The optimal single-dose regimen of rasburicase for management of tumour lysis syndrome in children and adults: a systematic review and meta-analysis

Effectiveness of a Single Fixed Dose of 3 mg Rasburicase for the Prevention and Management of Hyperuricemia in Tumor Lysis Syndrome in Adults With Cancer

BACKGROUND

Tumor lysis syndrome (TLS) is a critical and potentially fatal complication linked to specific types of cancer. Rasburicase stands as a crucial medication necessary for the prevention and treatment of hyperuricemia, a condition commonly associated with TLS. Due to a shortage of rasburicase during the COVID-19 pandemic, a fixed-dose strategy of 3 mg rasburicase was used in many adult cancer patients in our center.

OBJECTIVE

The objective of this study was to assess the effectiveness of a fixed dose of 3 mg rasburicase in preventing and managing hyperuricemia associated with TLS in adult cancer patients.

METHODS

 We conducted a retrospective, observational cohort study between March 2020 and February 2022. The study included adult patients who received a fixed dose of 3 mg rasburicase. The primary outcome measure was the reduction in serum uric acid (UA) levels at 24 and 48 hours after treatment, with the aim of achieving and maintaining normal UA levels.

RESULTS

 Seventeen patients in the treatment group and 20 patients in the prevention group were included. In the treatment group, 15 (88%) patients had normalization of serum UA, which is considered to be <7 mg/dL (median: 4.48 mg/dL) at 24 hours, and 16 (94%) patients had achieved normal UA at 48 hours (median: 2.78 mg/dL) after receiving the rasburicase dose. In the prevention group, all 20 (100%) patients achieved normal UA at 24 hours after receiving the rasburicase dose.

CONCLUSION

Based on these findings, a single fixed dose of 3 mg rasburicase is effective for preventing and managing hyperuricemia associated with TLS in high-risk patients.

Unexpected Rasburicase-Induced Hemolysis in a Patient With Normal Glucose-6-Phosphate Dehydrogenase Activity

Tumor lysis syndrome (TLS) presents significant challenges in oncology, primarily due to metabolic complications such as hyperuricemia, which can lead to acute kidney injury. Rasburicase, a recombinant urate oxidase, is frequently employed to manage hyperuricemia in TLS patients. However, its use is an absolute contraindication in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency due to the risk of hemolysis. In this case, the patient developed hemolytic anemia post-rasburicase administration even though she had normal G6PD activity, which was confirmed on two separate occasions, including during an acute episode and 3 months later. This case is unique as it documents hemolytic anemia induced by rasburicase in a patient without G6PD deficiency, challenging current understandings of the drug's safety profile. It suggests the need for caution and thorough screening before rasburicase use, even in patients considered low risk for G6PD deficiency. The report highlights the importance of close monitoring for adverse effects and the potential for alternative mechanisms of rasburicase-induced hemolysis.

Rasburicase dose optimization for tumor lysis syndrome management in a network of community oncology practices

INTRODUCTION

Single, fixed-dose rasburicase administration has been evaluated as an effective strategy in the management of hyperuricemia in the hospital setting, but this has not yet been described within ambulatory community oncology practices. The objective of this study is to evaluate and optimize the dosing strategy for rasburicase in the management of tumor lysis syndrome (TLS)-associated hyperuricemia in The US Oncology Network (The Network).

METHODS

A network-wide guideline was revised to standardize rasburicase dosing from a previous recommended fixed doses of 4.5 or 7.5 mg to either 3 or 6 mg for outpatient rasburicase use in management and prevention of TLS. The primary outcome evaluated mean dose of rasburicase among all patients before and after guideline revision. A retrospective chart review evaluated secondary endpoints.

RESULTS

The primary analysis included 291 patients (128 pre-revised and 163 post-revised guideline implementation). The primary outcome, mean rasburicase dose, was reduced in the post-revision compared to the pre-revision population (mean 6.2 mg pre vs. 4.5 mg post, p < 0.00001) resulting in a reduced cost per rasburicase dose of $974. Fifty patients were included for the secondary analysis. Guideline concordance was identified in 12 (48%) and 16 patients (64%), and uric acid <8 mg/dL post-rasburicase administration occurred in 14 (56%) and 16 patients (64%) before and after guideline revision, respectively.

