Fixed-Dose Recombinant Urate Oxidase in the Treatment of Paediatric Tumour Lysis Syndrome: A Regional Cancer Centre Experience.

Background: Tumor lysis syndrome (TLS) is an oncologic emergency commonly seen in children with hemato-lymphoid malignancies. Recombinant urate oxidase (RUO) is used in both the prophylaxis and treatment of TLS. However, in resource-constrained countries, its role is mostly limited to the treatment of established TLS and data regarding the use of RUO and its outcome is sparse.

Objective: To describe the outcome of Pediatric TLS following the use of a fixed - dose of RUO.

Methods: A retrospective chart review of all children <15 years of age admitted in the Department of Paediatric Oncology, Kidwai Cancer Institute from April 2017 to July 2018 with TLS and treated with a single, fixed - dose (1.5 mg) RUO was undertaken.

Results: During the study period, 255 children with hemato-lymphoid malignancies were diagnosed to be at risk of developing TLS. Of these, only 22 (8.6%) children developed TLS and received RUO. Among those with TLS, 15 (68.2%) had Acute Lymphoblastic Leukemia (ALL) while 7 (31.8%) had Non - Hodgkin lymphoma (NHL). 91% (20/22) children had spontaneous TLS and the remainder developed therapy-related TLS. Median age at presentation was 8 years (IQR 5.25,1.75) with 4.5:1 male: female ratio. The mean urate level at admission was 19.12 mg/dl (+/- 8mg/dl) (Range: 10.7-34.5). 91% (20/22) children received RUO at less than 0.15 mg/kg and the median dose of RUO was 0.05 mg/kg (IQR 0.038-0.08). Of the 22 children with TLS, 2 children failed to achieve normal serum urate levels at 24 hours in response to a single fixed-dose of RUO and hence received an extra dose of RUO. Serum urate levels remarkably declined following RUO administration from 19.12 mg/dl (+/-8) to 8.2 mg/dl (+/-3.9), 3.99 mg/dl (+/-1.6) and 2.84 mg/dl (+/-1.3) at 12h, 24h and 48h respectively. AKI was present in 15 (68.2%) children. The median eGFR of the group at diagnosis was 49 ml/min/1.73m2 (IQR 26.3, 70). None of the children required hemodialysis. No significant adverse events occurred.

Conclusion: Fixed-dose RUO can achieve rapid, adequate and sustained drop in serum urate levels in Paediatric TLS. It is a useful strategy for managing TLS in resource-constrained settings.