The COMPARE head-to-head, randomized controlled trial of SEL-212 (pegadricase plus rapamycin-containing nanoparticle, ImmTOR™) versus pegloticase for refractory gout

OBJECTIVES

Serum urate (SU) lowering with PEGylated uricases in gout can reduce flares and tophi. However, treatment-emergent anti-drug antibodies adversely affect safety and efficacy and the currently approved PEGylated uricase pegloticase requires twice-monthly infusions. Investigational SEL-212 therapy aims to promote uricase-specific tolerance via monthly sequential infusions of a proprietary rapamycin-containing nanoparticle (ImmTOR) and pegadricase.

METHODS

COMPARE was a randomized, phase 2, open-label trial of SEL-212 vs pegloticase in adults with refractory gout. SEL-212 [ImmTOR (0.15 mg/kg) and pegadricase (0.2 mg/kg)] was infused monthly or pegloticase (8 mg) twice monthly for 6 months. The primary endpoint was the proportion of participants with SU <6 mg/dl for ≥80% of the time during 3 and 6 months. Secondary outcomes were mean SU, gout flares, number of tender and/or swollen joints and safety.

RESULTS

During months 3 and 6 combined, numerically more participants achieved and maintained a SU <6 mg/dl for ≥80% of the time with SEL-212 vs pegloticase (53.0% vs 46.0%, P = 0.181). The percentage reductions in SU levels were statistically greater during months 3 and 6 with SEL-212 vs pegloticase (-73.79% and -47.96%, P = 0.0161). Reductions in gout flare incidence and number of tender and/or swollen joints were comparable between treatments. There were numerical differences between the most common treatment-related adverse events of interest with SEL-212 and pegloticase: gout flares (60.2% vs 50.6%), infections (25.3% vs 18.4%) and infusion-related reactions (15.7% vs 11.5%), respectively. Stomatitis (and related terms) was experienced by eight participants (9.6%) with SEL-212 and none with pegloticase. Stomatitis, a known event for rapamycin, was associated with ImmTOR only.

CONCLUSIONS

SEL-212 efficacy and tolerability were comparable to pegloticase in refractory gout. This was associated with a substantial reduction in treatment burden with SEL-212 due to decreased infusion frequency vs pegloticase.

CLINICAL TRIAL REGISTRATION

NCT03905512.

Use of rasburicase to improve kidney function in children with hyperuricemia and acute kidney injury

BACKGROUND

Hyperuricemia contributes to decrease in kidney function and induces additional renal damage in children with acute kidney injury (AKI). Rasburicase oxidizes uric acid (UA), decreasing its serum quantities in less than 24 h.

METHODS

This is a retrospective study involving hospitalized patients under 18 years of age with underlying pathology diagnosed with AKI and severe hyperuricemia treated with rasburicase over a 4-year period.

RESULTS

We describe 15 patients from 4 days of life to 18 years (median: 4.4 years). Seventy-three percent had known underlying pathologies. All presented worsening of basal renal function or AKI data. All received the usual medical treatment for AKI without response. Twenty percent received an extrarenal depuration technique. All had hyperuricemia with a mean (± SD) of 13.1 (± 2.19) mg/dl. After rasburicase administration UA levels fell to a mean (± SD) of 0.76 (± 0.62) mg/dl (p < 0.001) in less than 24 h. In parallel, a decrease in the mean plasma creatinine was observed (2.92 mg/dl to 1.93 mg/dl (p = 0.057)) together with a significant improvement of the mean glomerular filtration rate (16.3 ml/min/1.73 m2 to 78.6 ml/min/1.73 m2) (p = 0.001)). No side effects were recorded. Kidney function normalized in all cases or returned to baseline levels.

CONCLUSIONS

Although the use of rasburicase is not routinely approved in pediatric patients with severe hyperuricemia and AKI, it has been used successfully without complications, and helped prevent progressive kidney damage. This study could serve as a basis for suggesting the off-label use of rasburicase for the management of complex pediatric patients in whom UA plays an important role in the development of AKI.

Survey of Anaphylaxis during Rasburicase Re-Administration in Patients with Hematological Malignancies Using a Japanese Claims Database

Management of tumor lysis syndrome (TLS) associated with cancer chemotherapy for malignant tumors is important because of its potentially fatal course. The use of rasburicase, a recombinant urate oxidase, is recommended for TLS; however, because rasburicase is an enzymatic drug, one should be cautious of anaphylaxis during administration. Using claims data in Japan, we investigated the rate of rasburicase re-administration and the occurrence of anaphylaxis during re-administration in patients with hematopoietic malignancies in a multicenter setting. Re-administration of rasburicase was defined as administration after an interval of 21 days from the first dose. Of 373 patients, 18 were re-administered rasburicase (re-administration rate: 4.8%). No patient developed anaphylaxis. The median number of days from the first to the last dose of rasburicase was 256.5 days (interquartile range: 138.8-455.8 days). The median daily dose was 7.5 mg (4.5-11.3 mg), and the median total dose was 33.8 mg (19.1-64.1 mg). This claims database analysis revealed that the re-administration rate of rasburicase was low in Japanese patients with hematopoietic malignancies, suggesting that rasburicase was being used appropriately, and that associated anaphylaxis was not observed.

Rasburicase-induced Methemoglobinemia: A Case Report and Literature Review

Rasburicase is a recombinant urate oxidase enzyme indicated for tumor lysis syndrome, a potential life-threatening oncologic emergency that occurs most commonly during initial chemotherapy for hematological malignancies. As a result of the defects in the physiological antioxidant pathway, erythrocytes of patients with glucose-6-phosphate dehydrogenase deficiency are not protected against the oxidizing stress exerted by hydrogen peroxide generated with the administration of rasburicase. The authors report a 14-year-old patient, diagnosed with T-cell acute lymphoblastic leukemia, who developed methemoglobinemia and hemolytic anemia with low oxygen saturation after starting steroids, hyperhydratation, and rasburicase administration. The complications resolved with supportive therapy only.

