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

Anti-hyperuricemia bioactive peptides: a review on obtaining, activity, and mechanism of action

Hyperuricemia, a disorder of uric acid metabolism, serves as a significant risk factor for conditions such as hypertension, diabetes mellitus, renal failure, and various metabolic syndromes. The main contributors to hyperuricemia include overproduction of uric acid in the liver or impaired excretion in the kidneys. Despite traditional clinical drugs being employed for its treatment, significant health concerns persist. Recently, there has been growing interest in utilizing protein peptides sourced from diverse food origins to mitigate hyperuricemia. This article provides a comprehensive review of bioactive peptides with anti-hyperuricemia properties derived from animals, plants, and their products. We specifically outline the methods for preparing these peptides from food proteins and elucidate their efficacy and mechanisms in combating hyperuricemia, supported by in vitro and in vivo evidence. Uric acid-lowering peptides offer promising prospects due to their safer profile, enhanced efficacy, and improved bioavailability. Therefore, this review underscores significant advancements and contributions in identifying peptides capable of metabolizing purine and/or uric acid, thereby alleviating hyperuricemia. Moreover, it offers a theoretical foundation for the development of functional foods incorporating uric acid-lowering peptides.

Engineered microorganisms: A new direction in kidney stone prevention and treatment

Numerous studies have shown that intestinal and urinary tract flora are closely related to the formation of kidney stones. The removal of probiotics represented by lactic acid bacteria and the colonization of pathogenic bacteria can directly or indirectly promote the occurrence of kidney stones. However, currently existing natural probiotics have limitations. Synthetic biology is an emerging discipline in which cells or living organisms are genetically designed and modified to have biological functions that meet human needs, or even create new biological systems, and has now become a research hotspot in various fields. Using synthetic biology approaches of microbial engineering and biological redesign to enable probiotic bacteria to acquire new phenotypes or heterologous protein expression capabilities is an important part of synthetic biology research. Synthetic biology modification of microorganisms in the gut and urinary tract can effectively inhibit the development of kidney stones by a range of means, including direct degradation of metabolites that promote stone production or indirect regulation of flora homeostasis. This article reviews the research status of engineered microorganisms in the prevention and treatment of kidney stones, to provide a new and effective idea for the prevention and treatment of kidney stones.

Uric acid in health and disease: From physiological functions to pathogenic mechanisms

Owing to renal reabsorption and the loss of uricase activity, uric acid (UA) is strictly maintained at a higher physiological level in humans than in other mammals, which provides a survival advantage during evolution but increases susceptibility to certain diseases such as gout. Although monosodium urate (MSU) crystal precipitation has been detected in different tissues of patients as a trigger for disease, the pathological role of soluble UA remains controversial due to the lack of causality in the clinical setting. Abnormal elevation or reduction of UA levels has been linked to some of pathological status, also known as U-shaped association, implying that the physiological levels of UA regulated by multiple enzymes and transporters are crucial for the maintenance of health. In addition, the protective potential of UA has also been proposed in aging and some diseases. Therefore, the role of UA as a double-edged sword in humans is determined by its physiological or non-physiological levels. In this review, we summarize biosynthesis, membrane transport, and physiological functions of UA. Then, we discuss the pathological involvement of hyperuricemia and hypouricemia as well as the underlying mechanisms by which UA at abnormal levels regulates the onset and progression of diseases. Finally, pharmacological strategies for urate-lowering therapy (ULT) are introduced, and current challenges in UA study and future perspectives are also described.

Arthroscopic surgery for ankle gouty arthritis: a retrospective analysis of clinical outcomes at six month follow-up based on a novel classification system

PURPOSE

This study aimed to evaluate the clinical outcomes, patient-reported outcomes, and recurrence rate of patients diagnosed with ankle gouty arthritis who underwent arthroscopic surgery based on the new classification.

METHODS

A total of 51 patients diagnosed with ankle gouty arthritis were included in this retrospective study. A new classification was proposed based on the location and extent of MSU crystal deposition under an arthroscopy view. Patients are classified into different types and underwent arthroscopic surgery accordingly. The primary outcome measure was the American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot score. The secondary outcomes included the visual analog pain scale (VAS), serum uric acid levels, and the recurrence rate of ankle gouty arthritis at one year postoperatively.

RESULTS

Based on the new classification, five patients were Type I, 24 patients were Type II, five were Type III A, six were Type III B, and 11 were Type IV. The average follow-up time was 23.5 ± 10.9 months. The AOFAS hindfoot-ankle score improved significantly from 70.3 ± 15.9 to 85.6 ± 13.0 (p < 0.01). The mean serum uric acid level was significantly decreased from 442.0 ± 109.2 to 540.5 ± 132.4 (p < 0.01). The average VAS scale decreased from 3.8 ± 1.9 to 1.4 ± 1.7 (p < 0.01). The median of recurrences in one year postoperatively was significantly decreased from 1.5 (1, 3.75) to 0 (0, 0.75) (p < 0.01).

CONCLUSION

A new classification strategy for ankle gouty arthritis based on arthroscopic view was proposed. Patients with ankle gouty arthritis showed significant improvement in ankle function and pain relief after undergoing arthroscopic surgery driven by the new classification.

Mechanisms and rationale for uricase use in patients with gout

Xanthine oxidase inhibitors such as allopurinol and febuxostat have been the mainstay urate-lowering therapy (ULT) for treating hyperuricaemia in patients with gout. However, not all patients receiving oral ULT achieve the target serum urate level, in part because some patients cannot tolerate, or have actual or misconceived contraindications to, their use, mainly due to comorbidities. ULT dosage is also limited by formularies and clinical inertia. This failure to sufficiently lower serum urate levels can lead to difficult-to-treat or uncontrolled gout, usually due to poorly managed and/or under-treated gout. In species other than humans, uricase (urate oxidase) converts urate to allantoin, which is more soluble in urine than uric acid. Exogenic uricases are an exciting therapeutic option for patients with gout. They can be viewed as enzyme replacement therapy. Uricases are being used to treat uncontrolled gout, and can achieve rapid reduction of hyperuricaemia, dramatic resolution of tophi, decreased chronic joint pain and improved quality of life. Availability, cost and uricase immunogenicity have limited their use. Uricases could become a leading choice in severe and difficult-to-treat gout as induction and/or debulking therapy (that is, for lowering of the urate pool) to be followed by chronic oral ULT. This Review summarizes the evidence regarding available uricases and those in the pipeline, their debulking effect and their outcomes related to gout and beyond.

