Febuxostat, a Urate-Lowering Drug Bridging From Adults to Pediatrics; A Brief Report

PURPOSE

Febuxostat, a nonpurine selective inhibitor of xanthine oxidase has elucidated an effective urate-lowering in adults. However, data on febuxostat utility in children is limited. The present study summarizes the current knowledge on the efficacy and safety of febuxostat in children with hyperuricemia.

METHODS

We searched PubMed, Google Scholar, Embase, and Web of Science from inception to September 2024 for studies assessing febuxostat or comparing febuxostat with allopurinol in children and adolescents with hyperuricemia with diverse etiologies. Randomized controlled trials, prospective observational, and systematic reviews, meta-analyses, and retrospective studies were included.

FINDINGS

Search results illuminated three studies assessing febuxostat in children with hyperuricemia of different etiologies; including tumor lysis syndrome (TLS), asymptomatic hyperuricemia, and gout. An open-label observational study and one-retrospective study assessed febuxostat efficacy for asymptomatic hyperuricemia and gout, respectively. There was one retrospective study that compared febuxostat to allopurinol for TLS prevention.

IMPLICATIONS

Febuxostat is a promising medication that is effective in attaining the desired outcomes in children with hyperuricemia. However, existing evidence does not permit any conclusion regarding the comparative efficacy and safety of febuxostat with allopurinol in children. Future randomized clinical trials evaluating its effectiveness and safety are needed.

Emergencies in Hematology: Why, When and How I Treat?

Hematological emergencies are critical medical conditions that require immediate attention due to their rapid progression and life-threatening nature. As various examples, hypercalcemia, often associated with cancers such as multiple myeloma, can lead to severe neurological and cardiac dysfunction. Hyperleukocytosis, common in acute myeloid leukemias, increases the risk of leukostasis and multiorgan failure. Sickle cell crisis, a common complication in sickle cell disease, results from vaso-occlusion, leading to acute pain and tissue ischemia. Tumor lysis syndrome, reported in cases of rapid destruction of cancer cells, causes electrolyte imbalances and acute kidney injury. Acute transfusion reactions, fundamental in hematological conditions, can range from mild allergic responses to severe hemolysis and shock, requiring prompt management. Disseminated intravascular coagulation, involving excessive coagulation and bleeding, is commonly triggered by hematological malignancies, common in the first phases of acute promyelocytic leukemia. Recently, in the era of bispecific antibodies and chimeric antigen receptor T cells, cytokine release syndrome is a manifestation that must be recognized and promptly treated. Understanding the pathophysiology, recognizing the clinical manifestations, and ensuring adequate diagnostic strategies and management approaches for each condition are central to early intervention in improving patient outcomes and reducing mortality.

Rationally designed febuxostat-based hydroxamic acid and its pH-Responsive nanoformulation elicits anti-tumor activity

Attempts to furnish antitumor structural templates that can prevent the occurrence of drug-induced hyperuricemia spurred us to generate xanthine oxidase inhibitor-based hydroxamic acids and anilides. Specifically, the design strategy involved the insertion of febuxostat (xanthine oxidase inhibitor) as a surface recognition part of the HDAC inhibitor pharmacophore model. Investigation outcomes revealed that hydroxamic acid 4 elicited remarkable antileukemic effects mediated via HDAC isoform inhibition. Delightfully, the adduct retained xanthine oxidase inhibitory activity, though xanthine oxidase inhibition was not the underlying mechanism of its cell growth inhibitory effects. Also, compound 4 demonstrated significant in-vivo anti-hyperuricemic (PO-induced hyperuricemia model) and antitumor activity in an HL-60 xenograft mice model. Compound 4 was conjugated with poly (ethylene glycol) poly(aspartic acid) block copolymer to furnish pH-responsive nanoparticles (NPs) in pursuit of circumventing its cytotoxicity towards the normal cell lines. SEM analysis revealed that NPs had uniform size distributions, while TEM analysis ascertained the spherical shape of NPs, indicating their ability to undergo self-assembly. HDAC inhibitor 4 was liberated from the matrix due to the polymeric nanoformulation's pH-responsiveness, and the NPs demonstrated selective cancer cell targeting ability.

Febuxostat enhances the efficacy of dasatinib by inhibiting ATP-binding cassette subfamily G member 2 (ABCG2) in chronic myeloid leukemia cells

Dasatinib is a second-generation breakpoint cluster region-abelson 1 (BCR::ABL1) tyrosine kinase inhibitor (TKI) used for the treatment of chronic myeloid leukemia (CML). Overexpression of ATP-binding cassette subfamily G member 2 (ABCG2) in CML cells contributes to dasatinib resistance and poor chemotherapeutic responses. Considering that the xanthine oxidase inhibitor febuxostat has anti-ABCG2 activity, febuxostat may enhance the efficacy of dasatinib. However, the mechanism of action of febuxostat and its effects on the efficacy and safety of dasatinib in patients with CML are unknown. Therefore, this study aimed to retrospectively investigate the clinical impact of concomitant febuxostat on the efficacy of dasatinib in 65 patients with CML. Moreover, its underlying mechanism was explored in vitro using an ABCG2-overexpressing CML cell line (K562-ABCG2 cells). The retrospective study revealed that the achievement ratios of early molecular response at three months and major molecular response at 12 months after dasatinib treatment in patients with febuxostat were significantly higher than those in patients without febuxostat (91 % vs. 70 %, p = 0.034, 86 % vs. 53 %, p = 0.013, respectively). In vitro studies showed that febuxostat significantly decreased cell viability and increased the residual dasatinib concentration in dasatinib-treated K562-ABCG2 cells. Moreover, phosphorylated BCR::ABL1 levels in dasatinib-treated K562-ABCG2 cells were significantly decreased by febuxostat. Overall, concomitant febuxostat enhanced the efficacy of dasatinib in patients with CML. This was achieved partially by inhibition of ABCG2-mediated excretion of dasatinib from CML cells. Therefore, these findings provide important insights for improving CML treatment and overcoming TKI resistance.