Real-world patterns of pegloticase use for treatment of gout: descriptive multidatabase cohort study

OBJECTIVE

Pegloticase is used in severe refractory gout or in cases of intolerance to other urate-lowering therapies. We sought to evaluate the patterns of pegloticase use in the USA and the incidence of safety outcomes.

METHODS

We conducted a retrospective descriptive study using data from two US commercial insurance claims databases (2010-2018). We identified new initiators of pegloticase with ≥1 gout diagnosis code in the 365-day baseline period prior to pegloticase initiation. We measured the number and duration of pegloticase infusions. We assessed the risk of anaphylaxis or anaphylactoid reactions, cardiovascular events, including myocardial infarction or stroke, and hospitalisation for heart failure (new onset or exacerbations) while undergoing pegloticase therapy.

RESULTS

Among 2.9 million patients with ≥1 diagnosis of gout, we identified only 483 (179 in Optum and 304 in MarketScan) pegloticase initiators. The mean age and % female was 55.6 years, 10.9% for MarketScan and 60.6 years and 17.3% for Optum. Hypertension was present in up to 85%, diabetes mellitus in 38%, chronic kidney disease in 46% and heart failure in 21% of the patients. The median number of infusions was four and the duration of therapy was 3 months. During the mean 0.5-year follow-up time on pegloticase, there were 3 (0.6%) anaphylaxis, 7 (1.4%) composite cardiovascular, 31 (6.4%) heart failure hospitalisations and 3 (0.6%) deaths.

CONCLUSION

Pegloticase is rarely used in gout, and the median duration of pegloticase therapy was 3 months. There were few anaphylaxis events captured in this claims-based study, while heart failure hospitalisations were common.

Pegloticase hypersensitivity desensitisation: an outpatient, 3-bag, 12-step protocol

Pegloticase is a highly effective treatment for refractory gouty arthropathy. Unfortunately, the medication is also highly immunogenic, leading to infusion reactions, loss of drug efficacy and anaphylaxis. Desensitisation, a procedure to tolerise a patient to a medication previously causing a hypersensitivity reaction, has been used successfully in oncology for chemotherapy treatment. The same principle can be applied to other specialties. Presented is a 48-year-old man who experienced multiple, severe infusion reactions to pegloticase administered for gouty arthropathy. A rapid desensitisation was performed using an outpatient, 3-bag, 12-step protocol, which allowed multiple additional pegloticase infusions to be performed without incident. This is the first reported case of a patient successfully desensitised after an infusion reaction to pegloticase. Though additional patients are needed to confirm these results, this represents a significant opportunity to recapture and continue pegloticase therapy in patients treated for refractory gouty arthropathy.

Urate oxidase for the prevention and treatment of tumour lysis syndrome in children with cancer

BACKGROUND

Tumour lysis syndrome (TLS) is a serious complication of malignancies and can result in renal failure or death. Preliminary reports suggest that urate oxidase is effective in reducing serum uric acid, the build-up of which causes TLS. It is uncertain whether high-quality evidence exists to support its routine use in children with malignancies.

OBJECTIVES

To assess the effects and safety of urate oxidase for the prevention and treatment of TLS in children with malignancies.

SEARCH METHODS

This is an update of the original review. We performed a comprehensive search of the Cochrane Central Register of Controlled Trials (CENTRAL) (in The Cochrane Library issue 1, 2013), MEDLINE (1966 to February 2013), Embase (1980 to February 2013), and CINAHL (1982 to February 2013). In addition, we searched the reference lists of all identified relevant papers. We also explored other internet sources (updated search on 26 February 2013): the NHS' National Research Register, the US National Institutes of Health Ongoing Trials Register, the metaRegister of Controlled Trials, and ProQuest Dissertations & Theses Database. We also screened conference proceedings of the American Society of Clinical Oncology, the European Society for Medical Oncology, and the International Society of Paediatric Oncology meetings from 1993 to 2012. Finally, we contacted experts in the field and the manufacturer of rasburicase, Sanofi-aventis.

SELECTION CRITERIA

Randomised controlled trials (RCT) and controlled clinical trials (CCT) of urate oxidase for the prevention or treatment of TLS in children under 18 years with any malignancy.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted trial data and assessed individual trial quality. We used risk ratios (RR) for dichotomous data and mean difference (MD) for continuous data.

MAIN RESULTS

We included seven trials, involving 471 participants in the treatment groups and 603 participants in the control groups. One RCT and five CCTs compared urate oxidase and allopurinol. Three trials tested Uricozyme, and three trials tested rasburicase for the prevention of TLS.The RCT showed no significant difference in mortality (both all-cause mortality and mortality due to TLS), renal failure, and adverse effects between the treatment and the control groups. The frequency of normalisation of uric acid at four hours (Fisher's exact test P < 0.001) and area under curve of uric acid at four days (MD -201.00 mg/dLhr, 95% confidence interval (CI) -258.05 mg/dLhr to -143.95 mg/dLhr; P < 0.00001) were significantly better in the treatment group. The trial did not evaluate the primary outcome (incidence of clinical TLS).Pooled results of three CCTs showed significantly lower mortality due to TLS in the treatment group (RR 0.05, 95% CI 0.00 to 0.89; P = 0.04); all-cause mortality was not significantly different between the groups. Pooled results from five CCTs showed significantly lower incidence of renal failure in the treatment group (RR 0.26, 95% CI 0.08 to 0.89; P = 0.03). Results of CCTs also showed significantly lower uric acid in the treatment group at two days (three CCTs), three days (two CCTs), four days (two CCTs), and seven days (one CCT) after therapy, but not one day (three CCTs), five days (one CCT), and 12 days (one CCT) after therapy. Pooled results from three CCTs showed higher frequency of adverse effects in participants who received urate oxidase (RR 9.10, 95% CI 1.29 to 64.00; P = 0.03). One CCT evaluated the primary outcome; no significant difference was identified.Another included RCT, with 30 participants, compared different doses of rasburicase (0.2 mg/kg versus 0.15 mg/kg), which demonstrated no significant difference in uric acid normalisation and uric acid level at four hours). Common adverse events of urate oxidase included hypersensitivity, haemolysis, and anaemia, but no significant difference between treatment groups was identified. No significant difference in mortality (all-cause mortality and mortality due to TLS) and renal failure was identified. The primary outcome was not evaluated.All included trials were highly susceptible to biases.

