Efficacy and safety of rituximab in patients with active proliferative lupus nephritis: the Lupus Nephritis Assessment with Rituximab study

Prolonged improvement of childhood onset systemic lupus erythematosus following systematic administration of rituximab and cyclophosphamide

BACKGROUND

Although the combination of cyclophosphamide and rituximab has been utilized in case reports, there are no previous reports of the long term outcome of SLE treated systematically with this regimen. We report a pilot study to evaluate the efficacy of a systematically administered course of rituximab and cyclophosphamide over an eighteen month period to provide sustained improvement in childhood onset systemic lupus erythematosus (SLE).

FINDINGS

Twelve patients with childhood onset lupus nephritis or corticosteroid resistant SLE received systematic treatment with a combination of rituximab (750 mg/M2 up to 1 gram) and cyclophosphamide (750 mg/M2: no patient exceeded 1.8 M2). Two administrations of rituximab and cyclophosphamide, two weeks apart, were administered at the start of study, six months later, and eighteen months later. Clinical data were collected and analyzed after sixty months of follow up. There was sustained improvement in all clinical parameters with a dramatic reduction in both mean SLEDAI score (10.1 to 1 at one year and 0 at five years p<0.005) and mean daily prednisone dosage (29.7 mg/day to 12.7 by one year and 7.0 mg/day at five years p<0.005), with sustained improvement in mean C3 (55.5 mg/ml to 113 at one year and 107.5 at five years p<0.001) which was maintained through sixty months of follow up. Serum immunoglobulin levels were transiently depressed but mean values were within the normal range for both IgG and IgM at one and five years. Few complications were observed (two episodes of febrile neutropenia during the first year of treatment were the only serious adverse events) and patients routinely reported sustained wellbeing.

CONCLUSIONS

This pilot study demonstrates that a systematically administered course of rituximab and cyclophosphamide over an eighteen month period provided sustained relief for patients with childhood onset SLE which was maintained over a sixty month period, while minimizing the need for corticosteroids, without excessive toxicity.

Lupus nephritis: the evolving role of novel therapeutics

Immune complex accumulation in the kidney is the hallmark of lupus nephritis and triggers a series of events that result in kidney inflammation and injury. Cytotoxic agents and corticosteroids are standard of care for lupus nephritis treatment, but are associated with considerable morbidity and suboptimal outcomes. Recently, there has been interest in using novel biologic agents and small molecules to treat lupus nephritis. These therapies can be broadly categorized as anti-inflammatory (laquinamod, anti-tumor necrosis factor-like weak inducer of apotosis, anti-C5, and retinoids), antiautoimmunity (anti-CD20, anti-interferon α, and costimulatory blockers), or both (anti-interleukin 6 and proteasome inhibitors). Recent lupus nephritis clinical trials applied biologics or small molecules of any category to induction treatment, seeking short-term end points of complete renal response. These trials in general have not succeeded. When lupus nephritis comes to clinical attention during the inflammatory stage of the disease, the autoimmune stage leading to kidney inflammation will have been active for some time. The optimal approach for using novel therapies may be to initially target kidney inflammation to preserve renal parenchyma, followed by suppression of autoimmunity. In this review, we discuss novel lupus nephritis therapies and how they fit into a combinatorial treatment strategy based on the pathogenic stage.

Recent developments in the treatment of patients with systemic lupus erythematosus: focusing on biologic therapies

INTRODUCTION

Major trials hoping to obtain optimal disease control in systemic lupus erythematosus (SLE) are ongoing. Given its complex aetiology and pathogenesis, it is not surprising that multiple therapeutic targets have emerged and that none are uniformly successful.

AREAS COVERED

In this review, we highlight the recent, more significant studies focusing on the use of biologic therapies. There has been great emphasis on the role of B cells in SLE and many uncontrolled studies have encouraged the use of rituximab (an anti-CD20 monoclonal). Disappointingly, two major trials, EXPLORER and LUNAR did not confirm its utility, although doubts have been expressed on their trial design, and other trials using this drug are commencing. In contrast, belimumab, which blocks a B-cell activating factor, did meet its end points in two major randomised controlled clinical trials and has been approved for use in SLE by both the FDA and the European Medicines Agency. Encouraging, albeit preliminary, results with epratuzumab (which blocks CD22) have also been reported.