Comprehensive Evaluation of OATP- and BCRP-Mediated Drug-Drug Interactions of Methotrexate Using Physiologically-Based Pharmacokinetic Modeling

Methotrexate (MTX) is an antifolate agent widely used for treating conditions such as rheumatoid arthritis and hematologic cancer. This study aimed to quantitatively interpret the drug-drug interactions (DDIs) of MTX mediated by drug transporters using physiologically-based pharmacokinetic (PBPK) modeling. An open-label, randomized, 4-treatment, 6-sequence, 4-period crossover study was conducted to investigate the effects of rifampicin (RFP), an inhibitor of organic anionic transporting peptides (OATP) 1B1/3, and febuxostat (FBX), an inhibitor of breast cancer resistance protein (BCRP), on the pharmacokinetics of MTX in healthy volunteers. PBPK models of MTX, RFP, and FBX were developed based on in vitro and in vivo data, and the performance of the simulation results for final PBPK models was validated in a clinical study. In the clinical study, when MTX was co-administered with RFP or FBX, systemic exposure of MTX increased by 33% and 17%, respectively, compared with that when MTX was administered alone. When MTX was co-administered with RFP and FBX, systemic exposure increased by 52% compared with that when MTX was administered alone. The final PBPK model showed a good prediction performance for the observed clinical data. The PBPK model of MTX was well developed in this study and can be used as a potential mechanistic model to predict and evaluate drug transporter-mediated DDIs of MTX with other drugs.

Effectiveness of fractionated rituximab in preventing tumor lysis syndrome in aggressive B-cell lymphoma: Insights from real-life clinical practice

BACKGROUND

Tumor lysis syndrome (TLS) is a potentially life-threatening condition resulting from the rapid destruction of malignant cells, leading to electrolyte imbalances and severe complications, such as acute kidney injury, arrhythmias, and seizures. TLS can be managed through hyperhydration, urate-lowering treatments, and a steroid prophase strategy.

AIMS

This study aims to explore the impact of fractionated rituximab, an anti-CD20 antibody, on the occurrence and severity of TLS during the initial cycle in patients with aggressive B-cell non-Hodgkin lymphoma (B-NHL).

METHODS

Data was retrospectively collected from 94 of 186 patients.

RESULTS

Among the 94 patients included in the analysis, the median age was 70. Histologies were diffuse large B-cell lymphoma (75%), Burkitt lymphoma (13%) and high-grade B-cell lymphoma (8%). The majority were at an advanced stage (93%) with a high IPI score (75%). Most patients received anthracycline-containing regimens (72%) and prophylactic allopurinol (83%) and/or rasburicase (26%). Steroid prophase was administered to 82% of patients. The study identified one clinical TLS case and six laboratory TLS cases. Significant TLS factors included BL histology, elevated baseline LDH (⟩500 U/l), and rasburicase usage. Infusion reactions were rare (3%). Median progression-free survival was 2.6 years, and 2-year overall survival was 33%, irrespective of TLS occurrence.

CONCLUSION

In this real-life study, clinical TLS occurrence was low (1%). TLS appeared more frequent in BL but did not impact overall survival. Fractionated initial rituximab dosing in addition to preventive strategies is a feasible approach in preventing clinical TLS, warranting further prospective investigation.

[Electrolyte disorders in oncological patients]

Electrolyte disorders (ED) are common in patients with cancer and in most cases, the etiologies do not differ from the general population. They may also be induced by the cancer, its therapy or paraneoplastic syndromes. ED are associated with poor outcomes, increased morbidity and mortality in this population. Hyponatremia is the most common disorder, often multifactorial, iatrogenic or secondary to the syndrome of inappropriate antidiuretic hormone secretion, usually due to small cell lung cancer. More rarely, hyponatremia may reveal adrenal insufficiency. Hypokalemia is generally multifactorial and associated with other ED. Cisplatin and ifosfamide induce proximal tubulopathies with hypokalemia and/or hypophosphatemia. Hypomagnesemia is often iatrogenic, related to cisplatin or cetuximab, but can be prevented by supplementation. Hypercalcemia can impair life quality and be life-threatening in the most severe cases. Hypocalcemia is less common and often of iatrogenic origin. Finally, the tumor lysis syndrome is a diagnostic and therapeutic emergency that affects the prognosis of patients. Its incidence tends to increase in solid oncology, related to the improvement of therapies. Prevention and early diagnosis of ED are essential to optimize the overall management of patients with underlying cancer and cancer therapy. The aim of this review is to synthesize most frequent ED and their management.

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.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Strategies for mitigating adverse events related to selective RET inhibitors in patients with RET-altered cancers

The US Food and Drug Administration (FDA) approval of the selective RET inhibitors selpercatinib and pralsetinib has led to a paradigm change in the treatment of RET-altered lung and thyroid cancers through a higher response rate and a more tolerable safety and toxicity profile than multi-kinase inhibitors. Recently, selpercatinib has received a tissue-agnostic FDA approval for all RET-fusion-positive cancers, and pralsetinib has shown pan-cancer activity as well. Given the anticipated increase in the use of both drugs across multiple tumor types, it is crucial to recognize the possible side effects and approaches for their optimal management in order to maximize the clinical benefit for treated patients. In this review, we underscore potential toxicities associated with selective RET inhibitors and discuss strategies to mitigate them.

Past, present and future of xanthine oxidase inhibitors: design strategies, structural and pharmacological insights, patents and clinical trials

Xanthine oxidase, a molybdo-flavoenzyme, and an isoform of xanthine dehydrogenase both exist as xanthine oxidoreductase and are responsible for purine catabolism. Xanthine oxidase is more involved in pathological conditions when extensively modulated. Elevation of xanthine oxidase is not only the prime cause of gout but is also responsible for various hyperuricemia associated pathological conditions like diabetes, chronic wounds, cardiovascular disorders, Alzheimer's disease, etc. Currently available xanthine oxidase inhibitors in clinical practice (allopurinol, febuxostat and topiroxostat) suffer from fatal side effects that pose a serious problem to the healthcare system, raising global emergency to develop novel, potent and safer xanthine oxidase inhibitors. This review will provide key and systematic information about: a. design strategies (inspired from both marketed drugs in clinical practice and natural products), structural insights and pharmacological output (xanthine oxidase inhibition and associated activities) of various pre-clinical candidates reported by various research groups across the globe in the past two decades; b. patented xanthine oxidase inhibitors published in the last three decades and c. clinical trials and their outcomes on approved drug candidates. Information generated in this review has suggested fragment-based drug design (FBDD) and molecular hybridization techniques to be most suitable for development of desired xanthine oxidase inhibitors as one provides high selectivity toward the enzyme and the other imparts multifunctional properties to the structure and both may possess capabilities to surpass the limitations of currently available clinical drugs. All in combination will exclusively update researchers working on xanthine oxidase inhibitors and allied areas and potentially help in designing rational, novel, potent and safer xanthine oxidase inhibitors that can effectively tackle xanthine oxidase related disease conditions and disorders.

