Lesinurad: what the nephrologist should know

Controversies and practical management of patients with gout and chronic kidney disease

Uric acid is a toxin retained with advancing kidney disease. Clinical manifestations of hyperuricemia include gout and systemic inflammation that are associated with increased risk of cardiovascular mortality. As many as one-third of all patients with chronic kidney disease have a history of gout, yet <25% of these patients are effectively treated to target serum urate levels of ≤6 mg/dl. A major reason for ineffective management of gout and hyperuricemia is the complexity in managing these patients, with some medications contraindicated and others requiring special dosing, potential drug interactions, and other factors. Consequently, many nephrologists do not primarily manage gout despite it being a common complication of chronic kidney disease, leaving management to the primary physician or rheumatologist. We believe that kidney specialists should consider gout as a major complication of chronic kidney disease and actively manage it in their patients. Here, we present insights from nephrologists and rheumatologists for a team approach to gout management that includes the nephrologist.

A dose-escalation study of HP501, a highly selective URAT1 inhibitor, in male Chinese patients with hyperuricemia

HP501 is a highly selective renal urate transporter 1 (URAT1) inhibitor used for treating hyperuricemia. This study aimed to evaluate the tolerability, pharmacokinetics, and pharmacodynamics of HP501 in male Chinese patients. Patients with hyperuricemia were sequentially assigned to receive oral doses of HP501 (30, 50, 60, 90, and 120 mg) as a single dose on Day 1 and as once-daily doses from Days 4 to 13. Safety, pharmacokinetic, and pharmacodynamic data were collected. Multiple oral doses of HP501 were well-tolerated in all the cohorts. The most common adverse events (≥ 10% of patients) of any grade regardless of drug relationship were gout flare (14 patients, 25.93%), diarrhea (12 patients, 22.22%), elevated ALT (8 patients, 14.81%), hypertriglyceridemia (7 patients, 12.96%), dry mouth (7 patients, 12.96%) and oral ulcer (7 patients, 12.96%). All adverse events were mild or moderate. The Cmax and exposure (AUC) of HP501 was approximately dose-proportional between 30 and 120 mg. A dose-dependent serum uric acid (UA)-lowering effect was observed in the dose range of 30 to 60 mg and the serum UA lowering effect was similar between 90 and 120 mg on day 13, indicating that the maximal serum UA lowering effect of HP501 was achieved at 90 mg in the patients with hyperuricemia. In conclusion, the tolerability, pharmacokinetics, and pharmacodynamics supported 90 mg HP501 for subsequent clinical studies of this highly selective URAT1 inhibitor.Clinical Trial registration: No. CTR20212259 ( http://www.chinadrugtrials.org.cn/ ) was registered in September 2021, and No. CTR20222257 was registered in September 2022.

Agents for the Treatment of Gout: Current Advances and Future Perspectives

Gout is characterized by hyperuricemia and the deposition of monosodium urate (MSU) crystals around joints. Despite the availability of several drugs on the market, its treatment remains challenging owing to the notable side effects, such as hepatorenal toxicity and cardiovascular complications, that are associated with most existing agents. This perspective aims to summarize the current research progress in the development of antigout agents, particularly focusing on xanthine oxidase (XO) and urate anion transporter 1 (URAT1) inhibitors from a medicinal chemistry viewpoint and their preliminary structure-activity relationships (SARs). This perspective provides valuable insights and theoretical guidance to medicinal chemists for the discovery of antigout agents with novel chemical structures, better efficiency, and lower toxicity.

Design, synthesis and activity evaluation of novel lesinurad analogues containing thienopyrimidinone or pyridine substructure as human urate transporter 1 inhibitors

Urate Transporter 1 (URAT1) plays a crucial role in uric acid transport, making it an attractive target for the treatment of gout and hyperuricemia. As a representative URAT1 inhibitor, Lesinurad treat gout by promoting the uric acid excretion. However, its lower in vitro and in vivo activity should be highly attracted attention. Herein, the bioisosterism, molecular hybridization and scaffold hopping strategies were exploited to modify all the structural components of Lesinurad and finally thirty novel compounds bearing thienopyrimidinone or pyridine core were obtained. Most of the compounds displayed certain URAT1 inhibitory activity in vitro. Among them, thienopyrimidinones 6 (IC50 = 7.68 μM), 10 (IC50 = 7.56 μM), 14 (IC50 = 7.31 μM) and 15 (IC50 = 7.90 μM) showed slightly better potency than positive control Lesinurad (IC50 = 9.38 μM). Notably, 10 also displayed inhibitory activity (IC50 = 55.96 μM) against GLUT9. Additionally, in vivo serum uric acid (SUA)-lowering experiments were performed on some representative compounds and it was revealed that all the selected compounds could decrease the SUA level in mice, of which the decrease rate of SUA was 73.29% for the most promising compound 10, significantly greater than that of Lesinurad (26.89%). Meanwhile, the preliminary SARs based on the URAT1 inhibitory activity were discussed in detail, which pointed out the direction for further structural optimization. Overall, the thienopyrimidinone and pyridine are prospective skeletons for the developing novel URAT1 inhibitors with considerable potential for optimization.

