Dual renin-angiotensin system blockade for nephroprotection: still under scrutiny

Multidisciplinary supportive care in systemic light chain amyloidosis

The immunoglobulin light-chain amyloidosis is a multisystemic disease which manifests by damage to the vital organs by light chain-derived amyloid fibril. Traditionally, the treatment has been directed to the underlying plasma cell clone with or without high dose chemotherapy followed by autologous stem cell transplantation using melphalan based conditioning. Now with the approval of highly tolerable anti-CD38 monoclonal antibody daratumumab based anti-plasma cell therapy in 2021, high rates of hematologic complete responses are possible even in patients who are otherwise deemed not a candidate for autologous stem cell transplantation. However, despite the progress, there remains a limitation in the strategies to improve symptoms particularly in patients with advanced cardiac involvement, those with nephrotic syndrome and autonomic dysfunction due to underlying systemic AL amyloidosis. The symptoms can be an ordeal for the patients and their caregivers and effective strategies are urgently needed to address them. The supportive care is aimed to counteract the symptoms of the disease and the effects of the treatment on involved organs’ function and preserve patients’ quality of life. Here we discuss multidisciplinary approach in a system-based fashion to address the symptom management in this dreadful disease. In addition to achieving excellent anti-plasma cell disease control, using treatment directed to remove amyloid from the vital organs can theoretically hasten recovery of the involved organs thereby improving symptoms at a faster pace. Ongoing phase III clinical trials of CAEL-101 and Birtamimab will address this question.

Repurposing drugs for highly prevalent diseases: pentoxifylline, an old drug and a new opportunity for diabetic kidney disease

Diabetic kidney disease is one of the most frequent complications in patients with diabetes and constitutes a major cause of end-stage kidney disease. The prevalence of diabetic kidney disease continues to increase as a result of the growing epidemic of diabetes and obesity. Therefore, there is mounting urgency to design and optimize novel strategies and drugs that delay the progression of this pathology and contain this trend. The new approaches should go beyond the current therapy focussed on the control of traditional risk factors such as hyperglycaemia and hypertension. In this scenario, drug repurposing constitutes an economic and feasible approach based on the discovery of useful activities for old drugs. Pentoxifylline is a nonselective phosphodiesterase inhibitor currently indicated for peripheral artery disease. Clinical trials and meta-analyses have shown renoprotection secondary to anti-inflammatory and antifibrotic effects in diabetic patients treated with this old known drug, which makes pentoxifylline a candidate for repurposing in diabetic kidney disease.

Supportive Care in AL Amyloidosis

Immunoglobulin light-chain (AL) amyloidosis is a systemic disease characterized by the production and deposition of light chain-derived amyloid fibrils in different organs. Prompt treatment directed to the underlying plasma cell clone is crucial in order to achieve a rapid, deep and durable hematologic response. The decrease in the production of the amyloidogenic light chains is a required condition to obtain the organ response, which is commonly delayed. Meanwhile, supportive treatment is aimed to maintain quality of life of these patients and preserve their involved organs' function. From simple measures, such as salt restriction or compressive stockings, to very complex interventions, such as heart transplantation in very selected patients with isolated severe cardiac involvement, this supportive care is essential and has to be necessarily included in the multidisciplinary management of this disease.

Pentoxifylline for Renal Protection in Diabetic Kidney Disease. A Model of Old Drugs for New Horizons

Diabetic kidney disease is one of the most relevant complications in diabetes mellitus patients, which constitutes the main cause of end-stage renal disease in the western world. Delaying the progression of this pathology requires new strategies that, in addition to the control of traditional risk factors (glycemia and blood pressure), specifically target the primary pathogenic mechanisms. Nowadays, inflammation is recognized as a critical novel pathogenic factor in the development and progression of renal injury in diabetes mellitus. Pentoxifylline is a nonspecific phosphodiesterase inhibitor with rheologic properties clinically used for more than 30 years in the treatment of peripheral vascular disease. In addition, this compound also exerts anti-inflammatory actions. In the context of diabetic kidney disease, pentoxifylline has shown significant antiproteinuric effects and a delay in the loss of estimated glomerular filtration rate, although at the present time there is no definitive evidence regarding renal outcomes. Moreover, recent studies have reported that this drug can be associated with a positive impact on new factors related to kidney health, such as Klotho. The use of pentoxifylline as renoprotective therapy for patients with diabetic kidney disease represents a new example of drug repositioning.