Chapter 3: Management of kidney injury caused by cancer drug therapy, from clinical practice guidelines for the management of kidney injury during anticancer drug therapy 2022

Cisplatin should be administered with diuretics and Magnesium supplementation under adequate hydration to avoid renal impairment. Patients should be evaluated for eGFR (estimated glomerular filtration rate) during the treatment with pemetrexed, as kidney injury has been reported. Pemetrexed should be administered with caution in patients with a CCr (creatinine clearance) < 45 mL/min. Mesna is used to prevent hemorrhagic cystitis in patients receiving ifosfamide. Febuxostat is effective in avoiding hyperuricemia induced by TLS (tumor lysis syndrome). Preventative rasburicase is recommended in high-risk cases of TLS. Thrombotic microangiopathy could be triggered by anticancer drugs and there is no evidence of efficacy of plasma exchange therapy. When proteinuria occurs during treatment with anti-angiogenic agents or multi-kinase inhibitors, dose reductions or interruptions based on grading should be considered. Grade 3 proteinuria and renal dysfunction require urgent intervention, including drug interruption or withdrawal, and referral to a nephrologist should be considered. The first-line drugs used for blood pressure elevation due to anti-angiogenic agents are ACE (angiotensin-converting enzyme) inhibitors and ARBs (angiotensin receptor blockers). The protein binding of drugs and their pharmacokinetics are considerably altered in patients with hypoalbuminemia. The clearance of rituximab is increased in patients with proteinuria, and the correlation with urinary IgG suggests similar pharmacokinetic changes when using other antibody drugs. AIN (acute interstitial nephritis) is the most common cause of ICI (immune checkpoint inhibitor)-related kidney injury that is often treated with steroids. The need for renal biopsy in patients with kidney injury that occurs during treatment with ICI remains controversial.

Hepatic Safety of Febuxostat and Allopurinol for Gout Patients: A Systematic Review of Randomized Controlled Trial

Purpose

This study aims to systematically review the hepatic safety of febuxostat and allopurinol in adult gout patients.

Methods

We searched for information using the following databases: PubMed, Cochrane Library, and Scopus. The inclusion criteria were to review all randomized controlled trials (RCT) that compared allopurinol and febuxostat for adult gout patients that had an assessment of liver function outcomes. Non-English studies on case reports, case series, reviews, and abstracts only were excluded. We extracted information from the studies to answer the research question, ie, study design, publication year, population, sample size, patient characterization, duration, Jadad score, and liver function outcomes.

Results

We screened 512 publications from the databases and identified 11 studies that met the inclusion criteria. Ten out of 11 included studies were double-blind RCTs. In the majority of the included studies, no statistically significant differences were observed in terms of hepatic safety data between febuxostat and allopurinol. However, in studies where allopurinol titration was used, it posed a challenge to maintain blinding. Notably, consistent adverse events related to liver function findings were observed across all reviewed RCTs. These abnormal liver function test results sometimes led to study withdrawal based on the investigators' assessment. Nevertheless, the investigators classified most liver function test elevations as mild to moderate in severity.

Conclusion

Our analysis concluded that adult gout patients enrolled in the included RCTs exhibited similar hepatic safety profiles for both febuxostat and allopurinol treatment. Liver function abnormalities were identified in all RCTs included in this systematic review. Consequently, it is important for the product labeling information of both allopurinol and febuxostat to present and describe the current safety data to guide healthcare practitioners when prescribing these medications to patients. Pharmacovigilance and post-marketing pharmacoepidemiology data are essential in establishing the comprehensive safety profile.

Incidence, clinical characteristics and prognosis of tumor lysis syndrome following B-cell maturation antigen-targeted chimeric antigen receptor-T cell therapy in relapsed/refractory multiple myeloma

Background aims

B-cell maturation antigen (BCMA)-targeted chimeric antigen receptor-T cell (CAR-T) therapy is used for refractory or relapsed multiple myeloma (r/r MM). However, CAR-T-related tumor lysis syndrome (TLS) has been observed. We aimed to elucidate the incidence, clinical and laboratory characteristics, and prognosis of CAR-T cell-related TLS.

Methods

Patients (n=105) with r/r MM treated with BCMA-targeted CAR-T cell therapy were included. Patient characteristics, laboratory parameters, and clinical outcomes were assessed.

Results

Eighteen (17.1%) patients developed TLS after BCMA-targeted CAR-T cell therapy. The median time till TLS onset was 8 days. Patients with TLS had steep rise in uric acid (UA), creatinine, and lactate dehydrogenase (LDH) within 6 days following CAR-T cell infusion and presented earlier and persistent escalation of cytokines (C-reactive protein [CRP], interleukin-6 [IL-6], interferon-γ [IFN-γ], and ferritin levels). All 18 patients had cytokine release syndrome (CRS), of which 13 (72.2%) developed grade 3-4 CRS. Three of 18 patients (16.7%) developed immune effector cell-associated neurotoxicity syndrome (ICANS): two patients with grade 1 ICANS and one with grade 2 ICANS. TLS development had a negative effect on the objective response rate (77.8% in the TLS group vs. 95.4% in the non-TLS group, p<0.01). During the median follow-up of 15.1 months, the median PFS was poorer of patients with TLS (median: 3.4 months in the TLS group vs. 14.7 months in the non-TLS group, p<0.001, hazard ratio [HR]=3.5 [95% confidence interval [CI] 1.5-8.5]). Also, TLS development exhibited significant effects on OS (median: 5.0 months in the TLS group vs. 39.8 months in the non-TLS group, p<0.001, hazard ratio [HR]=3.7 [95% CI 1.3-10.3]). TLS was associated with a higher tumor burden, elevated baseline creatinine and UA levels, severe CRS, pronounced CAR-T cell expansion, and corticosteroid use.

Conclusion

TLS is a frequently observed CAR-T therapy complication and negatively influences clinical response and prognosis. Close monitoring for TLS should be implemented during CAR-T cell therapy, especially for those at high TLS risk.

Malignancy diseases and kidneys: A nephrologist prospect and updated review

Acute kidney injury (AKI), chronic renal failure, and tubular abnormalities represent the kidney disease spectrum of malignancy. Prompt diagnosis and treatment may prevent or reverse these complications. The pathogenesis of AKI in cancer is multifactorial. AKI affects outcomes in cancer, oncological therapy withdrawal, increased hospitalization rate, and hospital stay. Renal function derangement can be recovered with early detection and targeted therapy of cancers. Identifying patients at higher risk of renal damage and implementing preventive measures without sacrificing the benefits of oncological therapy improve survival. Multidisciplinary approaches, such as relieving obstruction, hydration, etc., are required to minimize the kidney injury rate. Different keywords, texts, and phrases were used to search Google, EMBASE, PubMed, Scopus, and Google Scholar for related original and review articles that serve the article's aim well. In this nonsystematic article, we aimed to review the published data on cancer-associated kidney complications, their pathogenesis, management, prevention, and the latest updates. Kidney involvement in cancer occurs due to tumor therapy, direct kidney invasion by tumor, or tumor complications. Early diagnosis and therapy improve the survival rate. Pathogenesis of cancer-related kidney involvement is different and complicated. Clinicians' awareness of all the potential causes of cancer-related complications is essential, and a kidney biopsy should be conducted to confirm the kidney pathologies. Chronic kidney disease is a known complication in malignancy and therapies. Hence, avoiding nephrotoxic drugs, dose standardization, and early cancer detection are mandatory measures to prevent renal involvement.