The Role of Uric Acid in Human Health: Insights from the Uricase Gene

Uric acid is the final product of purine metabolism and is converted to allantoin in most mammals via the uricase enzyme. The accumulation of loss of function mutations in the uricase gene rendered hominoids (apes and humans) to have higher urate concentrations compared to other mammals. The loss of human uricase activity may have allowed humans to survive environmental stressors, evolution bottlenecks, and life-threatening pathogens. While high urate levels may contribute to developing gout and cardiometabolic disorders such as hypertension and insulin resistance, low urate levels may increase the risk for neurodegenerative diseases. The double-edged sword effect of uric acid has resurrected a growing interest in urate's antioxidant role and the uricase enzyme's role in modulating the risk of obesity. Characterizing both the effect of uric acid levels and the uricase enzyme in different animal models may provide new insights into the potential therapeutic benefits of uric acid and novel uricase-based therapy.

Pegloticase in Uncontrolled Gout: The Infusion Nurse Perspective

Infused biologics, such as pegloticase, are a core component of managing uncontrolled gout, which is increasing in prevalence. Pegloticase is often the last line of therapy for patients with uncontrolled gout; therefore, achieving a successful course of treatment is critical. The infusion nurse's role in patient education, serum uric acid monitoring, and patient medication compliance is essential for ensuring patient safety and maximizing the number of patients who benefit from a full treatment course of pegloticase. Infusion nurses are on the front lines with patients and need to be educated on potential negative effects associated with the medications they infuse, such as infusion reactions, as well as risk management methods like patient screening and monitoring. Further, patient education provided by the infusion nurse plays a large role in empowering the patient to become their own advocate during pegloticase treatment. This educational overview includes a model patient case for pegloticase monotherapy, as well as one for pegloticase with immunomodulation and a step-by-step checklist for infusion nurses to refer to throughout the pegloticase infusion process. A video abstract is available for this article at http://links.lww.com/JIN/A105.

Gout Remission as a Goal of Urate-Lowering Therapy: A Critical Review

Urate-lowering therapies for the management of gout lead to a reduction in serum urate levels, monosodium urate crystal deposition, and the clinical features of gout, including painful and disabling gout flares, chronic gouty arthritis, and tophi. Thus, disease remission is a potential goal of urate-lowering therapy. In 2016, preliminary gout remission criteria were developed by a large group of rheumatologists and researchers with expertise in gout. The preliminary gout remission criteria were defined as: serum urate < 0.36 mmol/L (6 mg/dL); an absence of gout flares; an absence of tophi; pain due to gout < 2 on a 0-10 scale; and a patient global assessment < 2 on a 0-10 scale over a 12-month period. In this critical review, we describe the development of the preliminary gout remission criteria, the properties of the preliminary gout remission criteria, and clinical studies of gout remission in people taking urate-lowering therapy. We also describe a future research agenda for gout remission.

The Role of the Intestine in the Development of Hyperuricemia

Gout is a common inflammatory arthritis caused by the deposition of sodium urate crystals in the joints. Hyperuricemia is the fundamental factor of gout. The onset of hyperuricemia is related to purine metabolism disorders or uric acid excretion disorders. Current studies have shown that the intestine is an important potential organ for the excretion of uric acid outside the kidneys. The excretion of uric acid of gut is mainly achieved through the action of uric acid transporters and the catabolism of intestinal flora, which plays an important role in the body’s uric acid balance. Here we reviewed the effects of intestinal uric acid transporters and intestinal flora on uric acid excretion, and provide new ideas for the treatment of hyperuricemia and gout.

One- and 2-year flare rates after treat-to-target and tight-control therapy of gout: results from the NOR-Gout study

OBJECTIVES

To explore the frequency and predictors of flares over 2 years during a treat-to-target strategy with urate-lowering therapy (ULT) in patients with gout.

METHODS

In the treat-to-target, tight control NOR-Gout study patients started ULT with escalating doses of allopurinol. Flares were recorded over 2 years. Baseline predictors of flares during months 9-12 in year 1 and during year 2 were analyzed by multivariable logistic regression.

RESULTS

Of 211 patients included (mean age 56.4 years, disease duration 7.8 years, 95% males), 81% (150/186) of patients experienced at least one gout flare during the first year and 26% (45/173) during the second year. The highest frequency of flares in the first year was seen during months 3-6 (46.8% of patients). Baseline crystal depositions detected by ultrasound and by dual-energy computed tomography (DECT) were the only variables which predicted flares both during the first period of interest at months 9-12 (OR 1.033; 95% CI 1.010-1.057, and OR 1.056; 95% CI 1.007-1.108) and also in year 2. Baseline subcutaneous tophi (OR 2.42, 95% CI 1.50-5.59) and prior use of colchicine at baseline (OR 2.48, 95% CI 1.28-4.79) were independent predictors of flares during months 9-12, whereas self-efficacy for pain was a protective predictor (OR 0.98 per unit, 95% CI 0.964-0.996).

CONCLUSIONS

In patients with gout, flares remain frequent during the first year of a treat-to-target ULT strategy, especially during months 3-6, but are much less frequent during year 2. Baseline crystal depositions predict flares over 2 years, supporting ULT early during disease course.

TRIAL REGISTRATION

ACTRN12618001372279.

Treating gout - can hypouricemia produced by moderate doses of combined oral treatment give early treatment success? Preliminary observations

Six male patients with gout were treated with combined oral medication (febuxostat, 120 mg/d, and benzbromarone, 50 or 100 mg/d), aiming at a more rapid success of uric acid lowering treatment (ULT) compared to guideline suggestions. By combined oral medication in moderate dosage, the sUA was reduced to <2 mg/dl in all cases. We conclude that, by the treatment schedule outlined, the majority of patients with gout can be cured within 1 - 2 years, with uricase treatment being necessary very rarely only.

Impact of Serum Uric Acid Lowering and Contemporary Uric Acid-Lowering Therapies on Cardiovascular Outcomes: A Systematic Review and Meta-Analysis

Objective: This study aimed to evaluate the potential association between uric acid (UA) lowering and cardiovascular risk reduction among UA-lowering therapies in adults.

Methods: A systematic search for randomized controlled trials (RCTs) was conducted according to the protocol pre-registered in PROSPERO (No. CRD42020199259). We search for RCTs in PubMed, Embase, Web of Science, the Cochrane Library, and ClinicalTrials.gov up to July 1, 2020. A meta-analysis was performed using a fixed- or random-effects model.

Results: In total, 30 studies involving 18,585 hyperuricaemic patients were included. Xanthine oxidase inhibitor (XOI) therapy produced a 6.0% reduction in relative risk (RR) for major adverse cardiovascular events (MACEs). The use of febuxostat was associated with a higher risk of cardiovascular events (CVEs) (RR: 1.09, 95% CI 0.998–1.19, I² = 0.0%), but the difference was not statistically significant. Allopurinol treatment was associated with a lower CVE risk (RR: 0.61, 95% CI 0.46–0.80, I² = 21.0%). Among the UA-lowering therapies, the drug treatments were associated with all-cause mortality (RR: 1.20, 95% CI 1.02–1.41, I² = 0.0%). The subgroup with a UA endpoint <7 mg/dl was not associated with a higher CVE risk (RR: 0.57, 95% CI 0.35–0.92, I² = 0.0%), and in the subgroup with a UA endpoint <5 mg/dl group, a lower risk of CVEs was not observed (RR: 0.99, 95% CI 0.69–1.44, I² = 0.0%).

