B-cell numbers and phenotype at clinical relapse following rituximab therapy differ in SLE patients according to anti-dsDNA antibody levels

Evolution and trajectory of B-cell targeted therapies in rheumatic diseases

Aberrant B-cell function, which could arise from various underlying causes, is central to the pathogenesis of diverse autoimmune rheumatic diseases. B cells remain the only cell type to be specifically therapeutically targeted through depletion and have the only therapy with a routinely available flow cytometric biomarker of treatment. Since first use and subsequent licensing for rheumatoid arthritis, rituximab has had a transformative impact on patients globally and across the rheumatic diseases. Further insights from B-cell-activating factor (BAFF) blockade with belimumab in systemic lupus erythematosus have followed. Examination of B-cell depletion, clinical outcomes, and re-emergent disease after treatment have deepened our understanding of the identity, detailed phenotype, biology, and kinetics of the B-cell subsets that are central to disease. This Review reflects on 20 years of clinical and translational insights drawn from B-cell targeted therapies for adult autoimmune rheumatic diseases, and highlights how these therapies have informed an exciting new era of future therapeutic developments.

Synthetic receptor-based cell therapies for autoimmune diseases: an update

Increasing frequency of autoimmune diseases is one of the major problems in modern societies. Despite the introduction of new therapeutic agents for autoimmunity over the past several decades, more progress is needed. Synthetic receptor-based cell therapies are being adopted as an option for treating autoimmune diseases from the field of oncology. Currently evaluated strategies can be summarized into two approaches. The first one is the elimination of autoreactive cells by targeting them, for example, with CAR-T or CAAR-T cells. The second is based on rebalancing the proinflammatory milieu with engineered immunosuppressive cells, for example, CAR-Treg. Both approaches can be supplemented with the use of synthetic systems such as Split-CAR, SynNotch, MESA, GEMS, and SNIPR, or prospective off-the-shelf approaches, for example, in situ use of the in vitro transcribed mRNA, ultimately allowing for enhanced efficacy and safety. The primary goal of our review is to provide some perspective on both strategies in basic, translational, and clinical studies with all their advantages and disadvantages to allow for informed future design of adoptive cell therapies for autoimmune diseases.

Efficacy and safety of sequential therapy with subcutaneous belimumab and one cycle of rituximab in patients with systemic lupus erythematosus: the phase 3, randomised, placebo-controlled BLISS-BELIEVE study

OBJECTIVES

Disease activity control in patients with systemic lupus erythematosus (SLE) with corticosteroid and immunosuppressant withdrawal is a treatment goal. We evaluated whether this could be attained with sequential subcutaneous belimumab (BEL) and one cycle of rituximab (RTX).

METHODS

In this phase 3, double-blind BLISS-BELIEVE trial (GSK Study 205646), patients with active SLE initiating subcutaneous BEL 200 mg/week for 52 weeks were randomised to intravenous placebo (BEL/PBO) or intravenous RTX 1000 mg (BEL/RTX) at weeks 4 and 6 while stopping concomitant immunosuppressants/tapering corticosteroids; standard therapy for 104 weeks (BEL/ST; reference arm) was included.

PRIMARY ENDPOINT

proportion of patients achieving disease control (SLE Disease Activity Index-2000 (SLEDAI-2K) ≤2; without immunosuppressants; prednisone equivalent ≤5 mg/day) at week 52 with BEL/RTX versus BEL/PBO. Major (alpha-controlled) secondary endpoints: proportion of patients with clinical remission (week 64; clinical SLEDAI-2K=0, without immunosuppressants/corticosteroids); proportion of patients with disease control (week 104). Other assessments: disease control duration, anti-dsDNA antibody, C3/C4 and B cells/B-cell subsets.

RESULTS

The modified intention-to-treat population included 263 patients. Overall, 16.7% (12/72) of BEL/PBO and 19.4% (28/144) of BEL/RTX patients achieved disease control (OR (95% CI) 1.27 (0.60 to 2.71); p=0.5342) at week 52. For major secondary endpoints, differences between BEL/RTX and BEL/PBO were not statistically significant. Anti-dsDNA antibodies and most assessed B cells/B-cell subsets were lower with BEL/RTX versus BEL/PBO. Mean disease control duration through 52 weeks was significantly greater with BEL/RTX versus BEL/PBO.

CONCLUSIONS

BEL/RTX showed no superiority over BEL/PBO for most endpoints analysed; however, it led to significant improvements in disease activity markers compared with BEL/PBO. Further investigation of combination treatment is warranted.