CONCLUSIONS

Guideline revision and electronic health record modification resulted in a 27% reduction in the mean rasburicase dose and a 50% reduction in repeat rasburicase dosing without a negative impact on clinical efficacy.

A retrospective review of rasburicase utilization in pediatric and adult patients across a large health system

PURPOSE

This study aimed to characterize rasburicase dosing and duration. Secondary objectives included characterizing the indication of rasburicase and identifying the utilization of prophylactic therapy for tumor lysis syndrome (TLS).

METHODS

This retrospective review included patients 0 to 89 years old admitted between 1 January 2021 and 31 December 2021, and received at least one dose of rasburicase. Patients were excluded if they were >89 years old, pregnant, lactating, or received rasburicase outpatient.

RESULTS

A total of 192 patients, 176 adults and 16 pediatric patients were included in the retrospective review. Of the total population, 184 received a fixed dose of rasburicase and 8 patients received a weight-based dose (0.15 mg/kg/dose) of rasburicase. The average dose administered was 3.4 mg for fixed and 2.99 mg for weight-based dosing. Nearly half (49.5%) the patients received rasburicase for an elevated uric acid but did not meet Cairo-Bishop criteria for TLS. Only 42.2% received at least one dose of allopurinol within 5 days prior to rasburicase and 18.8% received aggressive hydration within 72 h prior to rasburicase.

CONCLUSION

The majority of rasburicase administered was ordered as fixed dose for a uric acid level ≥7.5 mg/dL. Most patients did not meet criteria for laboratory or clinical TLS and less than half the patients received prophylactic allopurinol and/or aggressive hydration. These study results are supported by recent literature for fixed dose rasburicase as a safe and economical dosing strategy compared to weight-based dosing.

Expert consensus guidelines for the prophylaxis and management of tumor lysis syndrome in the United States: Results of a modified Delphi panel

INTRODUCTION

Tumor lysis syndrome (TLS), which occurs spontaneously or in response to anticancer treatment, results in the release of intracellular potassium, phosphorus, and nucleic acids into the bloodstream, which results in secondary clinical complications that may be fatal. Prior TLS guidelines do not take into consideration potent novel oncologic agents or contemporary treatment paradigms with increased risk of TLS. Thus, a modified Delphi panel of experts was convened to provide an update for TLS management guidelines based upon a combination of supporting literature and practice consensus.

METHODS

A three-round modified Delphi process was implemented. For round 1, nine expert panelists completed a web-based questionnaire developed using published literature. In round 2, panelists were asked to reconsider their answers to questions that did not reach consensus (defined as ≥ 66% agreement among voting panelists). Round 3 was an unblinded, moderated virtual meeting to discuss any remaining questions that did not reach consensus.

RESULTS

Detailed recommendations are given for prophylaxis, monitoring, and management of TLS risks and complications, with hydration being a key element of TLS prophylaxis and management. Guidelines for the management of acute effects of TLS and prevention of long-term renal effects include management of hyperkalemia, hypocalcemia, hyperphosphatemia, and hyperuricemia.

DISCUSSION

Although the control of uric acid levels is quite effective with currently available agents, panelists emphasize the importance of monitoring and treating other dangerous electrolyte abnormalities such as hyperkalemia and hyperphosphatemia. Guidelines from this modified Delphi panel should aid clinicians in preventing and managing TLS.

