M2 Macrophage Hybrid Membrane-Camouflaged Targeted Biomimetic Nanosomes to Reprogram Inflammatory Microenvironment for Enhanced Enzyme-Thermo-Immunotherapy.

Excessive inflammatory reactions caused by uric acid deposition are the key factor leading to gout. However, clinical medications cannot simultaneously remove uric acid and eliminate inflammation. An M2 macrophage-erythrocyte hybrid membrane-camouflaged biomimetic nanosized liposome (USM[H]L) is engineered to deliver targeted self-cascading bienzymes and immunomodulators to reprogram the inflammatory microenvironment in gouty rats. The cell-membrane-coating endow nanosomes with good immune escape and lysosomal escape to achieve long circulation time and intracellular retention times. After being uptaken by inflammatory cells, synergistic enzyme-thermo-immunotherapies are achieved: uricase and nanozyme degraded uric acid and hydrogen peroxide, respectively; bienzymes improved the catalytic abilities of each other; nanozyme produced photothermal effects; and methotrexate has immunomodulatory and anti-inflammatory effects. The uric acid levels markedly decrease, and ankle swelling and claw curling are effectively alleviated. The levels of inflammatory cytokines and ROS decrease, while the anti-inflammatory cytokine levels increase. Proinflammatory M1 macrophages are reprogrammed to the anti-inflammatory M2 phenotype. Notably, the IgG and IgM levels in USM[H]L-treated rats decrease substantially, while uricase-treated rats show high immunogenicity. Proteomic analysis show that there are 898 downregulated and 725 upregulated differentially expressed proteins in USM[H]L-treated rats. The protein-protein interaction network indicates that the signaling pathways include the spliceosome, ribosome, purine metabolism, etc.

The Effective Control of Hyperuricemia in Cancer Patients: A New Recombinant Conjugated Variant of Urate Oxidase.

OBJECTIVE: Management of hyperuricemia is crucial to controlling tumor lysis syndrome (TLS) during cancer therapy. Urate oxidase (UOX) that catalyzes the enzymatic oxidation of uric acid into allantoin, is effective in lowering plasma uric acid levels and controlling hyperuricemia. Recently, we developed a new recombinant conjugate variant of UOX therapeutic drug using PASylation technology. This study was designed to evaluate the stability, plasma half-life and immunogencity of PASylated UOX. METHODS: A recombinant variant of PASylated UOX from the Aspergillus flavus was manufactured using bioinformatics and experimental techniques. Ex vivo evaluation of stability of PASylated UOX was done in 50% human serum. For half-life test, recombinant PASylated UOX and rasburicase were administered at 1.5 mg/kg to 10 rats in two different groups and samples were collected after injection Production of antibodies against PASylated drug was also assayed. RESULTS: Residual activity of PASylated UOX in 50% human serum was higher than rasburicase and native UOX. Stability of PASylated UOX at 25°C and 37°C was also higher than rasburicase and native UOX. The PASylated half-life was ~32.1 hours, whereas half-life for rasburicase and native UOX was ~25.1 and ~22.8 hours, respectively. In immunogenicity examination, there is 33% and 36% decrease in the absorbance of native UOX and rasburicase, respectively when compared with that of PASylated UOX. CONCLUSION: Our data confirmed the efficacy and stability of PASylated UOX in comparison to the rasburicase. In summary, the results indicated that PASylated UOX drug is effective at lowering plasma uric acid levels with prolonged plasma half-life and decreased cost.
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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.

A double blind placebo controlled randomized trial of the effect of acute uric acid changes on inflammatory markers in humans: A pilot study.

Uric acid has been linked with increased risk of chronic disease such as cardiovascular disease and this association has been attributed to a pro-inflammatory effect. Indeed, observational studies have shown that high uric acid is associated with high level of pro-inflammatory cytokines in the blood. However, whether high uric acid directly affects inflammation or rather represents a parallel defensive antioxidant mechanism in response to pathology that causes inflammation is unknown. To determine whether acute increase or decrease uric acid levels affects inflammation in healthy individuals, a randomized, placebo-controlled, double blind clinical study of uric acid or rasburicase with 20 healthy volunteers in each treatment-placebo group was conducted at the National Institute on Aging (NIA) Clinical Research Unit (CRU) at Harbor Hospital in Baltimore, MD. Change in inflammatory response was assessed by administering an oral lipid tolerance before and after the treatment of uric acid, rasburicase and placebo. Following uric acid administration, there was an accentuated increase in IL-6 during the oral lipid tolerance test (P<0.001). No significant differences were observed after lowering of uric acid with rasburicase. No side effects were reported throughout the trial. In health individuals, acute increase in uric acid results in an increased IL-6 response when challenged with lipid load. Such effect of amplification of inflammatory response may explain the higher risk of chronic diseases observed in subclinical hyperuricemia in observational studies. TRIAL REGISTRATION: ClinicalTrials.gov NCT01323335.