EXPERT OPINION

In addition to targeting B cells, other approaches including biologics, which modulate T-cell function and block interleukin-6 and interferon-α, have been explored. Finally, we review the recent developments in the use of conventional drugs, such as cyclophosphamide and mycophenolate.

Interleukin-10-producing B cells and the regulation of immunity

B cells are usually considered primarily for their unique capacity to produce antibodies after differentiation into plasma cells. In addition to their roles as antibody-producing cells, it has become apparent during the last 10 years that B cells also perform important functions in immunity through the production of cytokines. In particular, it was shown that B cells could negatively regulate immunity through provision of interleukin (IL)-10 during autoimmune and infectious diseases in mice. Here, we review data on the suppressive functions of B cells in mice with particular emphasis on the signals controlling the acquisition of such suppressive functions by B cells, the phenotype of the B cells involved in the negative regulation of immunity, and the processes targeted by this inhibitory circuit. Finally, we discuss the possibility that human B cells might also perform similar inhibitory functions through the provision of IL-10, and review data suggesting that such B cell-mediated regulatory activities might be impaired in patients with autoimmune diseases.

B cell depletion: rituximab in glomerular disease and transplantation

B cells play a central role in the pathogenesis of many autoimmune diseases. Selective targeting can be achieved with the use of the monoclonal antibody rituximab. In addition to being a drug for non-Hodgkin's lymphoma, rituximab is also an FDA-approved treatment for refractory rheumatoid arthritis and, since recently, ANCA vasculitis. It has shown efficacy in many autoimmune diseases. This review will discuss current evidence and the rationale of the use of rituximab in glomerular diseases, including randomized controlled trials. The focus will be on the use of rituximab in idiopathic membranous nephropathy, systemic lupus erythematosus and ANCA-associated vasculitis. The emerging role of rituximab in renal transplantation, where it seems to be important for the desensitization protocols for highly sensitized patients as well as for the preconditioning of ABO-incompatible recipients and the treatment of antibody-mediated rejection, will also be addressed.

Type I interferon blockade in systemic lupus erythematosus: where do we stand?

SLE is an autoimmune condition characterized by loss of tolerance to chromatin constituents and the production of ANAs. The majority of SLE patients display spontaneous expression of type I IFN-induced genes in circulating mononuclear cells and peripheral tissues, and type I IFNs play a role in the pathogenesis of the disease via the sustained activation of autoreactive T and B cells necessary for the production of pathogenic autoantibodies. Several IFN-blocking strategies are currently being evaluated in clinical trials: monoclonal antibodies directed against IFN-α and type I IFN-α receptor (IFNAR), as well as active immunization against IFN-α. This review describes the rationale behind these trials and the results obtained, and discusses the perspectives for further development of these drugs.

Understanding the role of B cells in atherosclerosis: potential clinical implications

Atherosclerosis is a progressive inflammatory disease of the medium to large arteries that is the largest contributor to cardiovascular disease. B-cell subsets have been shown in animal models of atherosclerosis to have both atherogenic and atheroprotective properties. In this review, we highlight the research that developed our understanding of the role of B cells in atherosclerosis both in humans and mice. From this we discuss the potential clinical impact B cells could have both as diagnostic biomarkers and as targets for immunotherapy. Finally, we recognize the inherent difficulty in translating findings from animal models into humans given the differences in both cardiovascular disease and the immune system between mice and humans, making the case for greater efforts at addressing the role of B cells in human atherosclerosis.

Rituximab in systemic lupus erythematosus: an updated systematic review and meta-analysis

The wide spectrum of clinical manifestations and high relapse rate represent a therapeutic challenge in systemic lupus erythematosus (SLE). Observational studies suggested efficacy of rituximab (RTX), a B-cell-targeting antibody, to control the activity of SLE. Two randomized trials controlled by placebo did not prove the superiority of RTX when used in addition to conventional treatment in nonrenal (EXPLORER) and renal (LUNAR) lupus.