Rasburicase in treating tumor lysis syndrome: An umbrella review

Tumor lysis syndrome (TLS) remains a debilitating cause of hospitalization and death in patients with cancer and is a significant challenge for healthcare providers despite advancements in its management. This umbrella review analyzed the results of meta-analyses on the use of rasburicase in the treatment of patients with cancer. A literature search was performed of five databases (PubMed, Google Scholar, Cochrane Library, Scopus, Global Index Medicus, and ScienceDirect) for articles with full texts available online. A measurement tool to assess systematic reviews 2 (AMSTAR 2) was used to assess the quality of the included studies, and Review Manager software was used to conduct all statistical analyses. The systematic search identified eight relevant meta-analyses, with primary analyses including outcome data that analyzed mortality, renal failure, and comparisons with allopurinol. The pooled data showed that rasburicase effectively reduced TLS development and serum uric acid levels in children and adults with malignancies. Most outcomes did not differ significantly compared with those of allopurinol. Future trials should focus on the cost-effectiveness of rasburicase compared to that of allopurinol while including high-, intermediate-, and low-risk patients. Rasburicase is safe and effective for managing patients with TLS. However, recent large-scale meta-analyses have reported conflicting results. Most meta-analyses were graded as low to critically low as per AMSTAR 2. The analysis revealed that the benefit of rasburicase did not differ significantly from that of allopurinol, which has higher cost-effectiveness and fewer side effects.

Rescue Therapies for AKI in Onconephrology: Rasburicase and Glucarpidase

Tumor lysis syndrome (TLS) and high-dose methotrexate (HD MTX) toxicity can present with potentially severe complications, including acute kidney injury, in patients with malignancy. Guidelines for using rasburicase and glucarpidase as rescue therapies for TLS and HD MTX toxicity, respectively, are widely used by clinicians intending to mitigate organ toxicity and decrease morbidity and mortality as a consequence of cancer therapy. This review discusses the pathogenesis of TLS and HD MTX-associated toxicity, to understand the mechanism of action of these therapeutic agents and to review the currently available evidence supporting their use.

A phase II study to evaluate the efficacy of low-dose rasburicase (1.5mg) in adolescent and adult acute leukemia and high-grade lymphomas with tumor lysis syndrome

The FDA recommended dose of rasburicase 0.2 mg/kg/day till the resolution of TLS or up to 5 days, might be in excess and is prohibitively expensive. The quality of evidence supporting low dose rasburicase is limited. The objective is to study the plasma uric acid response rate. This is a single center, non-randomised phase II study. Duration is 10 June 2017 till 30 July 2019. Study setting is at Adult Hematolymphoid Unit, Tata Memorial Center. Participants are patients with acute leukemia and high-grade lymphomas aged >/=18 years, with ECOG PS of 0-3, with either laboratory or clinical TLS. Rasburicase was administered at fixed-dose of 1.5 mg. The subsequent doses (1.5 mg each dose) were administered only if plasma UA levels did not decline by >50% on day 2, at the physician's discretion. We demonstrate that a low-dose rasburicase strategy leads to rapid and sustained reductions of uric acid in about 52% patients.

Rasburicase-Induced Falsely Low Measurement of Uric Acid in Tumor Lysis Syndrome: A Report of Two Cases

Rasburicase, a recombinant urate-oxidase enzyme, can significantly catalyze the oxidation of uric acid to allantoin. It was approved by the US Food and Drug Administration (FDA) to control blood uric acid levels in both pediatric and adult patients especially those with tumor lysis syndrome. It is quite important to realize that rasburicase can continue to be effective ex vivo and cause falsely low results if the blood sample is not contained and transported in ice water immediately. We presented two cases of falsely low measurement of blood uric acid caused by rasburicase and elaborated the proper method for collecting and transporting blood samples from patients using rasburicase.

Effectiveness and Safety of Allopurinol, Febuxostat, and Rasburicase in the Prevention of Tumor Lysis Syndrome: A Systematic Review and Network Meta-analysis

