B cell depletion therapy in systemic lupus erythematosus: long-term follow-up and predictors of response

Disease-modifying therapies in systemic lupus erythematosus for extrarenal manifestations

Our 2022 published working definition of disease modification in systemic lupus erythematosus (SLE) was 'minimising disease activity with the fewest treatment-associated toxicities and slowing or preventing organ damage progression'. The objective of this review was to classify current SLE treatments according to the proposed non-renal disease modification criteria excluding toxicities. Based on a review of select clinical trial (n=32) and observational study (n=54) publications for 14 SLE medications across different therapeutic classes, and the authors' clinical experience, we evaluated disease modification potential as per the proposed framework at three time points. Specific criteria used to determine disease modification potential included a drug's capacity to reduce: (1) non-renal disease activity, (2) severe flares, (3) use of steroids/immunosuppressants and (4) organ damage accrual. Criteria 1-3 were assessed at 1 year and 2-5 years and, when positive, were considered evidence for disease modification potential; criterion 4 was used to confirm disease modification at >5 years. Each treatment received one of four mutually exclusive designations at each time point: (a) criterion met, (b) indications of criterion met despite insufficient evidence in the literature, (c) inconclusive and (d) no available supportive data. This review excludes an assessment of potential toxicities. Eight of the 14 SLE treatments met ≥1 disease modification criteria up to year 5. Hydroxychloroquine improved overall survival at >5 years, suggesting long-term disease modification, but no data on specific organ systems were reported. Belimumab was the only treatment to meet all criteria. Belimumab and hydroxychloroquine met disease modification definitions across three time points. Evidence for other SLE therapies was incomplete, particularly at >5 years. Future studies are warranted for other treatments to meet the disease modification criteria. We discuss challenges to classification and possible updates to our published criteria.

From systemic lupus erythematosus to lupus nephritis: The evolving road to targeted therapies

Systemic lupus erythematosus is a chronic autoimmune disease characterized by loss of tolerance against nuclear and cytoplasmic self-antigens, induction of immunity and tissue inflammation. Lupus nephritis (LN), the most important predictor of morbidity in SLE, develops in almost 30% of SLE patients at disease onset and in up to 50-60% within the first 10 years. Firstly, in this review, we put the pathogenic mechanisms of the disease into a conceptual frame, giving emphasis to the role of the innate immune system in this loss of self-tolerance and the induction of the adaptive immune response. In this aspect, many mechanisms have been described such as dysregulation and acceleration of cell-death pathways, an aberrant clearance and overload of immunogenic acid-nucleic-containing debris and IC, and the involvement of antigen-presenting cells and other innate immune cells in the induction of this adaptive immune response. This result in a clonal expansion of autoreactive lymphocytes with generation of effector T-cells, memory B-cells and plasma cells that produce autoantibodies that will cause kidney damage. Secondly, we review the immunological pathways of damage in the kidney parenchyma, initiated by autoantibody binding and immune complex deposition, and followed by complement-mediated microvascular injury, activation of kidney stromal cells and the recruitment of leukocytes. Finally, we summarize the rationale for the treatment of LN, from conventional to new targeted therapies, focusing on their systemic immunologic effects and the minimization of podocytary damage.

Off-label use of rituximab in patients with systemic lupus erythematosus with extrarenal disease activity: a retrospective study and literature review

Introduction

Off-label rituximab is commonly used for patients with systemic lupus erythematosus (SLE) with extrarenal disease activity.

Methods

The outcomes and tolerability of rituximab in adult patients with non-renal SLE treated at our hospital from 2013 to 2020 were described. Patients were followed-up until December 2021. Data were retrieved from electronic medical records. Response was classified into complete, partial or no response according to the Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI 2 K)-based definitions.

Results

A total of 44 cycles were administered to 33 patients. Median age was 45 years and 97% were female. Median follow-up was 5.9 years (IQR 3.7-7.2). The most frequent symptoms that motivated rituximab use were thrombocytopenia (30.3%), arthritis (30.3%), neurological manifestations (24.2%) and cutaneous lupus (15.2%). After most treatment cycles a partial remission was achieved. The median SLEDAI-2 K score declined from 9 (IQR 5-13) to 1.5 (IQR 0-4) (p < 0.00001). The median number of flares significantly declined after receiving rituximab. Platelet counts significantly improved in patients with thrombocytopenia and patients with skin disorders or neurological manifestations also had a partial or complete response. Only 50% of patients with a predominant joint involvement had either a complete or a partial response. The median time to relapse after the first cycle was 1.6 years (95% CI, 0.6-3.1). Anti-dsDNA levels decreased significantly after rituximab from a median of 64.3 (IQR 12-373.9) to 32.7 (IQR 10-173), p = 0.00338. The most frequent adverse events were infusion-related reactions (18.2%) and infections (57.6%). All patients needed further treatment to maintain remission or to treat new flares.

Conclusion

A partial or complete response was documented after most rituximab cycles in patients with non-renal SLE. Patients with thrombocytopenia, neurolupus, and cutaneous lupus had better response than those with a predominant joint involvement.

Early stage clinical trials for the treatment of hemophilia A

INTRODUCTION

Hemophilia A is a severe bleeding disorder affecting about 1 in 5,000 males. The gold standard for prophylaxis and treatment of acute bleeding has been factor (F) VIII concentrate. A multitude of treatment modalities are now available and under clinical investigation.

AREAS COVERED

This review discusses ongoing/recently completed early-phase clinical trials registered on ClinicalTrials.gov in patients with hemophilia A through April 2022. These new pipeline therapies are focused on addressing the safety and efficacy of new factor-related products, non-factor related products, and gene therapy options for hemophilia.

EXPERT OPINION

Current standard of care effectively prevents and treats acute bleeding and has significantly improved the quality of life in hemophilia. The biggest challenges in the improvement of care are treatment-related burden and the burden of cost in developing countries. New drugs under development are likely to enter practice by the end of this decade and address many of the unmet needs particularly of those with severe disease. Data is limited in unique populations (e.g. congenital/inherited FVIII inhibitors, non-severe hemophilia A, women/girls with hemophilia and children) which are important areas for future research; additional clinical trials and long-term outcome data are necessary prior to incorporating these new therapies in our treatment arsenal.