A systematic review of studies exploring the efficacy of RTX in SLE patients was conducted. The pooled percentages of response were assessed.

Thirty studies with 1243 patients were analyzed. In studies using the British Isles Lupus Assessment Group (BILAG), the complete response (CR) rate was 46.7% (95% CI 36.8%–56.8%) and the partial response (PR) was 37.9% (95% CI 30.6%–45.8%). With the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI), the CR was 56.6% (95% CI 32.4%–78.1%) and the PR was 30.9% (95% CI 8.9%–46%). In renal lupus the CR was 36.1% (95% CI 25.2%–48.6%); PR was 37.4% (95% CI 28.5%–47.3%). In EXPLORER, CR was 12.4% and PR was 17.2%; in LUNAR CR was 26.4% and PR was 30.6%, in both cases not different from controls.

Assessment and standardization of SLE response to treatment remain a challenge. The discrepancy in the perceived efficacy of RTX between controlled and observational studies reflects the heterogeneity of lupus and stringency in criteria of response. Further randomized trials focusing on selected SLE manifestations and using composite response indices are warranted.

Refractory Proliferative Lupus Nephritis

Objective: To review the literature available regarding treatment of lupus nephritis (LN) refractory to cyclophosphamide, mycophenolate mofetil, azathioprine, and glucocorticoids. Data Sources: PubMed-MEDLINE and SCOPUS databases were searched through June 2013 using the terms lupus nephritis, refractory, induction, systemic lupus erythematosus, diffuse proliferative glomerulonephritis, rituximab, cyclosporine, tacrolimus, leflunomide, mizoribine, intravenous immunoglobulin, and belimumab. Study Selection and Data Extraction: Included studies were limited to human studies that evaluated clinical efficacy and English language articles. Articles assessing treatment with first-line agents such as glucocorticoids, cyclophosphamide, mycophenolate, and azathioprine were excluded from this review. Data Synthesis: There are an increasing number of medications being used in refractory LN, making the selection of an appropriate agent more difficult. Thirty studies evaluating the treatment of LN with alternative agents were identified. Although rituximab and calcineurin inhibitors have demonstrated the ability to induce remission in approximately 60% of patients with LN, large randomized trials have not confirmed these results. Leflunomide, mizoribine, and intravenous immunoglobulin have revealed potential benefits in some patient populations; however, there is not enough data to support the regular use of these agents for refractory LN. Conclusions: Rituximab and calcineurin inhibitors have the most evidence to support their use and should be the preferred agents in the treatment of refractory LN at this time. Further studies may elucidate the efficacy of other agents for refractory LN.

[Established medications : new areas of application]

During the last 10 years several new medications from hemato-oncology and transplantation medicine have been transferred to rheumatology. Additionally, medications which are approved for rheumatoid arthritis were increasingly also studied and used for other systemic inflammatory rheumatic diseases. This is especially the case for rituximab and mycophenolate and to a lesser extent also for leflunomide, tumor necrosis factor (TNF) antagonists, tocilizumab and abatacept. Recently, rituximab was approved for severe granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA) after the publication of two prospective randomized trials in 2010. The situation concerning rituximab is much more problematic for systemic lupus erythematosus (SLE) where randomized placebo-controlled trials exist but unfortunately did not meet the primary endpoint requirements (too many highly effective additional forms of treatment in both arms and unsuitable endpoints), although data from registries suggest efficacy especially in cases resistant to treatment. In the case of mycophenolate (MPS) the problem with SLE is totally different. All prospective trials met the endpoints and in one trial MPS was even superior to azathioprine for treatment of lupus nephritis (LN) which led to the recommendation of MPS for induction and maintenance in LN by EULAR and EDTRA as well as more recently by the ACR. However, MPS still is not approved for SLE or LN. The present manuscript gives an overview of existing data for selected connective tissue diseases and vasculitides (for which at least larger retrospective case series or registry data exist) being treated with medications approved for other indications.

