VALOR-CKD: A Multicenter, Randomized, Double-Blind Placebo-Controlled Trial Evaluating Veverimer in Slowing Progression of CKD in Patients with Metabolic Acidosis.

SIGNIFICANCE STATEMENT: Metabolic acidosis is a common complication of CKD and is associated with more rapid decline of kidney function, but well-powered controlled randomized trials testing the effect of treating metabolic acidosis on slowing CKD progression have not been conducted. The VALOR-CKD study randomized 1480 individuals with CKD and metabolic acidosis, across 320 sites to placebo or veverimer (a novel hydrochloric acid binder). The findings did not demonstrate the efficacy of veverimer in slowing CKD progression, but the difference in serum bicarbonate between placebo and drug arms was only approximately 1 mEq/L. Veverimer was safe and well tolerated. BACKGROUND: Metabolic acidosis is common in CKD, but whether its treatment slows CKD progression is unknown. Veverimer, a novel hydrochloric acid binder that removes acid from the gastrointestinal tract, leads to an increase in serum bicarbonate. METHODS: In a phase 3, double-blind, placebo-controlled trial, patients with CKD (eGFR of 20-40 ml/min per 1.73 m 2 ) and metabolic acidosis (serum bicarbonate of 12-20 mEq/L) from 35 countries were randomized to veverimer or placebo. The primary outcome was the composite end point of CKD progression, defined as the development of ESKD (kidney transplantation or maintenance dialysis), a sustained decline in eGFR of ≥40% from baseline, or death due to kidney failure. RESULTS: The mean (±SD) baseline eGFR was 29.2±6.3 ml/min per 1.73 m 2 , and serum bicarbonate was 17.5±1.4 mEq/L; this increased to 23.4±2.0 mEq/L after the active treatment run-in. After randomized withdrawal, the mean serum bicarbonate was 22.0±3.0 mEq/L and 20.9±3.3 mEq/L in the veverimer and placebo groups at month 3, and this approximately 1 mEq/L difference remained stable for the first 24 months. A primary end point event occurred in 149/741 and 148/739 patients in the veverimer and placebo groups, respectively (hazard ratio, 0.99; 95% confidence interval, 0.8 to 1.2; P = 0.90). Serious and overall adverse event incidence did not differ between the groups. CONCLUSIONS: Among patients with CKD and metabolic acidosis, treatment with veverimer did not slow CKD progression. The lower than expected bicarbonate separation may have hindered the ability to test the hypothesis. CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER: VALOR-CKD, NCT03710291 .

Design and population of the VALOR-CKD study: a multicenter, randomized, double-blind, placebo-controlled trial evaluating the efficacy and safety of veverimer in slowing progression of chronic kidney disease in patients with metabolic acidosis.

BACKGROUND: Whether treating metabolic acidosis slows progression of chronic kidney disease (CKD) has not been established. Veverimer is a novel hydrochloric acid binder that removes acid from the gastrointestinal tract leading to an increase in serum bicarbonate; it is being developed to treat metabolic acidosis with the goal of slowing progression of CKD. METHODS: The VALOR-CKD trial is an international, randomized, multicenter, double-blind, placebo-controlled study designed to evaluate the effect of once-daily veverimer on kidney disease progression in patients with metabolic acidosis and CKD. Eligibility criteria include a serum bicarbonate in the range of 12-20 mmol/L and an estimated glomerular filtration rate (eGFR) of 20-40 mL/min/1.73 m2. The primary outcome is kidney disease progression defined as the development of end-stage kidney disease, a sustained decline in eGFR of >40% from baseline or death due to kidney failure. Key secondary endpoints include effects on physical function. RESULTS: Between December 2018 and December 2021, 1480 participants were randomized. The mean age at baseline was 65.1 years and 42% of the patients were female. The mean baseline eGFR was 29.1 mL/min/1.73 m2 and mean serum bicarbonate was 17.5 mmol/L. The median urine albumin-to-creatinine ratio at screening was 201 mg/g and the median 5-year predicted risk of kidney failure was 32%. Diabetes and hypertension were present in 56% and 98% of participants, respectively. CONCLUSIONS: VALOR-CKD has recruited a large population of people with metabolic acidosis at high risk for CKD progression to determine the effects of veverimer on the risk of progressive loss of kidney function.

Assessment of the Potential for Veverimer Drug-Drug Interactions.

