerability profile to that of the intravenous formulation. Acute tumor lysis syndrome (TLS) induced by fludarabine appears to be a fairly unusual complication during the treatment of CLL. CASE REPORT: The present report describes the case of a 78-year-old man who developed acute renal failure associated with TLS following the first course of oral fludarabine. Laboratory investigations fulfilled the TLS typical criteria, including hyperkalemia, marked hyperuricemia, hyperphosphatemia, hypocalcemia, and acute renal failure. Despite the many documented side effects of oral fludarabine, there is only one similar case of oral fludarabine-induced TLS reported to date. Conventional therapy with short-term supportive hemodialysis and a short treatment of rasburicase for 2 days achieved a complete recovery of renal function and a decrease of the urate level to within the normal range. CONCLUSIONS: Clinicians should be alert to this potentially life-threatening metabolic emergency among CLL patients treated with oral fludarabine.