Urine Xanthine Crystals in Hematologic Malignancies with Tumor Lysis Syndrome

Tumor lysis syndrome (TLS) is a metabolic disorder caused by massive tumor lysis. Hypouricemic agents are administered to prevent TLS-related hyperuricemia and renal failure. We experienced three cases of urine xanthine crystals during TLS in patients with hematologic malignancies who received prophylactic febuxostat. Yellowish and pinkish deposits were observed in urinary tract catheters and urinary bags. Urine microscopy revealed that the deposits were xanthine crystals. In rapid tumor lysis, inhibition of xanthine oxidase can cause xanthine accumulation and urine xanthine crystallization. During TLS, urine xanthine crystals may be overlooked, so careful observation and management are required to avoid xanthine nephropathy.

Pharmacological Small Molecules against Prostate Cancer by Enhancing Function of Death Receptor 5

Death receptor 5 (DR5) is a membrane protein that mediates exogenous apoptosis. Based on its function, it is considered to be a target for the treatment of cancers including prostate cancer. It is encouraging to note that a number of drugs targeting DR5 are now progressing to different stages of clinical trial studies. We collected 38 active compounds that could produce anti-prostate-cancer effects by modulating DR5, 28 of which were natural compounds and 10 of which were synthetic compounds. In addition, 6 clinically used chemotherapeutic agents have also been shown to promote DR5 expression and thus exert apoptosis-inducing effects in prostate cancer cells. These compounds promote the expression of DR5, thereby enhancing its function in inducing apoptosis. When these compounds were used in combination with the natural ligand of DR5, the number of apoptotic cells was significantly increased. These compounds are all promising for development as anti-prostate-cancer drugs, while most of these compounds are currently being evaluated for their anti-prostate-cancer effects at the cellular level and in animal studies. A great deal of more in-depth research is needed to evaluate whether they can be developed as drugs. We collected literature reports on small molecules against prostate cancer through modulation of DR5 to understand the current dynamics in this field and to evaluate the prospects of small molecules against prostate cancer through modulation of DR5.

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.

Tumor Lysis Syndrome: An Endless Challenge in Onco-Nephrology

Tumor lysis syndrome (TLS) is a common cause of acute kidney injury in patients with malignancies, and it is a frequent condition for which the nephrologist is consulted in the case of the hospitalized oncological patient. Recognizing the patients at risk of developing TLS is essential, and so is the prophylactic treatment. The initiation of treatment for TLS is a medical emergency that must be addressed in a multidisciplinary team (oncologist, nephrologist, critical care physician) in order to reduce the risk of death and that of chronic renal impairment. TLS can occur spontaneously in the case of high tumor burden or may be caused by the initiation of highly efficient anti-tumor therapies, such as chemotherapy, radiation therapy, dexamethasone, monoclonal antibodies, CAR-T therapy, or hematopoietic stem cell transplantation. It is caused by lysis of tumor cells and the release of cellular components in the circulation, resulting in electrolytes and metabolic disturbances that can lead to organ dysfunction and even death. The aim of this paper is to review the scientific data on the updated definition of TLS, epidemiology, pathogenesis, and recognition of patients at risk of developing TLS, as well as to point out the recent advances in TLS treatment.

Tumor lysis syndrome, acute kidney injury and disease-free survival in critically ill patients requiring urgent chemotherapy

Background

Tumor lysis syndrome (TLS) is a life-threatening complication during the treatment of malignant neoplasia. We sought to describe characteristics and predictors of acute kidney injury (AKI), remission and mortality in high-risk TLS patients. In this retrospective monocentric study, we included all patients with the diagnosis of biological and/or clinical TLS from 2012 to 2018. The primary outcome was the prevalence of AKI during the acute phase of TLS. Secondary outcomes were overall mortality and remission of the underlying malignancy at 1 year.

Results

Among 153 patients with TLS, 123 (80.4%) patients experienced AKI and 83 (54.2%) required renal replacement therapy. mSOFA score (OR = 1.15, IC 95% [1.02–1.34]), age (OR = 1.05, IC 95% [1.02–1.08]) and male gender (OR = 6.79, IC 95% [2.59–19.44]) were associated with AKI. Rasburicase use (HR = 2.45, IC 95% [1.17–5.15]) was associated with remission of the underlying malignancy at 1 year. Parameters associated with mortality at 1 year were mechanical ventilation (HR = 1.96, IC 95% [1.02–3.78]), vasopressors (HR = 3.13, IC 95% [1.59–6.15]), age (HR = 1.02, IC 95% [1–1.03]), spontaneous TLS (HR = 1.65, IC 95% [1.01–2.69]) and delay of chemotherapy administration (HR = 1.01, IC 95% [1–1.03]).

Conclusions

AKI is highly prevalent in TLS patients. Rasburicase is associated with better outcomes regarding remission of the underlying malignancy. As rasburicase may be an indirect marker of a high degree of tumor lysis and chemosensitivity, more studies are warranted to confirm the protective role of urate oxidase. Delaying chemotherapy may be deleterious in terms of long-term outcomes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13613-022-00990-1.

Tumor Lysis Syndrome in Patients With Hepatocellular Carcinoma: A Systematic Review of Published Case Reports

Tumor lysis syndrome (TLS) is a life-threatening oncologic emergency. It is characterized by massive tumor cell death leading to metabolic derangements and multiple organ failure. It is a rare complication of hepatocellular carcinoma (HCC) with only a few cases have been reported in the literature to date.

We collected and summarized published case reports of tumor lysis syndrome in patients with HCC. We also reported one additional case who developed TLS after sorafenib therapy and wrote a clinical vignette. A comprehensive and current search for relevant articles was conducted in Medline and EMbase through May 2018. A systematic review was performed following the guideline of Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). 