Novel urate transporter 1 (URAT1) inhibitors: a review of recent patent literature (2020-present)

INTRODUCTION

The urate transporter 1 (URAT1) is a membrane transporter located in the apical membrane of human renal proximal tubule epithelial cells, which mediates most of the reabsorption of urate. Hyperuricemia (HUA) is a common disease caused by metabolic disorders, which has been considered as the key factor of gout. Approximately 90% of patients suffer from hyperuricemia due to insufficient or poor uric acid excretion. Therefore, the drug design of URAT1 inhibitors targeting improve the renal urate excretion by reducing the reabsorption of urate anions represent a hot topic in searching for anti-gout drugs currently.

AREAS COVERED

In this review, we summarize URAT1 inhibitors patents reported since 2020 to present through the public database at https://worldwide.espacenet.com and some medicinal chemistry strategies employed to develop novel drug candidates.

EXPERT OPINION

Ligand-based drug design (LBDD) strategies have been frequently used developing new URAT1 inhibitors. Meanwhile, the discovery of dual drugs targeting both inhibition of xanthine oxidase (XOD) and URAT1 may be an emerging horizon for designing novel uric acid-lowering candidates in future. Furthermore, advanced techniques in the field of molecular biology and computer science can increase the chances to discover and/or optimize URAT1 inhibitors, contributing to the development of novel drug candidates.

Rationale, design, demographics and baseline characteristics of the randomized, controlled, Phase 2b SAPPHIRE study of verinurad plus allopurinol in patients with chronic kidney disease and hyperuricaemia

BACKGROUND

Verinurad is a human uric acid (UA) transporter (URAT1) inhibitor known to decrease serum UA (sUA) levels and that may reduce albuminuria. In a Phase 2a study (NCT03118739), treatment with verinurad + febuxostat lowered urine albumin-to-creatinine ratio (UACR) at 12 weeks by 39% (90% confidence interval 4-62%) among patients with Type 2 diabetes mellitus, hyperuricaemia and albuminuria. The Phase 2b, randomized, placebo-controlled Study of verinurAd and alloPurinol in Patients with cHronic kIdney disease and hyperuRicaEmia (SAPPHIRE; NCT03990363) will examine the effect of verinurad + allopurinol on albuminuria and estimated glomerular filtration rate (eGFR) slope among patients with chronic kidney disease (CKD) and hyperuricaemia.

METHODS

Adults (≥18 years of age) with CKD, eGFR ≥25 mL/min/1.73 m2, UACR 30-5000 mg/g and sUA ≥6.0 mg/dL will be enrolled. Approximately 725 patients will be randomized 1:1:1:1:1 to 12, 7.5 or 3 mg verinurad + allopurinol, allopurinol or placebo. An 8-week dose-titration period will precede a 12-month treatment period; verinurad dose will be increased to 24 mg at Month 9 in a subset of patients in the 3 mg verinurad + allopurinol arm. The primary efficacy endpoint the is change from baseline in UACR at 6 months. Secondary efficacy endpoints include changes in UACR, eGFR and sUA from baseline at 6 and 12 months.

CONCLUSIONS

This study will assess the combined clinical effect of verinurad + allopurinol on kidney function in patients with CKD, hyperuricaemia and albuminuria, and whether this combination confers renoprotection beyond standard-of-care.