TRIAL REGISTRATION NUMBER

NCT03312907.

Sustained depression of B cell counts in lupus nephritis after treatment with rituximab and/or belimumab is associated with fewer disease flares

OBJECTIVE

To study the risk of lupus nephritis flare (LNF) or severe lupus flare (SLF) as a function of B cell count kinetics in lupus nephritis (LN) patients after they achieve at least a partial renal response (PRR) with induction treatment that includes rituximab (RTX) and/or belimumab (BLM).

METHODS

We performed a retrospective analysis of a cohort of 19 patients with severe LN that received a B cell agent (BCA), RTX and/or BLM, as part of an initial treatment regimen for an LN flare and had subsequent CD19+ B cell measurements in peripheral blood. We then characterized the follow-up periods, after B cell depressions occurred and PRR were achieved, by the corresponding trajectories of B cell counts (BCC). Time periods with sustained low BCC were type 1 (T1) episodes, while those with repletion of BCC>100 cells/μL were called type 2 (T2) episodes. Time periods with rapid BCC repletion, defined as >50 cells/μL in ≤6 months, were called T2b episodes. Corresponding C3, C4, and anti-dsDNA levels were recorded for each episode. The time from PRR until an event, either a LNF or SLF, or to censoring, either at the end of the study period or the end of available patient follow-up, was assessed for each episode type. Kaplan-Meier survival analysis was used to compare time to flare between T1 and T2 episodes.

RESULTS

There were 26 episodes of B cell depression. Seventeen (65%) were T1 and 9 (35%) were T2. Compared to T1 episodes, T2 episodes were 9.0 times more likely to result in flare over the follow-up period (hazard ratio (HR) = 9.0, 95% CI for HR = 2.2-36.7); this risk was even larger for T2b vs T1 episodes. Median BCC was 14 cells/μL in T1 and 160 cells/μL in T2 episodes. Both C3 and C4 levels significantly increased over the duration of the episode in T1 episodes only.

CONCLUSION

Sustained low BCC was associated with prolonged serologic and clinical response, whereas repletion, and particularly rapid repletion, of B cells after treatment with BCA was associated with subsequent disease flare.

Anticoagulant and non-anticoagulant therapy in thrombotic antiphospholipid syndrome: old drugs and new treatment targets

In this review, we discuss the current evidence on classic and newer oral anticoagulant therapy, older drugs such as HCQ and statins, and new potential treatment targets in APS. Vitamin K antagonists (VKAs) remain the cornerstone treatment for thrombotic events in APS. In patients fulfilling criteria for definite APS presenting with a first venous thrombosis, treatment with VKAs with a target international normalized ratio (INR) 2.0-3.0 is recommended. In patients with arterial thrombosis, treatment with VKA with target INR 2.0-3.0 or 3.0-4.0 is recommended by recent guidelines, considering the individual's bleeding and thrombosis recurrence risk. A combination of VKAs and low-dose aspirin (75-100 mg/daily) may also be considered. According to available evidence direct oral anticoagulants should be avoided in patients with arterial thrombosis and/or those with triple aPL positivity. Adjunctive treatment with HCQ and/or statins can be considered, especially in anticoagulation treatment-refractory APS. Potential targeted treatments in APS include B-cell targeting, complement inhibition, mammalian target of rapamycin inhibition, IFN targeting, adenosine receptors agonists, CD38 targeting or chimeric antigen receptor T-cell therapy. The safety and efficacy of these treatment targets needs to be examined in well-designed randomized controlled trials.

A cell-level discriminative neural network model for diagnosis of blood cancers

MOTIVATION

Precise identification of cancer cells in patient samples is essential for accurate diagnosis and clinical monitoring but has been a significant challenge in machine learning approaches for cancer precision medicine. In most scenarios, training data are only available with disease annotation at the subject or sample level. Traditional approaches separate the classification process into multiple steps that are optimized independently. Recent methods either focus on predicting sample-level diagnosis without identifying individual pathologic cells or are less effective for identifying heterogeneous cancer cell phenotypes.