Effectiveness of renoprotective approaches for persistent proteinuria in lupus nephritis: more than just immunosuppression

OBJECTIVE

The objective of this study is to evaluate the efficacy of a tightly controlled renoprotective protocol in systemic lupus erythematosus (SLE) patients with persistent proteinuria.

METHODS

Thirteen SLE patients with nephritis and persistent proteinuria (>1 g/24 hours) were included. The protocol consisted of regular clinical evaluations every two weeks to assess blood pressure (BP, target <130/80 mmHg), adherence to therapy, diet and smoking. No change in immunosuppressive drugs was allowed but reduction of glucocorticoid dose was permitted if indicated. Clinical, laboratory and treatment evaluations were performed at baseline and at the end of the study (after three months).

RESULTS

SLE patients had a mean age of 37.85 ± 7.68 years and disease duration of 9.85 ± 7.29 years. At baseline, patients had a mean duration of maintenance therapy of 10.38 ± 7.56 months, 12 with mycophenolate mofetil (92.3%) and one with azathioprine (7.7%). At least one dose optimization of antihypertensive regimen was required in all patients during the study. Seven patients (53.8%) had BP>130/80mmHg at baseline. At the end, 11 patients (84.6%) achieved stable BP target; 92.3% were using an angiotensin-converting enzyme inhibitor, 53.9% an angiotensin receptor blocker, and 46.2% were using combined therapy. All patients had a significant reduction in proteinuria levels (2.26 ± 1.09 vs 0.88 ± 0.54 g/24 hours, p < 0.001) and 61.5% achieved proteinuria <1 g/24 hours. A significant decrease in mean prednisone dose was observed (10.96 ± 6.73 vs 5.38 ± 3.36 mg/day, p = 0.013) as well as mean Systemic Lupus Erythematosus Disease Activity Index score (4.38 ± 0.72 vs 3.08 ± 1.86, p = 0.043). No significant changes were identified in serum creatinine, albumin, potassium, complement 3 and complement 4 levels ( p > 0.05).

CONCLUSION

This study provides evidence that a tightly controlled renoprotective protocol is effective in reducing persistent proteinuria in lupus nephritis. The concomitant reduction of prednisone without any change in immunosuppression reinforces the importance of strategies beyond the treatment of nephritis activity.

Therapeutic efficacy of pentoxifylline on proteinuria and renal progression: an update

Blood pressure control with renin-angiotensin system (RAS) blockade has remained the gold standard for treating patients with proteinuric chronic kidney disease (CKD) up to date. Nevertheless, RAS blockade slows but does not halt the progression of kidney disease, thus highlighting the need to search for additional therapeutic approaches. The nonselective phosphodiesterase (PDE) inhibitor pentoxifylline (PTX) is an old drug that exhibits prominent anti-inflammatory, anti-proliferative and anti-fibrotic activities both in vitro and in vivo. Studies in human subjects have shown that PTX monotherapy decreases urinary protein excretion, and add-on therapy of PTX to background RAS blockade additively reduces proteinuria in patients with CKD of various etiology. More recent studies find that PTX combined with RAS blockade delays the decline of glomerular filtration rate in diabetic patients with mild to moderate CKD, and reduces the risk of end-stage renal disease in diabetic and non-diabetic patients in late stage of CKD with high proteinuria levels. In this review, we update the clinical trial results of PTX as monotherapy, or in conjunction or in comparison with RAS blockade on patients with proteinuria and CKD, and propose a mechanistic scheme explaining the renoprotective activities of this drug.

