Elitek (Rasburicase) Immuno-Monitoring Study

Inclusion criteria: 1. Previous history of rasburicase exposure and history of administration of a repeat (2nd) series of rasburicase injections (in the context of supportive care for relapsing leukemia/lymphoma) and subsequent development of either a hypersensitivity reaction (HSR) or loss of uricolytic activity (defined as failure to achieve uric acid level of \< or = 7.5 mg/dl measured 48 hours after the first rasburicase injection). 1. A severe hypersensitivity reaction (NCI Grade 3, 4 or 5) is defined as: Allergic reaction; allergy; anaphylactic shock; bronchospasm; bullous skin eruption; dermatitis - exfoliative; drug hypersensitivity; dyspnea; hypotension; hypoxia; rash; rash - erythematous; rash - maculopapular, urticaria; pyrexia/fever; edema; chest discomfort; hypersensitivity (NOS); pharynx discomfort; hoarseness; pharyngeal erythema; pruritus; erythema; localized exfoliation; rash - papular; swelling ¿ face/facial; toxic skin eruption; hot flush; flushing; rash - macular; rash - pruritic; pruritus - allergic. 2. Loss of uricolytic activity can be defined as: * uric acid levels \> 7.5 mg/dl measured 48 hours after the first rasburicase injection¿, which is a time point coincident with administration of the third dose of rasburicase (within that second course of treatment with this agent). 2. Patients should have received at least 2 doses of rasburicase during the repeat (2nd) administration in the event of loss or uricolytic activity. At least 1 dose of rasburicase should be administered during the repeat (2nd) administration for diagnosis of HSR. Exclusion criteria: 1. Concomitant treatment with human IV immunoglobulin (IVIG) 2. Concomitant treatment with TNF-alpha antagonists/inhibitors, i.e. adalimumab, infliximab, and etanercept 3. Concomitant treatment with Interferon-alpha (IFN-alpha) 4. Unwillingness or inability to comply with the requirements of the protocol. The above information is not intended to contain all considerations relevant to a patient's potential participation in a clinical trial.