Conclusions: UA reduction caused by XOIs reduced the incidence of MACEs. UA-lowering medicines were associated with changes in all-cause mortality but not cardiovascular outcomes. The lower UA endpoint was not associated with reduced cardiovascular risk.

Expression, localization and metabolic function of "resurrected" human urate oxidase in human hepatocytes

A high serum uric acid (SUA) concentration is associated with hyperuricemia (HUA) and gout. In order to obtain long-acting therapeutic effect, correction of purine metabolism at genetic level is advantageous. For this purpose, we expressed three "human-like" urate oxidases in human hepatocytes (HL-7702) by lentivirus-mediated transduction. Enzymatic assay revealed that the recombinant urate oxidases expressed in HL-7702 cells were functionally active. Electron microscopy study showed that the recombinant enzymes were localized to peroxisome and formed distinct crystalloid core structures as in other mammal cells. Although similar rate of uric acid degradation was observed for all recombinant urate oxidases, HL-7702-pLVX-UOX₈₃ cells and HL-7702-pLVX-UOX_214/217 cells retained more cell viability compared with HL-7702-pLVX-UOX_PBC at high uric acid level. This study provides a new direction for the treatment of gout and hyperuricemia.

Pharmacologic Management of Gout in Patients with Cardiovascular Disease and Heart Failure

Gout is the most common inflammatory arthritis and is often comorbid with cardiovascular disease (CVD). Hyperuricemia and gout are also independent risk factors for cardiovascular events, worsening heart failure (HF), and death. The recommended treatment modalities for gout have important implications for patients with CVD because of varying degrees of cardiovascular and HF benefit and risk. Therefore, it is critical to both manage hyperuricemia with urate-lowering therapy (ULT) and treat acute gout flares while minimizing the risk of adverse cardiovascular events. In this review, the evidence for the safety of pharmacologic treatment of acute and chronic gout in patients with CVD and/or HF is reviewed. In patients with CVD or HF who present with an acute gout flare, colchicine is considered safe and potentially reduces the risk of myocardial infarction. If patients cannot tolerate colchicine, short durations of low-dose glucocorticoids are efficacious and may be safe. Nonsteroidal anti-inflammatory drugs should be avoided in patients with CVD or HF. The use of canakinumab and anakinra for acute gout flares is limited by the high cost, risk of serious infection, and relatively modest clinical benefit. For long-term ULT, allopurinol, and alternatively probenecid, should be considered first-line treatments in patients with CVD or HF given their safety and potential for reducing cardiovascular outcomes. An increased risk of cardiovascular death and HF hospitalization limit the use of febuxostat and pegloticase as ULT in this population. Ultimately, the selection of agents used for acute gout management and long-term ULT should be individualized according to patient and agent cardiovascular risk factors.

Development of a multivariable improvement measure for gout

Background

Gout is a heterogeneous inflammatory disease with numerous clinical manifestations. A composite means to assess the impact of therapy on numerous aspects of gout could be useful.

Methods

Results from patients treated with pegloticase or placebo in two randomized clinical trials and their open-label extension were assessed using a novel evidence-based Gout Multivariable Improvement Measure (GMIM) derived from previously reported criteria for remission and complete response. Improvement was defined as serum urate (sU) < 6 mg/dL and absence of flares during the preceding 3 months plus 20, 50, and 70% improvement in tophus size, patient global assessment, pain, and swollen and tender joints.

Results

Patients treated with pegloticase manifested a significantly greater GMIM20, 50, and 70 response vs those treated with placebo (GMIM20 at 6 months 37.1% vs 0%, respectively). Higher response rates were significantly more frequent in subjects with persistent urate lowering (GMIM 58.1% at 6 months) in response to pegloticase versus those with only transient urate lowering (GMIM 7.1% at 6 months). However, when the requirement for a decrease in sU to < 6 mg/dL was omitted, a substantial percentage of subjects with transient urate lowering met the GMIM clinical criteria. A sensitivity analysis indicated that gout flares contributed minimally to the model. The response measured by GMIM persisted into the open-level extension for as long as 2 years. Finally, subjects who received placebo in the randomized control trials, but pegloticase in the open-label extension, manifested GMIM responses comparable to that noted with pegloticase-treated subjects in the randomized controlled trials.

Conclusions

GMIM captures changes in disease activity in response to treatment with pegloticase and may serve as an evidence-based tool for assessment of responses to other urate-lowering therapies in gout patients.

2020 American College of Rheumatology Guideline for the Management of Gout

OBJECTIVE

To provide guidance for the management of gout, including indications for and optimal use of urate-lowering therapy (ULT), treatment of gout flares, and lifestyle and other medication recommendations.

METHODS

Fifty-seven population, intervention, comparator, and outcomes questions were developed, followed by a systematic literature review, including network meta-analyses with ratings of the available evidence according to the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology, and patient input. A group consensus process was used to compose the final recommendations and grade their strength as strong or conditional.

RESULTS

Forty-two recommendations (including 16 strong recommendations) were generated. Strong recommendations included initiation of ULT for all patients with tophaceous gout, radiographic damage due to gout, or frequent gout flares; allopurinol as the preferred first-line ULT, including for those with moderate-to-severe chronic kidney disease (CKD; stage >3); using a low starting dose of allopurinol (≤100 mg/day, and lower in CKD) or febuxostat (<40 mg/day); and a treat-to-target management strategy with ULT dose titration guided by serial serum urate (SU) measurements, with an SU target of <6 mg/dl. When initiating ULT, concomitant antiinflammatory prophylaxis therapy for a duration of at least 3-6 months was strongly recommended. For management of gout flares, colchicine, nonsteroidal antiinflammatory drugs, or glucocorticoids (oral, intraarticular, or intramuscular) were strongly recommended.

CONCLUSION

Using GRADE methodology and informed by a consensus process based on evidence from the current literature and patient preferences, this guideline provides direction for clinicians and patients making decisions on the management of gout.

2020 American College of Rheumatology Guideline for the Management of Gout

OBJECTIVE

To provide guidance for the management of gout, including indications for and optimal use of urate-lowering therapy (ULT), treatment of gout flares, and lifestyle and other medication recommendations.