Necrotizing Fasciitis: A Side Effect of Rituximab Administration in Steroid-Dependent Nephrotic Syndrome

Steroid-dependent nephrotic syndrome (SDNS) is a common type of childhood nephrotic syndrome. Remission following steroid therapy is achieved in 80-90% of the patients, while the remainder show steroid-resistant nephrotic syndrome (SRNS). Rituximab is an anti-CD20 chimeric monoclonal antibody with proven therapeutic effects in several diseases and has been used with great success in the treatment of NS since its discovery. We report a case of a 4-year-old girl diagnosed with SDNS at the age of 3. As treatment with steroids, enalapril, and mycophenolate failed to produce complete remission, rituximab was initiated, and remission was successfully achieved after administration of the first dose. Due to this response, rituximab therapy was continued; however, a day after being admitted to the nephrology ward for the second dose, she started to develop a high fever, which reached up to 40°C. In addition, she also displayed symptoms of upper respiratory tract infection and an ulcerated wound on her left cheek. The patient became drowsy with reactive pupils, cold peripheries, and weak peripheral pulses. The capillary refill time was prolonged to 3-4 seconds and it was decided to withhold the second dose of rituximab. The patient was shifted to the PICU as a case of septic shock secondary to facial cellulitis and started on inotropes (epinephrine and norepinephrine), meropenem, vancomycin, and hydrocortisone 15 mg. Thereafter, surgical debridement of the wound was carried out. The patient remained in remission with regard to nephrotic syndrome and was discharged in a healthy condition. In conclusion, rituximab used in conjunction with steroids and other immunosuppressants may increase the risk of serious infections like necrotizing fasciitis (NF). Further studies are needed to explore the relationship between rituximab and NF.

Off-Label Uses of Rituximab in Dermatology

Purpose of Review

Rituximab has transformed the treatment of B-cell malignancies and rheumatoid arthritis in the past 2 decades. More recently, this anti-CD20 monoclonal antibody has seen increasing usage in the field of dermatology. This review highlights the evidence supporting its use in several important dermatologic conditions.

Recent Findings

Key recent findings include the 2018 FDA approval of rituximab for the treatment of moderate-to-severe pemphigus.

Summary

Data from randomized controlled trials have demonstrated the efficacy of rituximab in pemphigus, ANCA-associated vasculitis, and cryoglobulinemic vasculitis. More limited data suggests its use in recalcitrant cases of diseases such as pemphigoid, epidermolysis bullosa acquisita, and dermatomyositis. There is scarce evidence and mixed results for rituximab when studied in cutaneous polyarteritis nodosa and cutaneous lupus erythematosus.

Longitudinal analysis of ANA in the Systemic Lupus International Collaborating Clinics (SLICC) Inception Cohort

OBJECTIVES

A perception derived from cross-sectional studies of small systemic lupus erythematosus (SLE) cohorts is that there is a marked discrepancy between antinuclear antibody (ANA) assays, which impacts on clinicians' approach to diagnosis and follow-up. We compared three ANA assays in a longitudinal analysis of a large international incident SLE cohort retested regularly and followed for 5 years.

METHODS

Demographic, clinical and serological data was from 805 SLE patients at enrolment, year 3 and 5. Two HEp-2 indirect immunofluorescence assays (IFA1, IFA2), an ANA ELISA, and SLE-related autoantibodies were performed in one laboratory. Frequencies of positivity, titres or absorbance units (AU), and IFA patterns were compared using McNemar, Wilcoxon and kappa statistics, respectively.

RESULTS

At enrolment, ANA positivity (≥1:80) was 96.1% by IFA1 (median titre 1:1280 (IQR 1:640-1:5120)), 98.3% by IFA2 (1:2560 (IQR 1:640-1:5120)) and 96.6% by ELISA (176.3 AU (IQR 106.4 AU-203.5 AU)). At least one ANA assay was positive for 99.6% of patients at enrolment. At year 5, ANA positivity by IFAs (IFA1 95.2%; IFA2 98.9%) remained high, while there was a decrease in ELISA positivity (91.3%, p<0.001). Overall, there was >91% agreement in ANA positivity at all time points and ≥71% agreement in IFA patterns between IFA1 and IFA2.

CONCLUSION

In recent-onset SLE, three ANA assays demonstrated commutability with a high proportion of positivity and titres or AU. However, over 5 years follow-up, there was modest variation in ANA assay performance. In clinical situations where the SLE diagnosis is being considered, a negative test by either the ELISA or HEp-2 IFA may require reflex testing.

New insights into the role of antinuclear antibodies in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease characterized by antinuclear antibodies (ANAs) that form immune complexes that mediate pathogenesis by tissue deposition or cytokine induction. Some ANAs bind DNA or associated nucleosome proteins, whereas other ANAs bind protein components of complexes of RNA and RNA-binding proteins (RBPs). Levels of anti-DNA antibodies can fluctuate widely, unlike those of anti-RBP antibodies, which tend to be stable. Because anti-DNA antibody levels can reflect disease activity, repeat testing is common; by contrast, a single anti-RBP antibody determination is thought to suffice for clinical purposes. Experience from clinical trials of novel therapies has provided a new perspective on ANA expression during disease, as many patients with SLE are ANA negative at screening despite previously testing positive. Because trial results suggest that patients who are ANA negative might not respond to certain agents, screening strategies now involve ANA and anti-DNA antibody testing to identify patients with so-called 'active, autoantibody-positive SLE'. Evidence suggests that ANA responses can decrease over time because of the natural history of disease or the effects of therapy. Together, these findings suggest that, during established disease, more regular serological testing could illuminate changes relevant to pathogenesis and disease status.

Are lupus animal models useful for understanding and developing new therapies for human SLE?

