Rasburicase in tumor lysis syndrome of the adult: a systematic review and meta-analysis

Spontaneous tumour lysis syndrome in chronic lymphocytic leukaemia: an unanticipated complication of an undiagnosed disease

Spontaneous tumour lysis syndrome (STLS) is a rare oncological emergency characterised by the spontaneous destruction of tumour cells in the absence of chemotherapy, with the release of large amounts of intracellular ions and metabolic products leading to organ damage and at times death. In chronic lymphocytic leukaemia (CLL), historically, tumour lysis syndrome has been rarely observed owing to low rate of proliferation and slow response to chemotherapy. We report a rare case of STLS in underlying undiagnosed CLL. A man in his 60s presented with vomiting, diarrhoea, breathlessness on exertion and oliguria. Laboratory evaluation revealed a typical constellation of metabolic abnormalities; hyperuricaemia, hyperkalaemia, hyperphosphataemia and hypocalcaemia with acute kidney injury. Peripheral blood examination showed lymphocytosis with smudge cells. Flow cytometry revealed atypical B lymphoid cells positive for CD5, CD19, CD23, CD45 and CD200. Bone marrow studies and lymph node biopsy supported the diagnosis of underlying CLL which was further confirmed by fluorescent in situ hybridisation. With prompt diagnosis, intervention and intensive monitoring, the end-organ damage was successfully prevented. This case report highlights the importance of keeping high index of suspicion for STLS even without a background history of malignancy as this life-threatening condition is potentially salvageable.

Tumor lysis syndrome in induction therapy for acute myeloid leukemia before the rasburicase era

Guidelines recommend rasburicase for high-risk patients to prevent tumor lysis syndrome (TLS). However, little information is available on the incidence and outcome of TLS in AML patients. We analyzed 145 patients with AML who underwent induction therapy before the approval of rasburicase to evaluate the incidence of TLS and the necessity of rasburicase as prophylaxis. Three patients had already developed clinical TLS (CTLS) at diagnosis of AML, and another three developed CTLS after the initiation of chemotherapy. In patients without TLS at diagnosis of AML, the risk for developing TLS was classified as high in 44 patients, intermediate in 41 and low in 57, according to the current guidelines. Allopurinol alone was administered to prevent hyperuricemia in all patients. All three patients who developed CTLS after diagnosis of AML were at high risk of TLS, and had elevated serum creatinine levels and a WBC count greater than 200,000 per microliter at diagnosis of AML. Allopurinol may be insufficient to prevent TLS in high-risk patients with renal dysfunction at diagnosis of AML, especially those with a high tumor burden and a WBC count of 200,000 or more, which indicates that prophylactic administration of rasburicase should be considered.

Important Considerations in the Intensive Care Management of Acute Leukemias

In the realm of hematologic disorders, acute leukemia is approached as an emergent disease given the multitude of complications and challenges that present both as a result of inherent disease pathology and adverse events associated with antineoplastic therapies and interventions. The heavy burden of leukemic cells may lead to complications including tumor lysis syndrome, hyperleukocytosis, leukostasis, and differentiation syndrome, and the initiation of treatment can further exacerbate these effects. Capillary leak syndrome is observed as a result of antineoplastic agents used in acute leukemia, and L-asparaginase, a bacterial-derived enzyme, has a unique side effect profile including association with thrombosis. Thrombohemorrhagic syndrome and malignancy-associated thrombosis are also commonly observed complications due to direct disequilibrium in coagulant and anticoagulant factors. Due to inherent effects on the white blood cell milieu, leukemia patients are inherently immunocompromised and vulnerable to life-threatening sepsis. Lastly, the advents of newer therapies such as chimeric antigen receptor (CAR) T-cells have clinicians facing the management of related toxicities on unfamiliar territory. This review aims to discuss these acute leukemia-associated complications, their pathology, and management recommendations.

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.

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.

Serum phosphate level and its kinetic as an early marker of acute kidney injury in tumor lysis syndrome

INTRODUCTION

Acute kidney injury (AKI) is a major cause of mortality in tumor lysis syndrome. The biochemical parameters and kinetics of tumor lysis syndrome remain poorly described. Particularly, whether blood serum phosphate variations may help in the identification and management of patients who will eventually develop AKI remains to be studied.

METHODS

In this retrospective study, we included patients with tumor lysis syndrome episodes without AKI at diagnosis, and analyzed serum phosphate kinetic, clinical and tumor lysis syndrome biochemical variables to identify factors associated with AKI onset, and determine threshold values of phosphatemia associated with AKI development.