Veverimer is a polymer being developed as a potential treatment of metabolic acidosis in patients with chronic kidney disease. Veverimer selectively binds and removes hydrochloric acid from the gastrointestinal tract, resulting in an increase in serum bicarbonate. Veverimer is not systemically absorbed, so potential drug-drug interactions (DDIs) are limited to effects on the absorption of other oral drugs through binding to veverimer in the gastrointestinal tract or increases in gastric pH caused by veverimer binding to hydrochloric acid. In in vitro binding experiments using a panel of 16 test drugs, no positively charged, neutral, or zwitterionic drugs bound to veverimer. Three negatively charged drugs (furosemide, aspirin, ethacrynic acid) bound to veverimer; however, this binding was reduced or eliminated in the presence of normal physiologic concentrations (100-170 mM) of chloride. Veverimer increased gastric pH in vivo by 1.5-3 pH units. This pH elevation peaked within 1 hour and had returned to baseline after 1.5-3 hours. Omeprazole did not alter the effect of veverimer on gastric pH. The clinical relevance of in vitro binding and the transient increase in gastric pH was evaluated in human DDI studies using two drugs with the most binding to veverimer (furosemide, aspirin) and two additional drugs with pH-dependent solubility effecting absorption (dabigatran, warfarin). None of the four drugs showed clinically meaningful DDI with veverimer in human studies. Based on the physicochemical characteristics of veverimer and results from in vitro and human studies, veverimer is unlikely to have significant DDIs. SIGNIFICANCE STATEMENT: Patients with chronic kidney disease, who are usually on many drugs, are vulnerable to drug-drug interactions (DDIs). The potential for DDIs with veverimer was evaluated based on the known site of action and physicochemical structure of the polymer, which restricts the compound to the gastrointestinal tract. Based on the findings from in vitro and human studies, we conclude that veverimer is unlikely to have clinically significant DDIs.

Long-term safety and efficacy of veverimer in patients with metabolic acidosis in chronic kidney disease: a multicentre, randomised, blinded, placebo-controlled, 40-week extension.

BACKGROUND: Metabolic acidosis, a complication of chronic kidney disease, causes protein catabolism and bone demineralisation and is associated with adverse kidney outcomes and mortality. Veverimer, a non-absorbed, counterion-free, polymeric drug candidate selectively binds and removes hydrochloric acid from the gastrointestinal lumen. METHODS: We did a multicentre, randomised, blinded, placebo-controlled, 40-week extension of a 12-week parent study at 29 sites (hospitals and specialty clinics) in seven countries (Bulgaria, Georgia, Hungary, Serbia, Slovenia, Ukraine, and the USA). Eligible patients were those with chronic kidney disease (estimated glomerular filtration rate 20-40 mL/min per 1·73 m2) and metabolic acidosis (serum bicarbonate 12-20 mmol/L), who had completed the 12-week parent study, for which they were randomly assigned (4:3) to veverimer (6 g/day) or placebo as oral suspensions in water with food. Participants in the extension continued with the same treatment assignment as in the parent study. The primary endpoint was safety; the four secondary endpoints assessed the long-term effects of veverimer on serum bicarbonate concentration and physical functioning. The safety analysis set was defined as all patients who received any amount of study drug. This trial is registered at ClinicalTrials.gov, number NCT03390842, and has now completed. FINDINGS: Participants entered the study between Dec 20, 2017, and May 4, 2018. Of the 217 patients randomly assigned to treatment in the parent study (124 to veverimer and 93 to placebo), 196 patients (114 veverimer and 82 placebo) continued on their blinded randomised treatment assignment into this 40-week extension study. Compared with placebo, fewer patients on veverimer discontinued treatment prematurely (3% vs 10%, respectively), and no patients on veverimer discontinued because of an adverse event. Serious adverse events occurred in 2% of veverimer-treated patients and in 5% of placebo patients (two of whom died). Renal system adverse events were reported in 8% and 15% in the veverimer and placebo groups, respectively. More patients on veverimer than placebo had an increase in bicarbonate (≥4 mmol/L or normalisation) at week 52 (63% vs 38%, p=0·0015) and higher bicarbonate concentrations were observed with veverimer than placebo at all timepoints starting at week 1 (p<0·001). Veverimer resulted in improved patient-reported physical functioning (Kidney Disease and Quality of Life-Physical Function Domain) versus placebo with a mean placebo-subtracted change at end of treatment of 12·1 points (SE 3·3; p<0·0001). Time to do the repeat chair stand test improved by 4·3 s (1·2) on veverimer versus 1·4 s (1·2) on placebo (p<0·0001). INTERPRETATION: In patients with chronic kidney disease and metabolic acidosis, veverimer safely and effectively corrected metabolic acidosis and improved subjective and objective measures of physical function. FUNDING: Tricida.

Veverimer versus placebo in patients with metabolic acidosis associated with chronic kidney disease: a multicentre, randomised, double-blind, controlled, phase 3 trial.