B-cell-targeted therapy in adult glomerulonephritis

INTRODUCTION

There are many mechanisms through which B lymphocytes have been implicated in the pathogenesis of glomerulonephritis. There are a number of trials and clinical studies in glomerulonephritis involving depletion of CD20(+) B lymphocytes using rituximab. Newer anti-CD20 agents are currently under evaluation, as are drugs targeting alternative B-cell targets such as B lymphocyte stimulator. Such selective, targeted B-cell therapies, if shown to be effective, may be of value in minimising toxicity from more conventional agents.

AREAS COVERED

This article reviews the role of B cells as a target for therapy in adult renal disease resulting from primary glomerulonephritis and that occurring secondary to systemic disease. It will not address intracellular signalling or co-stimulatory pathways as therapeutic targets.

EXPERT OPINION

There are indications for B-cell targeted therapies in a number of adult glomerulonephritides, with varying degrees of evidence. Further understanding of the mechanisms of B-cell depletion and repletion, and interplay with B-cell survival factors, is necessary in order to identify patients who will respond favourably.

The treatment of systemic lupus proliferative nephritis

Lupus nephritis is one of the most common and serious complications of systemic lupus erythematosus (SLE) in childhood affecting more than 80% of patients. Treatment of this complication has undergone significant evolution in recent years. A series of randomized controlled trials has clarified the role of a variety of immunomodulating regimens including some novel biologic medications. This review touches on the major trials that have influenced practice and shaped current thinking about the treatment of proliferative lupus glomerulonephritis.

The dialysis scenario in patients with systemic lupus erythematosus

Although prognosis of lupus nephritis has improved over time, a substantial amount of lupus patients still reach end-stage renal disease and require dialysis. Treatment of these patients can be challenging, since the disease poses a number of problems that can portend a poor prognosis, such as infections, lupus reactivations, vascular access thrombosis and cardiovascular complications. Consensus is lacking among investigators about the real incidence of these complications and related diagnosis and treatment. Moreover, the choice of the type of dialysis treatment and the overall prognosis are still a matter of debate. In this paper, we have reviewed the currently available literature in an attempt to answer the most controversial issues about the topic.

Rituximab-associated interstitial lung disease in fibrillary glomerulonephritis

Rituximab (RTX) is a chimeric monoclonal antibody against CD20+ B cells increasingly used to treat kidney disorders. RTX-induced pulmonary disease has been reported in patients treated for haematological disorders, and a few cases have been observed in patients with underlying rheumatological conditions. We report a case of non-infectious interstitial pneumonitis associated with RTX use in a 49-year-old patient with primary (fibrillary) glomerulonephritis. As typically observed, discontinuation of the drug and prompt initiation of glucocorticoids led to resolution of pulmonary manifestations. However, fatalities have been reported and nephrologists treating glomerulonephritis patients with RTX should be aware of the existence of this potentially lethal complication.

Systemic lupus erythematosus: immunopathogenesis and novel therapeutic targets

Systemic lupus erythematosus (SLE) is the prototype of autoimmune diseases with multiorgan involvement. SLE presents many genetic and epigenetic associations and the pathogenesis is characterized by a complex network of alterations affecting both adaptative and innate immunity. The disclosure of novel mechanisms of SLE pathogenesis suggested new therapeutic targets, based on interference with the cytokine pathways or on depletion of the immune cells.

Targeting the B-cell pathway in lupus nephritis: current evidence and future perspectives

Nephritis represents a frequent, severe complication of systemic lupus erythematosus. Autoantibodies appear to be fundamental in the pathogenesis of lupus nephritis. Several hypotheses are currently experimentally tested to further elucidate the direct induction of inflammation through interaction of the pathological autoantibodies with intrinsic glomerular components and the triggering of a complement-driven autoinflammatory cascade. B-cells have, in the last decade, emerged as a promising new therapeutic target, as biological treatments successfully attempting B-cell depletion, inhibition of B-cell proliferation and differentiation, or modulation of B-cell function have become bioengineered. Clinical trials have so far proved controversial regarding the efficacy of these new agents. Thus, despite the short and long-term side effects associated with immunosuppressive treatment alternative emerging treatments are still regarded "rescue" regimens in refractory patients. In an effort to accurately evaluate the potential of these therapies in lupus nephritis, several issues have been raised mainly in terms of patient selection criteria and trial duration. This review aims to expand on the proposed pathophysiologic mechanisms implicating the B-cell pathway in the pathogenesis of lupus nephritis and summarize current knowledge obtained from clinical trials introducing these biologics in its treatment. Finally, it will elaborate on potential applications of currently available biologic agents and forthcoming treatment options.