Genetic Basis of the Epidemiological Features and Clinical Significance of Renal Hypouricemia

A genetic defect in urate transporter 1 (URAT1) is the major cause of renal hypouricemia (RHUC). Although RHUC is detected using a serum uric acid (UA) concentration <2.0 mg/dL, the relationship between the genetic state of URAT1 and serum UA concentration is not clear. Homozygosity and compound heterozygosity with respect to mutant URAT1 alleles are associated with a serum UA concentration of <1.0 mg/dL and are present at a prevalence of ~0.1% in Japan. In heterozygous individuals, the prevalence of a serum UA of 1.1−2.0 mg/dL is much higher in women than in men. The frequency of mutant URAT1 alleles is as high as 3% in the general Japanese population. The expansion of a specific mutant URAT1 allele derived from a single mutant gene that occurred in ancient times is reflected in modern Japan at a high frequency. Similar findings were reported in Roma populations in Europe. These phenomena are thought to reflect the ancient migration history of each ethnic group (founder effects). Exercise-induced acute kidney injury (EI-AKI) is mostly observed in individuals with homozygous/compound heterozygous URAT1 mutation, and laboratory experiments suggested that a high UA load on the renal tubules is a plausible mechanism for EI-AKI.

EMT alterations in the solute carrier landscape uncover SLC22A10/A15 imposed vulnerabilities in pancreatic cancer

The involvement of membrane-bound solute carriers (SLCs) in neoplastic transdifferentiation processes is poorly defined. Here, we examined changes in the SLC landscape during epithelial-mesenchymal transition (EMT) of pancreatic cancer cells. We show that two SLCs from the organic anion/cation transporter family, SLC22A10 and SLC22A15, favor EMT via interferon (IFN) α and γ signaling activation of receptor tyrosine kinase-like orphan receptor 1 (ROR1) expression. In addition, SLC22A10 and SLC22A15 allow tumor cell accumulation of glutathione to support EMT via the IFNα/γ-ROR1 axis. Moreover, a pan-SLC22A inhibitor lesinurad reduces EMT-induced metastasis and gemcitabine chemoresistance to prolong survival in mouse models of pancreatic cancer, thus identifying new vulnerabilities for human PDAC.

Mini Review: Reappraisal of Uric Acid in Chronic Kidney Disease

Hyperuricemia predicts the development of chronic kidney disease (CKD) and metabolic complications, but whether it has a causal role has been controversial. This is especially true given the 2 recently conducted randomized controlled trials that failed to show a benefit of lowering uric acid in type 1 diabetes-associated CKD and subjects with stage 3-4 CKD. While these studies suggest that use of urate-lowering drugs in unselected patients is unlikely to slow the progression of CKD, there are subsets of subjects with CKD where reducing uric acid synthesis may be beneficial. This may be the case in patients with gout, hyperuricemia (especially associated with increased production), and urate crystalluria. Here, we discuss the evidence and propose that future clinical trials targeting these specific subgroups should be performed.

Membrane Carriers and Transporters in Kidney Physiology and Disease

The growing information suggests that chronic kidney disease may affect expression and function of membrane carriers and transporters in the kidney. The dysfunction of carriers and transporters entails deficient elimination of uremic solutes as well as xenobiotics (drugs and toxins) with subsequent clinical consequences. The renal carriers and transporters are also targets of drugs used in clinical practice, and intentional drug-drug interactions in the kidney are produced to increase therapeutic efficacy. The understanding of membrane carriers and transporters function in chronic kidney disease is important not only to better characterize drug pharmacokinetics, drug actions in the kidney, or drug-drug interactions but also to define the organ pathophysiology.