BACKGROUND: Patients with advanced chronic kidney disease lose the capacity to fully excrete endogenous acid, resulting in chronic metabolic acidosis that increases the risk of disease progression and causes muscle catabolism and bone resorption. Veverimer, a non-absorbed, counterion-free, polymeric drug, selectively binds and removes hydrochloric acid from the gastrointestinal lumen, unlike current oral sodium bicarbonate therapy for metabolic acidosis that only neutralises accumulated acid. We assessed the efficacy and safety of veverimer as a treatment for metabolic acidosis in patients with chronic kidney disease. METHODS: We did a multicentre, parallel, randomised, double-blind, placebo-controlled study at 37 sites (hospitals and specialty clinics) in Bulgaria, Croatia, Georgia, Hungary, Serbia, Slovenia, Ukraine, and the USA. Eligible participants were patients aged 18-85 years with non-dialysis-dependent chronic kidney disease (estimated glomerular filtration rate of 20-40 mL/min per 1·73 m2) and metabolic acidosis (serum bicarbonate concentration of 12-20 mmol/L). Patients were randomly assigned (4:3) to veverimer 6 g/day or placebo for 12 weeks while they consumed their typical diet. Both drugs were taken as oral suspensions in water with lunch. Randomisation was done by study site personnel with a computer-generated randomisation code with balanced permuted blocks (block size of seven) and stratified by baseline bicarbonate (≤18 mmol/L vs >18 mmol/L). Patients and investigators were masked to treatment allocation; however, because the appearance of placebo differed from veverimer, a non-masked site staff member who had no other role in the study dispensed, prepared, and supervised dosing of the study drugs. The composite primary efficacy endpoint was the difference (veverimer-placebo) in the proportion of patients achieving at week 12 either an increase of 4 mmol/L or more from baseline in serum bicarbonate concentration or serum bicarbonate in the normal range of 22-29 mmol/L, assessed in the modified intention-to-treat population (all patients with a baseline and at least one post-baseline serum bicarbonate value). Patients fasted for at least 4 h (consuming only water) before measurements of bicarbonate. Safety was assessed in all patients who received any amount of study drug. This trial is registered with ClinicalTrials.gov, number NCT03317444. FINDINGS: Between Sept 26, 2017, and Feb 9, 2018, we randomly assigned 124 participants to veverimer and 93 to placebo. The composite primary endpoint was met by 71 (59%) of 120 patients in the veverimer group versus 20 (22%) of 89 patients in the placebo group (a difference of 37%, 95% CI 23-49; p<0·0001). The most common body system in which adverse events in the veverimer group occurred was gastrointestinal; of these, non-treatment limiting diarrhoea was the most common event (11 [9%] vs three [3%] in the veverimer and placebo groups, respectively). The most common treatment-related adverse events were gastrointestinal (diarrhoea, flatulence, nausea, and constipation) occurring in 16 (13%) patients with veverimer and five (5%) patients with placebo. Two deaths occurred during the study, both in the placebo group (unstable angina and pneumonia). INTERPRETATION: Veverimer effectively and safely corrected metabolic acidosis. Longer-term studies are warranted to assess the effects of veverimer on physical functioning and to assess other deleterious consequences of metabolic acidosis including progression of chronic kidney disease and bone health. FUNDING: Tricida.

Randomized, Controlled Trial of TRC101 to Increase Serum Bicarbonate in Patients with CKD.

BACKGROUND AND OBJECTIVES: Metabolic acidosis is common in patients with CKD and has significant adverse effects on kidney, muscle, and bone. We tested the efficacy and safety of TRC101, a novel, sodium-free, nonabsorbed hydrochloric acid binder, to increase serum bicarbonate in patients with CKD and metabolic acidosis. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: One hundred thirty-five patients were enrolled in this randomized, double-blind, placebo-controlled, multicenter, in-unit study (designated the TRCA-101 Study). Patients had a mean baseline eGFR of 35 ml/min per 1.73 m2, a mean baseline serum bicarbonate of 17.7 mEq/L, and comorbidities, including hypertension (93%), diabetes (70%), and heart failure (21%). Patients ate a controlled diet and were treated for 14 days with placebo or one of four TRC101 dosing regimens (1.5, 3, or 4.5 g twice daily or 6 g once daily). After treatment, patients were discharged and followed for 7-14 days. RESULTS: All TRC101 treatment groups had a mean within-group increase in serum bicarbonate of ≥1.3 mEq/L (P<0.001) within 72 hours of the first dose and a mean increase in serum bicarbonate of 3.2-3.9 mEq/L (P<0.001) at the end of treatment compared with placebo, in which serum bicarbonate did not change. In the combined TRC101 treatment group, serum bicarbonate was normalized (22-29 mEq/L) at the end of treatment in 35% of patients and increased by ≥4 mEq/L in 39% of patients. After discontinuation of TRC101, serum bicarbonate decreased nearly to baseline levels within 2 weeks. All adverse events were mild or moderate, with gastrointestinal events most common. All patients completed the study. CONCLUSIONS: TRC101 safely and significantly increased the level of serum bicarbonate in patients with metabolic acidosis and CKD.