AUTHORS' CONCLUSIONS

Although urate oxidase might be effective in reducing serum uric acid, it is unclear whether it reduces clinical tumour lysis syndrome, renal failure, or mortality. Adverse effects might be more common for urate oxidase compared with allopurinol. Clinicians should weigh the potential benefits of reducing uric acid and uncertain benefits of preventing mortality or renal failure from TLS against the potential risk of adverse effects.

Urate oxidase for the prevention and treatment of tumour lysis syndrome in children with cancer

BACKGROUND

Tumour lysis syndrome (TLS) is a serious complication of malignancies and can result in renal failure or death. Preliminary reports suggest that urate oxidase is effective in reducing serum uric acid, the build-up of which causes TLS. It is uncertain whether high-quality evidence exists to support its routine use in children with malignancies.

OBJECTIVES

To assess the effects and safety of urate oxidase for the prevention and treatment of TLS in children with malignancies.

SEARCH METHODS

This is an update of the original review. We performed a comprehensive search of the Cochrane Central Register of Controlled Trials (CENTRAL) (in The Cochrane Library issue 1, 2013), MEDLINE (1966 to February 2013), Embase (1980 to February 2013), and CINAHL (1982 to February 2013). In addition, we searched the reference lists of all identified relevant papers. We also explored other internet sources (updated search on 26 February 2013): the NHS' National Research Register, the US National Institutes of Health Ongoing Trials Register, the metaRegister of Controlled Trials, and ProQuest Dissertations & Theses Database. We also screened conference proceedings of the American Society of Clinical Oncology, the European Society for Medical Oncology, and the International Society of Paediatric Oncology meetings from 1993 to 2012. Finally, we contacted experts in the field and the manufacturer of rasburicase, Sanofi-aventis.

SELECTION CRITERIA

Randomised controlled trials (RCT) and controlled clinical trials (CCT) of urate oxidase for the prevention or treatment of TLS in children under 18 years with any malignancy.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted trial data and assessed individual trial quality. We used risk ratios (RR) for dichotomous data and mean difference (MD) for continuous data.

MAIN RESULTS

We included seven trials, involving 471 participants in the treatment groups and 603 participants in the control groups. One RCT and five CCTs compared urate oxidase and allopurinol. Three trials tested Uricozyme, and three trials tested rasburicase for the prevention of TLS.The RCT showed no significant difference in mortality (both all-cause mortality and mortality due to TLS), renal failure, and adverse effects between the treatment and the control groups. The frequency of normalisation of uric acid at four hours (Fisher's exact test P < 0.001) and area under curve of uric acid at four days (MD -201.00 mg/dLhr, 95% confidence interval (CI) -258.05 mg/dLhr to -143.95 mg/dLhr; P < 0.00001) were significantly better in the treatment group. The trial did not evaluate the primary outcome (incidence of clinical TLS).Pooled results of three CCTs showed significantly lower mortality due to TLS in the treatment group (RR 0.05, 95% CI 0.00 to 0.89; P = 0.04); all-cause mortality was not significantly different between the groups. Pooled results from five CCTs showed significantly lower incidence of renal failure in the treatment group (RR 0.26, 95% CI 0.08 to 0.89; P = 0.03). Results of CCTs also showed significantly lower uric acid in the treatment group at two days (three CCTs), three days (two CCTs), four days (two CCTs), and seven days (one CCT) after therapy, but not one day (three CCTs), five days (one CCT), and 12 days (one CCT) after therapy. Pooled results from three CCTs showed higher frequency of adverse effects in participants who received urate oxidase (RR 9.10, 95% CI 1.29 to 64.00; P = 0.03). One CCT evaluated the primary outcome; no significant difference was identified.Another included RCT, with 30 participants, compared different doses of rasburicase (0.2 mg/kg versus 0.15 mg/kg), which demonstrated no significant difference in uric acid normalisation and uric acid level at four hours). Common adverse events of urate oxidase included hypersensitivity, haemolysis, and anaemia, but no significant difference between treatment groups was identified. No significant difference in mortality (all-cause mortality and mortality due to TLS) and renal failure was identified. The primary outcome was not evaluated.All included trials were highly susceptible to biases.

AUTHORS' CONCLUSIONS

Although urate oxidase might be effective in reducing serum uric acid, it is unclear whether it reduces clinical tumour lysis syndrome, renal failure, or mortality. Adverse effects might be more common for urate oxidase compared with allopurinol. Clinicians should weigh the potential benefits of reducing uric acid and uncertain benefits of preventing mortality or renal failure from TLS against the potential risk of adverse effects.