RESULTS

One hundred thirty tumor lysis syndrome episodes occurred in 120 patients during an 11-year period at the University Hospital of Angers. AKI developed in 56 tumor lysis syndrome episodes. In multivariable analysis, among the analyzed factors, only an increase in serum phosphate levels (before AKI diagnosis), exposure to platinum salts and an increase in LDH levels were associated with AKI development. Before AKI onset, a serum phosphate cut-off of 2.1 mmol/L was not effective in predicting AKI development (sensitivity 48%, specificity 84%, area under the receiver operating characteristic curve (AUC) 0.63 [0.52-0.74]). No other biochemical parameters were effective to better predict AKI occurrence.

CONCLUSION

This work suggests that increases in serum phosphate and LDH appear to be early and reliable biomarkers of AKI in tumor lysis syndrome. No valuable threshold value of serum phosphate was found to effectively predict AKI. This work is the basis for further prospective controlled studies on phosphate monitoring and phosphate lowering therapies to prevent AKI during tumor lysis syndrome.

Mesenchymal stromal cells as prophylaxis for graft-versus-host disease in haplo-identical hematopoietic stem cell transplantation recipients with severe aplastic anemia?-a systematic review and meta-analysis

BACKGROUND

Mesenchymal stromal cells (MSCs) are an emerging prophylaxis option for graft-versus-host disease (GVHD) in haplo-identical hematopoietic stem cell transplantation (haplo-HSCT) recipients with severe aplastic anemia (SAA), but studies have reported inconsistent results. This systematic review and meta-analysis evaluates the efficacy of MSCs as prophylaxis for GVHD in SAA patients with haplo-HSCT.

METHODS

Studies were retrieved from PubMed, EMBASE, Cochrane, Web of Science, and http://clinicaltrials.gov from establishment to February 2020. Twenty-nine single-arm studies (n = 1456) were included, in which eight (n = 241) studies combined with MSCs and eleven (n = 1215) reports without MSCs in haplo-HSCT for SAA patients. The primary outcomes were the incidences of GVHD. Other outcomes included 2-year overall survival (OS) and the incidence of cytomegalovirus (CMV) infection. Odds ratios (ORs) were calculated to compare the results pooled through random or fixed effects models.

RESULTS

Between MSCs and no MSCs groups, no significant differences were found in the pooled incidences of acute GVHD (56.0%, 95% CI 48.6-63.5% vs. 47.2%, 95% CI 29.0-65.4%; OR 1.43, 95% CI 0.91-2.25; p = 0.123), grade II-IV acute GVHD (29.8%, 95% CI 24.1-35.5% vs. 30.6%, 95% CI 26.6-34.6%; OR 0.97, 95% CI 0.70-1.32; p = 0.889), and chronic GVHD (25.4%, 95% CI 19.8-31.0% vs. 30.0%, 95% CI 23.3-36.6%; OR 0.79, 95% CI 0.56-1.11; p = 0.187). Furtherly, there was no obvious difference in 2-year OS (OR 0.98, 95% CI 0.60-1.61; p = 1.000) and incidence of CMV infection (OR 0.61, 95% CI 0.40-1.92; p = 0.018).

CONCLUSIONS

Our meta-analysis indicates that the prophylactic use of MSC co-transplantation is not an effective option for SAA patients undergoing haplo-HSCT. Hence, the general co-transplantation of MSCs for SAA haplo-HSCT recipients may lack evidence-based practice.

Oncologic Emergencies: Traditional and Contemporary

The recognition and management of oncologic emergencies are becoming increasingly relevant in the intensive care unit, particularly in the era of novel biologic therapies. Early recognition and multidisciplinary collaboration are essential to improving patient outcomes. This article discusses aspects of diagnosis and management for important malignancy-associated emergencies.

Spontaneous Tumor Lysis Syndrome

Tumor lysis syndrome (TLS) is a hemato-oncological emergency characterized by metabolic and electrolyte imbalances which are associated with disintegrating tumor cells. The syndrome is frequently observed when starting cytotoxic treatment of hematological malignancies, while the incidence of spontaneous tumor lysis prior to the start of tumor therapy is rare. Here, we present a case of spontaneous TLS in a male patient who was referred with unspecific symptoms and suspected metastatic malignancy. He developed acute renal failure before the diagnosis of a high-grade B-cell lymphoma (double hit lymphoma) and start of therapy. Although the course of TLS would have required intensive care, the patient rejected such treatment for personal reasons and died soon after the discontinuation of therapy. The case emphasizes the life-saving relevance of early detection and appropriate treatment of TLS. It also demonstrates the importance of actively screening for TLS, primarily in patients with malignant diseases and high tumor load, even if they are not receiving cytotoxic therapy.