A total of 28 cases of TLS associated with HCC were enrolled in our review. The median age of included cases was 55.5 years with a male to female ratio of 25:3. The two most common attributed factors of TLS were transcatheter arterial chemoembolization (TACE) (12 cases, 42.9 %) and sorafenib (nine cases, 32.1%). Among enrolled cases, the diameter of the largest tumor was 12 cm. Regarding Barcelona Clinic Liver Cancer (BCLC) staging, seven cases were at least stage A (22.6%), 11 cases were at least stage B (35.5%), and 10 cases were at least stage C (32.3%). The median time of onset of TLS was three days. As for uric acid-lowering agents, nine cases (32.1%) used allopurinol and four cases (14.3%) used rasburicase. Ten cases (35.7%) did not specify the medication prescribed. The overall mortality rate of this cohort was 67.9%.

Compared with patients developing TLS following TACE, patients who had TLS following sorafenib therapy had a later onset of TLS (two days versus seven days, p < 0.001) and a more advanced stage of HCC (p = 0.002). There was a trend toward increased mortality of patients in the sorafenib group in comparison with those in the TACE group (77.8% versus 41.7%, p = 0.18).

The results of this current review suggest that TLS rarely occurs in HCC but carries significantly higher mortality compared to TLS occurring in hematologic malignancies. It may occur shortly after TACE or with a delayed onset following sorafenib therapy. Considering the kaleidoscope of novel therapies and diverse pathogenesis of HCC, it is crucial for clinicians to recognize the clinicolaboratory derangements suggestive of TLS and initiate appropriate management. The present review highlights the need for clinicians to consider TLS within differentials when caring for patients with HCC.

Risk of Hematologic Events With Coadministration of Methotrexate and the Breast Cancer Resistance Protein Inhibitor Febuxostat

BACKGROUND

The breast cancer resistance protein (BCRP) is a key drug transporter found in the liver, kidney, central nervous system, and gastrointestinal tract. Due to the wide expression of BCRP, interactions of other drugs with methotrexate (MTX) may differ in oral and intravenous MTX users, and understanding of these interactions may be useful in preventing severe adverse events. Febuxostat, a urate-lowering drug, inhibits BCRP.

OBJECTIVE

The objective of this study was to clarify the differences in the drug-drug interaction profiles of oral and intravenous methotrexate, associated with BCRP.

METHODS

We analyzed the Japanese Adverse Drug Event Report database and compared the frequency of hematologic events in patients taking oral and intravenous MTX, with or without the concomitant use of febuxostat or allopurinol. Hematologic events were defined as pancytopenia and neutropenia. Multiple logistic regression analysis was then used to identify the risk factors for hematologic events in oral and intravenous MTX users.

RESULTS

We identified 8 453 oral and 810 intravenous MTX users with 546 and 126 cases of hematologic events, respectively. Compared with those not using febuxostat, a disproportionate number of hematologic events was observed in intravenous MTX users concomitantly using febuxostat (P < 0.01). The multivariate logistic analysis of intravenous MTX users showed that hematologic events were significantly associated with febuxostat use (P < 0.01) and age ≥ 60 years (P < 0.01).

CONCLUSION AND RELEVANCE

Our findings suggest that patients being treated with intravenous MTX who concomitantly use febuxostat may be at an increased risk of hematologic events, presumably due to BCRP-mediated drug-drug interaction.

Tumor Lysis Syndrome

Tumor lysis syndrome (TLS) is an oncologic emergency due to massive tumor cell lysis with the release of large amounts of potassium, phosphate, and nucleic acids into the systemic circulation. Clinical presentation is characterized by hyperkalemia, hyperphosphatemia, hyperuricemia, and hypocalcemia. Acute kidney injury due to tumor lysis is potentiated by the precipitation of uric acid and calcium phosphate as well as renal vasoconstriction. Early recognition of tumor lysis can help prevent cardiac arrhythmias, seizures, and death. Management includes intravenous hydration to maintain urine flow, medications targeting hyperuricemia including rasburicase and allopurinol and in severe cases renal replacement therapy may be required.

Advanced Practice Perspectives on Preventing and Managing Tumor Lysis Syndrome and Neutropenia in Chronic Lymphocytic Leukemia

Tumor lysis syndrome (TLS) and neutropenia are significant toxicities in the treatment of chronic lymphocytic leukemia (CLL). Both TLS and neutropenia can lead to potentially life-threatening complications for patients with chronic lymphocytic leukemia undergoing antineoplastic therapy. This article focuses on diligent risk assessment, prophylaxis, early identification, monitoring, patient education, and prompt intervention for TLS and neutropenia. These are all necessary steps to reduce life-threatening complications. Guidelines are available for risk assessments for both TLS and neutropenia. Once risk is established, prophylaxis and monitoring recommendations can be found in available guidelines. There are no established guidelines or widely used decision-making standards for the treatment of clinical TLS. General management strategies are well documented in the literature, with some degree of customization to each individual patient. If fever occurs in the setting of neutropenia, there are well-established guidelines for management, including guidance on anti-infective agents and use of growth factors. In addition, awareness and proper actions regarding TLS and neutropenia are key to preventing treatment delays, dose reductions, or treatment discontinuation. Adequate planning for TLS and neutropenia is critical to optimize patient outcomes.

Sulfasalazine alleviates neuropathic pain hypersensitivity in mice through inhibition of SGK-1 in the spinal cord

Diurnal variations in pain hypersensitivity are common in chronic pain disorders. Temporal exacerbation of neuropathic pain hypersensitivity is dependent on diurnal variations in glucocorticoid secretion from the adrenal glands. We previously demonstrated that spinal expression of serum- and glucocorticoid-inducible kinase-1 (SGK-1) is associated with glucocorticoid- induced exacerbation of pain hypersensitivity, but there are no available strategies to inhibit SGK-1 in the spinal cord. By screening a clinically approved drug library (more than 1,200 drugs), we found that sulfasalazine (SSZ) has inhibitory effects on SGK-1. SSZ is a prodrug composed of 5-aminosalicylic acid and sulfapyridine linked by NN bond, which is therapeutically effective for inflammatory bowel diseases. However, the NN bond in SSZ was necessary for its inhibitory action against SGK-1. Although intrathecal injection of SSZ to nerve-injured mice significantly alleviated mechanical pain hypersensitivity, no significant anti- neuropathic pain effects of SSZ were detected after oral administration due to its low bioavailability and limited spinal distribution, which were associated with efflux by the xenobiotic transporter breast cancer resistance protein (BCRP). Concomitant oral administration of SSZ with febuxostat (FBX), which is an approved drug to inhibit BCRP, improved the distribution of SSZ to the spinal cord. The concomitant oral administration with FBX also increased the anti-neuropathic pain effects of SSZ. Our study revealed a previously unrecognized pharmacological effect of SSZ to alleviate SGK-1-induced painful peripheral neuropathy, and concomitant oral administration of SSZ with FBX may also be a preventative option for diurnal exacerbation of neuropathic pain hypersensitivity.