Pegloticase. An excessively dangerous and inadequately evaluated hypouricaemic drug

When severe gout with tophi persists despite treatment with allopurinol, a xanthine oxidase inhibitor, the hypouricaemic drug of choice is probenecid, a uricosuric agent, in the absence of a better alternative. Pegloticase is a pegylated recombinant uricase. This enzyme catabolises uric acid into allantoin, a water-soluble substance that is excreted by the kidneys. Pegloticase has been granted EU marketing authorisation in patients who continue to have severe gout attacks despite treatment with a xanthine oxidase inhibitor such as allopurinol. Pegloticase has not been compared with probenecid nor has it been evaluated in patients who have no other treatment options. Two double-blind, randomised, placebo-controlled trials have been conducted. They lasted only 6 months and involved 212 patients in whom allopurino/therapy had failed, usually because of serious adverse effects. Pegloticase lowered uric acid levels but increased the frequency of gout flares early during treatment. At best, it had only a minor symptomatic effect on pain and disability. Its long-term effects are unknown. About 10% of patients had a serious adverse effect attributed to pegloticase, including reactions during the infusion, anaphylactic reactions, and skin infections. Thrombocytopenia and severe cardiac adverse effects are other probable adverse effects. About 90% of patients treated with pegloticase developed anti-pegloticase antibodies. Given the limited short-term symptomatic efficacy and the absence of comparative long-term evaluation, patients should not be exposed to the potentially serious adverse effects of pegloticase. Probenecid is a better choice when allopurinol is ineffective or poorly tolerated. Currently, patients with no remaining therapeutic options should simply continue to receive symptomatic treatment of gout attacks.

Rasburicase causing severe oxidative hemolysis and methemoglobinemia in a patient with previously unrecognized glucose-6-phosphate dehydrogenase deficiency

Rasburicase is frequently used in tumor lysis syndrome (TLS). Although it is very well tolerated, it can cause severe oxidative hemolytic anemia and methemoglobinemia in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency. We report another case of rasburicase-induced methemoglobinemia in a patient with previously unrecognized G6PD deficiency and review the cases of methemoglobinemia and oxidative hemolysis reported in the literature to date. Patients from ethnicities in which G6PD deficiency is prevalent at high risk of TLS should be screened for G6PD deficiency prior to administration of rasburicase where practical. Asymptomatic decrease in oxygen saturation by oximetry and cyanosis are signs of methemoglobinemia; patients recover with conservative measures including supplemental oxygen and packed red cell transfusion.

Long-term safety of pegloticase in chronic gout refractory to conventional treatment

Objective

To evaluate the long-term safety (up to 3 years) of treatment with pegloticase in patients with refractory chronic gout.

Methods

This open-label extension (OLE) study was conducted at 46 sites in the USA, Canada and Mexico. Patients completing either of two replicate randomised placebo-controlled 6-month trials received pegloticase 8 mg every 2 weeks (biweekly) or every 4 weeks (monthly). Safety was evaluated as the primary outcome, with special interest in gout flares and infusion-related reactions (IRs). Secondary outcomes included urate-lowering and clinical efficacy.

Results

Patients (n=149) received a mean±SD of 28±18 pegloticase infusions and were followed for a mean of 25±11 months. Gout flares and IRs were the most frequently reported adverse events; these were least common in patients with a sustained urate-lowering response to treatment and those receiving biweekly treatment. In 10 of the 11 patients with a serious IR, the event occurred when uric acid exceeded 6 mg/dl. Plasma and serum uric acid levels remained <6 mg/dl in most randomised controlled trial (RCT)-defined pegloticase responders throughout the OLE study and were accompanied by sustained and progressive improvements in tophus resolution and flare incidence.

Conclusions

The safety profile of long-term pegloticase treatment was consistent with that observed during 6 months of RCT treatment; no new safety signals were identified. Improvements in clinical status, in the form of flare and tophus reduction initiated during RCT pegloticase treatment in patients maintaining goal range urate-lowering responses were sustained or advanced during up to 2.5 years of additional treatment.

Urate oxidase for the prevention and treatment of tumor lysis syndrome in children with cancer

BACKGROUND

Tumor lysis syndrome (TLS) is a serious complication of malignancies and can result in renal failure or death. Preliminary reports suggest that urate oxidase is highly effective in reducing serum uric acid. It is uncertain whether high quality evidence exists to support its routine use in children with malignancies.

OBJECTIVES

We aimed to determine the effectiveness and safety of urate oxidase in the prevention and treatment of TLS in children with malignancies.

SEARCH STRATEGY

We performed a comprehensive search of the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library issue 2, 2009), MEDLINE (1966 to 2009), EMBASE (1980 to 2009) and CINAHL (1982 to 2009).

SELECTION CRITERIA

Randomized controlled trials (RCT) and controlled clinical trials (CCT) evaluating urate oxidase for the prevention or treatment of TLS in children under 18 years with any malignancy.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted trial data and assessed individual trial quality. We used relative risk (RR) for binary data and mean difference (MD) for continuous data.

MAIN RESULTS

We included five trials, involved 336 patients in the treatment groups and 458 patients in the control groups. One RCT and three CCTs compared urate oxidase and allopurinol. Two trials tested Uricozyme and two tested rasburicase for the prevention of TLS. The RCT showed no significant difference in mortality or renal failure between the treatment and the control groups. The frequency of normalization of uric acid (RR 19.09, 95% CI 1.28 to 285.41) and area under curve of uric acid (MD -201, 95% CI to -258.05 to -143.95) were significantly better in the treatment group. One patient developed hemolysis. One CCT reported significantly lower mortality due to TLS (RR 0.05, 95% CI 0.00 to 0.89) and lower incidence of renal failure (RR 0.13, 95% CI 0.05 to 0.35) in the treatment group. Another CCT found significantly lower uric acid in the treatment group at 72 hours (MD -98.33, 95% CI -170.66 to -26) and 168 hours (MD -103.67, 95% CI -179.00 to -28.34). All included trials are highly susceptible to biases.Another included RCT with 30 patients compared different doses of rasburicase (0.2 mg/kg versus 0.15 mg/kg), which demonstrated similar efficacy in the reduction of uric acid. Adverse events occurred in 20% of patients, including hemolysis, hypersensitivity and anemia.