Although prevention is vital in managing tumor lysis syndrome (TLS), no study directly compares various regimens. This study compared the effectiveness and safety of urate-lowering agents in preventing TLS. Databases were searched for randomized controlled trials involving adults with hematologic or solid malignancies on chemotherapy or cytoreductive agents given allopurinol, febuxostat, or rasburicase alone or in combination at any dose, form, or frequency published in English by December 2021. Outcomes included laboratory and clinical TLS expressed as relative risks, adverse events as described by authors, and mean serum uric acid (sUA) as mean differences of area under the curve. A network of meta-analysis and post-hoc meta-analysis based on TLS risk using a random-effects model was done using Stata 14.0 and Review Manager 5.3, respectively. Certainty of evidence was assessed using the GRADE approach. Three studies with a total of 633 participants given allopurinol, febuxostat, rasburicase, or rasburicase combined with allopurinol were included. Rasburicase is more effective than allopurinol in preventing laboratory TLS (relative risk: 0.51; 95% confidence interval [CI]: 0.32–0.81) based on moderate quality evidence. No significant differences were observed in clinical TLS. Adverse events were attributable to toxicities of chemotherapy. Rasburicase alone or in combination with allopurinol was better than allopurinol or febuxostat alone in reducing sUA level. Febuxostat is more effective than allopurinol in lowering sUA levels among patients at high-risk of TLS (mean difference −125.75; 95% CI: −223.47 to −28.02). Rasburicase may be the most effective agent in preventing laboratory TLS and maintaining low sUA levels.

Review of Hematological and Oncological Emergencies

Patients with hematological malignancies, both treated and untreated, or solid tumors undergoing treatment are at risk of life-threatening complications, which may present in the emergency department (ED). Such emergencies are diverse in etiology and often require prompt treatment. Traditional complications, such as febrile neutropenia, have had recent guideline updates, which incorporate new evidence and a new validated risk stratification tool. In addition, newer approaches to treatment, such as chimeric antigen receptor (CAR) T-cell therapy, are becoming more widely available and have unique associated toxicities. This review discusses the management of the following hematological and oncological emergencies likely to be encountered in the ED: febrile neutropenia, CAR T-cell toxicities, differentiation syndrome, tumor lysis syndrome, hypercalcemia of malignancy, and hyponatremia.

Management of Hyperleukocytosis in Childhood Acute Leukemia Without Leukapheresis and Rasburicase Prophylaxis

Indications of leukapheresis (LPh) and the prophylactic use of rasburicase in tumor lysis syndrome (TLS) of patients with acute leukemia with hyperleukocytosis are not clear. In this retrospective single-center pediatric study, the outcomes of patients with hyperleukocytosis were reviewed. There were 48 patients with acute lymphoblastic leukemia (ALL) and 13 patients with acute myeloblastic leukemia (AML). The treatment strategies included hyperhydration, allopurinol administration, strict monitoring, and early initiation of induction chemotherapy (CT). No patient underwent LPh because it was not available. Rasburicase was used only in 3 ALL patients with hyperuricemia when the drug was available. Laboratory and clinical TLS developed in 54.16% and 14.58% of patients with ALL, respectively. Laboratory and clinical TLS developed in 76.92% and 15.38% of patients with AML, respectively. No patient developed grade III to V TLS requiring dialysis. Thirteen patients (21.3%) had pulmonary leukostasis on admission, but recovered with CT and nasal oxygen. During the first 14 days of presentation, cerebral leukostasis/coagulopathy-related early death (ED) was 4.2% and 7.7% in patients with ALL and AML, respectively, and all of these patients had a white blood cell count ≥400,000/µL. There was also 1 infection-related death. Patients with hyperleukocytosis can be treated without LPh and liberal use of rasburicase. Renal failure is no longer a cause of ED. Intracranial hemorrhage is the main cause of ED, especially in patients already presenting with this complication. LPh may be performed in patients with leukostasis, if it is not possible to start induction CT early. When resources are limited, rasburicase should be administered in patients presenting with or developing hyperuricemia and/or renal dysfunction.

Single-Dose Rasburicase Might Be Adequate To Overcome Tumor Lysis Syndrome In Hematological Malignancies

INTRODUCTION

Tumor lysis syndrome (TLS) is a commonly observed oncological emergency that requires prompt diagnosis and treatment. Rasburicase is a recombinant urate oxidase endorsed in TLS for the treatment of hyperuricemia. The effect of single-dose 7.5 mg rasburicase at longer follow-ups was not widely investigated.

PATIENTS AND METHODS

Eighty-two patients included in the study with clinical TLS and laboratory TLS. The primary endpoint was the normalization of uric acid (<6mg/dL) within 24 hours of rasburicase administration, which was described as treatment success. The secondary endpoint was defined as having sustained response at the first week. The third endpoint was defined as the reaching the baseline renal function before TLS.