KDIGO Controversies Conference on onco-nephrology: kidney disease in hematological malignancies and the burden of cancer after kidney transplantation

The bidirectional relationship between cancer and chronic kidney disease (CKD) is complex. Patients with cancer, particularly those with hematological malignancies such as multiple myeloma and lymphoma, are at increased risk of developing acute kidney injury and CKD. On the other hand, emerging evidence from large observational registry analyses have consistently shown that cancer risk is increased by at least 2- to 3-fold in kidney transplant recipients, and the observed increased risk occurs not only in those who have received kidney transplants but also in those on dialysis and with mild- to moderate-stage CKD. The interactions between cancer and CKD have raised major therapeutic and clinical challenges in the management of these patients. Given the magnitude of the problem and uncertainties, and current controversies within the existing evidence, Kidney Disease: Improving Global Outcomes (KDIGO) assembled a global panel of multidisciplinary clinical and scientific expertise for a controversies conference on onco-nephrology to identify key management issues in nephrology relevant to patients with malignancy. This report covers the discussed controversies in kidney disease in hematological malignancies, as well as cancer after kidney transplantation. An overview of future research priorities is also discussed.

Perspectives From an Onconephrology Interest Group: Conference Report

INTRODUCTION AND OBJECTIVE

Onconephrology is a new and evolving field that deals with kidney complications in patients with cancer as well as the management of cancer in patients with preexisting kidney disease. With increasing numbers of patients with cancer with kidney-related complications, the field has garnered increased attention. Thus, an annual Greater Toronto Area Onconephrology Interest Group symposium was held in May 2019. The objective of the meeting was to demonstrate the junctures between oncology and nephrology by highlighting recent data regarding (1) kidney impairment in solid organ malignancies, (2) management and treatment of kidney cancer, (3) kidney impairment in hematologic malignancies, (4) malignancy and kidney transplantation, and (5) hyponatremia in patients with cancer.

METHODS AND SOURCES OF INFORMATION

Through a structured presentation, the group explored key topics discussed at a Kidney Disease Improving Global Outcomes (KDIGO) Controversies Conference on Onconephrology. Expert opinions, clinical trial findings, and publication summaries were used to illustrate patient and treatment-related considerations in onconephrology.

KEY FINDINGS

Kidney complications in patients with cancer are a central theme in onconephrology. An estimated 12% to 25% of patients with solid organ malignancies have chronic kidney disease (CKD), although in certain cancers, the prevalence of CKD is higher. Kidney impairment is also a common complication of some hematologic malignancies. The incidence of renal failure in patients with multiple myeloma is estimated at 18% to 56% and light chain cast nephropathy is seen in approximately 30% of these patients. In addition, there appears to be a bidirectional relationship between kidney cancer and CKD, with some data sets suggesting the risk increases as kidney function declines. Cancer is also of concern in patients with preexisting kidney disease. Kidney transplant recipients have a greater risk of cancer and a higher risk of cancer-related mortality. Kidney complications have also been associated with novel cancer therapies, such as immune checkpoint inhibitors and chimeric antigen receptor (CAR) T-cell therapy. An estimated 2% to 4% of patients initiating an immune checkpoint inhibitor may develop nephrotoxicity, whereas up to 40% of patients on CAR T-cell therapy experience cytokine release syndrome (CRS). Tumor lysis syndrome and electrolyte abnormalities, such as hyponatremia, have also been reported with CAR T-cell therapy. While the incidence and prevalence of hyponatremia vary depending on the cancer type and serum sodium cutoff point, hyponatremia may be seen in up to 46% of patients hospitalized in cancer centers.

CONCLUSIONS

Onconephrology is a developing field and the themes arising from this meeting indicate a need for greater collaboration between oncologists and nephrologists. Educational symposia and onconephrology fellowship programs may allow for improved cancer care for patients with kidney disease.

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

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

Febuxostat Use and Risks of Cardiovascular Disease Events, Cardiac Death, and All-cause Mortality: Metaanalysis of Randomized Controlled Trials

OBJECTIVE

To assess whether febuxostat use increases the risk of developing cardiovascular (CV) events, cardiac death, and all-cause mortalities.

METHODS

The relevant literature was searched in several databases including MEDLINE (PubMed, January 1, 1966-February 29, 2020), Web of Science, EMBASE (January 1, 1974-February 29, 2020), ClinicalTrials. gov, and Cochrane Central Register of Controlled Trials. Manual searches for references cited in the original studies and relevant review articles were also performed. All studies included in this metaanalysis were published in English.

RESULTS

In the end, 20 studies that met our inclusion criteria were included in our metaanalysis. Use of febuxostat was found not to be associated with an increased risk of all-cause mortality (RR 0.87, 95% CI 0.57-1.32, P = 0.51). Also, there was no association between febuxostat use and mortalities arising from CV diseases (CVD; RR 0.84, 95% CI 0.49-1.45, P = 0.53). The RR also revealed that febuxostat use was not associated with CVD events (RR 0.98, 95% CI 0.83-1.16, P = 0.83). Further, the likelihood of occurrence of CVD events was found not to be dependent on febuxostat dose (RR 1.04, 95% CI 0.84-1.30, P = 0.72).

CONCLUSION

Febuxostat use is not associated with increased risks of all-cause mortality, death from CVD, or CVD events. Accordingly, it is a safe drug for the treatment of gout.

Tumor lysis syndrome in childhood malignancies

BACKGROUND

Tumor lysis syndrome (TLS) is the most common life-threatening oncological emergency encountered by physicians treating children with lymphoproliferative malignancies. Healthcare providers should be aware of the condition in order to prevent occurrence and prompt timely management to avoid severe consequences.

OBJECTIVE

To provide an update on the current understanding, evaluation, and management of tumor lysis syndrome in childhood malignancies.

METHODS

A PubMed search was performed in Clinical Queries using the keywords 'tumor lysis syndrome' and 'malignancies' with Category limited to clinical trials and reviews for ages from birth to 18 years.

RESULTS

There were 22 clinical trials and 37 reviews under the search criteria. TLS is characterized by acute electrolyte and metabolic disturbances resulting from massive and abrupt release of cellular contents into the circulation due to breakdown of tumor cells. If left untreated, it can lead to multiorgan compromise and eventually death. Apart from close monitoring and medical therapies, early recognition of risk factors for development of TLS is also necessary for successful management.

