Primary Objectives:

To determine the efficacy of rasburicase administered as a single dose followed by as needed dosing (investigational arm) as compared to fixed dosing for 5 days (standard treatment arm) in the treatment of patients at high risk or potential risk for tumor lysis syndrome.

Secondary Objectives:

1. To evaluate the plasma uric acid area under the curve (AUC) from baseline through 7 days
2. To evaluate the incidence of renal insufficiency and electrolyte abnormalities.
3. To determine the safety and immunogenicity of rasburicase.
4. To evaluate the cost-effectiveness of the experimental treatment (investigational arm).

The Study Drug and TLS Rasburicase is designed to help decrease or prevent the high level of uric acid that may occur during the start of chemotherapy. A high level of uric acid in the blood may lead to decreased kidney function or kidney failure.

TLS occurs when high uric acid levels are caused by breakdown of tumor cells during the start of chemotherapy. The dead tumor cells can release uric acid and cause other symptoms of kidney failure, such as releasing large amounts of potassium and phosphorus (chemicals) into the blood.

Screening Tests Before you can start treatment on this study, you will have "screening tests." These tests will help the doctor decide if you are eligible to take part in this study.

Your complete medical history will be recorded. You will have a physical exam, including measurement of your vital signs (blood pressure, heart rate, temperature, and breathing rate), height, and weight.

Blood will be drawn (about 2 tablespoons) for routine tests. Women who are able to have children must have a negative blood (using a sample from the routine blood draw) or urine pregnancy test.

Study Groups If you are found to be eligible to take part in this study, you will be randomly assigned (as in the toss of a coin) to 1 of 2 groups. There is an equal chance of being in either group.

Group A Participants in Group A will receive rasburicase by vein, over 30 minutes, on Day 1 of Cycle 1 of chemotherapy. On Days 1-7 of Cycle 1 of chemotherapy, blood (about 2 tablespoons) will be drawn for routine tests, including a check of the level of uric acid in your blood. During Days 2-5 of Cycle 1 of chemotherapy, you will only receive rasburicase (once a day) if the levels of uric acid are high that day.

Group B Participants in Group B will receive rasburicase by vein, over 30 minutes, once a day from Days 1-5 of Cycle 1 of chemotherapy. On Days 1-7 of Cycle 1 of chemotherapy, blood (about 2 tablespoons) will be drawn for routine tests, including a check of the level of uric acid in your blood.

Both Groups Treatment with rasburicase will only be given in Cycle 1 of chemotherapy. The chemotherapy will be given at least 4 hours (up to 24 hours) after the first dose of rasburicase.

Length of Study When your blood test results show that you do not have antibodies to rasburicase, your participation in this study will be over. You will be taken off this study if the TLS gets worse or intolerable side effects occur.

This is an investigational study. Rasburicase is commercially available, but it is not FDA approved for treating TLS. It is FDA approved for pediatric patients with leukemia, lymphoma, and solid tumor cancers who are receiving anti-cancer therapy that is expected to increase the blood levels of uric acid (the result of cancer cells dying from treatment). For treating TLS in adult patients, it has been authorized for use in research only. Up to 80 evaluable patients will take part in this study. All will be enrolled at M. D. Anderson.

Inclusion Criteria:

1. Patients with hematological malignancies (leukemia/lymphoma) at high risk or potential risk for tumor lysis syndrome. High risk: hyperuricemia of malignancy (Uric acid levels >7.5); diagnosis of very aggressive lymphoma/leukemia based on Revised European-American Lymphoma (REAL) classification; acute myeloid leukemia, chronic myelocytic leukemia (CML) in blast crisis; high grade myelodysplastic syndrome only if they have >10% bone marrow blast involvement and given aggressive treatment similar to acute myeloid leukemia (AML) (continued on #2)
2. (continued from # 1) Potential risk: diagnosis of aggressive lymphoma/leukemia based on (REAL) classification. Plus one or more of the following criteria: lactate dehydrogenase (LDH) >/= 2 x upper limit of normal (ULN); Stage III-IV disease; Stage I-II disease with at least 1 lymph node/tumor >5cm in diameter.
3. ECOG performance status 0-3
4. Life expectancy >3 months
5. Negative pregnancy test (females of child bearing potential) within \

2 years, 1 month