B lymphocytes: development, tolerance, and their role in autoimmunity-focus on systemic lupus erythematosus

B lymphocytes are the effectors of humoral immunity, providing defense against pathogens through different functions including antibody production. B cells constitute approximately 15% of peripheral blood leukocytes and arise from hemopoietic stem cells in the bone marrow. It is here that their antigen receptors (surface immunoglobulin) are assembled. In the context of autoimmune diseases defined by B and/or T cell autoreactive that upon activation lead to chronic tissue inflammation and often irreversible structural and functional damage, B lymphocytes play an essential role by not only producing autoantibodies but also functioning as antigen-presenting cells (APC) and as a source of cytokines. In this paper, we describe B lymphocyte functions in autoimmunity and autoimmune diseases with a special focus on their abnormalities in systemic lupus erythematosus.

Future prospects in biologic therapy for systemic lupus erythematosus

With the approval by the FDA in 2011 of a biologic agent (namely belimumab) for the treatment of systemic lupus erythematosus (SLE), optimism abounds that additional biologic (and nonbiologic) agents will be similarly endorsed. Given the numerous immune-based abnormalities associated with SLE, the potential therapeutic targets for biologic agents and the candidate biologic approaches are also numerous. These approaches include: biologic agents that promote B-cell depletion, B-cell inactivation, or the generation of regulatory B cells; biologic agents that induce T-cell tolerance, block T-cell activation and differentiation, or alter T-cell trafficking; biologic agents that target the B-cell activating factor (BAFF) axis, type I interferons, IL-6 and its receptor, or TNF; and the adoptive transfer of ex vivo-generated regulatory T cells. Owing to the great heterogeneity inherent to SLE, no single approach should be expected to be effective in all patients. As our understanding of the pathogenic mechanisms of SLE continues to expand, additional therapeutic targets and approaches will undoubtedly be identified and should be fully exploited.

B-cell targeted therapies in systemic lupus erythematosus: successes and challenges

Systemic lupus erythematosus is a multisystem autoimmune disease characterized by the formation of autoantibodies that target a variety of self antigens. B cells are fundamental to the development of these antibodies and are a target for intervention in the disease. This review discusses four therapies that target B cells by inducing B-cell depletion, reduction in B-cell proliferation and differentiation, or modulation of B-cell function. Rituximab is an anti-CD20 chimeric monoclonal antibody that depletes B cells but not plasma cells. Systematic reviews of open label studies, particularly in lupus patients refractory to conventional therapy, have suggested that rituximab can be an effective treatment for non-renal lupus and lupus nephritis. However, randomized, double-blind, controlled trials comparing rituximab with placebo in addition to standard of care therapy for non-renal lupus and lupus nephritis over 12 months failed to demonstrate efficacy using the planned primary endpoints, although there were some post-hoc analyses suggesting that rituximab may have beneficial effects that would be worthy of further study as no significant toxicity has been demonstrated. Treatment with belimumab, a humanized monoclonal antibody targeted against B lymphocyte stimulator (BLys), was more efficacious than placebo and had no significant increase in adverse events in two non-renal, phase III lupus trials when given in addition to standard of care therapy for 52 weeks. Belimumab is licensed for the management of lupus in the US and in Europe. Atacicept is a humanized fusion protein that binds BLys and APRIL (a proliferation-inducing ligand) that might be more effective than belimumab in the management of lupus. Unfortunately a phase II/III trial of atacicept in lupus nephritis had to be stopped due to the development of low immunoglobulin levels and pneumonias in some patients. However, in retrospect these complications may have been due to concomitant treatment with mycophenolate mofetil and results of a 52-week, non-renal, phase III trial with atacicept are awaited. Epratuzumab is a humanized monoclonal antibody that targets CD22 on B cells and results in modulation of B-cell function and migration, as CD22 regulates adhesion and inhibits B-cell receptor (BCR) signalling. Epratuzumab at a cumulative dose of 2,400 mg over 4 weeks has been shown to improve lupus disease activity compared with placebo 12 weeks after initiation of therapy in a phase II study, and a 12-month phase III study is on-going. B-cell targeted therapies are an attractive prospect for treating lupus disease and the results of current phase III trials are eagerly awaited. Finding the most appropriate trial design to demonstrate efficacy in lupus trials has been a challenge. The SRI (SLE response index) used in the belimumab studies and the BICLA (British Isles Lupus Assessment Group-based Composite Lupus Assessment) used in the epratuzumab studies are currently the promising trial designs for non-renal studies. For lupus nephritis it is important that trials are of adequate duration to be able to demonstrate benefit of new therapies over conventional therapy.