Computational Approach for Rational Design of Fusion Uricase with PAS Sequences

Tumor lysis syndrome is a life-threatening condition for humans due to the lack of urate oxidase. In this study, several variants of PASylated uricase from the Aspergillus flavus species were analyzed computationally to find the appropriate fusions to solve short half-life and stability concern. The Ab initio method was performed using Rosetta software to structurally characterize the PAS sequences. The 3D structures of fusions were predicted for fused C- or N-terminally PAS sequences in different length to the uricase. The refinement and energy minimization steps revealed that physicochemical and conformational properties of fusions improved while the structures possessed prolonged PAS sequences. Molecular docking results showed that the highest binding affinity to uric acid belonged to uricase-PAS1-100 by the formation of six hydrogen and four non-hydrogen bonds. Altogether, the results indicated that the PASylation process would be promising upon the production of urate oxidase with improved solubility and stability.

Enhancement of Pharmaceutical Urate Oxidase Thermostability by Rational Design of De Novo Disulfide Bridge

Background and Purpose

As a therapeutic enzyme, urate oxidase is utilized in the reduction of uric acid in various conditions such as gout or tumor syndrome lysis. However, even bearing kinetical advantage over other counterparts, it suffers from structural instability most likely due to its subcellular and fungal origin.

Objectives

In this research, by using rational design and introduction of de novo disulfide bridge in urate oxidase structure, we designed and created a thermostable urate oxidase for the first time.

Materials and Methods

Utilizing site-directed mutagenesis and only with one point mutation we constructed two separate mutants: Ala6Cys and Ser282Cys which covalently linked subunits of enzyme each other. Single mutation to cysteine created three inter-chain disulfide bridges and one hydrogen bond in Ala6Cys and two disulfide bridges in Ser282Cys.

Results

Both mutants showed 10 °C increase in optimum activity compared to wild-type enzyme while the K_m values for both increased by 50% and their specific activity compromised. The thermal stability of Ser282Cys increased remarkably by comparing Ala6Cys and wild-type enzymes. Estimation of half life for wild-type enzyme demonstrated 38.5 min, while for Ala6Cys and Ser282Cys were 138 and 115 min, respectively. Interestingly, the optimal pH of both mutants was broaden from 7 to 10, which could make them candidates for industrial applications.

Conclusion

It seemed that introducing disulfide bridges resulted in local and overall rigidity by bringing two adjacent sites of enzyme together and decreasing the conformational entropy of unfolding state is responsible for the enhancement of thermostability.

Diagnosis and management of tumor lysis syndrome

Tumor lysis syndrome (TLS) is an oncological emergency characterized by a classic tetrad of hyperuricemia, hyperkalemia, hyperphosphatemia, and hypocalcemia. Risk assessment and prophylactic therapy is critical in preventing this oncological emergency. Treatment of established TLS involves aggressive hydration, electrolyte management, and the use of hypouricemic agents.

Onconephrology: An Evolving Field

This column is supplied by Ala Abudayyeh, MD, an internal medicine physician and associate professor of nephrology at The University of Texas MD Anderson Cancer Center in Houston, Texas. Dr. Abudayyeh earned her medical degree at the University of Texas-Houston Medical School and completed both her internal medicine residency and nephrology fellowship at Baylor College of Medicine in Houston. She is board certified in internal medicine and nephrology and joined the University of Texas MD Anderson Cancer Center in 2012.

Tumour lysis syndrome

Tumour lysis syndrome (TLS) is a life-threatening emergency characterised by a massive cytolysis with the release of intracellular electrolytes, nucleic acids, and metabolites into the circulation. TLS comprises laboratory derangements (hyperuricaemia, hyperkalaemia, hyperphosphataemia, and hypocalcaemia) responsible for acute kidney injury. In patients with hematologic malignancies after cytotoxic therapy or spontaneously and also in advanced solid tumours. Assessment of disease specific risk level for TLS in patients receiving anti-tumoural therapy is essential for early diagnosis. Prophylaxis is the mainstay of management of TLS. It is important to routinely initiate a risk-adapted prophylactic strategy to correct metabolic alterations and preserve renal function. High and intermediate risk patients and patients with established TLS should be managed with multidisciplinary medical care in a hospital unit to receive monitoring and medical care. Renal replacement therapy should be considered in patients with refractory TLS.