METHODS

Fifty-seven population, intervention, comparator, and outcomes questions were developed, followed by a systematic literature review, including network meta-analyses with ratings of the available evidence according to the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology, and patient input. A group consensus process was used to compose the final recommendations and grade their strength as strong or conditional.

RESULTS

Forty-two recommendations (including 16 strong recommendations) were generated. Strong recommendations included initiation of ULT for all patients with tophaceous gout, radiographic damage due to gout, or frequent gout flares; allopurinol as the preferred first-line ULT, including for those with moderate-to-severe chronic kidney disease (CKD; stage >3); using a low starting dose of allopurinol (≤100 mg/day, and lower in CKD) or febuxostat (<40 mg/day); and a treat-to-target management strategy with ULT dose titration guided by serial serum urate (SU) measurements, with an SU target of <6 mg/dl. When initiating ULT, concomitant antiinflammatory prophylaxis therapy for a duration of at least 3-6 months was strongly recommended. For management of gout flares, colchicine, nonsteroidal antiinflammatory drugs, or glucocorticoids (oral, intraarticular, or intramuscular) were strongly recommended.

CONCLUSION

Using GRADE methodology and informed by a consensus process based on evidence from the current literature and patient preferences, this guideline provides direction for clinicians and patients making decisions on the management of gout.

Pharmacokinetics of Polyethylene Glycol-Modified Canine Uricase Following Single and Multiple Intravenous Injections in Cynomolgus Monkeys

BACKGROUND AND OBJECTIVE

Polyethylene glycol-modified canine uricase (PEG-UHC) prepared with a lower-molecular-weight (5 kDa) PEG is used to treat gout. This study investigated the comparative pharmacokinetics of single and multiple doses of PEG-UHC administered intravenously and a single dose of uricase (UHC) administered intravenously in cynomolgus monkeys.

METHODS

A noncompartmental model was used to fit the plasma drug concentration-time curve and calculate the pharmacokinetic parameters of PEG-UHC, which were compared with those obtained for UHC at the equivalent dose (2 mg/kg). To study the pharmacokinetics after multiple dose administration, cynomolgus monkeys were administered five intravenous injections of PEG-UHC (0.5 mg/kg), with one injection performed every 15 days.

RESULTS

The area under the curve (AUC) and the maximum plasma concentration (C_max) of PEG-UHC were positively correlated with dose, whereas plasma half-life (t_1/2) and clearance (CL) did not change significantly with increasing dose, suggesting that these pharmacokinetic characteristics are linear. Intravenous PEG-UHC exhibited an average t_1/2 that was 125.79 times longer and an AUC_0-t that was 64.45 times larger than the corresponding values for UHC at the same dose (2 mg/kg), while the CL of PEG-UHC was 1/72.73 times the CL of intravenous UHC. The plasma drug concentration reached a steady state after five injections, and the t_1/2 values following the first and last drug administration did not differ significantly.

CONCLUSION

Our data show that PEG-UHC is markedly superior to UHC in terms of duration of action, and that the pharmacokinetics of PEG-UHC in cynomolgus monkeys are linear. Sequential administration of PEG-UHC did not accelerate drug clearance. Our findings provide the basis for future clinical studies of PEG-UHC.

Hyperuricemia and Cardiovascular Disease

Purine metabolism in the circulatory system yields uric acid as its final oxidation product, which is believed to be linked to the development of gout and kidney stones. Hyperuricemia is closely correlated with cardiovascular disease, metabolic syndrome, and chronic kidney disease, as attested by the epidemiological and empirical research. In this review, we summarize the recent knowledge about hyperuricemia, with a special focus on its physiology, epidemiology, and correlation with cardiovascular disease. This review also discusses the possible positive effects of treatment to reduce urate levels in patients with cardiovascular disease and hyperuricemia, which may lead to an improved clinical treatment plan.

Structure-based design of a hyperthermostable AgUricase for hyperuricemia and gout therapy

Arthrobacter globiformis Uricase (AgUricase) is a homotetrameric uricase with the potential for therapeutic use in treating hyperuricemia-related diseases. To achieve sufficient therapeutic effects, it is essential for this enzyme to have high thermostability and long half-life in physiological condition. To improve the thermostability of this enzyme, we introduced a series of cysteine pair mutations into the AgUricase subunits based on its structural model and studied the thermostability of the mutant enzymes with introduced disulfide bridges. Two intersubunit cysteine pair mutations, K12C-E286C and S296C-S296C, were found to markedly increase the melting temperatures of the corresponding mutant enzymes compared with WT AgUricase. The crystal structure of the K12C-E286C mutant at 1.99 Å resolution confirmed the formation of a distinct disulfide bond between the two subunits in the dimer. Structural analysis and biochemical data revealed that the C-terminal loop of AgUricase was flexible, and its interaction with neighboring subunits was required for the stability of the enzyme. We introduced an additional intersubunit K244C-C302 disulfide bond based on the crystal structure of the K12C-E286C mutant and confirmed that this additional disulfide bond further stabilized the flexible C-terminal loop and improved the thermostability of the enzyme. Disulfide cross-linking also protected AgUricase from protease digestion. Our studies suggest that the introduction of disulfide bonds into proteins is a potential strategy for enhancing the thermostability of multimeric proteins for medical applications.

Gout

Gout is a chronic disease caused by monosodium urate (MSU) crystal deposition. Gout typically presents as an acute, self-limiting inflammatory monoarthritis that affects the joints of the lower limb. Elevated serum urate level (hyperuricaemia) is the major risk factor for MSU crystal deposition and development of gout. Although traditionally considered a disorder of purine metabolism, altered urate transport, both in the gut and the kidneys, has a key role in the pathogenesis of hyperuricaemia. Anti-inflammatory agents, such corticosteroids, NSAIDs and colchicine, are widely used for the treatment of gout flare; recognition of the importance of NLRP3 inflammasome activation and bioactive IL-1β release in initiation of the gout flare has led to the development of anti-IL-1β biological therapy for gout flares. Sustained reduction in serum urate levels using urate-lowering therapy is vital in the long-term management of gout, which aims to dissolve MSU crystals, suppress gout flares and resolve tophi. Allopurinol is the first-line urate-lowering therapy and should be started at a low dose, with gradual dose escalation. Low-dose anti-inflammatory therapies can reduce gout flares during initiation of urate-lowering therapy. Models of care, such as nurse-led strategies that focus on patient engagement and education, substantially improve clinical outcomes and now represent best practice for gout management.

Evaluation of Proposed Criteria for Remission and Evidence-Based Development of Criteria for Complete Response in Patients With Chronic Refractory Gout

Objective

The objective of this study is to assess criteria for gout remission and to use the results to inform criteria for a complete response (CR).