RESULTS

We found that the use of a 7.5 mg dose of rasburicase controlled uric acid in 74 of 82 (90,2%) patients at the 24th hour. In the first week, uric acid remained at normal levels in 69 of 82 (84,1%) patients. At 24 hours, the TLS risk group was the only predictor for failing uric acid normalization; at the end of the first week, no predictive factor was identified for failing uric acid normalization.

CONCLUSION

Rasburicase at 7.5 mg dose is an important agent for controlling laboratory and clinical TLS at 24 hours and extending its effect to the first week.

A retrospective observational study of a low fixed-dose rasburicase protocol for the treatment of tumor lysis syndrome in adults

INTRODUCTION

Tumor lysis syndrome is an oncologic emergency characterized by hyperuricemia. Previous studies have demonstrated that a fixed-dose strategy of rasburicase is as effective as the FDA approved weight-based dose. Albany Medical Center employs rasburicase 1.5 mg in patients with a uric acid (UA) between 8 and 12 mg/dL and 3 mg for UA above12 mg/dL.We aimed to evaluate the UA lowering effectiveness and provider adherence to the institutional protocol, as well as the cost-efficiency of this dosing strategy.

METHODS

This is a single center, retrospective, cohort study. The electronic medical record was used to identify patients receiving rasburicase and to collect baseline demographic and laboratory data. The fixed-dose strategies of rasburicase 1.5 mg and 3 mg were compared in their degree of UA reduction and clinical outcomes. Cost-savings of fixed-dosing was compared to the FDA-approved weight-based dose.

RESULTS

Mean UA reduction in the 1.5 mg group (n = 49) from baseline to 24 hours was 2.88 ± 0.88 mg/dL (p < 0.0001) and 4.83 ± 1.39 mg/dL (p < 0.0001) in the 3 mg group (n = 105). A subgroup analysis of patients who received per protocol initial doses of rasburicase showed a mean reduction in UA from baseline to 24 hours of 2.83 ± 0.62 mg/dL in the 1.5 mg group (n = 42) and 6.12 ± 1.87 mg/dL in the 3 mg group (n = 42). Using a low fixed-dose approach resulted in a cost-savings of $138,077.30 annually.

CONCLUSION

Low fixed-dose rasburicase was an effective treatment, with a dose of 1.5 mg being sufficient to reach a goal UA of less than 8 mg/dL for serum UA levels below 12 mg/dL, while a 3 mg dose is appropriate for levels above 12 mg/dL. Cost analysis indicates this strategy is more cost-efficient than the FDA-approved weight-based dose.

A phase 2 trial of single low doses of rasburicase for treatment of hyperuricemia in adult patients with acute leukemia

BACKGROUND

Rasburicase can markedly and rapidly decrease uric acid (UA) levels, thereby preventing and treating tumor lysis syndrome. However, rasburicase is expensive, especially when used as per the manufacturer's recommended dosage of 0.2 mg/kg/day for up to 5 days. Numerous reports have shown that lower, and even single doses are effective in lowering UA levels but prospective randomized studies comparing low doses have not been performed.

OBJECTIVES

To prospectively determine the efficacy and safety of two single low doses of rasburicase in adult patients (pts) with acute leukemia and elevated plasma UA.

METHODS

Eligible pts aged ≥ 18 years old with acute leukemia and UA ≥ 7.5 mg/dL were randomized to receive an initial single dose of rasburicase 1.5 mg (Arm A) or 3 mg (Arm B) on day 1 in an unblinded fashion. All pts received allopurinol 300 mg daily on days 1-6.

RESULTS

Twenty-four pts (median age 69 years; 14 males and 10 females) were enrolled in this phase 2 study (12 on each arm). Twenty pts had acute myeloid leukemia while 3 had acute lymphoblastic leukemia, and 1 had acute promyelocytic leukemia. Median initial UA level was 9.8 mg/dL. Eighty-three percent of pts in both arms achieved UA < 7.5 mg/dL by 24 h after therapy. Five pts (21 %; 2 from Arm A and 3 from Arm B) required additional doses of rasburicase. The majority (23/24) of pts achieved UA goals after 1-2 doses of rasburicase. None had worsening renal function. Both doses were well tolerated, and no treatment related adverse events were reported.