Renin-angiotensin-aldosterone system blockade in chronic kidney disease: current strategies and a look ahead

The Renin-Angiotensin-Aldosterone System (RAAS) is profoundly involved in the pathogenesis of renal and cardiovascular organ damage, and has been the preferred therapeutic target for renal protection for over 30 years. Monotherapy with either an Angiotensin Converting Enzime Inhibitor (ACE-I) or an Angiotensin Receptor Blocker (ARB), together with optimal blood pressure control, remains the mainstay treatment for retarding the progression toward end-stage renal disease. Combining ACE-Is and ARBs, or either one with an Aldosterone Receptor Antagonist (ARA), has been shown to provide greater albuminuria reduction, and to possibly improve renal outcome, but at an increased risk of potentially severe side effects. Moreover, combination therapy has failed to provide additional cardiovascular protection, and large prospective trials on hard renal endpoints are lacking. Therefore this treatment should, at present, be limited to selected patients with residual proteinuria and high renal risk. Future studies with novel agents, which directly act on the RAAS at multiple levels or have a more favourable side effect profile, are greatly needed to further explore and define the potential for and the limitations of profound pharmacologic RAAS inhibition.

Current Understanding of the Pathogenesis of Progressive Chronic Kidney Disease in Cats

In cats with chronic kidney disease (CKD), the most common histopathologic finding is tubulointerstitial inflammation and fibrosis. However, these changes reflect a nonspecific response of the kidney to any inciting injury. The risk of developing CKD is likely to reflect the composite effects of genetic predisposition, aging, and environmental and individual factors that affect renal function over the course of a cat's life. However, there is still little information available to determine exactly which individual risk factors predispose a cat to develop CKD. Although many cats diagnosed with CKD have stable disease for years, some cats show overtly progressive disease.

Targeting inflammation in diabetic kidney disease: early clinical trials

INTRODUCTION

The age-standardized death rate from diabetic kidney disease increased by 106% from 1990 to 2013, indicating that novel therapeutic approaches are needed, in addition to the renin-angiotensin system (RAS) blockers currently in use. Clinical trial results of anti-fibrotic therapy have been disappointing. However, promising anti-inflammatory drugs are currently on phase 1 and 2 randomized controlled trials.

AREAS COVERED

The authors review the preclinical, phase 1 and 2 clinical trial information of drugs tested for diabetic kidney disease that directly target inflammation as a main or key mode of action. Agents mainly targeting other pathways, such as endothelin receptor or mineralocorticoid receptor blockers and vitamin D receptor activators are not discussed.

EXPERT OPINION

Agents targeting inflammation have shown promising results in the treatment of diabetic kidney disease when added on top of RAS blockade. The success of pentoxifylline in open label trials supports the concept of targeting inflammation. In early clinical trials, the pentoxifylline derivative CTP-499, the CCR2 inhibitor CCX140-B, the CCL2 inhibitor emapticap pegol and the JAK1/JAK2 inhibitor baricitinib were the most promising drugs for diabetic kidney disease. The termination of trials testing the anti-IL-1β antibody gevokizumab in 2015 will postpone the evaluation of therapies targeting inflammatory cytokines.

Emerging therapies in immunoglobulin A nephropathy

Despite advances in our understanding of immunoglobulin A nephropathy (IgAN) over the past decade, there are currently no specific therapies capable of targeting key pathways involved in the pathogenesis of the disease. Recent studies have, however, provided new insights into important molecular pathways that are likely to be amenable to therapeutic manipulation in the future. Specifically, a deeper understanding of the role of mucosal immunity, B-cell activation and mesangial cell activation in IgAN has provided the impetus for a number of exciting phase II/III clinical trials in IgAN. In this review, we examine some of these on-going studies, first examining studies that clarify the role of traditional immunosuppression in IgAN, then focusing on novel therapies in early clinical studies, looking closely at the rationale for these agents in relation to our current understanding of the pathogenesis of IgAN. Finally, we examine emerging pathways and therapeutic agents that have the potential to be developed as novel therapies in the coming years. It is hoped that as we continue to develop a greater understanding of IgAN, emerging therapies will soon become a reality in the day-to-day treatment of patients with IgAN.