The pathogenesis of lupus nephritis

Lupus nephritis is an immune complex GN that develops as a frequent complication of SLE. The pathogenesis of lupus nephritis involves a variety of pathogenic mechanisms. The extrarenal etiology of systemic lupus is based on multiple combinations of genetic variants that compromise those mechanisms normally assuring immune tolerance to nuclear autoantigens. This loss of tolerance becomes clinically detectable by the presence of antinuclear antibodies. In addition, nucleic acids released from netting or apoptotic neutrophils activate innate and adaptive immunity via viral nucleic acid-specific Toll-like receptors. Therefore, many clinical manifestations of systemic lupus resemble those of viral infection. In lupus, endogenous nuclear particles trigger IFN-α signaling just like viral particles during viral infection. As such, dendritic cells, T helper cells, B cells, and plasma cells all contribute to the aberrant polyclonal autoimmunity. The intrarenal etiology of lupus nephritis involves antibody binding to multiple intrarenal autoantigens rather than the deposition of circulating immune complexes. Tertiary lymphoid tissue formation and local antibody production add to intrarenal complement activation as renal immunopathology progresses. Here we provide an update on the pathogenic mechanisms that lead to lupus nephritis and provide the rationale for the latest and novel treatment strategies.

Systemic lupus erythematosus and other autoimmune rheumatic diseases: challenges to treatment

Increased understanding of the molecular mechanisms underlying the pathogenenesis of autoimmune rheumatic diseases has led to targeted biological treatments that modulate various aspects of the immune response. These new treatments, together with more judicious use of other immunosuppressive drugs, have resulted in marked improvements in morbidity and mortality. Although belimumab, an agent that inhibits B-cell survival, is the first drug to be approved by the US Food and Drug Administration for the treatment of systemic lupus erythematosus in 50 years, many other immunological targets are under investigation. We discuss the recent advances in the biological treatment of autoimmune rheumatic diseases, with a particular focus on systemic lupus erythematosus.

Targeted therapies in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic, multisystem disorder characterised by loss of tolerance to endogenous nuclear antigens and autoantibody formation. Recent insight into the immunopathogenesis of lupus has provided the foundation for a novel class of agents which target specific, dysregulated components of the immune system. Efforts have focused predominantly on B-cell depleting therapies, of which belimumab was the first to demonstrate success in phase III studies and thus receive marketing authorisation. Off-label prescribing of rituximab in refractory cases is common and supported by uncontrolled studies, which suggest a favourable risk:benefit profile. However, two placebo-controlled trials failed to show benefit, possibly because of inappropriate patient selection and other aspects of trial methodology.

Inhibition of dysregulated co-stimulatory signals and cytokines are other therapeutic strategies currently under investigation. Some candidate drugs failed to meet primary endpoints in early-phase clinical trials, yet demonstrated clinical benefit when alternative assessment criteria were applied or specific patient sub-groups analysed. Well-designed studies of greater size and duration are needed to clarify the therapeutic utility of these agents. Future immunomodulatory strategies targeting interferon-alpha, T cells, oxidative stress and epigenetic abnormalities may reduce multisystem disease activity and prolong survival in this complex and heterogeneic disease.