Risk-based management strategy and outcomes of tumor lysis syndrome in children with leukemia/lymphoma: Analysis from a resource-limited setting

BACKGROUND

Data from low- and middle-income countries on tumor lysis syndrome (TLS) in the pediatric population are limited. This study aims to analyze the clinical and biochemical characteristics and treatment outcomes of TLS in children with leukemia/lymphomas in a resource-limited setting.

PROCEDURE

Children with intermediate risk (IRD) and high risk (HRD) for developing TLS were retrospectively studied at a tertiary cancer center in India.

RESULTS

Over a three-year period, 224 children with acute leukemia/lymphoma having IRD (21.8%, n = 49) and HRD (78.1%, n = 175) were identified. TLS developed in 53.6% (n = 120) cases, of which 75% (n = 90) had laboratory TLS alone. Thirteen children had clinical TLS (C-TLS) at presentation while 17 patients progressed to develop C-TLS. TLS developed in 51% (n = 25) and 54.5% (n = 95) of children with IRD and HRD, respectively. Rasburicase was used in 8.5% (n = 19) cases and five children required hemodialysis. Two children (0.8%) expired during the course of TLS management. Multivariate analysis identified the presence of hyperuricemia as the single significant risk factor for developing TLS. When children in whom a 25% change in biochemical values from the baseline that falls within the normal range were excluded, 21.4% (48/224) cases were identified to have clinically relevant TLS (8% in IRD and 25% in HRD).

CONCLUSION

With hydration, supportive care and judicious use of rasburicase, it is feasible to manage TLS efficiently in resource-limited settings. A modification of the TLS definition criteria would help to identify clinically relevant TLS.

Trough concentration of itraconazole and its relationship with efficacy and safety: a systematic review and meta-analysis

Objectives

The optimum trough concentration of itraconazole for clinical response and safty is controversial. The objective of this systematic review and meta-analysis was to determine the optimum trough concentration of itraconazole and evaluate its relationship with efficacy and safety.

Methods

We searched PubMed, EMBASE, Web of Science, the Cochrane Library, Clinical-Trials.gov, and three Chinese literature databases (CNKI, WanFang, and CBM). We included observational studies that compared clinical outcomes below or above the trough concentration cut-off value which we set as 0.25, 0.5, and 1.0 mg/L. The efficacy outcomes were rate of successful treatment, rate of prophylaxis failure and invasive fungal infection (IFI)-related mortality. The safety outcomes included incidents of hepatotoxicity and other adverse events.

Results

The study included a total of 29 studies involving 2,346 patients. Our meta-analysis showed that compared with itraconazole trough concentrations (C_trough) of ≥0.25 mg/L, levels of <0.25 mg/L significantly increased the incidence of IFI for prophylaxis (RR =3.279, 95% confidence interval [CI] 1.73–6.206). Moreover, the success rate of treatment decreased significantly at a cut-off level of 0.5 mg/L (RR =0.396, 95% CI 0.176–0.889). An itraconazole trough level of 1.0 mg/L was associated with hepatotoxicity and other adverse events in a review of many studies.

Conclusion

An itraconazole trough concentration of 0.25 mg/L should be considered as the lower threshold for prophylaxis, and a target concentration of 0.5 mg/L should be the lower limit for effective treatment. A trough level of 1.0 mg/L is associated with increased hepatotoxicity and other adverse events (using High Performance Liquid Chromatography [HPLC]).

Single 6-mg dose of rasburicase: The experience in a large academic medical center

Background

Tumor lysis syndrome is an oncologic emergency due to the release of tumor cell contents, leading to metabolic derangements. Rasburicase, a recombinant urate oxidase, catabolizes uric acid. At our institution, we administer a single 6-mg dose of rasburicase to patients who are at risk for tumor lysis syndrome. We aimed to assess the efficacy of single 6-mg dose of rasburicase and explore risk factors associated with rasburicase failure.

Methods

We report results in 92 adult patients who had a baseline uric acid greater than 7.5 mg/dL and received a single 6-mg dose of rasburicase for the management of tumor lysis syndrome. Responders were defined as those whose uric acid was less than or equal to 7.5 mg/dL within 24–36 h of rasburicase administration. The primary end point was response based on uric acid level. Secondary end points included response to rasburicase in association with lactate dehydrogenase, serum creatinine, calcium, phosphorus, blood pH, and oncologic diagnosis.