CONCLUSIONS

Prophylactic measures to patients at risk of TLS include aggressive fluid management and judicious use of diuretics and hypouricemic agents. Both allopurinol and urate oxidase are effective in reducing serum uric acid. Allopurinol should be used as prophylaxis in low-risk cases while urate oxidase should be used as treatment in intermediate to high-risk cases. There is no evidence on better drug of choice among different urate oxidases. The routine use of diuretics and urine alkalinization are not recommended. Correction of electrolytes and use of renal replacement therapy may also be required during treatment of TLS.

Emergencies in haematology: tumour lysis syndrome

Tumour lysis syndrome (TLS) is a significant complication of haematologic malignancies and their management. The syndrome consists of laboratory abnormalities either alone (laboratory TLS) or with clinical sequelae including renal failure, seizures, and arrhythmias (clinical TLS). Clinical TLS is a predictor for worse overall morbidity and mortality in cancer patients, but can be prevented. Thus, accurate prognostication is critical to appropriate management of patients at risk for TLS, and incorporates both disease factors (tumour type and burden) and patient factors (baseline renal insufficiency or hyperuricaemia). Strategies to prevent TLS include hydration and allopurinol in low- and intermediate-risk patients and rasburicase in high-risk patients.

Concomitant febuxostat enhances methotrexate-induced hepatotoxicity by inhibiting breast cancer resistance protein

Methotrexate (MTX) is an antifolate agent used for the treatment of various malignancies and is eliminated by breast cancer resistance protein (BCRP). Because febuxostat (FBX) is known to inhibit BCRP activity, FBX might exacerbate MTX-related adverse effects. In this study, we examined the drug-drug interaction between FBX and MTX in BCRP-expressing membrane vesicles. Moreover, we retrospectively investigated the impact of FBX on MTX-related adverse effects in 38 patients (144 cycles) receiving high-dose MTX therapy (HDMTX). The Food and Drug Administration Adverse Event Reporting System (FAERS) database and human hepatocellular carcinoma cell line HepG2 cells were used to evaluate the effects of FBX on MTX-induced hepatotoxicity. In the membrane vesicle study, FBX significantly inhibited BCRP-mediated transport of MTX. Concomitant FBX significantly increased the incidence of hepatotoxicity, but not of nephrotoxicity and hematological toxicity in patients receiving HDMTX. FAERS database analyses revealed that the reporting odds ratio of FBX for MTX-induced hepatotoxicity was 4.16 (95% CI: 2.89-5.98). Co-incubated FBX significantly decreased the cell viability and increased cytotoxicity in MTX-treated HepG2 cells. These findings suggest that concomitant FBX enhances MTX-induced hepatotoxicity by inhibiting hepatic BCRP. These findings provide important information for the safe management of HDMTX therapy in clinical settings.

Acute kidney injury in the patient with cancer

Dramatic advances in the care of patients with cancer have led to significant improvement in outcomes and survival. However, renal manifestations of the underlying cancer as well as the effects of anti-neoplastic therapies leave patients with significant morbidity and chronic kidney disease risks. The most common renal manifestations associated with cancer include acute kidney injury (AKI) in the setting of multiple myeloma, tumor lysis syndrome, post-hematopoietic stem cell therapy, and AKI associated with chemotherapy. Knowledge of specific risk factors, modification of risk and careful attention to rapid AKI diagnosis are critical for improving outcomes.

Febuxostat administration for the prevention of tumour lysis syndrome: A meta-analysis

WHAT IS KNOWN AND OBJECTIVE

Tumour lysis syndrome is an oncological emergency, characterized by rapid cytolysis leading to an abrupt rise of serum uric acid levels. The aim of the present meta-analysis is to evaluate the efficacy and safety of febuxostat as a preventive measure in patients at risk of tumour lysis syndrome development, by comparing it with allopurinol administration.

METHODS

MEDLINE, Scopus, Cochrane Central Register of Controlled Trials, Clinicaltrials.gov and Google Scholar databases were searched from inception to 15 December 2018. All studies evaluating the effectiveness of febuxostat in preventing tumour lysis syndrome were held eligible.

RESULTS AND DISCUSSION

Six studies were included with a total of 658 patients. Compared to allopurinol, febuxostat achieved a similar response rate (OR: 1.39, 95% CI: [0.55, 3.51]) and tumour lysis syndrome incidence (OR: 1.01, 95% CI: [0.56, 1.81]). Serum uric acid levels did not differ between the investigated groups at the second (MD: -0.21 mg/dL, 95% CI: [-1.30, 0.88]) and seventh (MD: -0.43 mg/dL, 95% CI: [-1.38, 0.51]) day of treatment. Elevation of liver function tests was the most common adverse effect, although its incidence was similar among patients treated with allopurinol and febuxostat.

WHAT IS NEW AND CONCLUSIONS

The present meta-analysis suggests that febuxostat may serve as an effective alternative to allopurinol in the prevention of tumour lysis syndrome. Future large-scale studies should define the optimal febuxostat dosage, explore the most appropriate population for its administration and better define its safety profile.

Update on the prevention and treatment of tumor lysis syndrome

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

Inhibitors of Human ABCG2: From Technical Background to Recent Updates With Clinical Implications

The ATP-binding cassette transporter G2 (ABCG2; also known as breast cancer resistance protein, BCRP) has been suggested to be involved in clinical multidrug resistance (MDR) in cancer like other ABC transporters such as ABCB1 (P-glycoprotein). As an efflux pump exhibiting a broad substrate specificity localized on cellular plasma membrane, ABCG2 excretes a variety of endogenous and exogenous substrates including chemotherapeutic agents, such as mitoxantrone and several tyrosine kinase inhibitors. Moreover, in the normal tissues, ABCG2 is expressed on the apical membranes and plays a pivotal role in tissue protection against various xenobiotics. For this reason, ABCG2 is recognized to be an important determinant of the pharmacokinetic characteristics of its substrate drugs. Although the clinical relevance of reversing the ABCG2-mediated MDR has been inconclusive, an appropriate modulation of ABCG2 function during chemotherapy should logically enhance the efficacy of anti-cancer agents by overcoming the MDR phenotype and/or improving their pharmacokinetics. To confirm this possibility, considerable efforts have been devoted to developing ABCG2 inhibitors, although there is no clinically available substance for this purpose. As a clue for addressing this issue, this mini-review provides integrated information covering the technical backgrounds necessary to evaluate the ABCG2 inhibitory effects on the target compounds and a current update on the ABCG2 inhibitors. This essentially includes our recent findings, as we serendipitously identified febuxostat, a well-used agent for hyperuricemia as a strong ABCG2 inhibitor, that possesses some promising potentials. We hope that an overview described here will add value to further studies involving in the multidrug transporters.