AUTHORS' CONCLUSIONS

Although urate oxidase might be effective in reducing serum uric acid, it is still unclear whether this translates into a reduction in mortality or renal failure. Clinicians should weigh the potential benefits of reducing uric acid and uncertain benefits of preventing renal failure or mortality from TLS against the potential risk of adverse effects.

Pegloticase, a polyethylene glycol conjugate of uricase for the potential intravenous treatment of gout

Savient Pharmaceuticals Inc (formerly Bio-Technology General Corp), under license from Duke University, is developing pegloticase, PEG conjugates of uricase (urate oxidase), for the potential treatment of gout. The in-life portion of the phase III trials have been completed.

Catalase deficiency may complicate urate oxidase (rasburicase) therapy

Patients with low (inherited and acquired) catalase activities who are treated with infusion of uric acid oxidase because they are at risk of tumour lysis syndrome may experience very high concentrations of hydrogen peroxide. They may suffer from methemoglobinaemia and haemolytic anaemia which may be attributed either to deficiency of glucose-6-phosphate dehydrogenase or to other unknown circumstances. Data have not been reported from catalase deficient patients who were treated with uric acid oxidase. It may be hypothesized that their decreased blood catalase could lead to the increased concentration of hydrogen peroxide which may cause haemolysis and formation of methemoglobin. Blood catalase activity should be measured for patients at risk of tumour lysis syndrome prior to uric acid oxidase treatment.

Rasburicase in the prevention and treatment of tumour lysis syndrome

Tumour lysis syndrome (TLS) can be a life threatening complication of cancer therapy where cells undergo overwhelming lysis. The result is a pattern of metabolic abnormalities leading to acute renal failure and possible coagulopathy. Prophylactic pharmaceutical interventions can prevent this syndrome in almost all patients reducing possible admission to the intensive care unit. This article reviews the clinical efficacy, side effect profile, dosing and administration of rasburicase, an intravenous recombinant urate oxidase used in patients at risk of Tumour lysis syndrome due to a high tumour burden or where treatment is required. Rasburicase is an expensive but effective treatment option in the prevention and treatment of tumour lysis syndrome.

Prevention and treatment of hyperuricemia with rasburicase in children with leukemia and non-Hodgkin's lymphoma

To prevent acute renal failure in children at risk for developing tumor lysis syndrome due to acute lymphoblastic leukemia or non-Hodgkin's lymphoma treated according to international BFM protocols, we investigated recombinant urate oxidase (rasburicase) in the first Central European openlabeled, prospective, multicenter phase IV trial. Rasburicase was administered intravenously, at 0.2 mg/kg for 5 consecutive days to 36 patients. Blood levels of uric acid, creatinine, phosphorus, calcium, lactate dehydrogenase and complete blood count were measured daily during rasburicase treatment and on days 6, 7 and 12. Initial uric acid level decreased significantly by 4 hours (from 343 micromol/L to 58 micromol/L, p<0.001), except for one steroid-resistant patient who required hemodialysis on day 14 after having introduced combined cytostatic treatment. Comparing the data of a subgroup of 12 patients receiving rasburicase with that of a historic cohort of 14 patients treated with allopurinol indicated the superiority of rasburicase over allopurinol in prophylaxis and treatment of hyperuricemia in children with leukemia and lymphoma.

Rasburicase represents a new tool for hyperuricemia in tumor lysis syndrome and in gout

Hyperuricemia is a feature of several pathologies and requires an appropriate and often early treatment, owing to the severe consequences that it may cause. A rapid and massive raise of uric acid, during tumor lysis syndrome (TLS), and also a lower and chronic hyperuricemia, as in gout, mainly damage the kidney. To prevent or treat these consequences, a new therapeutic option is represented by rasburicase, a recombinant form of an enzyme, urate oxidase. This enzyme converts hypoxanthine and xanthine into allantoin, a more soluble molecule, easily cleared by kidney. The several types of urate oxidase have followed each other, with progressive reduction of adverse reactions. The most important among them are allergenicity and the development of antibodies which compromise their effectiveness. Nevertheless, a limit of rasburicase's use remains its cost, which obliges to a judicious choice to prevent TLS in high risk patients with cancer and in case of allergy or impossibility to take allopurinol orally both in TLS and in gout. A large body of evidence confirms the efficacy and safety of rasburicase, even in comparison to the standard drugs used in the aforementioned pathologies.

Pharmacokinetics and pharmacodynamics of intravenous PEGylated recombinant mammalian urate oxidase in patients with refractory gout

OBJECTIVE

To evaluate the efficacy, immunogenicity, and tolerability of intravenous (IV) PEGylated recombinant mammalian urate oxidase (PEG-uricase) for the treatment of severe gout.

METHODS

Single infusions of PEG-uricase (at doses ranging from 0.5 mg to 12 mg) were administered to 24 patients (6 cohorts of 4 patients each) in a phase I clinical trial. Plasma uricase activity (pUox), the plasma urate concentration (pUAc), and the uric acid-to-creatinine ratio (UAc:Cr) in urine were monitored for 21 days after dosing. Adverse events and the IgG antibody response to PEG-uricase were followed up for 35 days.