Results

Median age was 65 years and 70% were men. Most patients had leukemia (32%) or lymphoma (40%). Eighty-seven of 92 patients (95%), who received single 6-mg dose of rasburicase, achieved a uric acid less than 7.5 mg/dL within 24–36h of dosing. Body mass index was similar between responders and non-responders: 28.6 kg/m2 vs. 26.6 kg/m2, respectively, p = 0.6. Baseline lactate dehydrogenase levels were similar between the groups: 756 U/L vs. 892 U/L, respectively, p = 0.33. Blood pH values documented within 24 h of first dose of rasburicase were also similar between the two groups (n = 30; 7.33 vs. 7.34 respectively, p = 0.6). However, median baseline uric acid was lower in responders than non-responders: 12.3 mg/dL vs. 17.3 mg/dL, respectively, p = 0.012. Baseline serum creatinine and creatinine clearance were similar between responders and non-responders (2.2 mg/dL vs. 3.95 mg/dL; p = 0.12 and 29 mL/min vs. 16 mL/min; p = 0.11, respectively).

Conclusions

Higher baseline uric acid levels were observed in patients who did not respond to the first rasburicase dose. In our study, uric acid levels normalized in 95% of patients after a single 6-mg dose of rasburicase indicating that a single 6-mg dose of rasburicase may be sufficient to manage tumor lysis syndrome, for most patients.

Bone marrow versus peripheral blood as a graft source for haploidentical donor transplantation in adults using post-transplant cyclophosphamide-A systematic review and meta-analysis

BACKGROUND

Peripheral-blood (PB) and bone marrow (BM) are both widely used in hematopoietic stem cell transplantation (HSCT). However, it is unclear whether PB or BM produces a more satisfactory outcome in haploidentical HSCT, particularly for patients using post-transplant cyclophosphamide (PTCy), which is the standard therapy. However, to date, no meta-analysis focusing on this issue has been published.

METHODS

We systematically searched PubMed, MEDLINE, Web of Science, the Cochrane Library and the ClinicalTrials.gov website for studies regarding the use of BM or PB in haploidentical HSCT for hematological malignancies in adults using PTCy. Data were analyzed using Open Meta-Analyst statistical software.

RESULTS

Fourteen studies were extracted including four comparative retrospective reports and ten single-arm reports, with a total of 1759 patients received PTCy haploidentical HSCT (462 patients received PBSCT, 1297 patients received BMT). The pooled outcomes of comparative retrospective studies showed significantly higher incidence of grade III-IV acute graft-versus-host disease (GVHD) (OR = 1.741, 95%CI 1.032-2.938), incidence of grade IIIV acute GVHD (OR = 1.778, 95%CI 1.314, 2.406) and engraftment rate (OR = 1.843, 95%CI 1.066-3.185) in the PB group. No significant differences were found on the incidence of relapse, 2-year overall survival (OS) and disease-free survival (DFS), acute IIIV GVHD and chronic GVHD between PBSCT or BMT.

CONCLUSION

The efficacy of PB is not inferior to BM for patients undergoing PTCy haploidentical HSCT with regard to primary outcomes, including OS, DFS, NRM and relapse. However, with regards to convenience and pain relief, PB graft is suitable for haploidentical HSCT, but with a higher risk of acute GVHD.

[Metabolic disorders as paraneoplastic syndromes]

Paraneoplastic syndromes are characterized by the tumor-induced release of peptide hormones and/or the initiation of immune phenomena, which elicit clinical changes and alterations in laboratory parameters independent of the tumor size and spread. In addition to neurological, endocrinal and rheumatological phenotypes, metabolic alterations play a special role in the clinical routine as they commonly present with acute symptoms in an emergency situation and necessitate immediate diagnosis and prompt initiation of treatment. Metabolic alterations within the framework of malignant diseases should be treated in a multidisciplinary team and it is often necessary to perform monitoring and treatment in an intensive care unit. This article focuses on the diagnostic and therapeutic options for metabolic disorders due to paraneoplastic syndromes, such as hypercalcemia, hypocalcemia, hyperglycemia, hypoglycemia and a special variant of tumor-induced metabolic disorders due to tumor lysis syndrome.

Tumor Lysis Syndrome in Patients with Hematological Malignancies

Tumor lysis syndrome is a metabolic complication that may follow the initiation of cancer therapy. It commonly occurs in hematological malignant patients particularly non-Hodgkin's lymphoma and acute leukemia due to chemotherapy or spontaneously. It is characterized by a biochemical abnormality such as hyperuricemia, hyperkalemia, hyperphosphatemia, and hypocalcemia and its clinical outcome is directly related to these biochemical abnormalities. Prevention and treatment of tumor lysis syndrome depend on immediate recognition of patients at risk. Therefore, identifying patients at risk and prophylactic measures are important to minimize the clinical consequences of tumor lysis syndrome. Patients with low risk should receive hydration and allopurinol. On the other hand patients with high risk should receive hydration and rasburicase in an inpatient setting. It is important to start therapy immediately, to correct all parameters before cancer treatment, to assess risk level of patients for TLS, and to select treatment options based on the risk level. In this review a comprehensive search of literatures was performed using MEDLINE/PubMed, Hinari, the Cochrane library, and Google Scholar to summarize diagnostic criteria, incidence, predicting factors, prevention, and treatment options for tumor lysis syndrome in patients with hematological malignancies.