Potential New Agents for the Management of Hyperkalemia

Hyperkalemia is a common electrolyte disturbance with multiple potential etiologies. It is usually observed in the setting of reduced renal function. Mild to moderate hyperkalemia is usually asymptomatic, but is associated with poor prognosis. When severe, hyperkalemia may cause serious acute cardiac arrhythmias and conduction abnormalities, and may result in sudden death. The rising prevalence of conditions associated with hyperkalemia (heart failure, chronic kidney disease, and diabetes) and broad use of renin-angiotensin-aldosterone system (RAAS) inhibitors and mineralocorticoid receptor antagonists (MRAs), which improve patient outcomes but increase the risk of hyperkalemia, have led to a significant rise in hyperkalemia-related hospitalizations and deaths. Current non-invasive therapies for hyperkalemia either do not remove excess potassium or have poor efficacy and tolerability. There is a clear need for safer, more effective potassium-lowering therapies suitable for both acute and chronic settings. Patiromer sorbitex calcium and sodium zirconium cyclosilicate (ZS-9) are two new potassium-lowering compounds currently in development. Although they have not yet been approved by the US FDA, both have demonstrated efficacy and safety in recent trials. Patiromer sorbitex calcium is a polymer resin and sorbitol complex that binds potassium in exchange for calcium; ZS-9, a non-absorbed, highly selective inorganic cation exchanger, traps potassium in exchange for sodium and hydrogen. This review discusses the merits of both novel drugs and how they may help optimize the future management of patients with hyperkalemia.

New molecular insights in diabetic nephropathy

Diabetes mellitus represents one of the major causes of functional kidney impairment. The review highlights the most significant steps made over the last decades in understanding the molecular basis of diabetic nephropathy (DN), which may provide reliable biomarkers for early diagnosis and prognosis, along with new molecular targets for personalized medicine. There is an increased interest in developing new therapeutic strategies to slow DN progression for improving patients' quality of life and reducing all-cause morbidity and disease-associated mortality. It is highly important to have a science-based medical attitude when facing diabetic patients with associated comorbidities and risk of rapid evolution toward end-stage renal disease. The data discussed herein were mainly from MEDLINE and PubMed articles published in English from 1990 to 2015 and from up-to-date. The search term was "diabetic nephropathy and oxidative stress".

New insights into the pathogenesis of giant cell arteritis and hopes for the clinic

Giant cell arteritis is a complex immune-mediated disease that involves large blood vessels in individuals older than 50 years. Recent studies have confirmed a strong association of this form of vasculitis with the HLA region, particularly with HLA class II genes. However, other non-HLA loci, such as protein tyrosine phosphatase non-receptor type 22, may also account for the susceptibility to giant cell arteritis. In addition, genetic variants located in genes encoding proinflammatory cytokines seem to influence the phenotypic expression of the disease, including the risk of severe ischemic complications, the presence of polymyalgia rheumatica and the higher incidence of relapses observed in some patients. The identification of putative genetic markers of disease severity could have clear therapeutic implications, as it may allow us to identify patients who are potentially responders to specific treatments.