Treatment with patiromer decreases aldosterone in patients with chronic kidney disease and hyperkalemia on renin-angiotensin system inhibitors.

Elevated serum aldosterone can be vasculotoxic and facilitate cardiorenal damage. Renin-angiotensin system inhibitors reduce serum aldosterone levels and/or block its effects but can cause hyperkalemia. Patiromer, a nonabsorbed potassium binder, decreases serum potassium in patients with chronic kidney disease on renin-angiotensin system inhibitors. Here we examined the effect of patiromer treatment on serum aldosterone, blood pressure, and albuminuria in patients with chronic kidney disease on renin-angiotensin system inhibitors with hyperkalemia (serum potassium 5.1-6.5 mEq/l). We analyzed data from the phase 3 OPAL-HK study (4-week initial treatment phase of 243 patients; 8-week randomized withdrawal phase of 107 patients). In the treatment phase, the (mean ± standard error) serum potassium was decreased concordantly with the serum aldosterone (-1.99 ± 0.51 ng/dl), systolic/diastolic blood pressure (-5.64 ± 1.04 mm Hg/-3.84 ± 0.69 mm Hg), and albumin-to-creatinine ratio (-203.7 ± 54.7 mg/g), all in a statistically significant manner. The change in the plasma renin activity (-0.44 ± 0.63 µg/l/hr) was not significant. In the withdrawal phase, mean aldosterone levels were sustained with patiromer (+0.23 ± 1.07 ng/dl) and significantly increased with placebo (+2.78 ± 1.25 ng/dl). Patients on patiromer had significant reductions in mean systolic/diastolic blood pressure (-6.70 ± 1.59/-2.15 ± 1.06 mm Hg), whereas those on placebo did not (-1.21 ± 1.89 mm Hg/+1.72 ± 1.26 mm Hg). Significant changes in plasma renin activity were found only in the placebo group (-3.90 ± 1.41 µg/l/hr). Thus, patiromer reduced serum potassium and aldosterone levels independent of plasma renin activity in patients with chronic kidney disease and hyperkalemia on renin-angiotensin system inhibitors.

Effect of patiromer on reducing serum potassium and preventing recurrent hyperkalaemia in patients with heart failure and chronic kidney disease on RAAS inhibitors.

AIMS: We evaluated the effects of patiromer, a potassium (K(+))-binding polymer, in a pre-specified analysis of hyperkalaemic patients with heart failure (HF) in the OPAL-HK trial. METHODS AND RESULTS: Chronic kidney disease (CKD) patients on renin-angiotensin-aldosterone system inhibitors (RAASi) with serum K(+) levels ≥5.1 mEq/L to <6.5 mEq/L (n = 243) received patiromer (4.2 g or 8.4 g BID initially) for 4 weeks (initial treatment phase); the primary efficacy endpoint was mean change in serum K(+) from baseline to week 4. Eligible patients (those with baseline K(+) ≥5.5 mEq/L to <6.5 mEq/L and levels ≥3.8 mEq/L to <5.1 mEq/L at the end of week 4) entered an 8-week randomized withdrawal phase and were randomly assigned to continue patiromer or switch to placebo; the primary efficacy endpoint was the between-group difference in median change in the serum K(+) over the first 4 weeks of that phase. One hundred and two patients (42%) had heart failure (HF). The mean [± standard error (SE)] change in serum K(+) from baseline to week 4 was -1.06 ± 0.05 mEq/L [95% confidence interval (CI), -1.16,-0.95; P < 0.001]; 76% (95% CI, 69,84) achieved serum K(+), 3.8 mEq/L to <5.1 mEq/L. In the randomized withdrawal phase, the median increase in serum K(+) from baseline of that phase was greater with placebo (n = 22) than patiromer (n = 27) (P < 0.001); recurrent hyperkalaemia (serum K(+), ≥5.5 mEq/L) occurred in 52% on placebo and 8% on patiromer (P < 0.001). Mild-to-moderate constipation was the most common adverse event (11%); hypokalaemia occurred in 3%. CONCLUSION: In patients with CKD and HF who were hyperkalaemic on RAASi, patiromer was well tolerated, decreased serum K(+), and, compared with placebo, reduced recurrent hyperkalaemia.

Patiromer induces rapid and sustained potassium lowering in patients with chronic kidney disease and hyperkalemia.