CONCLUSIONS

Single doses of rasburicase (as low as 1.5-3 mg) used in addition to allopurinol were well tolerated and highly efficacious (83 % response rate) in decreasing UA levels within 24 h of administration in adult acute leukemia pts with hyperuricemia.

Efficacy of Single Low-Dose Rasburicase in Management of Tumor Lysis Syndrome in Leukemia and Lymphoma Patients

BACKGROUND

Tumor lysis syndrome (TLS) is a metabolic emergency in hematology patients. The recommended dose of rasburicase for the management of TLS is 0.2 mg/kg per day for 5 days, which is cost prohibitive for many patients. We sought to determine the efficacy of single low-dose rasburicase in the prevention and treatment of hyperuricemia in TLS.

PATIENTS AND METHODS

We planned a prospective study for the safety and efficacy of fixed (weight based) dose of rasburicase to manage TLS. Patients diagnosed with leukemia/lymphoma with laboratory or clinically confirmed TLS or presence of ≥ 2 high-risk factors and serum uric acid > 7.5 mg/dL were included. The primary endpoint was uric acid normalization (< 7.5 mg/dL) within 24 hours of rasburicase administration.

RESULTS

Fifty-five patients were recruited for this study. Pediatric patients (< 18 years) accounted for 43.6% of cases. Rasburicase was provided prophylactically to 43 patients (78.2%) and for treating TLS to 12 (21.8%). Mean ± standard deviation serum uric acid at baseline and 24 hours was 9.2 ± 1.8 mg/dL and 3.2 ± 2.1 mg/dL, respectively. There was significant reduction in the serum uric acid and creatinine (P < .001) within 24 hours of rasburicase administration. The response was maintained up to 72 hours. A single dose of rasburicase was effective in 94.5% of patients. Single low-dose rasburicase led to 95% direct cost savings compared to the recommended dose.

CONCLUSION

Single-dose rasburicase with frequent laboratory monitoring is effective in the management of TLS and offers significant cost reductions.

Prevention and Treatment of Tumor Lysis Syndrome in the Era of Onco-Nephrology Progress

Background: Tumor lysis syndrome (TLS) is an oncologic emergency due to a rapid break down of malignant cells usually induced by cytotoxic therapy, with hyperuricemia, hyperkalemia, hyperphosphatemia, hypocalcemia, and serious clinical consequences such as acute renal injury, cardiac arrhythmia, hypotension, and death. Rapidly expanding knowledge of cancer immune evasion mechanisms and host-tumor interactions has significantly changed our therapeutic strategies in hemato-oncology what resulted in the expanding spectrum of neoplasms with a risk of TLS. Summary: Since clinical TLS is a life-threatening condition, identifying patients with risk factors for TLS development and implementation of adequate preventive measures remains the most critical component of its medical management. In general, these consist of vigilant laboratory and clinical monitoring, vigorous IV hydration, urate-lowering therapy, avoidance of exogenous potassium, use of phosphate binders, and – in high-risk cases – considering cytoreduction before the start of the aggressive agent or a gradual escalation of its dose. Key Messages: In patients with a high risk of TLS, cytotoxic chemotherapy should be given in the facility with ready access to dialysis and a treatment plan discussed with the nephrology team. In the case of hyperkalemia, severe hyperphosphatemia or acidosis, and fluid overload unresponsive to diuretic therapy, the early renal replacement therapy (RRT) should be considered. One must remember that in TLS, the threshold for RRT initiation may be lower than in other clinical situations since the process of cell breakdown is ongoing, and rapid increases in serum electrolytes cannot be predicted.

Rasburicase in hemolytic uremic syndrome related to Shiga toxin-producing Escherichia coli: a report of nine cases

BACKGROUND

Hyperuricemia might induce additional renal damage in children with hemolytic uremic syndrome related to Shiga toxin-producing Escherichia coli (STEC-HUS). A few case reports have shown rasburicase to be effective in decreasing serum uric acid (UA) and improving renal function. However, there is only one report on the use of rasburicase in a child with STEC-HUS, which shows satisfactory results. We describe here the safety and efficacy of rasburicase in nine additional cases.