Systemic lupus erythematosus is a systemic autoimmune disease driven by a complex combination of genetic, environmental, and other immunoregulatory factors. The development of targeted therapies is complicated by heterogeneous clinical manifestations, varying organ involvement, and toxicity. Despite advances in understanding the mechanisms contributing to SLE, only one biologic drug, belimumab, is FDA-approved. The identification and development of potential therapies have largely been driven by studies in lupus animal models. Therefore, direct comparison of both the therapeutic and immunological findings in human and murine SLE studies is critical and can reveal important insights into indeed how useful and relevant are murine studies in SLE drug development. Studies involving belimumab, mycophenolate mofetil, abatacept, rituximab, and anti-interferon strategies generally demonstrated analogous findings in the attenuation of SLE manifestations and modulation of select immune cell populations in human and murine SLE. While further basic and translational studies are needed to identify SLE patient subsets likely to respond to particular therapeutic modalities and in dissecting complex mechanisms, we believe that despite some inherent weaknesses SLE mouse models will continue to be integral in developing targeted SLE therapies.

Bruton's Tyrosine Kinase Inhibitors: A New Therapeutic Target for the Treatment of SLE?

Systemic lupus erythematosus (SLE) is an autoimmune disease with a complex pathogenesis, which presents a great variability in its presentation and can affect almost all organs and systems. Multiple therapeutic targets have been discovered recently, but there also have been failed attempts to treat SLE using biologic agents. Bruton’s tyrosine kinase (BTK) is a cytoplasmic tyrosine kinase expressed in several types of cells of hematopoietic origin which participate in both innate and adaptive immunity. Ibrutinib, a BTK inhibitor, is approved for the treatment of several B cell malignancies, including some types of lymphoma and leukemia. As BTK is expressed on several immune cell types, the mechanism of action of BTK also suggests the use of BTK inhibitors in the treatment of autoimmune diseases. In this review, we will summarize what is known and what has been published so far about the treatment of mouse models of SLE and the human disease, using BTK inhibitors.

Rituximab as Maintenance Treatment for Systemic Lupus Erythematosus: A Multicenter Observational Study of 147 Patients

OBJECTIVE

The efficacy of rituximab (RTX) in systemic lupus erythematosus (SLE) is a subject of debate. This study was undertaken to investigate the outcomes of RTX treatment in a European SLE cohort, with an emphasis on the role of RTX as a maintenance agent.

METHODS

All patients with SLE who were receiving RTX as induction therapy in 4 centers were included. Patients who received a single course of RTX and those who received RTX maintenance treatment (RMT) were followed up after treatment. Disease flares during the follow-up period were defined as an increase in disease activity and the number or dose of immunosuppressive drugs.

RESULTS

Of 147 patients, 27% experienced treatment failure at 6 months. In a multivariate analysis, a low number of previous immunosuppressive therapies (P = 0.034) and low C4 levels (P = 0.008) reduced the risk of treatment failure. Eighty patients received RMT over a median of 24.5 months during which 85 relapses, mainly musculoskeletal, were recorded (1.06 per patient). At the time of the last RTX course, 84% of the patients were in remission. Twenty-eight (35%) of 80 patients never experienced a flare during RMT and had low damage accrual. Active articular disease at the time of the first RTX administration was associated with a risk of flare during RMT (P = 0.011). After RMT, relapse-free survival was similar to that in patients receiving a single RTX course (P = 0.72).

CONCLUSION

RMT is a potential treatment option for patients with difficult-to-treat disease. Relapses occur during RMT and are more likely in those with active articular disease at the time of the first RTX administration. Relapse risk after RMT remains high and apparently comparable to that seen after a single RTX course.

Predictive and prognostic factors influencing outcomes of rituximab therapy in systemic lupus erythematosus (SLE): A systematic review

BACKGROUND

The clinical outcomes following rituximab (RTX) treatment in patients with systemic lupus erythematosus (SLE) is highly variable. We aimed to identify predictive and prognostic factors associated with RTX therapy outcomes in patients with SLE.

METHODS

Studies in adults and paediatric patients with SLE were included. We included randomized clinical trials (RCTs) for predictors of differential treatment effect and cohort studies for potential prognostic factors in patients treated with RTX (global clinical, cutaneous and renal either response or relapse, and side effects). Methodological quality was assessed using Cochrane Collaboration Risk of Bias tool and the Quality In Prognosis Studies Tool (QUIPS) for RCTs and cohort studies, respectively. The quality of subgroup analyses testing predictors of differential treatment response was also evaluated. A best evidence synthesis was performed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) framework.

RESULTS

Sixteen articles were included (3 from 2 RCTs and 13 from 6 cohort studies). The overall quality of evidence (QoE) was low to very low (GRADE framework). QoE for predictive factors based on RCTs analysing sociodemographic variables, was rated very low due to the lack of interaction tests, limited power of subgroup analyses, study limitations, and imprecisions. Disease-related factors including clinical phenotype and severity, baseline anti-ENA antibodies and anti-Ro antibodies, interleukin (IL) 2/21 single nucleotide polymorphism (SNP), as well as post-RTX complete B-cell depletion and earlier B-cell repopulation showed some evidence for prognostic value, but were rated low to very low QoE because of early phase of investigation (exploratory analysis), insufficient adjustment for confounding in most studies, high risk of bias, inconsistency, and imprecisions.

CONCLUSIONS

To date, studies addressing prognostic factors are hypothesis generating and cannot be used to make any specific recommendations for routine clinical practice. A number of potential predictors/prognostic factors were identified, which require to be validated as being specific for response to RTX therapy and to enable more personalised use of this agent.

Predictive biological markers of systemic lupus erythematosus flares: a systematic literature review

BACKGROUND

The aim of this study was to identify the most reliable biomarkers in the literature that could be used as flare predictors in systemic lupus erythematosus (SLE).