Emergencies in Hematology and Oncology

The development of medical emergencies related to the underlying disease or as a result of complications of therapy are common in patients with hematologic or solid tumors. These oncological emergencies can occur as an initial presentation or in a patient with an established diagnosis and are encountered in all medical care settings, ranging from primary care to the emergency department and various subspecialty environments. Therefore, it is critically important that all physicians have a working knowledge of the potential oncological emergencies that may present in their practice and how to provide the most effective care without delay. This article reviews the most common oncological emergencies and provides practical guidance for initial management of these patients.

Acute kidney injury in the perioperative period and in intensive care units (excluding renal replacement therapies)

Acute kidney injury (AKI) is a syndrome that has progressed a great deal over the last 20 years. The decrease in urine output and the increase in classical renal biomarkers, such as blood urea nitrogen and serum creatinine, have largely been used as surrogate markers for decreased glomerular filtration rate (GFR), which defines AKI. However, using such markers of GFR as criteria for diagnosing AKI has several limits including the difficult diagnosis of non-organic AKI, also called "functional renal insufficiency" or "pre-renal insufficiency". This situation is characterized by an oliguria and an increase in creatininemia as a consequence of a reduction in renal blood flow related to systemic haemodynamic abnormalities. In this situation, "renal insufficiency" seems rather inappropriate as kidney function is not impaired. On the contrary, the kidney delivers an appropriate response aiming to recover optimal systemic physiological haemodynamic conditions. Considering the kidney as insufficient is erroneous because this suggests that it does not work correctly, whereas the opposite is occurring, because the kidney is healthy even in a threatening situation. With current definitions of AKI, normalization of volaemia is needed before defining AKI in order to avoid this pitfall.

Acute kidney injury in critically ill cancer patients: an update

Patients with cancer represent a growing group among actual ICU admissions (up to 20 %). Due to their increased susceptibility to infectious and noninfectious complications related to the underlying cancer itself or its treatment, these patients frequently develop acute kidney injury (AKI). A wide variety of definitions for AKI are still used in the cancer literature, despite existing guidelines on definitions and staging of AKI. Alternative diagnostic investigations such as Cystatin C and urinary biomarkers are discussed briefly. This review summarizes the literature between 2010 and 2015 on epidemiology and prognosis of AKI in this population. Overall, the causes of AKI in the setting of malignancy are similar to those in other clinical settings, including preexisting chronic kidney disease. In addition, nephrotoxicity induced by the anticancer treatments including the more recently introduced targeted therapies is increasingly observed. However, data are sometimes difficult to interpret because they are often presented from the oncological rather than from the nephrological point of view. Because the development of the acute tumor lysis syndrome is one of the major causes of AKI in patients with a high tumor burden or a high cell turnover, the diagnosis, risk factors, and preventive measures of the syndrome will be discussed. Finally, we will briefly discuss renal replacement therapy modalities and the emergence of chronic kidney disease in the growing subgroup of critically ill post-AKI survivors.

Efficacy and safety of febuxostat for prevention of tumor lysis syndrome in patients with malignant tumors receiving chemotherapy: a phase III, randomized, multi-center trial comparing febuxostat and allopurinol

BACKGROUND

Control of serum uric acid (sUA) levels is very important during chemotherapy in patients with malignant tumors, as the risks of tumor lysis syndrome (TLS) and renal events are increased with increasing levels of sUA. We investigated the efficacy and safety of febuxostat, a potent non-purine xanthine oxidase inhibitor, compared with allopurinol for prevention of hyperuricemia in patients with malignant tumors, including solid tumors, receiving chemotherapy in Japan.

METHODS

An allopurinol-controlled multicenter, open-label, randomized, parallel-group comparative study was carried out. Patients with malignant tumors receiving chemotherapy, who had an intermediate risk of TLS or a high risk of TLS and were not scheduled to be treated with rasburicase, were enrolled and then randomized to febuxostat (60 mg/day) or allopurinol (300 or 200 mg/day). All patients started to take the study drug 24 h before chemotherapy. The primary objective was to confirm the non-inferiority of febuxostat to allopurinol based on the area under the curve (AUC) of sUA for a 6-day treatment period.