RESULTS

All patients completed the trial. Maximum pUox was linearly related to the IV dose of PEG-uricase, the area under the curve (AUC) value increased linearly (up to a dose of 8 mg), and the pUox half-life was 6.4-13.8 days. After doses of 4-12 mg, the pUAc fell within 24-72 hours, from a mean +/- SD value of 11.1 +/- 0.6 mg/dl to 1.0 +/- 0.5 mg/dl; the AUC value for the pUAc was equivalent to maintaining the pUAc at 1.2-4.7 mg/dl for 21 days postinfusion. The UAc:Cr ratio in urine fell in parallel with the pUAc. IgG antibodies to PEG-uricase, mostly IgG2 and specific for PEG, developed in 9 patients, who had more rapid enzyme clearance but no allergic reactions. All adverse events were mild to moderate, with gout flares being most common.

CONCLUSION

The bioavailability, efficacy, and tolerability of IV PEG-uricase were greater than the bioavailability, efficacy, and tolerability observed in a previous phase I trial of subcutaneous PEG-uricase. Infusing 4-12 mg of PEG-uricase every 2-4 weeks should maintain the pUAc well below the therapeutic target of 6 mg/dl and greatly reduce renal uric acid excretion. This treatment could be effective in depleting expanded tissue urate stores in patients with chronic or tophaceous gout.

Recombinant urate oxidase (Rasburicase) for the treatment of hyperuricemia in pediatric patients with hematologic malignancies: Results of a compassionate prospective multicenter study in Korea

BACKGROUND

Hyperuricemia accompanying tumor lysis syndrome is a serious complication in neoplasia with rapid proliferation and destruction. To confirm the efficacy of recombinant urate oxidase (rasburicase) and its safety profile, a phase IV compassionate use prospective study was performed in Korean pediatric patients with hematologic malignancies.

PROCEDURE

Rasburicase was administered at 0.2 mg/kg/day once daily for 3-5 days (twice daily allowed during the first 72 hr) by intravenous route for hyperuricemia (uric acid > 7.5 mg/dl). The study period was 5 weeks and consisted of a baseline assessment within 48 hr before the administration of rasburicase, 3-5 days of assessment during treatment and a follow-up assessment at 4 weeks after its final administration.

RESULTS

The uric acid endpoint (< or =7.0 mg/dl) was reached in 97.3% (36/37) of the patients and uric acid levels were significantly reduced in all patients (P < 0.001). Drug related toxicities were mild and reversible without any grade 4 or serious adverse event associated with rasburicase.

CONCLUSION

This study confirms that rasburicase is a safe and effective agent for the treatment of hyperuricemia associated with hematologic malignancies in pediatric patients.

Rasburicase

Intravenous rasburicase (Elitek, Fasturtec) is the first recombinant uricolytic agent. It is indicated for the management of anticancer therapy-induced hyperuricaemia in paediatric patients in the EU and US, and in adult patients in the EU. Rasburicase is effective and generally well tolerated in adult and paediatric patients with, or at risk of developing, anticancer therapy-induced hyperuricaemia. It is associated with potentially serious haematological adverse events and hypersensitivity reactions, which must be considered prior to and during administration; rasburicase is contraindicated in patients predisposed to haemolysis or methaemoglobinaemia and in patients with glucose-6-phosphate dehydrogenase deficiency. Unlike allopurinol, rasburicase acts on existing uric acid concentrations. Rasburicase treatment resulted in significantly less systemic exposure to uric acid and a quicker therapeutic response than allopurinol in paediatric patients; further studies are needed to determine the comparative efficacy and tolerability of rasburicase versus allopurinol in adult patients. Although further pharmacoeconomic data would be useful, rasburicase was most cost effective for the prevention of hyperuricaemia in children and for treatment of this condition in adults. Thus, rasburicase is a useful option for the prophylaxis or treatment of anticancer therapy-induced hyperuricaemia in both adult and paediatric patients.

Rasburicase: A New Approach for Preventing and/or Treating Tumor Lysis Syndrome

Tumor lysis syndrome (TLS) is an oncologic emergency requiring prompt attention to the management of potentially life-threatening metabolic derangements. Hyperuricaemia is one of the prominent features of TLS which, if not adequately prevented or treated, may lead to renal failure, requiring dialysis. Conventional management of hyperuricaemia involved the use of aggressive hydration, urinary alkalinization and allopurinol. Despite these measures, as many as 14.1% of high-risk patients may still develop renal failure. With the advent of newer agents such as rasburicase, the paradigm of TLS management has shifted towards risk stratification and the use of rasburicase in conjunction with hydration in patients at high risk for TLS. The advantage of rasburicase over allopurinol is its rapid onset of action, lack of need for urine alkalinization, which may worsen hyperphosphataemia and a satisfactory safety profile. Overall, rasburicase offers a safe and more effective alternative to allopurinol in patients at highest risk for TLS. Some of the unanswered questions requiring further investigation with regard to rasburicase use include the optimal number of doses needed, optimal dose based on uric acid levels and tumor burden, dosing in obese patients and maximum dose.

Hemolysis and Methemoglobinemia Secondary to Rasburicase Administration

OBJECTIVE

To report a case of hemolytic anemia and methemoglobinemia developing after rasburicase administration to a patient with glucose-6-phosphate dehydrogenase (G6PD) deficiency.

CASE SUMMARY

A 50-year-old African American man was hospitalized with new onset seizure, diabetic ketoacidosis, respiratory failure, and acute renal failure. Serum uric acid concentrations were elevated, and the patient was treated with one dose of intravenous rasburicase 22.5 mg for acute renal failure secondary to hyperuricemia. Routine arterial blood gas analyses performed after rasburicase was administered revealed elevated methemoglobin concentrations, which peaked at 14.7%. Hemolytic anemia developed as evidenced by a fall in blood hemoglobin from 14.8 to 5.3 g/dL. The patient made a full recovery following aggressive fluid therapy, blood transfusions, and respiratory support. G6PD deficiency was subsequently confirmed. The Naranjo probability scale indicated that rasburicase was a probable cause of hemolytic anemia and methemoglobinemia.