RESULTS

We developed a generalized end-to-end differentiable model, the Cell Scoring Neural Network (CSNN), which takes sample-level training data and predicts the diagnosis of the testing samples and the identity of the diagnostic cells in the sample, simultaneously. The cell-level density differences between samples are linked to the sample diagnosis, which allows the probabilities of individual cells being diagnostic to be calculated using backpropagation. We applied CSNN to two independent clinical flow cytometry datasets for leukemia diagnosis. In both qualitative and quantitative assessments, CSNN outperformed preexisting neural network modeling approaches for both cancer diagnosis and cell-level classification. Post hoc decision trees and 2D dot plots were generated for interpretation of the identified cancer cells, showing that the identified cell phenotypes match the cancer endotypes observed clinically in patient cohorts. Independent data clustering analysis confirmed the identified cancer cell populations.

AVAILABILITY AND IMPLEMENTATION

The source code of CSNN and datasets used in the experiments are publicly available on GitHub (http://github.com/erobl/csnn). Raw FCS files can be downloaded from FlowRepository (ID: FR-FCM-Z6YK).

Anti-topoisomerase 1 Antibody Level Changes after B Cell Depletion Therapy in Systemic Sclerosis

The aim of our study was to assess the relationship between the changes of antinuclear autoantibodies (ANAs) and autoantibodies to topoisomerase 1 (anti-Topo 1) in systemic sclerosis (SSs) patients on rituximab (RTX) therapy. The prospective study included 88 patients (73 women) with a mean age of 47 (17-71) years. The mean disease duration was 5.9 ± 4.8 years. The mean follow-up period was more than 2 years (27 (12-42) months). We documented a statistically significant change in skin score, the disease activity index, improvement of pulmonary function and reduction of mean dose of prednisolone after RTX treatment. There was a significant decrease in the number of patients with high levels of ANA and overall decrease of the ANA and anti-Topo 1 levels. A moderate positive statistically significant correlation was found between ANA and anti-Topo 1 (r = 0.403). In the group of patients positive for anti-Topo 1 there were a more pronounced depletion of B lymphocytes, significantly higher increase in forced vital capacity and diffusion capacity, decrease in the disease activity index, compared with patients negative for anti-Topo 1. We observed the decline in the level of ANA and anti-Topo 1 in SSc patients after RTX therapy, and it was correlated by an improvement of the main outcome parameters of the disease. Therefore, anti-Topo 1 positivity could be considered as a predictor of a better response to RTX treatment, especially in SSc patients with hyperproduction of anti-Topo 1.

Promising Experimental Treatments for Lupus Nephritis: Key Talking Points and Potential Opportunities

Lupus nephritis (LN) is a frequent and serious complication of systemic lupus erythematosus (SLE), impairing patients' quality of life and significantly increasing mortality. Despite optimizing the use of conventional immunosuppressants and other biological drugs, its management remains unsatisfactory. This is mainly due to the heterogeneity of SLE, but also to insufficiently effective treatment regimens and clinical trial limitations (strict criteria, low number of patients included, and side effects). Most clinical trials of new biological therapies have failed to meet their primary endpoints in both general SLE and LN, with only two biological drugs (belimumab and anifrolumab) being approved by the Food and Drug Administration (FDA) for the treatment of SLE. Recently, several Phase II randomized controlled trials have evaluated the efficacy and safety of new biologics in LN, and some of them have demonstrated an improvement in clinical and laboratory measures. Multi-target therapies are also being successfully developed and encourage a belief that there will be an improvement in LN outcomes.

Current Treatment Approach, Emerging Therapies and New Horizons in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE), the prototype of systemic autoimmune diseases is characterized by extreme heterogeneity with a variable clinical course. Renal involvement may be observed and affects the outcome. Hydroxychloroquine should be administered to every lupus patient irrespective of organ involvement. Conventional immunosuppressive therapy includes corticosteroids, methotrexate, cyclophosphamide, mycophenolate mofetil, azathioprine, cyclosporine and tacrolimus. However, despite conventional immunosuppressive treatment, flares occur and broad immunosuppression is accompanied by multiple side effects. Flare occurrence, target organ involvement, side effects of broad immunosuppression and increased knowledge of the pathogenetic mechanisms involved in SLE pathogenesis as well as the availability of biologic agents has led to the application of biologic agents in SLE management. Biologic agents targeting various pathogenetic paths have been applied. B cell targeting agents have been used successfully. Belimumab, a B cell targeting agent, has been approved for the treatment of SLE. Rituximab, an anti-CD20 targeting agent is also used in SLE. Anifrolumab, an interferon I receptor-targeting agent has beneficial effects on SLE. In conclusion, biologic treatment is applied in SLE and should be further evaluated with the aim of a good treatment response and a significant improvement in quality of life.

