Rasburicase (recombinant urate oxidase) for the management of hyperuricemia in patients with cancer: report of an international compassionate use study.

BACKGROUND: Hyperuricemia and tumor lysis syndrome (TLS) are serious complications that can occur during chemotherapy for hematologic malignancies, even if standard management procedures, including administration of allopurinol, are undertaken. Rasburicase, a recombinant urate oxidase that converts uric acid (UA) into the soluble compound allantoin, has been shown to control hyperuricemia faster and more reliably than allopurinol.(1)

METHODS: A compassionate use trial, running from January 1999 to December 2001, provided access to rasburicase for patients in nine countries who were at risk for TLS during the initiation of chemotherapy. Of the 280 patients enrolled in the study, 278 received rasburicase and were included in the analysis. A total of 166 pediatric patients who had leukemia (approximately 74%), lymphoma (approximately 24%), or solid tumors (approximately 3%) were treated with rasburicase. One hundred twelve adults with either leukemia (68%) or lymphoma (30%) also were treated. Rasburicase (0.20 mg/kg) was administered intravenously once a day for 1 to 7 days, at the investigator's discretion. Two doses daily could be administered during the first 3 days. A response was defined as a reduction in UA level or maintenance of a UA level less than 7.5 mg/dL (or less than 6.5 mg/dL, for children age < 13 years).

RESULTS: UA levels at 24-48 hours after administration of the last dose of rasburicase were available for 122 pediatric patients and 97 adult patients. The mean UA level in 29 hyperuricemic children decreased from 15.1 mg/dL to 0.4 mg/dL, whereas in 27 hyperuricemic adults, the mean level decreased from 14.2 mg/dL to 0.5 mg/dL. Prophylactic administration of rasburicase to prevent TLS during chemotherapy reduced UA levels from a mean of 4.4 mg/dL to 0.8 mg/dL in 93 nonhyperuricemic children and from 4.8 mg/dL to 0.4 mg/dL in 70 nonhyperuricemic adults (for all reductions in UA levels, P < 0.001). The response rate was 100%. Rasburicase was very well tolerated. Serious adverse events related to rasburicase were observed in one patient.

CONCLUSIONS: The results of the current study confirm that rasburicase is safe and highly effective in the prevention and treatment of chemotherapy-induced hyperuricemia in both children and adults.