Old Drugs for New Indications in Cardiovascular Medicine

Inflammation participates in the initiation and progression of atherosclerotic cardiovascular disease, and it is a critical inciting factor leading to acute ischemic events. Evidence has shown that certain anti-inflammatory medications used to treat non-atherosclerotic inflammatory diseases reduce cardiovascular events. This article reviews evidence that commonly used anti-inflammatory therapies (colchicine, allopurinol, methotrexate), reduce cardiovascular events. We discuss potential mechanisms of action, efficacy, and safety of these therapies and propose a clinical trials design to investigate their efficacy.

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.

[Prevention of acute kidney injury in critically ill patients : Recommendations from the renal section of the DGIIN, ÖGIAIN and DIVI]

BACKGROUND

Acute kidney injury (AKI) has both high mortality and morbidity.

OBJECTIVES

To prevent the occurrence of AKI, current recommendations from the renal section of the DGIIN (Deutschen Gesellschaft für Internistische Intensivmedizin und Notfallmedizin), ÖGIAIN (Österreichischen Gesellschaft für Internistische und Allgemeine Intensivmedizin und Notfallmedizin) and DIVI (Deutschen Interdisziplinären Vereinigung für Intensiv- und Notfallmedizin) are stated.

MATERIALS AND METHODS

The recommendations stated in this paper are based on the current Kidney Disease Improving Global Outcomes (KDIGO) guidelines, the published statements of the "Working Group on Prevention, AKI section of the European Society of Intensive Care Medicine" and the expert knowledge and clinical experience of the authors.

RESULTS

Currently there are no approved clinically effective drugs for the prevention of AKI. Therefore the mainstay of prevention is the optimization of renal perfusion by improving the mean arterial pressure (>65 mm Hg, higher target may be considered in hypertensive patients). This can be done by vasopressors, preferably norepinephrine and achieving or maintaining euvolemia. Hyperhydration that can lead to AKI itself should be avoided. In patients with maintained diuresis this can be done by diuretics that are per se no preventive drug for AKI. Radiocontrast enhanced imaging should not be withheld from patients at risk for AKI; if indicated, however, the contrast media should be limited to the smallest possible volume.

[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 Chronic Lymphocytic Leukemia with Novel Targeted Agents

Tumor lysis syndrome (TLS) is an uncommon but potentially life-threatening complication associated with the treatment of some cancers. If left untreated, TLS may result in acute renal failure, cardiac dysrhythmia, neurologic complications, seizures, or death. Tumor lysis syndrome is most commonly observed in patients with hematologic malignancies with a high proliferation rate undergoing treatment with very effective therapies. In chronic lymphocytic leukemia (CLL), historically, TLS has been observed less often, owing to a low proliferation rate and slow response to chemotherapy. New targeted therapies have recently been approved in the treatment of CLL, including the oral kinase inhibitors, idelalisib and ibrutinib, and the B-cell lymphoma-2 protein inhibitor, venetoclax. Several others are also under development, and combination strategies of these agents are being explored. This review examines the diagnosis, prevention, and management of TLS and summarizes the TLS experience in CLL clinical trials with newer targeted agents. Overall, the risk of TLS is small, but the consequences may be fatal; therefore, patients should be monitored carefully. Therapies capable of eliciting rapid response and combination regimens are increasingly being evaluated for treatment of CLL, which may pose a higher risk of TLS. For optimal management, patients at risk for TLS require prophylaxis and close monitoring with appropriate tests and appropriate management to correct laboratory abnormalities, which allows for safe and effective disease control.

IMPLICATIONS FOR PRACTICE

Tumor lysis syndrome (TLS) is a potentially fatal condition observed with hematologic malignancies, caused by release of cellular components in the bloodstream from rapidly dying tumor cells. The frequency and severity of TLS is partly dependent upon the biology of the disease and type of therapy administered. Novel targeted agents highly effective at inducing rapid cell death in chronic lymphocytic leukemia (CLL) may pose a risk for TLS in patients with tumors characterized by rapid growth, high tumor burden, and/or high sensitivity to treatment. In this review, prevention strategies and management of patients with CLL who develop TLS are described.

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.

Prevention and treatment of tumor lysis syndrome, and the efficacy and role of rasburicase

Tumor lysis syndrome (TLS) is a potentially life-threatening condition that occurs in oncologic and hematologic patients with large tumor burden, either due to cytotoxic therapy or, less commonly, spontaneously because of massive tumor cell lysis. TLS is clinically characterized by acute renal failure, hyperuricemia, hyperkalemia, hyperphosphatemia, and hypocalcemia. While limited options are available for treating TLS, identifying patients at high risk for developing TLS and prevention in high-risk patients remain an important aspect in the treatment of cancer patients. In general, treatment of TLS consists of intensive hydration, stimulation of diuresis, and, more specifically, in the use of allopurinol and rasburicase. Rasburicase, a recombinant urate oxidase, rapidly and effectively reduces hyperuricemia, which subsequently significantly decreases the risk of acute renal failure and other clinical manifestations of TLS. For this review, a comprehensive literature search using the term “tumor lysis syndrome” and/or “rasburicase” was performed considering articles listed in MEDLINE. Incidence, prevention, and therapy of TLS with a special focus on the role of rasburicase are discussed. We evaluated 120 relevant articles including 35 case reports, 32 clinical trials, and 14 meta-analyses.

Febuxostat-associated eosinophilic polymyositis in marginal zone lymphoma

Febuxostat is an orally administered selective inhibitor of xanthine oxidase approved for the treatment of gout and prevention of tumor lysis syndrome. It is a relatively safe medication. Hypersensitivity reactions associated with the use of febuxostat are quite rare with only one reported case of DRESS syndrome. Recently, two case reports of rhabdomyolysis following the initiation of febuxostat were published. We hereby present the first case of rhabdomyolysis with hypereosinophilia following the administration of febuxostat to a 50-year-old patient newly diagnosed with marginal zone lymphoma. Three weeks after the initiation of febuxostat for tumor lysis syndrome prophylaxis, the patient presented with generalized weakness, diffuse myalgia and low-grade fever. Initial studies showed creatinine kinase level of 4471, hypereosinophilia of 1900/mm³, and LDH of 2691. All infectious and autoimmune diseases were ruled out. TSH level was normal. Muscle biopsy showed myonecrosis in addition to an eosinophilic inflammatory infiltrate in the endomysium and perimysium. Discontinuation of febuxostat led to prompt symptom resolution and normalization of blood tests eight days later.

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.