Combination use of medicines from two classes of renin-angiotensin system blocking agents: risk of hyperkalemia, hypotension, and impaired renal function

European and United States regulatory agencies recently issued warnings against the use of dual renin-angiotensin system (RAS) blockade therapy through the combined use of angiotensin-converting enzyme inhibitors (ACEIs), angiotensin II receptor blockers (ARBs) or aliskiren in any patient, based on absence of benefit for most patients and increased risk of hyperkalemia, hypotension, and renal failure. Special emphasis was made not to use these combinations in patients with diabetic nephropathy. The door was left open to therapy individualization, especially for patients with heart failure, when the combined use of an ARB and ACEI is considered absolutely essential, although renal function, electrolytes and blood pressure should be closely monitored. Mineralocorticoid receptor antagonists were not affected by this warning despite increased risk of hyperkalemia. We now critically review the risks associated with dual RAS blockade and answer the following questions: What safety issues are associated with dual RAS blockade? Can the safety record of dual RAS blockade be improved? Is it worth trying to improve the safety record of dual RAS blockade based on the potential benefits of the combination? Is dual RAS blockade dead? What is the role of mineralocorticoid antagonists in combination with other RAS blocking agents: RAAS blockade?

The Envy of Scholars: Applying the Lessons of the Framingham Heart Study to the Prevention of Chronic Kidney Disease

During the past 50 years, a dramatic reduction in the mortality rate associated with cardiovascular disease has occurred in the US and other countries. Statistical modeling has revealed that approximately half of this reduction is the result of risk factor mitigation. The successful identification of such risk factors was pioneered and has continued with the Framingham Heart Study, which began in 1949 as a project of the US National Heart Institute (now part of the National Heart, Lung, and Blood Institute). Decreases in total cholesterol, blood pressure, smoking, and physical inactivity account for 24%, 20%, 12%, and 5% reductions in the mortality rate, respectively. Nephrology was designated as a recognized medical professional specialty a few years later. Hemodialysis was first performed in 1943. The US Medicare End-Stage Renal Disease (ESRD) Program was established in 1972. The number of patients in the program increased from 5,000 in the first year to more than 500,000 in recent years. Only recently have efforts for risk factor identification, early diagnosis, and prevention of chronic kidney disease (CKD) been undertaken. By applying the approach of the Framingham Heart Study to address CKD risk factors, we hope to mirror the success of cardiology; we aim to prevent progression to ESRD and to avoid the cardiovascular complications associated with CKD. In this paper, we present conceptual examples of risk factor modification for CKD, in the setting of this historical framework.

Horizon 2020 in Diabetic Kidney Disease: The Clinical Trial Pipeline for Add-On Therapies on Top of Renin Angiotensin System Blockade

Diabetic kidney disease is the most frequent cause of end-stage renal disease. This implies failure of current therapeutic approaches based on renin-angiotensin system (RAS) blockade. Recent phase 3 clinical trials of paricalcitol in early diabetic kidney disease and bardoxolone methyl in advanced diabetic kidney disease failed to meet the primary endpoint or terminated on safety concerns, respectively. However, various novel strategies are undergoing phase 2 and 3 randomized controlled trials targeting inflammation, fibrosis and signaling pathways. Among agents currently undergoing trials that may modify the clinical practice on top of RAS blockade in a 5-year horizon, anti-inflammatory agents currently hold the most promise while anti-fibrotic agents have so far disappointed. Pentoxifylline, an anti-inflammatory agent already in clinical use, was recently reported to delay estimated glomerular filtration rate (eGFR) loss in chronic kidney disease (CKD) stage 3–4 diabetic kidney disease when associated with RAS blockade and promising phase 2 data are available for the pentoxifylline derivative CTP-499. Among agents targeting chemokines or chemokine receptors, the oral small molecule C-C chemokine receptor type 2 (CCR2) inhibitor CCX140 decreased albuminuria and eGFR loss in phase 2 trials. A dose-finding trial of the anti-IL-1β antibody gevokizumab in diabetic kidney disease will start in 2015. However, clinical development is most advanced for the endothelin receptor A blocker atrasentan, which is undergoing a phase 3 trial with a primary outcome of preserving eGFR. The potential for success of these approaches and other pipeline agents is discussed in detail.