Patients with chronic kidney disease (CKD) have a high risk of hyperkalemia, which increases mortality and can lead to renin-angiotensin-aldosterone system inhibitor (RAASi) dose reduction or discontinuation. Patiromer, a nonabsorbed potassium binder, has been shown to normalize serum potassium in patients with CKD and hyperkalemia on RAASi. Here, patiromer's onset of action was determined in patients with CKD and hyperkalemia taking at least one RAASi. After a 3-day potassium- and sodium-restricted diet in an inpatient research unit, those with sustained hyperkalemia (serum potassium 5.5 - under 6.5 mEq/l) received patiromer 8.4 g/dose with morning and evening meals for a total of four doses. Serum potassium was assessed at baseline (0 h), 4 h postdose, then every 2-4 h to 48 h, at 58 h, and during outpatient follow-up. Mean baseline serum potassium was 5.93 mEq/l and was significantly reduced by 7 h after the first dose and at all subsequent times through 48 h. Significantly, mean serum potassium under 5.5 mEq/l was achieved within 20 h. At 48 h (14 h after last dose), there was a significant mean reduction of 0.75 mEq/l. Serum potassium did not increase before the next dose or for 24 h after the last dose. Patiromer was well tolerated, without serious adverse events and no withdrawals. The most common gastrointestinal adverse event was mild constipation in two patients. No hypokalemia (serum potassium under 3.5 mEq/l) was observed. Thus, patiromer induced an early and sustained reduction in serum potassium and was well tolerated in patients with CKD and sustained hyperkalemia on RAASis.

Effect of Patiromer on Serum Potassium Level in Patients With Hyperkalemia and Diabetic Kidney Disease: The AMETHYST-DN Randomized Clinical Trial.

IMPORTANCE: Hyperkalemia is a potentially life-threatening condition predominantly seen in patients treated with renin-angiotensin-aldosterone system (RAAS) inhibitors with stage 3 or greater chronic kidney disease (CKD) who may also have diabetes, heart failure, or both. OBJECTIVES: To select starting doses for a phase 3 study and to evaluate the long-term safety and efficacy of a potassium-binding polymer, patiromer, in outpatients with hyperkalemia. DESIGN, SETTING, AND PARTICIPANTS: Phase 2, multicenter, open-label, dose-ranging, randomized clinical trial (AMETHYST-DN), conducted at 48 sites in Europe from June 2011 to June 2013 evaluating patiromer in 306 outpatients with type 2 diabetes (estimated glomerular filtration rate, 15 to <60 mL/min/1.73 m2 and serum potassium level >5.0 mEq/L). All patients received RAAS inhibitors prior to and during study treatment. INTERVENTIONS: Patients were stratified by baseline serum potassium level into mild or moderate hyperkalemia groups and received 1 of 3 randomized starting doses of patiromer (4.2 g [n = 74], 8.4 g [n = 74], or 12.6 g [n = 74] twice daily [mild hyperkalemia] or 8.4 g [n = 26], 12.6 g [n = 28], or 16.8 g [n = 30] twice daily [moderate hyperkalemia]). Patiromer was titrated to achieve and maintain serum potassium level 5.0 mEq/L or lower. MAIN OUTCOMES AND MEASURES: The primary efficacy end point was mean change in serum potassium level from baseline to week 4 or prior to initiation of dose titration. The primary safety end point was adverse events through 52 weeks. Secondary efficacy end points included mean change in serum potassium level through 52 weeks. RESULTS: A total of 306 patients were randomized. The least squares mean reduction from baseline in serum potassium level at week 4 or time of first dose titration in patients with mild hyperkalemia was 0.35 (95% CI, 0.22-0.48) mEq/L for the 4.2 g twice daily starting-dose group, 0.51 (95% CI, 0.38-0.64) mEq/L for the 8.4 g twice daily starting-dose group, and 0.55 (95% CI, 0.42-0.68) mEq/L for the 12.6 g twice daily starting-dose group. In those with moderate hyperkalemia, the reduction was 0.87 (95% CI, 0.60-1.14) mEq/L for the 8.4 g twice daily starting-dose group, 0.97 (95% CI, 0.70-1.23) mEq/L for the 12.6 g twice daily starting-dose group, and 0.92 (95% CI, 0.67-1.17) mEq/L for the 16.8 g twice daily starting-dose group (P < .001 for all changes vs baseline by hyperkalemia starting-dose groups within strata). From week 4 through week 52, statistically significant mean decreases in serum potassium levels were observed at each monthly point in patients with mild and moderate hyperkalemia. Over the 52 weeks, hypomagnesemia (7.2%) was the most common treatment-related adverse event, mild to moderate constipation (6.3%) was the most common gastrointestinal adverse event, and hypokalemia (<3.5 mEq/L) occurred in 5.6% of patients. CONCLUSIONS AND RELEVANCE: Among patients with hyperkalemia and diabetic kidney disease, patiromer starting doses of 4.2 to 16.8 g twice daily resulted in statistically significant decreases in serum potassium level after 4 weeks of treatment, lasting through 52 weeks. TRIAL REGISTRATION: clinicaltrials.gov Identifier:NCT01371747.