Methods

A post hoc analysis of two clinical trials was undertaken to determine the frequency with which subjects with chronic refractory gout who were treated with pegloticase met remission criteria. Mixed modeling was then employed to identify the components that best correlated with time to maximum benefit.

Results

Of the 56 subjects treated with biweekly pegloticase for whom adequate data were collected, 48.2% met the remission criteria. When subjects with persistent lowering of urate levels were examined separately, 27 of 32 (84.4%) met the criteria for remission. In contrast, even when the requirement for lowering of serum urate levels was waived, only 2 of 24 (8.3%) subjects without persistent lowering of urate levels and 0 of 43 subjects receiving placebo met criteria. Mixed modeling indicated that in addition to urate levels, assessment of tophi, swollen joints, and tender joints and patient global assessment best correlated with time to maximum benefit. Using these criteria of CR, 23 of the responders (71.9%) met the criteria. All patients who achieved a CR maintained it for a mean duration of 507.4 days. Finally, 64% of persistent responders to monthly pegloticase also met criteria for CR.

Conclusion

These results have validated the proposed remission criteria for gout and have helped define criteria for CR in individuals with chronic gout treated with pegloticase. This composite CR index can serve as an evidence-based target to inform the design and end points of future clinical trials.

Management of complex gout in clinical practice: Update on therapeutic approaches

Increasing therapeutic options are available for gout management. Anti-inflammatory agents are used in the acute management of gout flares, and interleukin-1 inhibitors are effective for those unable to take conventional anti-inflammatory treatments. Lowering of serum urate remains the cornerstone of effective long-term management. Allopurinol is the first-line urate-lowering therapy, and a gradual dose-escalation strategy to serum urate target is recommended. Febuxostat and lesinurad have been approved more recently. In a large cardiovascular outcomes trial, higher all-cause and cardiovascular mortality was observed with febuxostat than with allopurinol. Lesinurad should be co-prescribed with a xanthine oxidase inhibitor, and close monitoring of kidney function is required. Evidence for non-pharmacological management is limited, but personalised lifestyle modification may reduce associated cardiovascular risk. In this review, we discuss current principles in the gout management paradigm, consider strategies for managing complex, clinical scenarios, and review emerging therapies.

Safety and tolerability of available urate-lowering drugs: a critical review

INTRODUCTION

Urate-lowering therapy (ULT) is the cornerstone of gout management, which is a widespread chronic illness characterized by hyperuricemia, arthropathy, tophus development, and urolithiasis. Since asymptomatic increased serum urate levels are associated with a higher risk of cardiovascular, renal and metabolic disorders, a larger use of ULTs in the general population is expected in the near future.

AREAS COVERED

This review will focus on the safety and tolerability profile of the available urate-lowering drugs: xanthine oxidase inhibitors (XOIs), uricosuric agents and injectable uricases.

EXPERT OPINION

Older drugs for ULT like allopurinol are well studied and extensively described from typical adverse effects (mild skin rash) to unusual fatal reactions, while febuxostat seems to be overall well tolerated. More evidence is required to define the safety profile of topiroxostat, arhalofenate, tranilast, and sulfinpyrazone. Furthermore, there are some unanswered questions about the pharmacological interactions of probenecid and the hepatotoxicity of benzbromarone. Despite a limited use in clinical practice, combination therapy with lesinurad or verinurad and XOI is not frequently accompanied by side effects. Rasburicase and pegloticase are usually well tolerated with some specific exceptions. Before prescribing UL drugs, physicians should take into account their safety profile tailoring the treatment on the patient characteristics.

Use of Pre-Infusion Serum Uric Acid Levels as a Biomarker for Infusion Reaction Risk in Patients on Pegloticase

Introduction

The aim of this work is to evaluate the impact of the timing of pre-infusion serum uric acid (sUA) test results for use in applying stopping rules for pegloticase to identify patients at risk for infusion reactions (IRs) while on therapy.

Methods

Data from the phase 3 clinical trials of pegloticase were reviewed and individual uric acid levels of the 85 patients who received the approved regimen of biweekly infusions were examined in relation to the occurrence of IRs.

Results

Of the 22 patients (26%) who experienced an IR on pegloticase therapy without uric acid stopping rules, only seven (8%) would have had IRs if pegloticase therapy had been discontinued after two consecutive pre-infusion sUA levels above 6 mg/dl. If pegloticase therapy was stopped after a single pre-infusion sUA above 6 mg/dl, only two patients (2%) would have experienced IRs during the clinical studies.

Conclusions

A pre-infusion sUA level functions as a highly accurate biomarker for identification of patients who are at risk of IRs while on pegloticase therapy. Stopping pegloticase in patients who have a rise in pre-infusion uric acid levels to above 6 mg/dl while on therapy would result in most IRs being avoided.

Funding

Horizon Pharma.

Characterization of patients with chronic refractory gout who do and do not have clinically apparent tophi and their response to pegloticase

OBJECTIVES

To determine the characteristics and response to pegloticase of patients with chronic refractory gout with and without clinically apparent tophi.

METHODS

Results from two randomized controlled trials of pegloticase in patients with chronic refractory gout with clinically apparent tophi or without tophi were used to assess baseline and on-treatment between-group differences.

RESULTS

Patients with tophi were significantly older than those without tophi, had a significantly longer duration of disease, higher numbers of tender and swollen joints, higher Patient Global Assessment scores and Health Assessment Questionnaire-Disability Index scores, and lower Arthritis-Specific Health Index scores. Patients with tophaceous gout also had significantly lower scores for physical functioning, role physical, social functioning, and the physical component summary scores of the Short Form 36 vs patients without tophi. In addition, subjects with clinically apparent tophi had a significantly lower mean estimated glomerular filtration rate. Pegloticase treatment of tophaceous patients caused significant reductions in serum urate, flares, Patient Global Assessment, tender joints, swollen joints, Health Assessment Questionnaire-Disability Index, visual analogue scale pain and Short Form 36 Bodily Pain, whereas patients without tophi had significant improvement in serum urate, flares, Patient Global Assessment, tender joints, and Short Form 36 Bodily Pain, but not swollen joints, Health Assessment Questionnaire-Disability Index functional score or pain visual analogue scale. Treatment with pegloticase had no effect on estimated glomerular filtration rate despite significant lowering of the urinary uric acid: creatinine ratio.

CONCLUSION

Patients with chronic refractory gout and clinically apparent tophi have more severe disease as well as reduced renal function. Both groups experienced significant clinical benefit with pegloticase treatment, although no change in renal function was noted.