Efficacy and Safety of Dotinurad in Hyperuricemic Patients With or Without Gout: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Introduction A systematic review and meta-analysis of the available randomized controlled trials (RCTs) were conducted to investigate the efficacy and safety of dotinurad in hyperuricemic patients with or without gout. Dotinurad is a novel selective urate reabsorption inhibitor (SURI) that increases uric acid excretion by selectively inhibiting urate transporter 1 (URAT1). To the best of our knowledge, this is the first meta-analysis conducted to gauge the efficacy and safety of dotinurad.  Methods Electronic databases (PubMed, the Cochrane Library, and ClinicalTrials.gov) were searched from inception till March 2, 2021, according to the Preferred Reporting Items for Systematic Review and Meta-Analysis statement. Randomized controlled trials comparing the efficacy and safety of dotinurad with placebo- or active (febuxostat or benzbromarone) control were included. The eligible studies were analyzed with RevMan 5.3 Software (The Nordic Cochrane Centre, Cochrane Collaboration, Copenhagen). Results Four eligible studies, consisting of 684 hyperuricemic patients were included. The number of patients who achieved serum uric acid (sUA) levels ≤ 6.0 mg/dl favoured dotinurad 1 mg group as compared to placebo group (risk ratio {RR} = 39.27, 95% onfidence interval {CI}, 5.59 to 275.65; p = 0.0002), dotinurad 2 mg group compared with placebo group (RR = 45.36, 95% CI, 6.48 to 317.38; p= 0.0001), and dotinurad 4 mg group compared with placebo group (RR = 54.16, 95% CI, 7.76 to 377.77; p < 0.0001). Conversely, there was no significant difference in the number of patients who achieved the target sUA levels between dotinurad 2 mg and active control (RR = 1.00, 95% CI, 0.92 to 1.08; p = 0.91). Moreover, the percentage change in sUA levels from baseline to final visit favoured dotinurad 1 mg vs. placebo ((RR = 36.51, 95% CI, 33.00 to 40.02; p < 0.00001), dotinurad 2 mg vs. placebo (RR = 46.70, 95% CI, 42.53 to 50.87; p < 0.00001), and dotinurad 4 mg vs. placebo (RR = 63.84, 95% CI, 60.51 to 67.16; p < 0.00001), while no significant difference was seen in dotinurad 2 mg vs. active control (RR = -0.08, 95% CI, -4.27 to 4.11; p= 0.97). Compared with active or placebo control, dotinurad 2 mg showed no significant difference in the number of events of gouty arthritis (RR= 1.31, 95% CI, 0.47 to 3.71; p = 0.60), the number patients with adverse events (RR = 1.09, 95% CI, 0.91 to 1.30; p = 0.36), and the number of patients who experienced adverse drug reactions (RR = 1.00, 95% CI, 0.68 to 1.47; p = 0.99). Conclusion Dotinurad shows significant improvement in serum uric acid levels in hyperuricemic individuals with or without gout. Its urate-lowering effect is comparable to the commonly available anti-hyperuricemic agents. Moreover, it is effective at doses 1 mg, 2 mg, and 4 mg and well-tolerated at a dose of 2 mg.

The dirty little secret of urate-lowering therapy: useless to stop chronic kidney disease progression and may increase mortality

Hyperuricaemia is frequent in chronic kidney disease (CKD). Observational studies have shown an association with adverse outcomes and acquired hyperuricaemia (meaning serum urate levels as low as 1.0 mg/dL) in animal models induces kidney injury. This evidence does not justify the widespread use of urate-lowering drugs for asymptomatic hyperuricaemia in CKD. However, promising results from small, open-label studies led some physicians to prescribe urate-lowering drugs to slow CKD progression. Two recent, large, placebo-controlled trials (CKD-FIX and PERL) showed no benefit from urate lowering with allopurinol on the primary endpoint of CKD progression, confirming prior negative results. Despite these negative findings, it was still argued that the study population could be optimized by enrolling younger non-proteinuric CKD patients with better preserved glomerular filtration rate (GFR). However, in these low-risk patients, GFR may be stable under placebo conditions. Additionally, the increased mortality trends already identified in gout trials of urate-lowering therapy were also observed in CKD-FIX and PERL, sending a strong safety signal: 21/449 (4.7%) and 10/444 (2.2%) patients died in the combined allopurinol and placebo groups, respectively [chi-squared P-value 0.048; relative risk 2.07 (95% CI 0.98-4.34); P = 0.06]. Given the absent evidence of benefit in multiple clinical trials and the potentially serious safety issues, the clear message should be that urate-lowering therapy should not be prescribed for the indication of slowing CKD progression. Additionally, regulatory agencies should urgently reassess the safety of chronic prescription of urate-lowering drugs for any indication.

Hyperuricemia in Kidney Disease: A Major Risk Factor for Cardiovascular Events, Vascular Calcification, and Renal Damage

Kidney disease, especially when it is associated with a reduction in estimated glomerular filtration rate, can be associated with an increase in serum urate (uric acid), suggesting that hyperuricemia in subjects with kidney disease may be a strictly secondary phenomenon. Mendelian randomization studies that evaluate genetic scores regulating serum urate also generally have not found evidence that serum urate is a causal risk factor in chronic kidney disease. Nevertheless, this is countered by a large number of epidemiologic, experimental, and clinical studies that have suggested a potentially important role for uric acid in kidney disease and cardiovascular disease. Here, we review the topic in detail. Overall, the studies strongly suggest that hyperuricemia does have an important pathogenic role that likely is driven by intracellular urate levels. An exception may be the role of extracellular uric acid in atherosclerosis and vascular calcification. One of the more striking findings on reviewing the literature is that the primary benefit of lowering serum urate in subjects with CKD is not by slowing the progression of renal disease, but rather by reducing the incidence of cardiovascular events and mortality. We recommend large-scale clinical trials to determine if there is a benefit in lowering serum urate in hyperuricemic subjects in acute and chronic kidney disease and in the reduction of cardiovascular morbidity and mortality in subjects with end-stage chronic kidney disease.