DISCUSSION

Rasburicase is contraindicated in patients with G6PD deficiency as it may cause hemolytic anemia and methemoglobinemia. As of September 26, 2005, simultaneous occurrence of hemolytic anemia and methemoglobinemia has not been reported in patients receiving rasburicase.

CONCLUSIONS

As of September 26, 2005, screening for G6PD deficiency should be performed whenever possible prior to chemotherapy administration in patients at risk of developing tumor lysis syndrome.

Efficacy and safety of rasburicase, a recombinant urate oxidase (Elitek), in the management of malignancy-associated hyperuricemia in pediatric and adult patients: final results of a multicenter compassionate use trial

The recombinant urate oxidase, rasburicase (Elitek, Sanofi-Synthelabo, Inc.), has recently received regulatory approval for the prevention and treatment of hyperuricemia in children with leukemia, lymphoma, and solid tumors. Prior to approval, 682 children and 387 adults in the US and Canada received rasburicase on compassionate-use basis. Uric acid concentration declined rapidly in both adult and pediatric patients after rasburicase treatment. Similar responses were observed in patients treated with subsequent courses. Possible drug-related adverse events, including allergic reactions, were uncommon. These data confirm that rasburicase is effective and safe for the treatment and prophylaxis of children and adults with malignancy-associated hyperuricemia.

Managing malignancy-associated hyperuricemia with rasburicase

Along with hydration and urinary alkalinization, allopurinol has been the standard agent for the management of hyperuricemia in patients with a high tumor burden who are at risk for tumor lysis syndrome. However, this agent often fails to prevent and treat this complication effectively. Rasburicase, a recombinant urate oxidase, acts at the end of the purine catabolic pathway and, therefore, does not induce accumulation of xanthine or hypoxanthine, which can precipitate in the kidneys and lead to impaired renal function. Rasburicase may represent an effective alternative to allopurinol in rapidly reducing uric acid levels, improving patients' electrolyte status, and reversing renal insufficiency. The drug initially was studied in pediatric patients with acute lymphoblastic leukemia and aggressive non-Hodgkin lymphoma; data may suggest comparable benefit in adults with similar lymphoid malignancies. Current and future trials will evaluate alternate doses and schedules of rasburicase to maintain its efficacy while reducing its cost.

Recombinant urate oxidase (rasburicase) in the prophylaxis and treatment of tumor lysis syndrome

Spontaneous or treatment-induced tumor lysis syndrome (TLS) can cause significant morbidity and potential mortality. Vigorous hydration, alkalinization and inhibition of uric acid synthesis are the most frequently used methods for prevention of TLS. However, this approach requires hospitalization and tedious nursing care, and fails to prevent renal insufficiency in up to 25% of high-risk patients. With increased intensity and efficacy of cancer therapies, and the current trend to deliver treatment in the outpatient setting, novel approaches at management of TLS are needed. Unlike allopurinol, urate oxidase promptly reduces the existing uric acid pool, prevents accumulation of xanthine and hypoxanthine, and does not require alkalinization, facilitating phosphorus excretion. A recombinant form of urate oxidase, rasburicase, is now available. In this chapter we will present an overview of rasburicase development and discuss the impact of rasburicase in the prevention and management of TLS.

Stabilization of rasburicase and physico-chemical characterization of the resulting injectable formulation

Rasburicase (Fasturtec/Elitek) is a new generation of recombinant urate oxidase administred therapeutically by intravenous infusion for the prevention or treatment of hyperuricemia during chemotherapy. To ensure a long storage period, a freeze-dried formulation was developed to guarantee the molecular integrity and enzyme activity. Screening of potential excipients was the first stage of the preformulation study. The selection was based on stability results (rasburicase solution with excipient) obtained with the isoelectric focusing profiles and residual enzyme activity. The different excipients were classified as stabilising, neutral or destabilising. A stability study was then carried out on different freeze-dried formulations containing the usual bulking agents for freeze-drying, excipients with a high glass transition temperature or competitive enzyme inhibitors having a stabilising effect. A mannitol/alanine mixture in phosphate buffer was selected from these preliminary results. Finally, the optimal content of mannitol and alanine in the freeze-dried powder was determined by an experimental design study. The water content and the appearance of the "cake", the osmolality, pH, clarity, and enzyme activity of the reconstituted solution were assessed. The formula with a mannitol/alanine ratio of 0.7 was found to be the best composition. Differential scanning calorimetry and ThermoStimulated Current technique experiments were carried out to study the amorphous phase. A glass transition temperature of about 45-500 degrees C was found. Glassy state is known to preserve stability, which was verified by the real stability data. X-ray diffraction studies have shown that alanine is in a crystallised state and that mannitol remains amorphous. Crystallised excipients participate in forming the structure of the powder and therefore help to prevent any collapse. Amorphous mannitol creates a surrounding medium favourable to the stability of the protein.

Rasburicase: potential role in managing tumor lysis in patients with hematological malignancies

Acute tumor lysis syndrome with hyperuricemia and renal failure usually occurs during the initial period of chemotherapy in patients with aggressive hematological malignancies. Standard therapy for hyperuricemia includes hydration, urine alkalinization and pharmacoreduction of uric acid with allopurinol. In the USA, rasburicase has recently been approved by the US Food and Drug Administration for the reduction of uric acid. Rasburicase is a recombinant urate oxidase enzyme that converts uric acid to allantoin, which has increased urine solubility. It is administered intravenously once-daily and leads to rapid, dramatic declines in serum uric acid values. The toxicity profile is excellent, with rare incidence of bronchospasm and allergies and a known contraindication for patients with glucose-6-phosphate dehydrogenase deficiency. A Phase III trial in high-risk pediatric patients conclusively demonstrated that rasburicase is more effective than allopurinol in controlling uric acid. Ongoing evidence is accumulating suggesting that the drug is also safe and effective in adults with hematological malignancies.

