Current and Emerging Treatment Options for Patients with Tumor Lysis Syndrome*

Tumor lysis syndrome (TLS) is a life-threatening complication of cancer chemotherapy in which hyperuricemia is the principal characteristic. High serum uric acid levels can lead to uric acid precipitation in the renal tubules, which results in acute kidney failure. TLS is typically associated with rapidly dividing cell types observed with high-risk leukemia and lymphoma, which are more prone to rapid breakdown, triggering TLS. Although potentially fatal, TLS is a desired result of chemotherapy and complications can be prevented. Traditionally, the management of TLS includes hydration to force diuresis and alkalinization of the urine to promote uric acid excretion. Uric acid-lowering agents are used to control the serum levels of the final end product of the purine metabolism cascade in humans. Dialysis is reserved as a last resort treatment for uncontrolled hyperuricemia, hyperkalemia, hyperphosphatemia, or decreased urine output with fluid overload. Allopurinol, a xanthine oxidase inhibitor, has historically been the uric acid-lowering agent of choice and works by preventing the conversion of xanthine and hypoxanthine to uric acid. Although it inhibits the production of uric acid, allopurinol is ineffective in reducing existing uric acid pools. Rasburicase is a recombinant form of urate oxidase that interferes with the cascade at a later stage, allowing the conversion of all insoluble precursors to uric acid, then converting all existing uric acid to soluble allantoin. In clinical studies that enrolled patients at high risk of TLS, rasburicase was superior to allopurinol in controlling uric acid in adult and pediatric patients with lymphoma or leukemia. The agent is well tolerated and has resulted in minimal adverse events and no reported drug interactions. Unlike allopurinol, rasburicase has a rapid onset of action, and its effect can be measured within a few hours of administration. The drug can help avoid delays in chemotherapy because of electrolyte imbalances, has a good safety profile, and effectively reduces uric acid levels. By breaking down uric acid, rasburicase reduces the potential for uric acid crystallization, which leads to renal failure and the need for dialysis. (Adv Stud Nurs. 2006;4(3):49-57)