Uric Acid and Hypertension: An Update With Recommendations

The association between increased serum urate and hypertension has been a subject of intense controversy. Extracellular uric acid drives uric acid deposition in gout, kidney stones, and possibly vascular calcification. Mendelian randomization studies, however, indicate that serum urate is likely not the causal factor in hypertension although it does increase the risk for sudden cardiac death and diabetic vascular disease. Nevertheless, experimental evidence strongly suggests that an increase in intracellular urate is a key factor in the pathogenesis of primary hypertension. Pilot clinical trials show beneficial effect of lowering serum urate in hyperuricemic individuals who are young, hypertensive, and have preserved kidney function. Some evidence suggest that activation of the renin-angiotensin system (RAS) occurs in hyperuricemia and blocking the RAS may mimic the effects of xanthine oxidase inhibitors. A reduction in intracellular urate may be achieved by lowering serum urate concentration or by suppressing intracellular urate production with dietary measures that include reducing sugar, fructose, and salt intake. We suggest that these elements in the western diet may play a major role in the pathogenesis of primary hypertension. Studies are necessary to better define the interrelation between uric acid concentrations inside and outside the cell. In addition, large-scale clinical trials are needed to determine if extracellular and intracellular urate reduction can provide benefit hypertension and cardiometabolic disease.

Clinical efficacy and safety of dotinurad, a novel selective urate reabsorption inhibitor, in Japanese hyperuricemic patients with or without gout: randomized, multicenter, double-blind, placebo-controlled, parallel-group, confirmatory phase 2 study

BACKGROUND

Dotinurad, a novel selective urate reabsorption inhibitor (SURI), reduces serum uric acid levels by selectively inhibiting urate transporter 1 (URAT1) for the treatment of hyperuricemia with or without gout. We confirmed the serum uric acid lowering effect and safety of dotinurad.

METHODS

This was a confirmatory, 12-week, randomized, multicenter, double-blind, placebo-controlled, parallel-group, dose escalation, late phase 2 study. The study arms were dotinurad 0.5, 1, 2, or 4 mg and placebo. The primary endpoint was the percent change in serum uric acid level from the baseline to the final visit. The secondary endpoint was the percentage of patients achieving a serum uric acid level ≤ 6.0 mg/dL at the final visit.

RESULTS

The study drugs were administered to 200 Japanese hyperuricemic patients with or without gout. The mean percent change in serum uric acid level from the baseline to the final visit in the dotinurad 0.5, 1, 2, and 4 mg groups and the placebo group was 21.81%, 33.77%, 42.66%, 61.09%, and - 2.83%, respectively. The percentage of patients achieving a serum uric acid level ≤ 6.0 mg/dL at the final visit in each group was 23.1%, 65.9%, 74.4%, 100%, and none, respectively. Regarding safety, the incidence of adverse events did not increase with dose escalation in the dotinurad groups. No significant differences were observed in the incidence of gouty arthritis in each group.

CONCLUSION

The serum uric acid lowering effect and safety of dotinurad were confirmed in hyperuricemic patients with or without gout. CLINICALTRIALS.

GOV IDENTIFIER

NCT02416167.

N-Butyrylated hyaluronic acid ameliorates gout and hyperuricemia in animal models

Context: Hyaluronic acid (HA) plays critical roles in the structural skeleton, joint lubrication, renal function and cell signaling. We previously showed that partially N-butyrylated, low molecular weight, hyaluronic acid (BHA) exhibited an anti-inflammatory effect in cultured human macrophage, where inflammation was induced either by a TL-4 agonist or the low molecular weight HA itself, in dose-dependent fashion. Objectives: To investigate the anti-inflammatory, antioxidative, and antihyperuricemic effects of BHA using animal models of acute gouty arthritis and hyperuricemia. Materials and methods: The anti-inflammatory effect of articular BHA (10 and 50 μg) injections was evaluated by measuring joint swelling and the serum levels of inflammatory cytokines in a model of acute gouty arthritis induced by intra-articular injection of monosodium urate crystals in Wistar rats (n = 10/group), in comparison to the control group with saline injection. Antioxidative and antihyperuricemic activities were investigated using intraperitoneal injections of oteracil potassium and yeast extract hyperuricemic Balb/C mice, which were treated with intraperitoneal injection of BHA at day 6-8 in the model. Results: In the gouty arthritis rat model, BHA at a higher dosage (50 μg) demonstrated a strong anti-inflammatory effect by reducing the degree of articular swelling and the serum levels of IL-1β, IL-8, IFN-γ, and MCP-1 by 5.56%, 6.55%, 15.58% and 33.18%. In the hyperuricemic mouse model, lower dosage BHA (10 μg) was sufficient to provide antioxidative activities by significantly decreasing the ROS levels in both serum and liver by 14.87% and 8.04%, while improving liver SOD by 12.77%. Intraperitoneal injection of BHA suppressed uric acid production through reducing liver XO activity by 19.78% and decreased the serum uric acid level in hyperuricemic mice by 30.41%. Conclusions: This study demonstrated for the first time that BHA exhibits anti-inflammatory, antioxidative and antihyperuricemic effects in vivo, suggesting a potential therapeutic application of BHA in gouty arthritis and hyperuricemia.