METHODS

A systematic review of the literature was performed using two databases (MEDLINE and EMBASE) through April 2015 and congress abstracts from the American College of Rheumatology and the European League Against Rheumatism were reviewed from 2010 to 2014. Two independent reviewers screened titles and abstracts and analysed selected papers in detail, using a specific questionnaire. Reports addressing the relationships between one or more defined biological test(s) and the occurrence of disease exacerbation were included in the systematic review.

RESULTS

From all of the databases, 4668 records were retrieved, of which 69 studies or congress abstracts were selected for the systematic review. The performance of seven types of biomarkers performed routinely in clinical practice and nine types of novel biological markers was evaluated. Despite some encouraging results for anti-double-stranded DNA antibodies, anti-C1q antibodies, B-lymphocyte stimulator and tumour necrosis factor-like weak inducer of apoptosis, none of the biomarkers stood out from the others as a potential gold standard for flare prediction. The results were heterogeneous, and a lack of standardized data prevented us from identifying a powerful biomarker.

CONCLUSIONS

No powerful conclusions could be drawn from this systematic review due to a lack of standardized data. Efforts should be undertaken to optimize future research on potential SLE biomarkers to develop validated candidates. Thus, we propose a standardized pattern for future studies.

Effector and regulatory B cells in Multiple Sclerosis

The role of B cells in the pathogenesis of Multiple Sclerosis (MS), an autoimmune neurodegenerative disease, is becoming eminent in recent years, but the specific contribution of the distinct B cell subsets remains to be elucidated. Several B cell subsets have shown regulatory, anti-inflammatory capacities in response to stimuli in vitro, as well as in the animal model of MS: Experimental Autoimmune Encephalomyelitis (EAE). However, the functional role of the B regulatory cells (Bregs) in vivo and specifically in the human disease is yet to be clarified. In the present review, we have summarized the updated information on the roles of effector and regulatory B cells in MS and the immune-modulatory effects of MS therapeutic agents on their phenotype and function.

Pragmatic Treatment of Patients With Systemic Lupus Erythematosus With Rituximab: Long-Term Effects on Serum Immunoglobulins

Objective

B cell–depletion therapy based on rituximab is a therapeutic option for refractory disease in patients with systemic lupus erythematosus (SLE). The aim of this observational study was to document long‐term effects on B cell function by following serum immunoglobulin levels in patients with SLE treated with rituximab in routine clinical practice.

Methods

We included 57 consecutive patients with SLE treated with rituximab and concomitant/sequential immunosuppressants and measured serum total IgG, IgM, and IgA and IgG anti‐dsDNA antibodies, over a median of 48 months most recent followup. Flow cytometry was used prospectively to assess B cell phenotypes in 17 of 57 patients.

Results

Twelve patients (21%) had persistent IgM hypogammaglobulinemia (<0.4 gm/liter), and 4 of 57 (5%) had low IgG (<7 gm/liter) at the most recent followup (range 12–144 months). This was not associated with serious adverse events or high anti–double‐stranded DNA (anti‐dsDNA) antibodies (>1,000 IU/ml; normal <50 IU/ml). Factors predictive of low serum IgM included baseline serum IgM ≤0.8 gm/liter (receiver operator curve analysis) and subsequent therapy with mycophenolate mofetil (MMF; odds ratio 6.8, compared with other immunosuppressants). In patients maintaining normal IgM levels (9 of 17), the frequency of circulating IgD+CD27+ B cells was significantly higher (P = 0.05). At 12 months after rituximab, 7 of 30 SLE patients with baseline anti‐dsDNA ≤1,000 IU/ml had lost seropositivity.

Conclusion

Lower baseline serum IgM levels and sequential therapy with MMF were predictive of IgM hypogammaglobulinemia after rituximab in SLE, but this was not associated with higher levels of anti‐dsDNA antibodies or an increased risk of infections. This provides useful directions for clinicians regarding rituximab and sequential immunosuppressive treatment for patients with SLE.

Systemic lupus erythematosus: still a challenge for physicians

Systemic lupus erythematosus (SLE) has a complex clinical picture, and a number of defects in the immune system have been described in patients with the disease. Most organs can be involved in SLE, and in addition to the typical major organ manifestations (e.g. from kidneys and the central nervous system), early cardiovascular disease is a major determinant of prognosis. Several important findings during the last decade have increased the understanding of the mechanisms behind the disease characteristics and the underlying autoimmune process. Amongst, these are defects in the handling of apoptotic cells, increased expression of type I interferon-regulated genes and activation of autoreactive B cells, with both the type I interferon system and the B lymphocyte stimulator (BLyS) having key roles. In addition, a large number of genes have been identified that contribute to these abnormalities. It has also become clear that certain SLE risk genes are associated with some organ manifestations, such as STAT4 with nephritis and IRF8 with myocardial infarction. Furthermore, environmental factors that can induce SLE or trigger a disease flare have been identified. As a consequence of this increased knowledge, new treatments for SLE have been developed. The most recently approved drug for SLE is belimumab, which blocks BLyS, and several new therapies and therapeutic strategies are in the pipeline for clinical application.

Improving B-cell depletion in systemic lupus erythematosus and rheumatoid arthritis

INTRODUCTION

Rituximab-based B-cell depletion (BCD) therapy is effective in refractory rheumatoid arthritis (RA) and although used to treat patients with refractory systemic lupus erythematosus (SLE) in routine clinical practice, rituximab failed to meet the primary endpoints in two large randomised controlled trials (RCTs) of non-renal (EXPLORER) and renal (LUNAR) SLE. Areas covered: We review how BCD could be improved to achieve better clinical responses in RA and SLE. Insights into the variability in clinical response to BCD in RA and SLE may help develop new therapeutic strategies. To this end, a literature search was performed using the following terms: rheumatoid arthritis, systemic erythematosus lupus, rituximab and B-cell depletion. Expert commentary: Poor trial design may have, at least partly, contributed to the apparent lack of response to BCD in the two RCTs of patients with SLE. Enhanced B-cell depletion and/or sequential therapy with belimumab may improve clinical response at least in some patients with SLE.