Prediction of Therapeutic Effect of Rasburicase on Hyperuricemia Associated with Chemotherapy Based on Theoretical Model.

Rasburicase has a strong and fast effect for reducing blood levels of uric acid. However, there have been no reports of theoretical analysis for the rational dose and interval of administration. Thus we constructed a pharmacokinetic and pharmacodynamic model to determine changes in uric acid level after rasburicase administration at various doses and regimens. The time courses of uric acid level predicted using our model were in good agreement with observed data, indicating adequate performance for our model. The therapeutic effects after a single infusion at various rates of generation of uric acid were predicted. The maximum effect was not a large difference, in spite of the generation rate. Then, the therapeutic effects of repeated administrations were predicted. The effect did not change when rasburicase was administered at more than the usual dose. Besides, as the administration interval increased, the difference between minimum and maximum level of uric acid became greater. However, in all doses and regimens, adequate therapeutic effects were obtained. In conclusion, the model was found useful for predicting therapeutic effect of rasburicase and individually determining rational dosage regimen of rasburicase.

Pre-treatment with allopurinol or uricase attenuates barrier dysfunction but not inflammation during murine ventilator-induced lung injury.

INTRODUCTION: Uric acid released from injured tissue is considered a major endogenous danger signal and local instillation of uric acid crystals induces acute lung inflammation via activation of the NLRP3 inflammasome. Ventilator-induced lung injury (VILI) is mediated by the NLRP3 inflammasome and increased uric acid levels in lung lavage fluid are reported. We studied levels in human lung injury and the contribution of uric acid in experimental VILI. METHODS: Uric acid levels in lung lavage fluid of patients with acute lung injury (ALI) were determined. In a different cohort of cardiac surgery patients, uric acid levels were correlated with pulmonary leakage index. In a mouse model of VILI the effect of allopurinol (inhibits uric acid synthesis) and uricase (degrades uric acid) pre-treatment on neutrophil influx, up-regulation of adhesion molecules, pulmonary and systemic cytokine levels, lung pathology, and regulation of receptors involved in the recognition of uric acid was studied. In addition, total protein and immunoglobulin M in lung lavage fluid and pulmonary wet/dry ratios were measured as markers of alveolar barrier dysfunction. RESULTS: Uric acid levels increased in ALI patients. In cardiac surgery patients, elevated levels correlated significantly with the pulmonary leakage index. Allopurinol or uricase treatment did not reduce ventilator-induced inflammation, IκB-α degradation, or up-regulation of NLRP3, Toll-like receptor 2, and Toll-like receptor 4 gene expression in mice. Alveolar barrier dysfunction was attenuated which was most pronounced in mice pre-treated with allopurinol: both treatment strategies reduced wet/dry ratio, allopurinol also lowered total protein and immunoglobulin M levels. CONCLUSIONS: Local uric acid levels increase in patients with ALI. In mice, allopurinol and uricase attenuate ventilator-induced alveolar barrier dysfunction.

Lowering serum uric acid to prevent acute kidney injury.

Epidemiological, experimental and clinical studies support a role for uric acid in acute kidney injury (AKI). We discuss how the conventional role of uric acid in AKI has now evolved from intratubular crystal deposition to pro-inflammatory, anti-angiogenic and immunological function. Data from recent studies are presented to support the hypothesis that uric acid may have a role in AKI via a crystal-independent process in addition to its traditionally accepted role to induce injury via crystal-dependent pathways.

Rasburicase for the treatment of tumor lysis in hematological malignancies.

Tumor lysis syndrome (TLS) is a common oncologic emergency in patients with hematological malignancies sensitive to cytotoxic treatment that present a high proliferative rate. High proliferative cancer rate, high sensitivity of cytotoxic treatment and renal failure represent risk factors for development of TLS. TLS is also responsible for several electrolytic alterations, such as hyperuricemia, hyperkalemia, hyperphosphatemia and hypocalcemia. There are different established therapeutic options for the treatment of TLS such as hydration, allopurinol and rasburicase. Rasburicase reduces uric acid levels within 4 h, both in pediatric and adult patients, catalyzing the oxidation of uric acid into allantoin, rapidly excreted by the kidneys. Rasburicase is well tolerated and was approved in the EU and in the USA for the management of acute hyperuricemia.

