ORIGINAL ARTICLE Low-dose Rasburicase in Hematologic Malignancies Somasundaram Jayabose & Vignesh Kumar & Rajeswari Dhanabalan & Priya Rajan & Krishnakumar Rathnam & T. Kasi Viswanathan Received: 10 June 2014 /Accepted: 30 September 2014 # Dr. K C Chaudhuri Foundation 2014 Abstract Objective To define the efficacy and safety of low-dose rasburicase in children from south India with hematologic malignancies. Methods This study is a retrospective analysis of data on 41 children with hematologic malignacies with laboratory evi- dence of tumor lysis syndrome (TLS) or clinical features indicating high risk for developing TLS. Patients were treated with rasburicase in doses of 0.1–0.15 mg/kg dose, repeated when necessary. Results Male : Female ratio was 32:9. Thirty-six children had laboratory evidence of TLS and 5 were at risk for TLS. Diagnoses were T-cell acute lymphoblastic leukemia (ALL), 19; Pre-B ALL, 17; B-non-Hodgkin lymphoma (NHL), 2; T- NHL, 2; and acute myeloid leukemia (AML), 1. Initial plasma uric acid (PUA): median, 8.5 mg/dl (range, 4.3 to 45.5). Six had creatinine levels of >2 mg/dl on admission; and 10 had peak PO 4 levels of >10 mg/dl. Dose of rasburicase used: median, 0.12 mg/kg (range, 0.08–0.24). Median reduction of PUA at 6 h: 80 % (range 40 to 98 %). Twenty-seven needed only one dose; 12 needed 2 or 3 doses; and two needed 5 doses each. One child required dialysis. None of the children developed anaphylaxis or hemolysis and there were no deaths from TLS. Conclusions Low-dose rasburicase (0.1–0.15 mg/kg) is safe and effective in reducing PUA in Indian children with lymphoid malignancies, and thus it may reduce the risk of renal failure from TLS. Keywords Rasburicase . Tumor lysis syndrome . Hyperuricemia . Hyperphosphatemia . Leukemia . Lymphoma Introduction Tumor lysis syndrome (TLS) is an important cause of mor- bidity and mortality in children with hematologic malignan- cies [1]. It is a medical emergency presenting with hyperuri- cemia, hyperkalemia, hyperphosphatemia and hypocalce- mia—resulting from the release of nucleic acids, phosphates and potassium from lysing malignant cells into the plasma [2, 3]. Central to its pathogensis is hyperuricemia (from the conversion of xanthine to uric acid), which results in acute kidney injury, limiting the clearance of uric acid, potas- sium and phosphates thus aggravating hyperkalemia and hyperphosphatemia [3]. Rasburicase is a recombinant urate oxidase, very effective in reducing plasma uric acid (PUA) and thus very useful in the prevention and treatment of TLS [4]. It breaks down the uric acid into allantoin which is more readily soluble than uric acid [5]. Thus, it is more effective than allopurinol, which only prevents the formation of more uric acid by inhibiting xan- thine oxidase, but does not breakdown the uric acid already formed [4]. Rasburicase has been well studied and is being widely used for more than a decade in the developed countries in patients at high-risk for TLS. It has been available in India for more than 2 years; yet its use has been limited by its high cost and thus there is only limited data about its use in Indian children [6]. Herein the authors retrospectively review their experience in using low-dose rasburicase (0.1–0.15 mg/kg) in children with hematologic malignancies. S. Jayabose : V. Kumar : R. Dhanabalan : P. Rajan : K. Rathnam : T. K. Viswanathan Division of Pediatric Hematology-Oncology, Meenakshi Mission Hospital & Research Centre, Lake Area, Melur Road, Madurai, Tamil Nadu, India S. Jayabose (*) Rutgers Cancer Institute of New Jersey, 195 Little Albany Street, New Brunswick, NJ 08901, USA e-mail: sjayabose@gmail.com Indian J Pediatr DOI 10.1007/s12098-014-1606-1