HM71224, a novel Bruton's tyrosine kinase inhibitor, suppresses B cell and monocyte activation and ameliorates arthritis in a mouse model: a potential drug for rheumatoid arthritis

BACKGROUND

Bruton's tyrosine kinase (Btk) is critical for activation of B cells and myeloid cells. This study aimed to characterize the effects of HM71224, a novel Btk inhibitor, both in vitro and in a mouse model of experimental arthritis.

METHODS

The kinase inhibition profile of HM71224 was analyzed. The in vitro effects of HM71224 on B cells and monocytes were analyzed by examining phosphorylation of Btk and its downstream signaling molecules, along with cytokine production and osteoclast formation. The in vivo effects of HM71224 were investigated in a mouse model of collagen-induced arthritis (CIA).

RESULTS

HM71224 irreversibly bound to and inhibited Btk (IC50 = 1.95 nM). The compound also inhibited the phosphorylation of Btk and its downstream molecules such as PLCγ2, in activated Ramos B lymphoma cells and primary human B cells in a dose-dependent manner. Furthermore, HM71224 effectively inhibited the production of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1β by human monocytes, and osteoclast formation by human monocytes. Finally, HM71224 improved experimental arthritis and prevented joint destruction in a murine model of CIA.

CONCLUSIONS

HM71224 inhibits Btk in B cells and monocytes and ameliorates experimental arthritis in a mouse model. Thus, HM71224 is a potential novel therapeutic agent for rheumatoid arthritis in humans.

Role and regulation of CD1d in normal and pathological B cells

CD1d is a nonpolymorphic, MHC class I-like molecule that presents phospholipid and glycosphingolipid Ags to a subset of CD1d-restricted T cells called invariant NKT (iNKT) cells. This CD1d-iNKT cell axis regulates nearly all aspects of both the innate and adaptive immune responses. Expression of CD1d on B cells is suggestive of the ability of these cells to present Ag to, and form cognate interactions with, iNKT cells. In this article, we summarize key evidence regarding the role and regulation of CD1d in normal B cells and in humoral immunity. We then extend the discussion to B cell disorders, with emphasis on autoimmune disease, viral infection, and neoplastic transformation of B lineage cells, in which CD1d expression can be altered as a mechanism of immune evasion and can have both diagnostic and prognostic importance. Finally, we highlight current and future therapeutic strategies that aim to target the CD1d-iNKT cell axis in B cells.

Etanercept in refractory lupus arthritis: An observational study

OBJECTIVE

To investigate the long-term safety and preliminary efficacy of etanercept in patients with refractory lupus arthritis.

METHODS

We evaluated 43 patients in this observational cohort study. All received etanercept (50mg/week) in addition to concomitant immunosuppressive agents. Patient and disease characteristics were collected. Incidence of adverse events and the effect on autoantibody levels were evaluated. Clinical efficacy was measured by the 28-joint count and the SLEDAI-2K scores. Remission of lupus arthritis was defined by a 28-joint score = 0. Clinically inactive systemic disease was defined by a SLEDAI-2K score <4.

RESULTS

The total follow-up time was 93 patient-years (median: 2.3 years per patient; range: 0.4-6.8 years). Most side effects were minor and related to local reactions. Only 2 significant adverse events occurred (8%), both were of infectious nature. The rate of autoantibody production was low (18%). A mild increase in titres of ANA (2), IgG anti-dsDNA (3) and IgM anticardiolipin (aCL) (2) antibodies was observed. All anti-dsDNA antibody increments were transient and coincided with systemic flares. No vascular events occurred. In general, disease activity declined during therapy. Most patients (83%) with lupus arthritis achieved clinical remission by week 12. All patients with simultaneous serositis experienced clinical and radiological resolution of this condition. Relapses were frequent (23%), mostly mild and related to etanercept reduction. A total of 24 patients discontinued treatment, 12 of them due to clinical remission.

CONCLUSIONS

Long-term therapy with etanercept was relatively safe and had remarkable long-term efficacy for refractory lupus arthritis. In view of these results, further controlled trials are warranted.

Efficacy and safety of rituximab in the treatment of non-renal systemic lupus erythematosus: a systematic review

OBJECTIVE

To analyse the efficacy and safety of rituximab in the treatment of non-renal systemic lupus erythematosus (SLE).

METHODS

We systematically searched MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials up to June 2013. The following were the selection criteria: (1) adult patients with SLE, (2) rituximab treatment, (3) placebo or active comparator, (4) outcome measures assessing efficacy and/or (5) safety. Meta-analysis, systematic literature reviews, randomised control trials (RCT), open clinical trials and cohort studies were included. Independent extraction of articles by 2 authors using predefined data fields was performed. The quality of each study was graded using the Oxford Levels of Evidence and Jadad's scale.

RESULTS

A total of 26 articles met our inclusion criteria: one RCT and its exploratory analysis, 2 open studies and 22 cohort studies, which analysed 1,231 patients. Overall, patients had active disease refractory to steroids and/or immunosuppressant drugs. Acceptable evidence suggested improvements in disease activity, arthritis, thrombocytopaenia, complement and anti-dsDNA, with a steroid-sparing effect. But relapses of disease were demonstrated too. Weak evidence suggested a response in anaemia, cutaneous and neuropsychiatric manifestations. Available evidence revealed few major adverse events. Studies had medium methodological quality and in general were applicable to current practice.

CONCLUSION

Rituximab has been shown to be safe and effective in the treatment of non-renal SLE, especially in terms of disease activity, immunologic parameters and steroid-sparing effect. However, it can only be recommended for organ-specific manifestations such as arthritis and thrombocytopaenia. High-quality studies are needed in order to consider the long-term effects of re-treatment on different organ-specific manifestations.