Moving the Needle: Improving the Care of the Gout Patient

Gout is a the most common inflammatory arthritis in the United States. It is a significant cause of morbidity, disability, lost work days, and high healthcare utilization due to intermittent attacks, chronic inflammation, and joint damage. Despite our understanding of the prelude and pathophysiology of gout, hyperuricemia, it is still poorly misunderstood by patients and poorly managed by healthcare providers. Several parallel treatment paradigms have been developed by professional societies around the world based on the understanding of how hyperuricemia occurs, gout epidemiology, expert opinion, and clinical trials data in order to lower uric acid and eventually eliminate the patient's crystal burden. This review focuses on both the treatment of acute attacks, and more importantly, the long-term management of gout and the lowering of serum uric acid levels to a goal of < 6 mg/dl (0.360 mmol/l) or treating to target. Treating to a target serum uric acid goal is an opportunity to decrease morbidity and improve the quality of care of every gout patient.

Tophus resolution in patients with chronic refractory gout who have persistent urate-lowering responses to pegloticase

BACKGROUND

Pegloticase is a recombinant mammalian uricase conjugated to polyethylene glycol approved in the United States for treatment of chronic refractory gout. It can profoundly decrease serum urate to < 1 mg/dl. In patients receiving pegloticase who did not generate high-titer antidrug antibodies (responders), the serum urate remained low for the duration of therapy, 6 months in the phase III clinical trials plus the open-label extension. The objective of this study was to assess the velocity of tophus resolution in subjects treated with pegloticase.

METHODS

Data from two randomized controlled trials of pegloticase in chronic refractory gout were analyzed. Tophi were assessed by computer-assisted measurements of standardized digital photographs. Subjects were designated as responders and nonresponders based on maintenance of serum urate < 6 mg/dl at months 3 and 6 of treatment. The projected time of complete resolution of all tophi was determined by linear regression analysis.

RESULTS

The mean total tophus area at baseline was 585.8 mm² for responders, 661.5 mm² for nonresponders, and 674.4 mm² for placebo-treated patients. Complete resolution at 6 months of at least one tophus was achieved by 69.6% of 23 responders, 27.9% of 43 nonresponders, and 14.3% of 21 patients who received placebo. Complete resolution of all photographed tophi was achieved by 34.8% of biochemical responders, 11.6% of nonresponders, and 0% of placebo-treated patients. The mean velocity of resolution of all tophi was 60.1 mm²/month in responders with a mean projected time of complete resolution of 9.9 months (4.6-32.6 months). There was a significant inverse correlation between serum urate AUC and tophus resolution velocity (r = - 0.40, P = 0.0002), although considerable heterogeneity in the velocity of resolution was noted. The only patient characteristic that correlated with the velocity of tophus resolution was the baseline tophus area.

CONCLUSIONS

Pegloticase treatment caused a rapid resolution of tophi in responders that correlated with the serum urate lowering associated with this therapy.

Impact of pegloticase on patient outcomes in refractory gout: current perspectives

Gout is currently the most frequent cause of inflammatory arthritis worldwide and is responsible for poor health-related quality of life and loss of work productivity. It is caused by high levels of serum urate, leading to the deposition of monosodium urate crystals in joints and soft tissues. This condition is associated with acute flares and, if untreated or refractory, chronic and potentially destructive arthritis and tophi formation. Pegloticase is a recombinant, pegylated uricase used in the treatment of gout patients who fail conventional urate-lowering therapy. In this review, we discuss the impact of pegloticase on patient outcomes in refractory gout. We analyze different parameters, such as plasma uric acid concentration, frequency of flares, tophi reduction, pain, function, quality of life, and safety.

Serum urate as surrogate endpoint for flares in people with gout: A systematic review and meta-regression analysis

OBJECTIVES

The primary efficacy outcome in trials of urate lowering therapy (ULT) for gout is serum urate (SU). The aim of this study was to examine the strength of the relationship between SU and patient-important outcomes to determine whether SU is an adequate surrogate endpoint for clinical trials.

METHODS

Multiple databases through October 2017 were searched. Randomized controlled trials comparing any ULT in people with gout with any control or placebo, ≥three months duration were included. Open label extension (OLE) trial data were included in secondary analyses. Standardized data elements were extracted independently by two reviewers.

RESULTS

Ten RCTs and 3 OLE studies were identified. From the RCTs (maximum duration 24 months) meta-regression did not reveal an association between the relative risk of a gout flare and the difference in proportions of individuals with SU < 6mg/dL (P = 0.47; R2 = 8%). In a post hoc analysis, the ratio of the time in months at which the proportion of individuals having a flare was reported/time in months at which the proportion of individuals with SU < 6mg/dL was reported was calculated and studies where the ratio was <2 were excluded. Using the remaining 6 studies there was an association between proportion of individuals achieving SU < 6mg/dL and gout flares (over patient years). Duration of ULT was inversely associated with the proportion of patients experiencing a flare. Study duration and variability in reporting of outcomes limited the analysis. Observational studies supported the trend of fewer flares in those with lower SU.

CONCLUSIONS

Based on aggregate clinical trial-level data an association between SU and gout flare could not be confirmed. However, based on observational ecological study design data-including longer duration extension studies-SU < 6mg/dL was associated with reduced gout flares.

Patient considerations in the management of gout and role of combination treatment with lesinurad

Gouty arthritis is one of the most common rheumatic diseases, and the prevalence continues to rise, which is likely related to increased incidence of comorbidities, lifestyle factors, and suboptimal utilization of urate-lowering therapy. In recent years, multiple new guidelines have been published along with the approval of novel drug therapies. Still, gout remains a poorly controlled disease state that is accompanied by a reduced health-related quality of life, increased health care utilization, and overall negative socioeconomic effects, all of which have a negative impact on patient-related health outcomes. The key to success in gout management is utilization of urate-lowering therapy to prevent recurrence of acute gouty arthritis and to resolve tophi, if present. Xanthine oxidase inhibitors are first-line medications for the prevention of recurrent gout followed by uricosurics, including lesinurad (a uric acid reabsorption inhibitor) as an add-on option. The recent US Food and Drug Administration Safety Communication related to cardiovascular risk with febuxostat may result in increased use of allopurinol in combination therapy with a uricosuric agent such as lesinurad. In this review, we discuss gout management, clinical end points, and patient-related outcomes for consideration, summarize the evidence for combination therapy to achieve serum urate targets, and focus on lesinurad as a novel newer medication for the prevention of gout.

Retreatment with Pegloticase after a Gap in Therapy in Patients with Gout: A Report of Four Cases

Introduction

Pegloticase, a potent uricolytic biologic enzyme, has been shown to be an effective therapeutic option in patients with uncontrolled gout. However, there are limited data on clinical response after a gap in therapy and retreatment with pegloticase.