Spectrum and dosing of urate-lowering drugs in a large cohort of chronic kidney disease patients and their effect on serum urate levels: a cross-sectional analysis from the German Chronic Kidney Disease study

Background

Despite a plethora of studies on the effect of urate-lowering therapy (ULT) in patients with chronic kidney disease (CKD), current guidelines on the treatment of hyperuricaemia and gout vary, especially concerning the need for dose adjustment of allopurinol, whose main metabolite is accumulating with declining renal function. Data on allopurinol dosing and its relationship to renal function, co-medication and sex and the resulting urate level in large cohorts are missing.

Methods

We studied a subgroup of 2378 patients of the German Chronic Kidney Disease (GCKD) study to determine prescription patterns of ULT among CKD patients under nephrological care and the relationship of ULT dose to urate levels. Prescription and dosing of ULT were manually abstracted from the patient’s paper charts at the baseline visit, in which all currently used medications and their dosing were recorded.

Results

In this cohort, 39.6% were women, the mean estimated glomerular filtration rate (eGFR) was 51.3 ± 19.3 mL/min/1.73 m² and the mean age was 59.0 ± 12.4 years. Of the 2378 examined patients, 666 (28.0%) received ULT. The dose of ULT was available for 572 patients. The main ULT agent was allopurinol (94.4%), followed by febuxostat (2.9%) and benzbromarone (2.6%). Of the 540 patients who used allopurinol with a reported daily dose, 480 had an eGFR <60 mL/min/1.73 m² and 320 had an eGFR <45 mL/min/1.73 m², 31.5% of the latter (n = 101) received a dose >150 mg/day, the recommended maximal dose for this level of eGFR. The prescribed dose was not related to eGFR: the median eGFR for patients taking 100, 150 and 300 mg/day was 40 [interquartile range (IQR) 32–49], 43 (34–52) and 42 (35–54) mL/min/1.73 m², respectively. Patients with lower doses of allopurinol had higher serum urate levels than patients with higher (than recommended) allopurinol doses. Sex, alcohol intake, eGFR, use of diuretics and treatment with allopurinol were independent determinants of serum urate levels in multivariate regression analysis.

Conclusions

The most frequently used drug to lower serum urate levels in this CKD cohort was allopurinol. Even in patients regularly seen by nephrologists, the dose of allopurinol is often not adjusted to the current eGFR. Patients with higher ULT doses achieved better control of their serum urate levels. Lowering of serum urate in CKD patients requires balancing potential adverse effects of allopurinol with suboptimal control of serum urate levels.

Potential Dangers of Serum Urate-Lowering Therapy

In observational studies, high serum urate levels are associated with adverse outcomes, including mortality. However, the hypothesis that urate-lowering may improve nongout outcomes has not been confirmed by placebo-controlled clinical trials. On the contrary, 7 recent placebo-controlled trials of urate-lowering drugs with different mechanisms of action (uricosuric: lesinurad; xanthine oxidase inhibition: febuxostat; uricase: pegloticase) have observed higher mortality or trends to higher mortality in gout patients, with the largest decreases in serum urate. Because all urate-lowering mechanisms were implicated, this raises safety concerns about urate-lowering itself. Far from unexpected, the higher mortality associated with more intense urate-lowering is in line with the U-shaped association of urate with mortality in some observational studies. Urate accounts for most of the antioxidant capacity of plasma, and strategies to increase urate are undergoing clinical trials in neurological disease. Post hoc analysis of recent trials should explore whether the magnitude of urate-lowering is associated with adverse outcomes, and safety trials are needed before guidelines recommend lowering serum urate below certain thresholds.