RESULTS

Forty-nine and 51 patients took febuxostat and allopurinol, respectively. sUA decreased over time after initiation of study treatment. The least squares mean difference of the AUC of sUA between the treatment groups was -33.61 mg h/dL, and the 95 % confidence interval was -70.67 to 3.45, demonstrating the non-inferiority of febuxostat to allopurinol. No differences were noted in safety outcomes between the treatment groups.

CONCLUSION

Febuxostat demonstrated an efficacy and safety similar to allopurinol in patients with malignant tumors receiving chemotherapy.

TRIAL REGISTRY

http://www.clinicaltrials.jp ; Identifier: JapicCTI-132398.

Uricase alkaline enzymosomes with enhanced stabilities and anti-hyperuricemia effects induced by favorable microenvironmental changes

Enzyme therapy is an effective strategy to treat diseases. Three strategies were pursued to provide the favorable microenvironments for uricase (UCU) to eventually improve its features: using the right type of buffer to constitute the liquid media where catalyze reactions take place; entrapping UCU inside the selectively permeable lipid vesicle membranes; and entrapping catalase together with UCU inside the membranes. The nanosized alkaline enzymosomes containing UCU/(UCU and catalase) (ESU/ESUC) in bicine buffer had better thermal, hypothermal, acid-base and proteolytic stabilities, in vitro and in vivo kinetic characteristics, and uric acid lowering effects. The favorable microenvironments were conducive to the establishment of the enzymosomes with superior properties. It was the first time that two therapeutic enzymes were simultaneously entrapped into one enzymosome having the right type of buffer to achieve added treatment efficacy. The development of ESU/ESUC in bicine buffer provides valuable tactics in hypouricemic therapy and enzymosomal application.

Nanosomal Microassemblies for Highly Efficient and Safe Delivery of Therapeutic Enzymes

Enzyme therapy has unique advantages over traditional chemotherapies for the treatment of hyperuricemia, but overcoming the delivery obstacles of therapeutic enzymes is still a significant challenge. Here, we report a novel and superior system to effectively and safely deliver therapeutic enzymes. Nanosomal microassemblies loaded with uricase (NSU-MAs) are assembled with many individual nanosomes. Each nanosome contains uricase within the alkaline environment, which is beneficial for its catalytic reactions and keeps the uricase separate from the bloodstream to retain its high activity. Compared to free uricase, NSU-MAs exhibited much higher catalytic activity under physiological conditions and when subjected to different temperatures, pH values and trypsin. NSU-MAs displayed increased circulation time, improved bioavailability, and enhanced uric acid-lowering efficacy, while decreasing the immunogenicity. We also described the possible favorable conformational changes occurring in NSU-MAs that result in favorable outcomes. Thus, nanosomal microassemblies could serve as a valuable tool in constructing delivery systems for therapeutic enzymes that treat various diseases.

Tumor lysis syndrome: A clinical review

Tumor lysis syndrome is an oncometabolic emergency resulting from rapid cell death. Tumor lysis syndrome can occur as a consequence of tumor targeted therapy or spontaneously. Clinicians should stratify every hospitalized cancer patient and especially those receiving chemotherapy for the risk of tumor lysis syndrome. Several aspects of prevention include adequate hydration, use of uric acid lowering therapies, use of phosphate binders and minimization of potassium intake. Patients at high risk for the development of tumor lysis syndrome should be monitored in the intensive care unit. Established tumor lysis syndrome should be treated in the intensive care unit by aggressive hydration, possible use of loop diuretics, possible use of phosphate binders, use of uric acid lowering agents and dialysis in refractory cases.

Rasburicase in the management of tumor lysis: an evidence-based review of its place in therapy