Treatment of vitiligo with a chimeric monoclonal antibody to CD20: a pilot study

Five patients with active disseminated vitiligo were given 1g of a chimeric (murine/human) monoclonal antibody to CD20 in a single intravenous infusion and followed-up for 6 months. Three of the patients showed an overt clinical and histological improvement of the disease, one presented slight improvement and the remaining patient showed no changes. Improvement was neither associated with changes in laboratory parameters nor to a specific human leucocyte antigen D-related (HLA-DR) phenotype. We believe that these preliminary results are encouraging, and further clinical trials should be undertaken. An important aim should be the finding of a marker with a good response to this therapeutic approach.

Rituximab in dermatology

Rituximab was introduced into clinical practice as a medication with considerable potential. Its use in patients with B-cell lymphoma and rheumatoid arthritis revealed numerous indications in autoimmune diseases, many of which involve the skin, thus requiring dermatologists to become familiar with both the characteristics of anti-CD20 antibodies and the role of B cells in multiple skin diseases. Thanks to these developments, we will be able to use rituximab more frequently and appropriately in our patients and draw up consensus guidelines based on large case series. In other words, establishing the indications for rituximab will make it possible to shorten disease course and reduce morbidity due to more specific drugs.

Rituximab in the treatment of resistant lupus nephritis: therapy failure in rapidly progressive crescentic lupus nephritis

OBJECTIVE

The objective of this paper is to report the clinical outcome of B cell depletion therapy in 18 patients with refractory lupus nephritis (LN).

METHODS

Eighteen patients received rituximab on an open-label basis with prospective evaluations. All patients had renal disease refractory to conventional immunosuppressive therapy, including intravenous cyclophosphamide (CyC). All patients fulfilled the revised ACR classification criteria for SLE. Rituximab was given as 2 × 1 g infusions with 500 mg iv CyC and 500 mg iv methylprednisolone, two weeks apart. Complete remission (CR) of nephritis at six months was defined as normal serum creatinine and serum albumin levels, inactive urine sediment, and proteinuria < 0.5 g/day; partial remission (PR) was defined as a ≥50% improvement in all renal parameters that were abnormal at baseline. Clinical response was assessed by the British Isles Lupus Assessment Group (BILAG) score pre- and post-rituximab treatment, and efficacy was recorded by extent and duration of B lymphocyte depletion (normal range 0.100-0.500 × 10(9)/l). Follow-up data were collected at six months, one year post-treatment and at the most recent clinic visit.

RESULTS

At six months, 11/18 patients reached renal CR and two of 18 PR. The mean global BILAG scores for responders decreased from 15 (SD 10) to 5 (SD 3), and a total of ten A scores disappeared. Five patients failed to show complete or partial renal response despite peripheral B lymphocyte count depletion, and progressed to end-stage renal failure (ESRF) and dialysis. Four of these patients had severe proliferative, crescentic nephritis, of whom three had Class IV-G, one Class III and one late membranous glomerulonephritis. One patient died six years after rituximab therapy from overwhelming sepsis while on long-term haemodialysis.

CONCLUSION

Rituximab therapy achieved a response in 13/18 patients with refractory LN. However, in patients with rapidly progressive crescentic LN, when there is already evidence of significant renal impairment, rituximab therapy may not prevent progression to ESRF and dialysis. Our data also suggest that severe Class IV-G LN may be associated with a poor response to therapy.

Anti B-cell therapy against refractory thrombocytopenia in SLE and MCTD patients: long-term follow-up and review of the literature

OBJECTIVE

The objective of this study was to retrospectively evaluate the clinical and immunological effects of anti-B cell treatment in patients with systemic lupus erythematosus (SLE) and mixed connective-tissue disease (MCTD) with autoimmune thrombocytopenia (AITP) refractory to conventional immunosuppressive treatment.

METHODS

Rituximab (RTX) was added to the ongoing treatment of 16 patients (median age 36 years, range 17-84, all female) with treatment-resistant AITP. Thirteen patients had SLE and three had MCTD. RTX was given intravenously on four occasions during four consecutive weeks at a dose of 375 mg/m(2). Clinical and laboratory disease activity variables recorded at every follow-up visit were analyzed.

RESULTS

The median disease duration before RTX treatment was nine years (range 0.2-27) and the median post-treatment follow-up time was 28 months (range 3 to 92). Ten patients (63%) were treated repeatedly with RTX during the follow-up period. Complete depletion of B cells was achieved in 94% of cases one month after RTX treatment. A significant increase (p = 0.0001) of platelet counts was seen already after one month (median 58 × 10(9)/ml vs 110 × 10(9)/ml) whereas within three months platelet counts normalized in 10 patients (median 223 × 10(9)/ml). Three patients did not respond to RTX treatment (median platelet count 69 × 10(9)/ml). High titers of anti-platelet antibodies were detected in seven patients before RTX treatment, and the autoantibody titers decreased significantly (p < 0.03) after RTX treatment in six of these patients who also achieved complete remission. A review of the literature revealed 24 articles including 18 case reports, one retrospective cohort study and five prospective studies documenting the outcomes of 65 RTX-treated patients with SLE- or MCTD-related thrombocytopenia with an overall treatment response rate of 80%. In conclusion, these findings indicate that RTX is an additional potent therapeutic treatment option for SLE patients with AITP refractory to conventional immunosuppressive treatment whereas best response may be expected in patients with high titers of anti-platelet antibodies at baseline.

Rituximab biosimilars

INTRODUCTION

Rituximab is a monoclonal antibody targeting CD20, used to treat B cell malignancies and B cell-mediated autoimmune diseases. Rituximab has the largest market of any monoclonal antibody therapeutic. Its patent will expire within the next few years and several manufacturers have already produced or are developing rituximab biosimilars that aim to match the innovator rituximab as closely as possible.

AREAS COVERED

In this review, we discuss key factors that determine the efficacy of rituximab therapy, potential technical challenges in the manufacture and evaluation of biosimilars, regulatory considerations regarding the review and approval of biosimilars, and the current status of biosimilar rituximab development by various manufacturers. Due to the nature of the topic, literature searches included conference abstracts, regulatory and industry websites as well as peer reviewed literature.

