Recombinant urate oxidase for the prophylaxis or treatment of hyperuricemia in patients With leukemia or lymphoma.

PURPOSE: To improve the control of hyperuricemia in patients with leukemia or lymphoma, we tested a newly developed uricolytic agent, recombinant urate oxidase (SR29142; Rasburicase; Sanofi-Synthelabo, Inc, Paris, France), which catalyzes the oxidation of uric acid to allantoin, a highly water-soluble metabolite readily excreted by the kidneys. PATIENTS AND METHODS: We administered Rasburicase intravenously, at 0.15 or 0.20 mg/kg, for 5 to 7 consecutive days to 131 children, adolescents, and young adults with newly diagnosed leukemia or lymphoma, who either presented with abnormally high plasma uric acid concentrations or had large tumor cell burdens. Blood levels of uric acid, creatinine, phosphorus, and potassium were measured daily. The pharmacokinetics of Rasburicase, the urinary excretion rate of allantoin, and antibodies to Rasburicase were also studied. RESULTS: At either dosage, the recombinant enzyme produced a rapid and sharp decrease in plasma uric acid concentrations in all patients. The median level decreased by 4 hours after treatment, from 9.7 to 1 mg/dL (P =.0001), in the 65 patients who presented with hyperuricemia, and from 4.3 to 0.5 mg/dL (P =.0001) in the remaining 66 patients. Despite cytoreductive chemotherapy, plasma uric acid concentrations remained low throughout the treatment (daily median level, 0.5 mg/dL). The urinary excretion rate of allantoin increased during Rasburicase treatment, peaking on day 3. Serum phosphorus concentrations did not change significantly during the first 3 days of treatment, decreased significantly by day 4 in patients presenting with hyperuricemia (P =.0003), and fell within the normal range in all patients by 48 hours after treatment. Serum creatinine levels decreased significantly after 1 day of treatment in patients with or without hyperuricemia at diagnosis (P =.0003 and P =.02, respectively) and returned to normal range in all patients by day 6 of treatment. Toxicity was negligible, and none of the patients required dialysis. The mean plasma half-lives of the agent were 16.0 +/- 6.3 (SD) hours and 21.1 +/- 12.0 hours, respectively, in patients treated at dosages of 0.15 or 0.20 mg/kg. Seventeen of the 121 assessable patients developed antibodies to the enzyme. CONCLUSION: Rasburicase is safe and highly effective for the prophylaxis or treatment of hyperuricemia in patients with leukemia or lymphoma.

Severe aplastic anaemia: a prospective study of the effect of androgens or transplantation on haematological recovery and survival.

A prospective study was performed (1) to evaluate the role of androgens in treatment of severe aplastic anaemia, and (2) to compare the efficacy of early bone marrow transplantation with more conventional therapy for severe marrow aplasia. Results fail to support a beneficial effect of androgens on the course of patients with severe aplastic anaemia. In contrast, histocompatible bone marrow transplantation significantly improves survival and haematological recovery. Alternative therapies should be carefully evaluated for non-transplantable patients with severe marrow aplasia.

Safety of delayed leucovorin "rescue" following high-dose methotrexate in children.

High-dose methotrexate (HDMTX) with leucovorin (CF) "rescue" is being investigated for treatment of many malignant tumors. CF is usually begun 2 hours after ending the HDMTX infusion. However, since CF and methotrexate compete for the same cellular transport system, at high extracellular methotrexate concentrations it may be impossible to "rescue" cells with CF. A regimen of HDMTX with delayed leucovorin "rescue" was therefore designed. In this program, a 6-hour infusion of methotrexate (7.5 gm/m2) was followed 24 hours later by leucovorin "rescue." Nine patients with osteogenic sarcoma received 115 courses of this treatment. Toxicity was minimal. Plasma methotrexate values were identical to those following early CF 'rescue" regimens. HDMTX with delayed "rescue" is well tolerated. Although theoretically sound, further studies are needed to determine its efficacy in comparison to standard early "rescue" regimens.