Patiromer in patients with kidney disease and hyperkalemia receiving RAAS inhibitors.

BACKGROUND: Hyperkalemia increases the risk of death and limits the use of inhibitors of the renin-angiotensin-aldosterone system (RAAS) in high-risk patients. We assessed the safety and efficacy of patiromer, a nonabsorbed potassium binder, in a multicenter, prospective trial. METHODS: Patients with chronic kidney disease who were receiving RAAS inhibitors and who had serum potassium levels of 5.1 to less than 6.5 mmol per liter received patiromer (at an initial dose of 4.2 g or 8.4 g twice a day) for 4 weeks (initial treatment phase); the primary efficacy end point was the mean change in the serum potassium level from baseline to week 4. Eligible patients at the end of week 4 (those with a baseline potassium level of 5.5 to <6.5 mmol per liter in whom the level decreased to 3.8 to <5.1 mmol per liter) entered an 8-week randomized withdrawal phase in which they were randomly assigned to continue patiromer or switch to placebo; the primary efficacy end point was the between-group difference in the median change in the serum potassium level over the first 4 weeks of that phase. RESULTS: In the initial treatment phase, among 237 patients receiving patiromer who had at least one potassium measurement at a scheduled visit after day 3, the mean (±SE) change in the serum potassium level was -1.01±0.03 mmol per liter (P<0.001). At week 4, 76% (95% confidence interval, 70 to 81) of the patients had reached the target potassium level (3.8 to <5.1 mmol per liter). Subsequently, 107 patients were randomly assigned to patiromer (55 patients) or placebo (52 patients) for the randomized withdrawal phase. The median increase in the potassium level from baseline of that phase was greater with placebo than with patiromer (P<0.001); a recurrence of hyperkalemia (potassium level, ≥5.5 mmol per liter) occurred in 60% of the patients in the placebo group as compared with 15% in the patiromer group through week 8 (P<0.001). Mild-to-moderate constipation was the most common adverse event (in 11% of the patients); hypokalemia occurred in 3%. CONCLUSIONS: In patients with chronic kidney disease who were receiving RAAS inhibitors and who had hyperkalemia, patiromer treatment was associated with a decrease in serum potassium levels and, as compared with placebo, a reduction in the recurrence of hyperkalemia. (Funded by Relypsa; OPAL-HK ClinicalTrials.gov number, NCT01810939.).

Randomized trial of an inhibitor of secretory phospholipase A2 on atherogenic lipoprotein subclasses in statin-treated patients with coronary heart disease.

AIMS: To investigate the effects of secretory phospholipase A2 (sPLA(2)) inhibition on plasma lipoproteins. Secretory phospholipase A2 isoenzymes promote atherosclerosis by mechanisms that include lipoprotein modification, retention, and oxidation. METHODS AND RESULTS: Phospholipase Levels And Serological Markers of Atherosclerosis II (PLASMA II) is a Phase II, randomized, double-blind, placebo-controlled parallel-arm study of two once-daily doses of the novel sPLA(2) inhibitor, 1-H-indole-3-glyoxamide or varespladib methyl (Anthera Pharmaceuticals, Hayward, CA, USA). One hundred and thirty-five stable coronary heart disease patients were treated with either varespladib methyl 250 mg once daily, varespladib methyl 500 mg once daily, or placebo for 8 weeks. Varespladib methyl treatment resulted in statistically significant dose-dependent reductions that were different from placebo in sPLA(2) concentration, low-density lipoprotein (LDL) cholesterol, and non-high-density lipoprotein (HDL) cholesterol. When compared with placebo, varespladib methyl 500 mg once daily reduced LDL cholesterol by 15% (P < 0.001), non-HDL cholesterol by 15% (P < 0.001), total very LDL (VLDL) particle concentration by 14% (P = 0.022), and small VLDL particle concentration by 24% (P = 0.030). Relative to baseline, varespladib methyl 500 mg once daily reduced total LDL particle concentration (7%, P = 0.002) and small LDL particle concentration (11%, P = 0.014). CONCLUSION: Reductions in atherogenic lipoproteins suggest that varespladib methyl 500 mg once daily may be an effective anti-atherosclerotic agent. Trial registered at ClinicalTrials.gov, identifier: NCT00525954.