EXPERT OPINION

Cost is a key limitation of current biologics usage and there is a political impetus to the licensing of biosimilars. Concerns regarding potential dissimilarities of biosimilars are legitimate, but surmountable with techniques for in vitro, in vivo and clinical testing and more clearly defined regulatory requirements. These should provide reassurance to prescribers. However, the cost of manufacturing and licensing a biosimilar remains high and the reduction in cost may be more limited than for a non-biologic small molecule drug and its generic version. This cost reduction will be critical to the impact and use of rituximab biosimilars.

B-cell depletion in SLE: clinical and trial experience with rituximab and ocrelizumab and implications for study design

B cells are believed to be central to the disease process in systemic lupus erythematosus (SLE), making them a target for new therapeutic intervention. In recent years there have been many publications regarding the experience in SLE of B-cell depletion utilising rituximab, an anti-CD20 mAb that temporarily depletes B cells,reporting promising results in uncontrolled open studies and in routine clinical use. However, the two large randomised controlled trials in extra-renal lupus (EXPLORER study) and lupus nephritis (LUNAR study) failed to achieve their primary endpoints. Based on the clinical experience with rituximab this failure was somewhat unexpected and raised a number of questions and concerns, not only into the true level of benefit of B-cell depletion in a broad population but also how to test the true level of effectiveness of an investigational agent as we seek to improve the design of therapeutic trials in SLE. A better understanding of what went wrong in these trials is essential to elucidate the underlying reasons for the disparate observations noted in open studies and controlled trials. In this review, we focus on various factors that may affect the ability to accurately and confidently establish the level of treatment effect of the investigational agent, in this case rituximab, in the tw studies and explore hurdles faced in the randomised controlled trials investigating the efficacy of ocrelizumab, the humanised anti-CD20 mAb, in SLE. Further, based on the lessons learned from the clinical trials, we make suggestions that could be implemented in future clinical trial design to overcome the hurdles faced.

B cell biomarkers of rituximab responses in systemic lupus erythematosus

OBJECTIVE

Rituximab appears to be effective in many studies of systemic lupus erythematosus (SLE), with variable initial clinical response and time to relapse. However, results of a randomized controlled trial of rituximab were negative. This study was undertaken to evaluate the effectiveness of rituximab in SLE, using highly sensitive flow cytometry (HSFC), which can define B cell numbers 50-100 times lower than conventional techniques and predicts responses in rheumatoid arthritis.

METHODS

Thirty-nine patients with active SLE were started on a standard regimen of rituximab with intravenous and oral steroids. Clinical response and relapse were defined using the British Isles Lupus Assessment Group (BILAG) index with criteria for major clinical response, partial clinical response, and nonresponse. HSFC, including analysis of B cell subsets, was performed.

RESULTS

There was a significant reduction from baseline in global BILAG score at all time points analyzed (P<0.0001), and major clinical response and partial clinical response rates were 51% and 31%, respectively. Time to relapse was highly variable. Fifty percent of the patients relapsed after 6-18 months (earlier relapse); the remainder relapsed at a slower rate (later relapse). B cell depletion and repopulation were variable and were predictive of these clinical outcomes. There was a persistent B cell presence in 21 patients after 2 infusions of rituximab, which included all 7 patients with no response (P=0.012 versus patients with complete depletion of B cells). Memory B cell (P=0.02) and plasmablast (P<0.001) repopulation after 26 weeks was markedly faster in patients with earlier relapse versus patients with later relapse.

CONCLUSION

Our findings indicate that rituximab is effective in SLE, and clinical responses are supported by close correlation with B cell numbers. HSFC is a valuable tool in the assessment and prediction of response in SLE.

B-cell targeted therapy in systemic lupus erythematosus: potential of rituximab

Systemic lupus erythematosus (SLE) is a complex autoimmune disease of unknown etiology, and the limited available therapeutic options for this disease, are frustrating to both clinicians and patients. However, recent advances in the understanding of disease mechanisms have given rise to numerous studies on specific approaches to SLE treatment. Rituximab, the first chimeric, mouse-human monoclonal antibody which is directed against CD20, seems to be a new therapeutic option. The purpose of this review is to explain the current clinical evidence on the therapeutic use of rituximab in adult SLE patients. Two randomized clinical trials with rituximab (the EXPLORER and LUNAR studies) failed to prove efficacy of this drug on SLE. Ongoing data analysis continues to explain the reasons behind why this treatment fails to work. However data from open source and observational studies contrast with clinical trials results. The global analysis of this data supports the off-label use of rituximab in subsets of SLE that are refractory to standard treatment.

Multicenter longitudinal study of B-lymphocyte depletion in refractory systemic lupus erythematosus: the LESIMAB study

OBJECTIVE

This study aimed to investigate the effectiveness and safety of single and repeated courses of rituximab in patients with refractory lupus.

METHODS

LESIMAB is a multicenter, retrospective, longitudinal study of lupus patients who have not responded to standard therapy and have been treated with rituximab. Response rates at six months and at follow-up were defined as efficacy outcomes. Complete response was defined as a SELENA-SLEDAI score ≤ two and a SELENA-SLEDAI Flare Index of zero. Partial response was defined as a reduction in the SELENA-SLEDAI score of ≥four points with no new or worsening of symptoms. Adverse events were collected.

RESULTS

Seventy-three (62.9%) of 116 patients achieved a response at six months (complete in 22 and partial in 51). Ninety-seven (77.6%) of 128 patients achieved a response after a mean follow-up of 20.0 ± 15.2 months (complete in 50 and partial in 47). High baseline SLEDAI score, previous treatment with ≥100 mg/day prednisone, and no history of severe hematologic flare were associated with response after the first treatment course. The median time to response was 6.5 months (95% CI, 5.0-8.0). Thirty-seven patients (38.1%) relapsed after the first infusion. The flare was severe in seven cases and mild to moderate in 29 cases. Serious infection rate was 12.6/100 patient-years. A schedule of four weekly doses was associated with more serious infections. Six patients died: two of infection and four of lupus complications.