Rasburicase in cancer-related hyperuricemia.

Tumor lysis syndrome (TLS) is an oncological emergency consisting of several metabolic derangements: hyperuricemia, hyperkalemia, hyperphosphatemia and hypocalcemia. The rupture of tumor cells in cancer patients can be spontaneous or caused by anticancer therapy. Clinical manifestations of TLS include nausea, anorexia, arrhythmias or renal failure. Prevention and treatment measures include aggressive hydration and concomitant antihyperuricemic therapy. Allopurinol has historically been the only available pharmacological option. Rasburicase was subsequently approved for the management of elevated plasma uric acid levels in adults. This recombinant urate oxidase converts uric acid to allantoin, a more soluble byproduct that is safely eliminated by the kidneys. Manufacturer-labeled dosing for rasburicase in the pediatric and adult populations is 0.2 mg/kg as a daily intravenous (i.v.) infusion for up to 5 days. This review summarizes several studies suggesting that flat, single rasburicase dosing regimens may be just as effective as weight-based dosing. The optimal, most cost-effective adult dose and schedule have yet to be determined.

Effect of allopurinol versus urate oxidase on methotrexate pharmacokinetics in children with newly diagnosed acute lymphoblastic leukemia.

BACKGROUND: Allopurinol and urate oxidase are both effective in preventing or treating hyperuricemia during remission induction therapy for lymphoid malignancies, but to the authors' knowledge, their effects on concomitant anticancer drug therapy have not been compared. METHODS: The authors compared plasma methotrexate pharmacokinetics in pediatric patients with newly diagnosed acute lymphoblastic leukemia who received concomitant allopurinol (n = 20) versus those treated with nonrecombinant or recombinant urate oxidase (n = 96) during high-dose methotrexate administration before conventional remission induction therapy. RESULTS: The minimum plasma concentration of uric acid was significantly (P < .0001) lower after urate oxidase treatment than the concentration after allopurinol treatment. Methotrexate clearance was significantly higher (median, 117.1 mL/minute/m(2) vs 91.1 mL/minute/m(2); P = .019) in patients who received urate oxidase. A higher proportion of patients in the allopurinol group had elevated methotrexate plasma concentrations (36% vs 7%; P = .003) and experienced mucositis (45% vs 16%; P = .003) after methotrexate treatment compared with the urate oxidase group. CONCLUSIONS: The lower rate of methotrexate clearance in patients who received allopurinol likely reflected a less potent hypouricemic effect of allopurinol, leading to precipitation of uric acid in renal tubules. Hence, during remission induction therapy for lymphoid malignancies, the authors concluded that renally excreted drugs should be monitored closely, especially in patients who are receiving allopurinol.

Effective treatment and prophylaxis of hyperuricemia and impaired renal function in tumor lysis syndrome with low doses of rasburicase.

BACKGROUND: Tumor lysis syndrome (TLS) is a complication that can cause renal failure by precipitation of uric acid (UA) and phosphate crystals in renal tubules. Rasburicase proved to be effective in rapidly reducing UA levels. Costs of rasburicase average up to 4500 euros. To assess if lower doses of rasburicase are effective, we treated patients with lower doses than recommended. PATIENTS AND METHODS: Fifty patients received rasburicase for prophylaxis (n = 8) or treatment (n = 42) of TLS. The median age was 67 yr (16-88), 21 were female. The majority of patients (n = 46) had hematologic malignancies (acute leukemia, 14; lymphoma, 26; myeloproliferative/myelodysplastic syndromes, 6) and four had solid tumors. Creatinine levels were increased in 42 patients. RESULTS: Baseline median UA and creatinine levels were 856.5 micromol/L (339-1659.5 micromol/L) and 192.7 micromol/L (65.4-761.1 micromol/L), respectively. Patients received between one and eight doses of rasburicase, the median total dose was 0.049 mg/kg. UA levels were lowered by 83%. After rasburicase treatment, median serum UA and creatinine levels were 160.6 micromol/L (5.9-779.2 micromol/L) and 111.4 micromol/L (46.9-610 micromol/L), respectively. Treatment costs were reduced by 96.8%. CONCLUSIONS: Low doses of rasburicase are effective and cost-saving for prophylaxis and treatment of TLS. Application of an initial dose of 3-4.5 mg of rasburicase and subsequently dosage as needed, depending on UA levels, is feasible.