CASE-DIAGNOSIS/TREATMENT

Data from 9 children (5 females, median age 2 years) who received rasburicase were reviewed. At admission, 6 were dehydrated and 3 euvolemic. Dehydrated patients received saline solution and afterwards, as well as for those initially euvolemic, we aimed to keep a neutral fluid balance. Despite this, urine output did not increase. Baseline creatinine was 3.35 mg/dL (1.47-9.1) and UA 11.4 mg/dL (8.3-19.2). A single dose of rasburicase (0.2 mg/kg) was given 6-8 h after admission, which reduced UA levels to 1.8 mg/dL (0.3-5, p = 0.009) on the next day. However, renal parameters worsen and dialysis had to be initiated. Then, while still on dialysis, a UA rebound occurred in all cases reaching a peak of 8.9 mg/dL (4.5-13.8). Just after a steady increase in urine output, a sustained decline in UA levels concomitantly occurred with an improvement in renal function. At discharge, all patients reached normal UA levels. No side effects were recorded.

CONCLUSIONS

Administration of rasburicase in children with STEC-HUS was safe but failed to provide any significant benefit despite fall in serum UA levels.

Recent approaches to gout drug discovery: an update

INTRODUCTION

Inflammation induced by urate deposition in joints causes gout. Healthy individuals maintain serum levels of urate by balancing urate production/excretion, whereas a production/excretion imbalance increases urate levels. Hyperuricemia is diagnosed when the serum urate level is continuously above 7 mg/dl as the solubility limit, and urate accumulates in the kidneys and joints. Because hyperuricemia increases the risk of gout, therapies aim to eliminate urate deposition to prevent gouty arthritis and kidney injury.

AREAS COVERED

This review discusses the mechanism underlying hyperuricemia with respect to urate production and urate transport, along with urate-lowering therapeutics, including urate synthesis inhibitors, uricolytic enzymes, and uricosuric agents. The authors asses published data on relevant commercial therapy development projects and clinical trials.

EXPERT OPINION

Available treatment options for hyperuricemia are limited. Allopurinol, a urate synthesis inhibitor, is generally administered at a reduced dosage to patients with renal impairment. Some URAT1 inhibitors have an unfavorable side effect profile. A promising strategy for treatment is the use of uricosuric agents that inhibit transporters (e.g. URAT1, URATv1/GLUT9, OAT10) which reabsorb urate from the urine.

Impact of early rasburicase on incidence of clinical tumor lysis syndrome in lymphoma

Early administration of rasburicase to enhance uric acid (UA) elimination has been adopted without robust evidence in support of its impact on clinical outcomes in tumor lysis syndrome (TLS), specifically, the prevention of acute kidney injury (AKI). This was a retrospective cohort study of adult lymphoma patients at intermediate or high risk for TLS. Excluded patients had AKI or were on dialysis at hospital admission. The incidence of new AKI in the setting of TLS was described along with predictors of its development, including early rasburicase use. In 383 included patients, the incidence of new-onset AKI during hospitalization was 6%. Predictors included age, history of renal or cardiovascular disease, and UA >8 mg/dL. Rasburicase use did not significantly impact the risk of developing AKI (HR 2.3; p = .11). The UA level at the time of administration did not modify the effect of rasburicase on prevention of AKI (p = .36 for the interaction term).

A retrospective analysis of tumor lysis syndrome management in a quaternary care hospital

PURPOSE

Due to an increased use of rasburicase, the study's purpose was to evaluate both the management of tumor lysis syndrome and the utilization of rasburicase in the hospital system. Additionally, the efficacy of flat dose rasburicase in lowering uric acid levels was evaluated. Based on the study's findings, the investigators will evaluate the usefulness of implementing a tumor lysis syndrome order set.

METHODS

This study evaluated patients from January 2013 through December 2016 for the rasburicase dose and the tumor lysis syndrome therapy administered.