Reassessing the Safety Profile of Lesinurad in Combination with Xanthine Oxidase Inhibitor Therapy

INTRODUCTION

The rate of adverse renal events has been shown to be higher in patients treated with lesinurad plus a xanthine-oxidase inhibitor (XOI) than in patients treated only with a XOI. We reassessed the risks for various adverse renal events from a different perspective and devised a hypothesis to explain the results.

METHODS

We used data from phase 3 trials that were publicly available from the full prescribing information document and estimated the relative risk and the number needed to treat for increased serum creatinine (sCri), renal failure, and renal lithiasis. We examined these risks for each treatment group and the risks stratified by estimated glomerular filtration rate (eGFR).

RESULTS

Overall, the relative risk for sCri was > 1.0 with the 400 mg/day dose of lesinurad and higher with the 200 mg/day dose, but it was < 1.0 for both lithiasis and renal failure with the 200 mg/day dose. The relative risk was only statistically significant for sCri with the highest dose of lesinurad. When results stratified by eGFR were considered, the rates of adverse events increased with declining renal function, but the relative risks decreased in parallel, as the rate of adverse events increased much more in the placebo arm than in the active arm (200 mg/day dose). Indeed, the relative risk was only significant for the highest dose of lesinurad in patients with normal eGFR.

CONCLUSION

The rate of sCri events was higher in patients treated with both lesinurad and a XOI rather than a XOI alone. This rate was found to increase with decreasing eGFR, but as it does in for both active and placebo arms the relative risk is not different from that observed in the placebo arms in the labeled 200 mg/day dose. This may be explained by pathophysiological changes that develop in chronic kidney disease.

The new Clinical Kidney Journal, 4 years later

The February 2015 issue of ckj started a new era with renewed efforts to be useful to the training and practicing nephrologists and a new focus on Clinical and Translational Nephrology. Four years later, it has become a truly global journal with contributors and readers from all over the world. The increase in quality of the published material has resulted in a nearly exponential growth of citations. Since 2016, ckj is listed in the new Emerging Sources Citation Index (ESCI) database from Clarivate Analytics and from January 2019 it will be listed in the full Science Citation Index. ckj will therefore receive its first official impact factor based upon 2018 citation to 2016 and 2017 articles. While no official impact factor was awarded for 2017, the estimated impact factors calculated from data available in Clarivate's Web of Science database rose to 2.987 in 2017, which would correspond to an estimated journal impact factor percentile of 72.4% in the Urology and Nephrology field.

Effects of febuxostat on serum cytokines IL-1, IL-4, IL-6, IL-8, TNF-α and COX-2

Effects of febuxostat on serum cytokines interleukin (IL)-1, IL-4, IL-6, IL-8, tumor necrosis factor-α (TNF-α) and cyclooxygenase-2 (COX-2) in patients with gout were investigated. A total of 80 patients with gout admitted and treated in the Affiliated Zhongshan Hospital of Dalian University from January 2015 to September 2017 were selected and divided into two groups by virtue of a random number table, with 40 patients in each group. All the enrolled patients received strict gout diet adjustment and took colchicine at the same time. Patients in the control group were additionally treated with allopurinol, while those in the the observation group were administered with febuxostat. The serum uric acid levels were compared between the two groups. The number of gout attacks and adverse reactions were recorded, and the variations in COX-2 positive value integral were clarified. At different time-points of observation, the serum uric acid levels in the observation group were significantly lower than those in the control group (p<0.05). Moreover, at 3 months after treatment, the levels of inflammatory cytokines in the serum in the observation group were decreased compared with those in the control group (p<0.05). The IL-1 and TNF-α levels were lower in the observation group at 1 week, 1 and 3 months after treatment compared with those in the control group (p<0.05). Furthermore, it was discovered that at 3 months after treatment, the COX-2 positive value integral in the observation group was superior to that in the control group (p<0.05). During follow-up, the number of gout attacks that needed medical intervention in the observation group was smaller than that in the control group (p<0.05). Compared with allopurinol therapy, febuxostat therapy can remarkably inhibit inflammatory responses in the body, relieve clinical symptoms and reduce relapse of the patients with gout.