The increase in human plasma antioxidant capacity after red wine consumption is due to both plasma urate and wine polyphenols.

By using red wine, dealcoholized red wine, polyphenols-stripped red wine, ethanol-water solution and water, the role of wine polyphenols and induction of plasma urate elevation on plasma antioxidant capacity was examined in humans (n=9 per beverage). Healthy males randomly consumed each beverage in a cross-over design. Plasma antioxidant capacity (measured by ferric reducing antioxidant power, FRAP), ethanol, catechin and urate concentrations were determined before and 30, 60, 90, 120 and 180 min after beverage intake. Dealcoholized red wine and polyphenols-stripped red wine induced similar increase in FRAP values which represented nearly half the effect of the original red wine. This indicates that consumption of red wine involves two separate mechanisms in elevation of plasma FRAP values and both wine phenols and plasma urate contribute to that effect.

Avoiding dialysis in tumour lysis syndrome: is urate oxidase effective? - a case report and review of literature.

INTRODUCTION: Hyperuricaemia in tumour lysis syndrome (TLS) can cause acute renal failure (ARF), necessitating dialysis. Recombinant urate oxidase (rasburicase) converts uric acid to soluble allantoin, which is excreted easily. CASE REPORT: An 8-year-old boy with stage 3 Burkitt's lymphoma, TLS was successfully treated with hyper-hydration, diuretics and rasburicase, without dialysis. This is the first paediatric case in Kandang Kerbau Women's & Children's Hospital (KKH) in which rasburicase was used. We review the literature on the effectiveness of urate oxidase in avoiding dialysis in TLS. TREATMENT AND OUTCOME: Our patient developed rapidly rising serum uric acid (SUA) and progressive renal impairment. Hyper-hydration and rasburicase (0.2mg/kg) were administered. SUA rapidly decreased from 1308 to 437 mmol/L within 12 hours. Urate oxidase has shown better results than allopurinol. There was a need for dialysis in 0.4% to 1.7% of patients with haematological malignancies given rasburicase, compared to 20% in patients given allopurinol. CONCLUSIONS: Rasburicase can reverse renal insufficiency. Though expensive, it may be cost-effective by lowering incidence of dialysis, shortening the duration of intensive care and hospitalisation, allowing early chemotherapy.

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.

Rasburicase: a review of its use in the management of anticancer therapy-induced hyperuricaemia.

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.

Protective effect of urate oxidase on uric acid induced-monocyte apoptosis.

Uremic patients have a higher risk of infection and malignancy than normal subjects. Previous studies have deomonstrated that monocytes isolated from uremic patients display an increased apoptosis rate compared to normal subjects; furthermore uremic plasma can increase apoptosis rates on U937, a human monocytic cell line. In several pathological conditions, precipitation of uric acid crystals can lead to renal insufficiency or acute renal failure by different mechanisms. In recent studies uric acid has been shown to induce inflammatory response from monocytes and it has been suggested to be involved in cell dysfunction. Rasburicase is a new recombinant urate oxidase developed to prevent and treat hyperuricaemia in patients with cancer or renal failure; it degrades uric acid to allantoin, a less toxic and more soluble product. In the present study, we aimed at determining whether uric acid may be a factor affecting U937 apoptosis, and whether urate oxidase may reduces or even prevent uric acid induced cell apoptosis. Hoechst staining and internucleosome ledder fragmentation of DNA showed that uric acid increased the percentage of apoptotic cells comparing to the control and that when the U937 cells were incubated with uric acid and urate oxidase the percentage of apoptosis significantly decreased (from 43+/-7% to 19+/- 3%, p<0.05). Also, the activity of caspase-8 and caspase-3 showed the same trend (caspase 3: from 2.7+/-0.53 to 1.6+/-0.42; caspase-8: from 2.2+/-0.43 to 1.3+/-0.57). A reduction of intracellular reduced glutathione (GSH) concentration was found in uric acid treated cells while the addition of urate oxidase in the uric acid incubated cells decreased the GSH extrusion. The concentration of TNF-alpha was increased in the sample incubated with uric acid comparing to the control. Uric acid is an inducer of apoptosis on U937 cell line, and therefore it may be a component of the mosaic of uremic toxins both in acute and chronic renal disease. We can hypothesize that uric acid might be directly involved in the apoptotic process trough the activation of both death receptor and mitochondrial-mediated pathways. We have, also, demonstrated that urate oxidase is able to prevent at least in part, the effect of uric acid on U937 apoptosis. This effect might be a result of different mechanisms of action.