Rasburicase for the treatment and prevention of hyperuricemia

OBJECTIVE

To review the information currently available on rasburicase for treatment and prevention of hyperuricemia.

DATA SOURCES

MEDLINE (1966-August 2002) was searched for primary and review articles.

STUDY SELECTION/DATA EXTRACTION

Studies evaluating rasburicase, including abstracts and proceedings, were considered for inclusion. English-language literature was evaluated for the pharmacology, pharmacodynamics, pharmacokinetics, therapeutic use, and adverse effects of rasburicase.

DATA SYNTHESIS

Rasburicase, a recombinant urate oxidase, has been shown to be effective in lowering uric acid and preventing uric acid accumulation in patients with hematologic malignancies who had hyperuricemia or who were at high risk for developing hyperuricemia. It has been approved for pediatric use in the US.

CONCLUSIONS

In addition to allopurinol, hydration, and urinary alkalinization, rasburicase is a new alternative for the treatment and prevention of hyperuricemia in patients with hematologic malignancies. Its rapid onset of action and the ability to lower preexisting elevated uric acid levels are the advantages of rasburicase compared with allopurinol. It may allow the patient to receive chemotherapy treatment without delay.

Urate-oxidase in the prevention and treatment of metabolic complications in patients with B-cell lymphoma and leukemia, treated in the Société Française d'Oncologie Pédiatrique LMB89 protocol

PURPOSE

To evaluate the frequency of metabolic complications and dialysis due to tumor lysis syndrome in patients with B-cell advanced-stage non-Hodgkin's lymphoma (NHL) and L3 leukemia at initiation of chemotherapy including the use of urate-oxidase.

PATIENTS AND METHODS

Retrospective review of the clinical records of 410 patients with stage III and IV B-cell NHL and L3 leukemia treated in France and prospectively registered in the LMB89 protocol.

RESULTS

During the first week of chemotherapy, only 34 of 410 patients recorded metabolic problems that included hypocalcemia (< 70 mg/dl) in 24 patients, hyperphosphatemia (> 6.5 mg/dl) in 28 and elevation of creatinine > or = 2 SD in 16. Six patients underwent dialysis for life-threatening problems and a seventh as a preventive measure. In the other 27 cases, metabolic problems were successfully resolved using urate-oxidase in combination with alkaline hyperhydration. Among the 410 patients, one case of hemolysis was reported and there was no severe allergic reaction to urate-oxidase.

CONCLUSIONS

Only 1.7% of patients in our study receiving urate-oxidase during their induction chemotherapy needed renal dialysis. Urate-oxidase was well tolerated, and used as prophylaxis and/or treatment of hyperuricemia and tumor lysis syndrome consistently gave a lower rate of renal and metabolic complications than in other series of similar patients.

Rasburicase

Rasburicase (recombinant urate oxidase) is a uricolytic agent which has been developed for the prevention and treatment of chemotherapy-induced hyperuricaemia at a dosage of 0.15 or 0.2 mg/kg/day in patients with haematological malignancies. Significant reductions from baseline in plasma uric acid levels were seen in 3 noncomparative and 1 randomised comparative trial of rasburicase in patients with, or at high risk of, hyperuricaemia. A multicentre, nonblind, randomised trial found that patients who received intravenous rasburicase 0.2 mg/kg/day experienced an average 2.6-fold less exposure to uric acid than those who received oral allopurinol 10 mg/kg/day. There was no evidence of renal insufficiency in 3 noncomparative trials which monitored creatinine levels to assess renal function during chemotherapy and rasburicase treatment. Rasburicase was generally well tolerated in clinical trials, with skin rashes reported in approximately equals 2% of patients. Bronchospasm, nausea and vomiting, and haemolysis occurred less frequently. In all cases the patients had also received chemotherapy prior to the adverse event.

A randomized comparison between rasburicase and allopurinol in children with lymphoma or leukemia at high risk for tumor lysis

Standard therapy in the United States for malignancy-associated hyperuricemia consists of hydration, alkalinization, and allopurinol. Urate oxidase catalyzes the enzymatic oxidation of uric acid to a 5 times increased urine soluble product, allantoin. Rasburicase is a new recombinant form of urate oxidase available for clinical evaluation. This multicenter randomized trial compared allopurinol to rasburicase in pediatric patients with leukemia or lymphoma at high risk for tumor lysis. Patients received the assigned uric acid-lowering agent for 5 to 7 days during induction chemotherapy. The primary efficacy end point was to compare the area under the serial plasma uric acid concentration curves during the first 96 hours of therapy (AUC(0-96)). Fifty-two patients were randomized at 6 sites. In an intent-to-treat analysis, the mean uric acid AUC(0-96) was 128 +/- 70 mg/dL.hour for the rasburicase group and 329 +/- 129 mg/dL.hour for the allopurinol group (P <.0001). The rasburicase versus allopurinol group experienced a 2.6-fold (95% CI: 2.0-3.4) less exposure to uric acid. Four hours after the first dose, patients randomized to rasburicase compared to allopurinol achieved an 86% versus 12% reduction (P <.0001) of initial plasma uric acid levels. No antirasburicase antibodies were detected at day 14. This randomized study demonstrated more rapid control and lower levels of plasma uric acid in patients at high risk for tumor lysis who received rasburicase compared to allopurinol. For pediatric patients with advanced stage lymphoma or high tumor burden leukemia, rasburicase is a safe and effective alternative to allopurinol during initial chemotherapy.