Treatment of lupus nephritis: consensus, evidence and perspectives

Despite the continuing development of immunomodulatory agents and supportive care, the prognosis associated with lupus nephritis (LN) has not improved substantially in the past decade, with end-stage kidney disease still developing in 5-30% of patients within 10 years of LN diagnosis. Moreover, inter-ethnic variation in the tolerance of, clinical response to and level of evidence regarding various therapeutic regimens for LN has led to variation in treatment prioritization in different international recommendations. Modalities that better preserve kidney function and reduce the toxicities of concomitant glucocorticoids are unmet needs in the development of therapeutics for LN. In addition to the conventional recommended therapies for LN, there are newly approved treatments as well as investigational drugs in the pipeline, including the newer generation calcineurin inhibitors and biologic agents. In view of the heterogeneity of LN in terms of clinical presentation and prognosis, the choice of therapies depends on a number of clinical considerations. Molecular profiling, gene-signature fingerprints and urine proteomic panels might enhance the accuracy of patient stratification for treatment personalization in the future.

A cell-level discriminative neural network model for diagnosis of blood cancers

Motivation

Precise identification of cancer cells in patient samples is essential for accurate diagnosis and clinical monitoring but has been a significant challenge in machine learning approaches for cancer precision medicine. In most scenarios, training data are only available with disease annotation at the subject or sample level. Traditional approaches separate the classification process into multiple steps that are optimized independently. Recent methods either focus on predicting sample-level diagnosis without identifying individual pathologic cells or are less effective for identifying heterogeneous cancer cell phenotypes.

Results

We developed a generalized end-to-end differentiable model, the Cell Scoring Neural Network (CSNN), which takes the available sample-level training data and predicts both the diagnosis of the testing samples and the identity of the diagnostic cells in the sample, simultaneously. The cell-level density differences between samples are linked to the sample diagnosis, which allows the probabilities of individual cells being diagnostic to be calculated using backpropagation. We applied CSNN to two independent clinical flow cytometry datasets for leukemia diagnosis. In both qualitative and quantitative assessments, CSNN outperformed preexisting neural network modeling approaches for both cancer diagnosis and cell-level classification. Post hoc decision trees and 2D dot plots were generated for interpretation of the identified cancer cells, showing that the identified cell phenotypes match the cancer endotypes observed clinically in patient cohorts. Independent data clustering analysis confirmed the identified cancer cell populations.

Availability

The source code of CSNN and datasets used in the experiments are publicly available on GitHub and FlowRepository.

Contact

Edgar E. Robles: roblesee@uci.edu and Yu Qian: mqian@jcvi.org.

Supplementary information

Supplementary data are available on GitHub and at Bioinformatics online.

B cell depletion therapies in autoimmune diseases: Monoclonal antibodies or chimeric antigen receptor-based therapy?

Immune system detects foreign pathogens, distinguishes them from self-antigens and responds to defend human body. When this self-tolerance is disrupted, the overactive immune system attacks healthy tissues or organs and the autoimmune diseases develop. B cells and plasma cells contribute a lot to pathogenesis and persistence of autoimmune diseases in both autoantibody-dependent and autoantibody-independent ways. Accumulating data indicates that treatments aiming to eliminate antibody-secreting cells (B cells or plasma cells) are effective in a wide spectrum of autoimmune diseases. Monoclonal antibodies (mAbs) deplete B cell lineage or plasma cells by signaling disruption, complement-dependent cytotoxicity (CDC) and antibody-dependent cellular cytotoxicity (ADCC). Engineered-T cells armed with chimeric antigen receptors (CARs) have been adopted from field of hematological malignancies as a method to eliminate B cells or plasma cells. In this review, we update our understanding of B cell depletion therapies in autoimmune diseases, review the mechanism, efficacy, safety and application of monoclonal antibodies and CAR-based immunotherapies, and discuss the strengths and weaknesses of these treatment options for patients.