Case Series

This report describes four patients with chronic gout who were successfully managed with pegloticase and were retreated following a gap in therapy. Patient charts from a practice-based rheumatology clinic were retrospectively analyzed; four male patients, aged 70–75 years, with chronic gout and a more than 4-week gap in pegloticase therapy were reviewed. Before pegloticase treatment, patients had received allopurinol or febuxostat, but they continued exhibiting symptoms, including visible tophi and serum uric acid (SUA) levels of 5.2–10.2 mg/dL (309–607 μmol/L), despite oral urate-lowering therapy. The first pegloticase treatment (8-mg infusion every 2 weeks) lasted 22–124 weeks. Pegloticase resolved tophi and improved SUA to below 1.5 mg/dL (less than 89 μmol/L); however, patients discontinued pegloticase because of symptom resolution, poor adherence, or personal reasons. Following treatment gaps (12–156 weeks), symptoms and SUA levels increased and patients were retreated with pegloticase (4–147 weeks). In three of four patients, reinitiating pegloticase lowered SUA levels to below 1.0 mg/dL (less than 59 μmol/L) and resolved symptoms. One patient experienced an infusion reaction and discontinued; no infusion reactions, gout flares, or adverse events occurred among the other three patients.

Conclusion

Retreatment with pegloticase after a gap in therapy appears to be an effective and tolerated option in prior responders.

Funding

Horizon Pharma.

Accuracy of the HumaSensplus point-of-care uric acid meter using capillary blood obtained by fingertip puncture

BACKGROUND

The uric acid (UA) level in patients with gout is a key factor in disease management and is typically measured in the laboratory using plasma samples obtained after venous puncture. This study aimed to assess the reliability of immediate UA measurement with capillary blood samples obtained by fingertip puncture with the HumaSensplus point-of-care meter.

METHODS

UA levels were measured using both the HumaSensplus meter in the clinic and the routine plasma UA method in the biochemistry laboratory of 238 consenting diabetic patients. HumaSensplus capillary and routine plasma UA measurements were compared by linear regression, Bland-Altman plots, intraclass correlation coefficient (ICC), and Lin's concordance coefficient. Values outside the dynamic range of the meter, low (LO) or high (HI), were analyzed separately. The best capillary UA thresholds for detecting hyperuricemia were determined by receiver operating characteristic (ROC) curves. The impact of potential confounding factors (demographic and biological parameters/treatments) was assessed. Capillary and routine plasma UA levels were compared to reference plasma UA measurements by liquid chromatography-mass spectrometry (LC-MS) for a subgroup of 67 patients.

RESULTS

In total, 205 patients had capillary and routine plasma UA measurements available. ICC was 0.90 (95% confidence interval (CI) 0.87-0.92), Lin's coefficient was 0.91 (0.88-0.93), and the Bland-Altman plot showed good agreement over all tested values. Overall, 17 patients showed values outside the dynamic range. LO values were concordant with plasma values, but HI values were considered uninterpretable. Capillary UA thresholds of 299 and 340 μmol/l gave the best results for detecting hyperuricemia (corresponding to routine plasma UA thresholds of 300 and 360 μmol/l, respectively). No significant confounding factor was found among those tested, except for hematocrit; however, this had a negligible influence on the assay reliability. When capillary and routine plasma results were discordant, comparison with LC-MS measurements showed that plasma measurements had better concordance: capillary UA, ICC 0.84 (95% CI 0.75-0.90), Lin's coefficient 0.84 (0.77-0.91); plasma UA, ICC 0.96 (0.94-0.98), Lin's coefficient 0.96 (0.94-0.98).

CONCLUSIONS

UA measurements with the HumaSensplus meter were reasonably comparable with those of the laboratory assay. The meter is easy to use and may be useful in the clinic and in epidemiologic studies.

What Is the Evidence for Treat-to-Target Serum Urate in Gout?

PURPOSE OF REVIEW

Most current clinical guidelines for gout management advocate a treat-to-target serum urate approach, although notable differences exist. Serum urate is a rational target for gout treatment given the central role of urate in disease causality, its association with key outcomes and its practicality of use in clinical practice. This review analyses the evidence for this strategy in gout.

RECENT FINDINGS

Recent studies have confirmed the efficacy of urate-lowering therapy in achieving serum urate targets, both in trials using fixed doses and those applying a treat-to-target strategy. In a limited number of long-term studies (> 12-month duration), interventions that incorporate a treat-to-target serum urate approach have been shown to promote regression of tophi, reduce the frequency of gout flares and improve MRI-detected synovitis. A strong case can be made for a treat-to-target serum urate strategy in gout, supported by existing knowledge of disease pathophysiology, outcomes from urate-lowering therapy studies and emerging results of randomised strategy trials of sufficient duration.

Variability in the Reporting of Serum Urate and Flares in Gout Clinical Trials: Need for Minimum Reporting Requirements

Objective.

To describe the ways in which serum urate (SU) and gout flares are reported in clinical trials, and to propose minimum reporting requirements.

Methods.

This analysis was done as part of a systematic review aiming to validate SU as a biomarker for gout. The ways in which SU and flares were reported were extracted from each study by 2 reviewers.

Results.

A total of 22 studies (10 randomized controlled trials, 3 open-label extension studies, and 9 observational studies) were identified. There were 3 broad categories of SU reporting: percentage at target SU, mean SU, and change in SU. A median of 2 (range 1–3) categories were reported across all studies. The most common method of reporting SU was percentage at target in 17/22 (77.3%) studies, with all studies reporting a target of SU < 6 mg/dl. There were 12/22 (54.5%) studies reporting mean SU at some time after study entry, with 7 (58.3%) of these reporting at more than just the final study visit. Two ways of reporting gout flares were identified: mean flare rate and percentage of participants with flares. There was variability in time periods over which flares rates were reported.

Conclusion.

There is inconsistent reporting of SU and flares in gout studies. Reporting the percentage of participants who achieve a target SU reflects international treatment guidelines. SU should also be reported as a continuous variable with a relevant central and dispersion estimate. Gout flares should be reported as both percentage of participants and mean flare rates at each timepoint.

Cardiovascular effects of urate-lowering therapies in patients with chronic gout: a systematic review and meta-analysis

Objectives

To determine if urate-lowering treatment (ULT) in gout can reduce cardiovascular (CV) outcomes.

Methods

Randomized trials were searched for treatment with ULT in gout. Eligible trials had to report CV safety of a ULT. Potential medications included allopurinol, febuxostat, pegloticase, rasburicase, probenecid, benzbromarone, sulphinpyrazone, losartan, fenofibrate and sodium-glucose linked transporter 2 inhibitors.