Comparison of alternative primary outcome measures for use in lupus nephritis clinical trials

OBJECTIVE

Clinical trials of therapies for lupus nephritis have used many different primary outcome measures, ranging from complete response to time to end-stage renal disease. The objective of this study was to compare several possible outcome measures, using data from a large, multicenter trial of abatacept in lupus nephritis, to gain insight into which outcome measure, if any, was best able to discern differences among treatment groups.

METHODS

Study patients received either abatacept or placebo, on a background of mycophenolate mofetil and glucocorticoids. Using data from this trial, the following primary outcome measures at 24 and 52 weeks were compared: complete response rate, major clinical response rate, total response rate (complete plus partial response), improvement in proteinuria, improvement in estimated glomerular filtration rate, and frequency of treatment failure. Time to complete response was also evaluated.

RESULTS

Complete response rate, major clinical response rate, and time to complete response were the measures that best discriminated between the abatacept groups and placebo, and the sensitivities of these 3 measures were comparable. For these measures, sample sizes of 50 patients would have been sufficient to demonstrate a statistically significant difference between treatment and control at 52 weeks. Each of the other measures also discriminated between treatment and control, but much larger group sizes would have been required to determine statistical significance.

CONCLUSION

The choice of primary outcome measure can substantially influence the ability to detect therapeutic benefit in lupus nephritis trials. This study suggests that complete response rate, major clinical response rate at 52 weeks, and time to complete response may be the most sensitive outcome measures for detecting differences among therapeutic regimens.

Latest advances in connective tissue disorders

The connective tissue disorders comprise a number of related conditions that include systemic lupus erythematosus (SLE) and the antiphospholipid (Hughes) syndrome, scleroderma, myositis and Sjögren's syndrome. They are characterized by autoantibody production and other immune-mediated dysfunction. There are common clinical and serological features with some patients having multiple overlapping connective tissue disorders. The latest advances include new approaches to therapy, including more focused utilization of existing therapies and the introduction of biological therapies in SLE, more precise protocols for assessment of severe disease manifestations such as in interstitial lung disease and pulmonary artery hypertension in scleroderma, new antibodies for disease characterization in myositis and new approaches to patient assessment in Sjögren's syndrome. B cells have a critical role in most, if not all of these disorders such that B-cell depletion or suppression of B-cell activating cytokines improves disease in many patients. In particular, the introduction of rituximab, a monoclonal antibody targeting the CD20 molecule on B cells, into clinical practice for rheumatoid arthritis and B-cell lymphoma has been a key driver of experimental approaches to therapy in connective tissue disorders. Genetic studies also suggest a role for the innate immune system in disease pathogenesis, suggesting further future targets for biological therapies over the next few years.

Lupus nephritis: enigmas, conflicting models and an emerging concept

Autoantibodies to components of chromatin, which include double-stranded DNA (dsDNA), histones and nucleosomes, are central in the pathogenesis of lupus nephritis. How anti-chromatin autoantibodies exert their nephritogenic activity, however, is controversial. One model assumes that autoantibodies initiate inflammation when they cross-react with intrinsic glomerular structures such as components of membranes, matrices or exposed nonchromatin ligands released from cells. Another model suggests glomerular deposition of autoantibodies in complex with chromatin, thereby inducing classic immune complex-mediated tissue damage. Recent data suggest acquired error of renal chromatin degradation due to the loss of renal DNaseI enzyme activity is an important contributing factor to the development of lupus nephritis in lupus-prone (NZBxNZW)F1 mice and in patients with lupus nephritis. Down-regulation of DNaseI expression results in reduced chromatin fragmentation and in deposition of extracellular chromatin-IgG complexes in glomerular basement membranes in individuals who produce IgG anti-chromatin autoantibodies. The main focus of the present review is to discuss whether exposed chromatin fragments in glomeruli are targeted by potentially nephritogenic anti-dsDNA autoantibodies or if the nephritogenic activity of these autoantibodies is explained by cross-reaction with intrinsic glomerular constituents or if both models coexist in diseased kidneys. In addition, the role of silencing of the renal DNaseI gene and the biological consequences of reduced chromatin fragmentation in nephritic kidneys are discussed.