CONCLUSION

Rituximab can be an effective treatment option for patients who have refractory lupus with severe or life-threatening disease with an acceptable tolerance profile.

Taming lupus-a new understanding of pathogenesis is leading to clinical advances

Systemic lupus erythematosus (SLE) is an autoimmune disease that is characterized by the loss of tolerance to nuclear self antigens, the production of pathogenic autoantibodies and damage to multiple organ systems. Over the years, patients with SLE have been managed largely with empiric immunosuppressive therapies, which are associated with substantial toxicities and do not always provide adequate control of the disease. The development of targeted therapies that specifically address disease pathogenesis or progression has lagged, largely because of the complex and heterogeneous nature of the disease, as well as difficulties in designing uniform outcome measures for clinical trials. Recent advances that could improve the treatment of SLE include the identification of genetic variations that influence the risk of developing the disease, an enhanced understanding of innate and adaptive immune activation and regulation of tolerance, dissection of immune cell activation and inflammatory pathways and elucidation of mechanisms and markers of tissue damage. These discoveries, together with improvements in clinical trial design, form a platform from which to launch the development of a new generation of lupus therapies.

Lipid-antigen presentation by CD1d(+) B cells is essential for the maintenance of invariant natural killer T cells

B cells perform many immunological functions, including presenting lipid antigen to CD1d-restricted invariant natural killer T (iNKT) cells, known to contribute to maintaining tolerance in autoimmunity. Patients with systemic lupus erythematous (SLE) display dysregulated B cell responses and reduced peripheral iNKT cell frequencies. The significance of these defects and how they relate to SLE pathogenesis remain elusive. We report that B cells are essential for iNKT cell expansion and activation in healthy donors but fail to exert a similar effect in SLE patients. Defective B cell-mediated stimulation of iNKT cells in SLE patients was associated with altered CD1d recycling, a defect recapitulated in B cells from healthy donors after stimulation with interferon-α (IFN-α) and anti-immunoglobulin (Ig). iNKT cell number and function were restored in SLE patients responding to anti-CD20 treatment upon normalization of CD1d expression exclusively in repopulated immature B cells. We propose that healthy B cells are pivotal for iNKT cell homeostasis.

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

OBJECTIVE

To evaluate the efficacy and safety of rituximab in a randomized, double-blind, placebo-controlled phase III trial in patients with lupus nephritis treated concomitantly with mycophenolate mofetil (MMF) and corticosteroids.

METHODS

Patients (n = 144) with class III or class IV lupus nephritis were randomized 1:1 to receive rituximab (1,000 mg) or placebo on days 1, 15, 168, and 182. The primary end point was renal response status at week 52.

RESULTS

Rituximab depleted peripheral CD19+ B cells in 71 of 72 patients. The overall (complete and partial) renal response rates were 45.8% among the 72 patients receiving placebo and 56.9% among the 72 patients receiving rituximab (P = 0.18); partial responses accounted for most of the difference. The primary end point (superior response rate with rituximab) was not achieved. Eight placebo-treated patients and no rituximab-treated patients required cyclophosphamide rescue therapy through week 52. Statistically significant improvements in serum complement C3, C4, and anti-double-stranded DNA (anti-dsDNA) levels were observed among patients treated with rituximab. In both treatment groups, a reduction in anti-dsDNA levels greater than the median reduction was associated with reduced proteinuria. The rates of serious adverse events, including infections, were similar in both groups. Neutropenia, leukopenia, and hypotension occurred more frequently in the rituximab group.

CONCLUSION

Although rituximab therapy led to more responders and greater reductions in anti-dsDNA and C3/C4 levels, it did not improve clinical outcomes after 1 year of treatment. The combination of rituximab with MMF and corticosteroids did not result in any new or unexpected safety signals.

Translational Mini-Review Series on B cell subsets in disease. Transitional B cells in systemic lupus erythematosus and Sjögren's syndrome: clinical implications and effects of B cell-targeted therapies

Systemic lupus erythematosus (SLE) and Sjögren's syndrome are autoimmune disorders which are characterized by a disturbed B cell homeostasis which leads ultimately to dysfunction of various organs. One of the B cell subsets that appear in abnormal numbers is the population of transitional B cells, which is increased in the blood of patients with SLE and Sjögren's syndrome. Transitional B cells are newly formed B cells. In mice, transitional B cells undergo selection checks for unwanted specificity in the bone marrow and the spleen in order to eliminate autoreactive B cells from the circulating naive B cell population. In humans, the exact anatomical compartments and mechanisms of the specificity check-points for transitional B cells remain unclear, but appear to be defective in SLE and Sjögren's syndrome. This review aims to highlight the current understanding of transitional B cells and their defects in the two disorders before and after B cell-targeted therapies.

Rituximab therapy in refractory neuropsychiatric lupus: current clinical evidence

OBJECTIVE

To review and summarize published information on the effectiveness and safety of rituximab (RTX) in adult patients with refractory neuropsychiatric systemic lupus erythematosus (NPSLE).

METHODS

We describe a patient with persistently active NPSLE, despite conventional therapy, who responded dramatically to RTX. Current evidence on the therapeutic use of RTX in this complex situation is also analyzed through a systematic review of the English-language literature, based on a PubMed search.

RESULTS

Available data on the use of RTX in refractory NPSLE come from a large number of case reports and some open-label studies. Including our case, 35 patients have been well documented. A complete or partial therapeutic response was achieved in 85% of patients after 1 cycle of treatment. A positive correlation between serological markers of disease activity and clinical outcome has also been demonstrated in some of these patients. Clinical improvement was accompanied by a significant reduction in the daily dose of oral corticosteroids. Relapse after RTX treatment was noted in 45% of cases (median 9.5 months; range, 4-33 months). Infections were observed in 29% of patients.

CONCLUSION

Evidence for the effectiveness of RTX as induction therapy in NPSLE is based solely on several case reports and noncontrolled trials. Although it is not yet possible to make definite recommendations, the global analysis of these cases supports the off-label use of RTX in cases of severe refractory NPSLE.