Results

A total of 3084 citations were found, with 642 duplicates. After the primary screen, 35 studies were selected for review. Several trials did not report CV events. Six were not randomized controlled trials (RCTs). Four studies reported no events in either intervention arm while the other four had 40 events in the febuxostat group ( n = 3631) and 5 in allopurinol group ( n = 1154). Overall, the pooled analysis did not show a significant difference between the two [febuxostat vs allopurinol: relative risk (RR) 1.69 (95% CI 0.54, 5.34), P = 0.37]. CV events did not decrease over time. Comparing shorter studies (<52 weeks) to longer ones did not reveal any statistical differences. However, in long-term studies with febuxostat vs allopurinol, results were nearly significant, with more CVE occurring with febuxostat treatment. Comparing any ULT to placebo (eight studies, n = 2221 patients) did not demonstrate a significant difference in non-Anti-Platelet Trialists' Collaboration events [any ULT vs placebo: RR 1.47 (95% CI 0.49, 4.40), P = 0.49] or all-cause mortality [any ULT vs placebo: RR 1.45 (95% CI 0.35, 5.77), P = 0.60].

Conclusion

RCT data do not suggest differences in CV events among ULTs in gout. Trials had few events despite high-risk patients being enrolled and may have been too short to show CV reduction by controlling inflammatory attacks and lowering uric acid.

Pegloticase in gout treatment - safety issues, latest evidence and clinical considerations

Gout is a common rheumatic condition, with increasing prevalence in recent decades. The mainstay of treatment for gout is oral urate-lowering therapy (ULT), typically with xanthine oxidase inhibitors (XOIs). Unfortunately, a proportion of patients have persistent gout that is refractory to ULT. Pegloticase, a recombinant pegylated uricase, has been approved by the US Food and Drug Administration for the treatment of refractory gout. However, concern has been raised regarding the risk of infusion reactions, which are now understood to be largely due to the development of antipegloticase antibodies. Discontinuation of pegloticase upon failure to lower serum urate has been shown to markedly reduce infusion reaction risk, but deprives patients of what, in many cases, is a last-resort treatment. In this manuscript, we review the rationale, mechanism of action, efficacy and safety of pegloticase. Additionally, we focus on potential strategies to reduce pegloticase immunogenicity and potentially make this important agent available to a wider group of patients requiring treatment.

Frequency, distribution and immunologic nature of infusion reactions in subjects receiving pegloticase for chronic refractory gout

BACKGROUND

To assess frequency and distribution of infusion reactions (IRs) in responders and nonresponders in randomized clinical trials (RCTs) of intravenous pegloticase and the utility of the National Institute of Allergy and Infectious Disease/Food and Allergy and Anaphylaxis Network (NIAID/FAAN) criteria for identifying anaphylaxis in subjects experiencing IRs.

METHODS

IRs from two RCTs of pegloticase were evaluated and categorized as anaphylaxis, hypersensitivity, or other. Serum levels of tryptase and total hemolytic complement (CH50) were evaluated at the time of all IRs. Frequency of IRs by each category was evaluated in all subjects, responders or nonresponders to pegloticase.

RESULTS

There were 113 IRs in 1695 infusions. Of the 113 IRs, 6 met criteria for anaphylaxis, 53 had one feature of anaphylaxis and were designated as "hypersensitivity", and 54 had no features and were designated "other". In subjects receiving pegloticase every 2 weeks (Q2w), a total of 852 infusions were administered and the IR frequency was 0.5% in responders and 9.7% in nonresponders. In subjects receiving pegloticase every 4 weeks (Q4w), a total of 846 infusions were given and the IR frequency was 2.6% in responders and 12.2% in nonresponders. There were no differences among the three categories of IRs with regard to clinical course or biochemical evidence of immune activation determined by CH50 or tryptase levels.

CONCLUSION

IRs mostly occurred in nonresponders. NIAID/FAAN criteria for anaphylaxis did not identify pegloticase-related IRs as having a higher frequency of immune activation or a more severe course. The results are consistent with the conclusion that discontinuance of pegloticase if uric acid rises to >6 mg/dL will decrease the frequency of IRs.

Discordant American College of Physicians and international rheumatology guidelines for gout management: consensus statement of the Gout, Hyperuricemia and Crystal-Associated Disease Network (G-CAN)

In November 2016, the American College of Physicians (ACP) published a clinical practice guideline on the management of acute and recurrent gout. This guideline differs substantially from the latest guidelines generated by the American College of Rheumatology (ACR), European League Against Rheumatism (EULAR) and 3e (Evidence, Expertise, Exchange) Initiative, despite reviewing largely the same body of evidence. The Gout, Hyperuricemia and Crystal-Associated Disease Network (G-CAN) convened an expert panel to review the methodology and conclusions of these four sets of guidelines and examine possible reasons for discordance between them. The G-CAN position, presented here, is that the fundamental pathophysiological knowledge underlying gout care, and evidence from clinical experience and clinical trials, supports a treat-to-target approach for gout aimed at lowering serum urate levels to below the saturation threshold at which monosodium urate crystals form. This practice, which is truly evidence-based and promotes the steady reduction in tissue urate crystal deposits, is promoted by the ACR, EULAR and 3e Initiative recommendations. By contrast, the ACP does not provide a clear recommendation for urate-lowering therapy (ULT) for patients with frequent, recurrent flares or those with tophi, nor does it recommend monitoring serum urate levels of patients prescribed ULT. Results from emerging clinical trials that have gout symptoms as the primary end point are expected to resolve this debate for all clinicians in the near term future.

My Treatment Approach to Gout

Gout is the most common form of inflammatory arthritis in the United States. Nevertheless, gout remains misunderstood, misdiagnosed, underdiagnosed, and undertreated. Several new recommendation and guideline documents regarding the management of gout have been published in the past few years. New diagnostic modalities, such as ultrasound and dual-energy computed tomography, are now available. Newer treatment options exist, and older agents and their interactions are now better understood. This review addresses these recent diagnostic and therapeutic developments and describes our management protocol with the aim of providing the clinician with a pragmatic approach to gout management.

Current and future therapies for gout

INTRODUCTION

Gout is a common disease responsible for recurrent flares triggered by the deposition of monosodium urate crystals secondary to longstanding hyperuricaemia. The management of gout implies both the treatment of flares and the treatment of hyperuricaemia itself. Recent improvement in the understanding of the disease led to the development of new drugs. Areas covered: This review covers data related to 'old' treatments of flares and hyperuricaemia, evidence on the recently approved drugs and emerging therapies in development. Expert opinion: Recent data provide a good grasp of the optimal use of colchicine, corticosteroids and NSAIDs for the treatment of flares. Interleukin-1 blocking therapies have an increasing role in the management of difficult-to-treat gout. Sub-optimal use of allopurinol is common and its potency to reduce serum uric acid (SUA) levels is underestimated. Febuxostat effectively reduces SUA levels. New uricosurics, notably lesinurad and arhalofenate, in combination with xanthine oxidase inhibitors, offer promising perspectives to help a greater number of patients achieve sufficient SUA reduction.