Effects of varespladib methyl on biomarkers and major cardiovascular events in acute coronary syndrome patients.

OBJECTIVES: The purpose of this study was to investigate the effects of varespladib on cardiovascular biomarkers in acute coronary syndrome patients. BACKGROUND: Secretory phospholipase A(2) (sPLA(2)) represents a family of proatherogenic enzymes that hydrolyze lipoprotein phospholipids, increasing their affinity for intimal proteoglycans; contribute to cholesterol loading of macrophages by nonscavenger receptor mediated pathways; and activate inflammatory pathways. In prospective studies, high sPLA(2)-IIA levels predicted major adverse cardiovascular events in acute coronary syndrome (ACS) and stable coronary heart disease patients. METHODS: This randomized, double-blind, prospective controlled clinical trial (phase 2B) was designed to investigate the effects of sPLA(2) inhibition with varespladib 500 mg daily versus placebo as adjunctive therapy to atorvastatin 80 mg daily on biomarkers (low-density lipoprotein cholesterol [LDL-C], high-sensitivity C-reactive protein [hsCRP], and sPLA(2)-IIA levels), major adverse cardiovascular events (unstable angina, myocardial infarction, death), and safety. In all, 625 ACS subjects were randomized within 96 h of the index event and treated for a minimum of 6 months. RESULTS: After 8 weeks (primary efficacy end point), varespladib/atorvastatin reduced mean LDL-C levels from baseline by 49.6% compared with 43.4% with placebo/atorvastatin (p = 0.002). Respective 8-week median reductions in sPLA(2)-IIA levels were 82.4% and 15.6% (p < 0.0001), and hsCRP levels were lowered by 75.0% and 71.0% (p = 0.097). At 24 weeks, respective reductions with varespladib and placebo were as follows: LDL-C 43.5% versus 37.6% (p < 0.05), hsCRP 79.8% versus 77.0% (p = 0.02), and sPLA(2)-IIA 78.5% versus 6.4% (p < 0.0001). Major adverse cardiovascular events were not different from placebo 6 months post-randomization (7.3% varespladib vs. 7.7% placebo). No treatment differences in elevated liver function studies on >1 occasion were observed. CONCLUSIONS: Varespladib therapy effectively reduced LDL-C and inflammatory biomarkers in ACS patients treated with conventional therapy including atorvastatin 80 mg daily. There were no treatment differences in clinical cardiovascular events. (FRANCIS [Fewer Recurrent Acute Coronary Events With Near-Term Cardiovascular Inflammation Suppression]-ACS Trial: A Study of the Safety and Efficacy of A 002 in Subjects With Acute Coronary Syndromes; NCT00743925).

Effects of 1-H-indole-3-glyoxamide (A-002) on concentration of secretory phospholipase A2 (PLASMA study): a phase II double-blind, randomised, placebo-controlled trial.

BACKGROUND: Secretory phospholipase A(2) (sPLA(2)) enzymes, produced and secreted in human blood vessels and hepatocytes, contribute to the development of atherosclerosis through mechanisms that are both dependent and independent of lipoprotein. We examined the effects of an sPLA(2) inhibitor on enzyme concentration and on plasma lipoproteins and inflammatory biomarkers in patients with coronary heart disease. METHODS: Patients aged 18 years and older with stable coronary heart disease from the USA and Ukraine were eligible for enrolment in this phase II, randomised, double-blind, placebo-controlled, parallel-arm, dose-response study. 393 patients were randomly assigned by computer-generated sequence to receive either placebo (n=79) or one of four doses of an sPLA(2) inhibitor, A-002 (1-H-indole-3-glyoxamide; 50 mg [n=79], 100 mg [n=80], 250 mg [n=78], or 500 mg [n=77] twice daily), for 8 weeks. The primary endpoint was the change in sPLA(2) group IIA (sPLA(2)-IIA) concentration or activity from baseline to week 8. Analysis was by modified intention to treat (ITT). The ITT population consisted of all patients who received one dose of study treatment; data for patients who dropped out before the end of the study were carried forward from last observation. This trial is registered with ClinicalTrials.gov, number NCT00455546. FINDINGS: All randomised patients received at least one dose and were included in the ITT population. Data for 45 patients were carried forward from last observation (36 in the A-002 group and nine in the placebo group); the main reason for dropout before completion was because of adverse events. 348 patients reached the primary endpoint (A-002 n=278, placebo n=70). Mean sPLA(2)-IIA concentration fell by 86.7%, from 157 pmol/L to 21 [corrected] pmol/L, in the overall active treatment group, and by 4.8%, from 157 pmol/L to 143 [corrected] pmol/L, in the placebo group (p<0.0001 treatment vs placebo). The reductions in sPLA(2)-IIA concentration in the A-002 groups were dose dependent (ranging from 69.2% in the 50 mg group to 95.8% in the 500 mg group) and differed significantly from placebo (p<0.0001 for all doses). In the 500 mg A-002 treatment group, there was one serious adverse event (exacerbation of underlying chronic obstructive pulmonary disease), but the proportion of patients reporting treatment-emergent adverse events did not differ from placebo. The main side-effects of the drug included headache (n=20), nausea (n=17), and diarrhoea (n=12). INTERPRETATION: The reductions in sPLA(2)-IIA concentration suggest that A-002 might be an effective anti-atherosclerotic agent.