Tumor lysis syndrome (TLS) is a potentially life-threatening complication of cancer therapy characterized by two or more of the following laboratory abnormalities: hyperuricemia, hyperkalemia, hypocalcemia, and hyperphosphatemia, with resultant end-organ damage, eg, renal failure, seizures, or cardiac arrhythmias. High-risk patients include those with highly proliferative cancers and/or large tumor burdens, particularly in the setting of highly effective chemotherapy, among other risk factors. Before 2002, antihyperuricemic drug therapy was limited to allopurinol, a xanthine oxidase inhibitor. Rasburicase, a recombinant urate oxidase, was approved by the US Food and Drug Administration for children in 2002 and adults in 2009, ushering in a new era in TLS therapy. We attempted to critically appraise the available evidence supporting the perceived benefits of rasburicase in the management of TLS. A Medline search yielded 98 relevant articles, including 26 retrospective and 22 prospective studies of rasburicase for the treatment of TLS, which were then evaluated to determine the best available evidence for the effectiveness of rasburicase in terms of disease-oriented, patient-oriented, and economic outcomes. Rasburicase is now a standard of care for patients at high risk of TLS despite continuing debate on the correlation between its profound and rapid lowering of plasma uric acid levels with hard patient outcomes, eg, need for renal replacement therapy and mortality. Rasburicase is dramatically effective in lowering plasma uric acid levels. The mortality and cost-effectiveness benefits of this expensive drug remain to be conclusively proven, and well designed, randomized controlled trials are needed to answer these fundamentally important questions.

Methaemoglobinaemia in a G6PD-deficient child treated with rasburicase

A 5-year-old boy from the Congo, was admitted for hyperleucocytic acute lymphoblastic leukaemia, with a high risk of tumour lysis syndrome (TLS). He had splenomegaly and mediastinal lymphadenopathy on chest X-ray. We started steroids and hyperhydration with rasburicase to prevent TLS. Respiratory failure with mediastinal enlargement developed rapidly. A few hours after intensive care unit (ICU) admission, he was started on mechanical ventilation. Chemotherapy was started immediately given the strong suspicion of mediastinal compression. Low oxygen saturation with high partial arterial oxygen pressure persisted. Blood tests confirmed 20% methaemoglobinaemia and glucose-6-phosphate dehydrogenase (G6PD) deficiency. Allopurinol was substituted for rasburicase. The methaemoglobinaemia disappeared rapidly and he was discharged from the ICU after 72 h. In case of rasburicase use, a close clinical monitoring is mandatory, especially in populations where G6PD deficiency is highly prevalent. Methaemoglobinaemia must be suspected in case of low oxygen saturation when all other potential causes have been ruled out.

Prognostic factors, long-term survival, and outcome of cancer patients receiving chemotherapy in the intensive care unit

Prognostic factors and outcomes of cancer patients with acute organ failure receiving chemotherapy (CT) in the intensive care unit (ICU) are still incompletely described. We therefore retrospectively studied all patients who received CT in any ICU of our institution between October 2006 and November 2013. Fifty-six patients with hematologic (n = 49; 87.5 %) or solid (n = 7; 12.5 %) malignancies, of which 20 (36 %) were diagnosed in the ICU, were analyzed [m/f ratio, 33:23; median age, 47 years (IQR 32 to 62); Charlson Comorbidity Index (CCI), 3 (2 to 5); Simplified Acute Physiology Score II (SAPS II), 50 (39 to 61)]. The main reasons for admission were acute respiratory failure, acute kidney failure, and septic shock. Mechanical ventilation and vasopressors were employed in 34 patients (61 %) respectively, hemofiltration in 22 (39 %), and extracorporeal life support in 7 (13 %). Twenty-seven patients (48 %) received their first CT in the ICU. Intention of therapy was cure in 46 patients (82 %). Tumor lysis syndrome (TLS) developed in 20 patients (36 %). ICU and hospital survival was 75 and 59 %. Hospital survivors were significantly younger; had lower CCI, SAPS II, and TLS risk scores; presented less often with septic shock; were less likely to develop TLS; and received vasopressors, hemofiltration, and thrombocyte transfusions in lower proportions. After discharge, 88 % continued CT and 69 % of 1-year survivors were in complete remission. Probability of 1- and 2-year survival was 41 and 38 %, respectively. Conclusively, administration of CT in selected ICU cancer patients was feasible and associated with considerable long-term survival as well as long-term disease-free survival.

Tumor lysis syndrome: new challenges and recent advances

Tumor lysis syndrome (TLS) is an oncologic emergency triggered by the rapid release of intracellular material from lysing malignant cells. Most common in rapidly growing hematologic malignancies, TLS has been reported in virtually every cancer type. Central to its pathogenesis is the rapid accumulation of uric acid derived from the breakdown of nucleic acids, which leads to kidney failure by various mechanisms. Kidney failure then limits the clearance of potassium, phosphorus, and uric acid leading to hyperkalemia, hyperphosphatemia, and secondary hypocalcemia, which can be fatal. Prevention of TLS may be more effective than treatment, and identification of at-risk individuals in whom to target preventative efforts remains a key research area. Herein, we discuss the pathophysiology, epidemiology, and treatment of TLS with an emphasis on the kidney manifestations of the disease.