Urate transporter inhibitor lesinurad is a selective peroxisome proliferator-activated receptor gamma modulator (sPPARγM) in vitro

Gout is the most common arthritic disease in human but was long neglected and therapeutic options are not satisfying. However, with the recent approval of the urate transporter inhibitor lesinurad, gout treatment has experienced a major innovation. Here we show that lesinurad possesses considerable modulatory potency on peroxisome proliferator-activated receptor γ (PPARγ). Since gout has a strong association with metabolic diseases such as type 2 diabetes, this side-activity appears as very valuable contributing factor to the clinical efficacy profile of lesinurad. Importantly, despite robustly activating PPARγ in vitro, lesinurad lacked adipogenic activity, which seems due to differential coactivator recruitment and is characterized as selective PPARγ modulator (sPPARγM).

Deleting Death and Dialysis: Conservative Care of Cardio-Vascular Risk and Kidney Function Loss in Chronic Kidney Disease (CKD)

The uremic syndrome, which is the clinical expression of chronic kidney disease (CKD), is a complex amalgam of accelerated aging and organ dysfunctions, whereby cardio-vascular disease plays a capital role. In this narrative review, we offer a summary of the current conservative (medical) treatment options for cardio-vascular and overall morbidity and mortality risk in CKD. Since the progression of CKD is also associated with a higher cardio-vascular risk, we summarize the interventions that may prevent the progression of CKD as well. We pay attention to established therapies, as well as to novel promising options. Approaches that have been considered are not limited to pharmacological approaches but take into account lifestyle measures and diet as well. We took as many randomized controlled hard endpoint outcome trials as possible into account, although observational studies and post hoc analyses were included where appropriate. We also considered health economic aspects. Based on this information, we constructed comprehensive tables summarizing the available therapeutic options and the number and kind of studies (controlled or not, contradictory outcomes or not) with regard to each approach. Our review underscores the scarcity of well-designed large controlled trials in CKD. Nevertheless, based on the controlled and observational data, a therapeutic algorithm can be developed for this complex and multifactorial condition. It is likely that interventions should be aimed at targeting several modifiable factors simultaneously.

Hyperuricemia, Acute and Chronic Kidney Disease, Hypertension, and Cardiovascular Disease: Report of a Scientific Workshop Organized by the National Kidney Foundation

Urate is a cause of gout, kidney stones, and acute kidney injury from tumor lysis syndrome, but its relationship to kidney disease, cardiovascular disease, and diabetes remains controversial. A scientific workshop organized by the National Kidney Foundation was held in September 2016 to review current evidence. Cell culture studies and animal models suggest that elevated serum urate concentrations can contribute to kidney disease, hypertension, and metabolic syndrome. Epidemiologic evidence also supports elevated serum urate concentrations as a risk factor for the development of kidney disease, hypertension, and diabetes, but differences in methodologies and inpacts on serum urate concentrations by even subtle changes in kidney function render conclusions uncertain. Mendelian randomization studies generally do not support a causal role of serum urate in kidney disease, hypertension, or diabetes, although interpretation is complicated by nonhomogeneous populations, a failure to consider environmental interactions, and a lack of understanding of how the genetic polymorphisms affect biological mechanisms related to urate. Although several small clinical trials suggest benefits of urate-lowering therapies on kidney function, blood pressure, and insulin resistance, others have been negative, with many trials having design limitations and insufficient power. Thus, whether uric acid has a causal role in kidney and cardiovascular diseases requires further study.

New urate-lowing therapies

PURPOSE OF REVIEW

To discuss recent studies of lesinurad and arhalofenate.

RECENT FINDINGS

Lesinurad acts by blocking urate reabsorption channels URAT-1 and OAT-4. It has urate-lowering effect when used alone and in combination with xanthine oxidase inhibitors (XOIs). Its uricosuric activity depends on glomerular filtration, and its' efficacy is impaired at eGFR less than 30 ml/min. Lesinurad monotherapy (400 mg/day) associates with serum creatinine elevations. However, this risk is substantially attenuated with coprescription of a XOI and when prescribed at a dose of 200 mg/day. Given its' modest urate-lowering effect, and the risk of serum creatinine elevation when used alone, it is licenced for use in combination with XOI for people unable to achieve target serum uric acid with XOI alone. Lesinurad does not have the drug interactions associated with probenecid, however, it is metabolized by CYP2C9, and should be used with caution if CYP2C9 inhibitors are coprescribed. Arhalofenate also acts by blocking URAT-1; however, it also blocks the NALP-3 inflammasome providing gout-specific anti-inflammatory effect. Arhalofenate has a weaker urate-lowering effect than lesinurad and further phase III evaluation is planned.

SUMMARY

Lesinurad provides an additional option for people with gout unable to achieve target serum uric acid with XOI alone.