Neuronal nitric oxide synthase contributes to the regulation of hematopoiesis.

Nitric oxide (NO) signaling is important for the regulation of hematopoiesis. However, the role of individual NO synthase (NOS) isoforms is unclear. Our results indicate that the neuronal NOS isoform (nNOS) regulates hematopoiesis in vitro and in vivo. nNOS is expressed in adult bone marrow and fetal liver and is enriched in stromal cells. There is a strong correlation between expression of nNOS in a panel of stromal cell lines established from bone marrow and fetal liver and the ability of these cell lines to support hematopoietic stem cells; furthermore, NO donor can further increase this ability. The number of colonies generated in vitro from the bone marrow and spleen of nNOS-null mutants is increased relative to wild-type or inducible- or endothelial NOS knockout mice. These results describe a new role for nNOS beyond its action in the brain and muscle and suggest a model where nNOS, expressed in stromal cells, produces NO which acts as a paracrine regulator of hematopoietic stem cells.

noxin, a novel stress-induced gene involved in cell cycle and apoptosis.

We describe a novel stress-induced gene, noxin, and a knockout mouse line with an inactivated noxin gene. The noxin gene does not have sequelogs in the genome and encodes a highly serine-rich protein with predicted phosphorylation sites for ATM, Akt, and DNA-dependent protein kinase kinases; nuclear localization signals; and a Zn finger domain. noxin mRNA and protein levels are under tight control by the cell cycle. noxin, identified as a nitric oxide-inducible gene, is strongly induced by a wide range of stress signals: gamma- and UV irradiation, hydrogen peroxide, adriamycin, and cytokines. This induction is dependent on p53. Noxin accumulates in the nucleus in response to stress and, when ectopically expressed, Noxin arrests the cell cycle at G1; although it also induces p53, the cell cycle arrest function of Noxin is independent of p53 activity. noxin knockout mice are viable and fertile; however, they have an enlarged heart, several altered hematopoietic parameters, and a decreased number of spermatids. Importantly, loss or downregulation of Noxin leads to increased cell death. Our results suggest that Noxin may be a component of the cell defense system: it is activated by various stress stimuli, helps cells to withdraw from cycling, and opposes apoptosis.

Regulation of multimers via truncated isoforms: a novel mechanism to control nitric-oxide signaling.

Nitric oxide (NO) is an essential regulator of Drosophila development and physiology. We describe a novel mode of regulation of NO synthase (NOS) function that uses endogenously produced truncated protein isoforms of Drosophila NOS (DNOS). These isoforms inhibit NOS enzymatic activity in vitro and in vivo, reflecting their ability to form complexes with the full-length DNOS protein (DNOS1). Truncated isoforms suppress the antiproliferative action of DNOS1 in the eye imaginal disc by impacting the retinoblastoma-dependent pathway, yielding hyperproliferative phenotypes in pupae and adult flies. Our results indicate that endogenous products of the dNOS locus act as dominant negative regulators of NOS activity during Drosophila development.

Nitric oxide negatively regulates mammalian adult neurogenesis.

Neural progenitor cells are widespread throughout the adult central nervous system but only give rise to neurons in specific loci. Negative regulators of neurogenesis have therefore been postulated, but none have yet been identified as subserving a significant role in the adult brain. Here we report that nitric oxide (NO) acts as an important negative regulator of cell proliferation in the adult mammalian brain. We used two independent approaches to examine the function of NO in adult neurogenesis. In a pharmacological approach, we suppressed NO production in the rat brain by intraventricular infusion of an NO synthase inhibitor. In a genetic approach, we generated a null mutant neuronal NO synthase knockout mouse line by targeting the exon encoding active center of the enzyme. In both models, the number of new cells generated in neurogenic areas of the adult brain, the olfactory subependyma and the dentate gyrus, was strongly augmented, which indicates that division of neural stem cells in the adult brain is controlled by NO and suggests a strategy for enhancing neurogenesis in the adult central nervous system.