RESULTS

Overall, 251 patients were included: prophylactic rasburicase group (n = 125) vs. treatment rasburicase group (n = 126) and of rasburicase 3 mg (R3) group (n = 168) vs. 6 mg (R6) group (n = 83). The prophylactic rasburicase vs. treatment rasburicase group had a significantly lower rate of receiving a xanthine oxidase inhibitor (48.0% vs. 64.3%, p = 0.009), a phosphate binder (6.4% vs. 17.5%, p = 0.007) and an additional dose of rasburicase (20.8% vs. 41.3%, p = 0.001). Intravenous hydration was neither significantly different between the rasburicase groups (p = 0.399) nor between the two rasburicase dosing groups (p = 0.874). Between the rasburicase dosing groups, there was no significant difference in the rate of receiving a xanthine oxidase inhibitor (p = 0.521) or a phosphate binder (p = 0.390). R6 patients had a significantly greater reduction in uric acid change compared to R3 patients (median = -7.9 (-10.1, -5.5) vs. -4.3 (-6.0, -2.7), p < 0.0001). There was no significant difference in uric acid change between the prophylactic rasburicase and treatment rasburicase groups (p = 0.875).

CONCLUSION

The study's findings justified the need to implement a tumor lysis syndrome order set. In the study population, utilizing a flat dosing method was effective for hyperuricemia.

Update on the prevention and treatment of tumor lysis syndrome

Tumor lysis syndrome is a constellation of metabolic derangements seen when tumor cells die and release their intracellular contents into the systemic circulation. Hyperkalemia, hyperphosphatemia, hypocalcemia, and hyperuricemia may lead to severe organ dysfunction and even death. Tumor lysis syndrome is classically considered a complication of successful cancer treatment, but it can also occur in untreated malignancies characterized by rapid proliferation. In this review, we cover the types of cancers and chemo- and immunotherapies associated with tumor lysis syndrome, the mechanisms by which severe metabolic derangements can develop, and the available treatments.

A cost comparison of rasburicase versus dialysis in the management of children with acute leukaemia and lymphoma at a South African centre

Background: Tumour lysis syndrome is a common complication of haematological malignancies and has historically been managed with hyperhydration, urine alkalinisation and allopurinol with renal dialysis reserved for patients in acute renal failure. Rasburicase has been shown to drastically reduce the need for dialysis; however, its use is limited in developing countries owing to its cost and availability.Aim: This retrospective analysis aimed to compare the cost to state per patient of rasburicase compared to dialysis in the management and prevention of tumour lysis syndrome in paediatric patients presenting with haematological malignancies admitted to Red Cross War Memorial Children’s Hospital (RCWMCH).Setting: Red Cross War Memorial Children’s Hospital.Methods: Patients from two consecutive 35 month periods, before and after the availability of rasburicase at RCWMCH, were grouped according to treatment modality, and the cumulative costs of hospitalisation, dialysis and drug administration were compared.Results: The groups were comparable in mean age and gender. The mean total length of hospital stay was 10.04 days shorter for the rasburicase group than the dialysis group with the average cost per patient in the rasburicase group being R40 989.64 lower than the dialysis group.Conclusion: The use of rasburicase results in a significant per patient cost saving when compared to dialysis, which often requires intensive care admission, and results in extended hospitalisation. The study supports the continued use of rasburicase as an essential adjunct in the management and prevention of tumour lysis syndrome, reaffirming its use as a cost-effective and efficient drug.

Rasburicase-induced Hemolytic Anemia in an Adolescent With Unknown Glucose-6-Phosphate Dehydrogenase Deficiency

Rasburicase, used in the prevention and treatment of tumor lysis syndrome (TLS), may cause hemolytic anemia and methemoglobinemia in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency. Although routine screening for G6PD deficiency has been recommended, given the turnaround time for test results and the urgency to treat TLS, such screening may not be feasible. We report a case of rasburicase-induced hemolytic anemia without methemoglobinemia in an adolescent with T-cell lymphoblastic lymphoma, TLS, and previously unrecognized G6PD deficiency. Previous reports of hemolytic anemia with rasburicase are reviewed, mechanisms discussed, and preventative strategies presented.