KDOQI US commentary on the 2012 KDIGO clinical practice guideline for glomerulonephritis

Glomerulonephritis (GN) is an important cause of morbidity and mortality in patients of all ages throughout the world. Because these disorders are relatively rare, it is difficult to perform randomized clinical trials to define optimal treatment for many of the specific glomerulopathies. In the absence of high-grade evidence to guide the care of glomerular diseases, in June 2012, KDIGO (Kidney Disease: Improving Global Outcomes) published an international clinical guideline for GN. The Work Group report represents an important review of the literature in this area and offers valid and useful guidelines for the most common situations that arise in the management of patients with glomerular disease. This commentary, developed by a panel of clinical experts convened by the National Kidney Foundation, attempts to put the GN guideline into the context of the US health care system. Overall, we support the vast majority of the recommendations and highlight select areas in which epidemiological factors and medical practice patterns in this country justify modifications and adjustments in order to achieve favorable outcomes. There remain large gaps in our knowledge of the best approaches to treat glomerular disease and we strongly endorse an expanded clinical research effort to improve the health and long-term outcomes of children and adults with GN.

Biomarkers and updates on pediatrics lupus nephritis

Lupus nephritis is a common complication of systemic lupus erythematosus in children and adolescents. This article reviews the clinical relevance of lupus nephritis and its current treatment. The reader is introduced to novel biomarkers that are expected to improve the management of lupus nephritis in the future, and support the testing of novel medication regimens.

Indications for use and safety of rituximab in childhood renal diseases

Rituximab was initially developed for the treatment of patients with B cell lymphoma but has during the last decade proven to be quite effective in treating a range of kidney diseases including lupus nephritis, nephrotic syndrome, and also in different situations before and after a renal transplant. We will here review the scientific basis for the use of rituximab in children with renal diseases and give recommendations both regarding its clinical use and need for further research.

Contribution of renal and non-renal clearance on increased total clearance of adalimumab in glomerular disease

The contribution of renal and non-renal clearance toward targeted concentrations and/or effects of therapeutic proteins in nephrotic patients are unknown. This study dissected the contribution of clearance pathways to adalimumab elimination in patients with focal segmental glomerulosclerosis (FSGS). Urine was collected from seven patients treated with adalimumab. Renal clearance (ClR ) was measured and non-renal clearance (ClNR ) was calculated as the difference between total clearance and ClR . Differences in cumulative amount in urine, ClR, and ClNR between study weeks 1 and 16 and relationships between proteinuria (protein:creatinine ratio (Up/c)), and ClR and ClNR were evaluated. Up to 13% of the adalimumab dose was lost in urine. ClNR contributed more than ClR to enhanced total clearance. There was a nonlinear relationship between Up/c and ClR (R(2) 0.7059); an increase in ClR beginning at Up/c of 12 mg/mg [slope 1.755, (C.I. -7.825 to 11.34)]. There was a linear relationship between Up/c and ClNR (R(2) 0.5039); for every one unit increase in Up/c, ClNR would increase by 3.5 mL/hr (P = 0.01). Both ClR and ClNR contribute to enhanced total clearance of adalimumab in glomerular disease secondary to FSGS. Additional research is needed to identify mechanisms for the increased ClNR pathways.

CD20 antibody primes B lymphocytes for type I interferon production

CD20 is a B cell surface marker that is expressed in various stages in B lymphocytes and certain lymphomas. Clinical administration of CD20 antibody, such as rituximab, is used widely to treat human B-cell lymphomas and other diseases. However, CD20 antibody failed to treat systemic lupus erythematosus (SLE or lupus). The reason for the failure is currently unknown. Type I interferons (IFN) are a major component for the host innate immunity, and a key pathogenic factor in lupus. We found that CD20 antibody potentiated human B cells for its production of IFNs in vitro. This function was specific to CD20-expressing cells and the potentiation function seems to be instant. In addition, ectopic expression of CD20 in non-B-lymphocytes increased the IFN promoter reporter activities. Because IFNs are a key pathogenic factor in lupus, our data suggest that, in the presence of virus infection, the CD20-antibody-mediated enhancement of IFN production might be related to its failure in lupus treatments. This work may provide new insights for CD20-Ab therapeutic applications.