The rapid inhibition of B-cell activation markers by belimumab was associated with disease control in systemic lupus erythematosus patients

Objective: To examine the kinetics of B cell subsets and activation markers in the early stage of belimumab treatment and their correction with treatment response. Methods: We enrolled 27 systemic lupus erythematosus (SLE) patients receiving 6 months belimumab treatment. Flow cytometry was used to test their B cell subsets and activation markers (including CD40, CD80, CD95, CD21^low, CD22, p-SYK and p-AKT). Results: During belimumab treatment, SLEDAI-2K declined, the proportions of CD19⁺ B cells and naïve B cells decreased, whereas the switched memory B cells and non-switched B cells increased. The larger variations of the B cell subsets and the activation markers were in the first 1 month than the other later time frames. The ratio of p-SYK/p-AKT on non-switched B cell at 1 month was associated with the SLEDAI-2K decline rate in the 6 months of belimumab treatment. Conclusion: B cell hyperactivity was rapidly inhibited in the early stage of belimumab treatment, and the ratio of p-SYK/p-AKT may predict SLEDAI-2K decline. Clinical Trial Registration: https://www.clinicaltrials.gov/ct2/show/NCT04893161?term=NCT04893161&draw=2&rank=1; identifier: NCT04893161.

Dual B-cell targeting therapy ameliorates autoimmune cholangitis

OBJECTIVE

The ability to regulate B cell development has long been recognized to have therapeutic potential in a variety of autoimmune diseases. However, despite the presence of a classic autoantibody in primary biliary cholangitis (PBC), B cell depleting therapy and indeed therapy with other biologic agents has been disappointing. Unsuccessful treatment using Rituximab is associated with elevation of B-cell activating factor (BAFF) level. Indeed, therapies for PBC remain directed at modulating bile salt biology, rather than targeting effector pathways. With these data in mind, we proposed that targeting two major stages of B cell development, namely long-lived memory B cells and short-lived peripheral autoreactive plasma cells would have therapeutic potential.

METHODS

To address this thesis, we administrated anti-BAFF and anti-CD20 monoclonal antibody to ARE-Del mice, a well-characterized murine model of human PBC. We evaluated and compared the therapeutic efficacy of the two agents individually and the combination of anti-BAFF and anti-CD20 in female mice with well-established disease.

RESULTS

Our data demonstrate that there was an increased level of B cell depletion that resulted in a significantly more effective clinical and serologic response using the combination of agents as compared with the use of the individual agents. The combination of anti-BAFF and anti-CD20 treatment was more effective in reducing serum levels of antimitochondrial antibody (AMA), total IgM and IgG compared to mice treated with the 2 individual agents. Combination treatment efficiently depleted B cells in the peripheral blood, peritoneal cavity and spleen. Importantly, we identified a unique IgM+ FCRL5+ B cell subset which was sensitive to dual B-cell targeting therapy and depletion of this unique population was associated with reduced portal infiltration and bile duct damage. Taken together, our data indicate that dual B cell targeting therapy with anti-BAFF and anti-CD20 not only led to the efficient depletion of B cells both in the peripheral blood and tissues, but also led to significant clinical improvement. These findings highlight the potential application of combination of anti-BAFF and anti-CD20 in treating patients with PBC. However, additional studies in other animal models of PBC should be undertaken before considering human trials in those PBC patients who have incomplete responses to conventional therapy.

Keratinocytes: From passive targets to active mediators of systemic autoimmunity

Keratinocyte-mediated interferon production in nonlesional skin drives activation of CD16+ dendritic cells and is associated with cutaneous inflammation in lupus (Billi et al.).

Effectiveness of Belimumab After Rituximab in Systemic Lupus Erythematosus : A Randomized Controlled Trial

BACKGROUND

B-cell depletion with rituximab is commonly used for patients with systemic lupus erythematosus (SLE) that is refractory to conventional therapy, but it yields variable responses. We hypothesized that high B-cell activating factor (BAFF) levels after rituximab can cause disease flares, thereby limiting its effectiveness.

OBJECTIVE

To obtain preliminary evidence for efficacy of the anti-BAFF therapeutic belimumab after rituximab in SLE.

DESIGN

Phase 2, randomized, double-blind (patients, assessors, researchers, care providers), placebo-controlled, parallel-group, superiority trial. (ISRCTN: 47873003).

SETTING

England.

PARTICIPANTS

Fifty-two patients who had SLE that was refractory to conventional treatment and whose physicians had recommended rituximab therapy were recruited between 2 February 2017 and 28 March 2019.

INTERVENTION

Participants were treated with rituximab and 4 to 8 weeks later were randomly assigned (1:1) to receive intravenous belimumab or placebo for 52 weeks.

MEASUREMENTS

The prespecified primary end point was serum IgG anti-double-stranded DNA (anti-dsDNA) antibody levels at 52 weeks. Secondary outcomes included incidence of disease flares and adverse events.

RESULTS

At 52 weeks, IgG anti-dsDNA antibody levels were lower in patients treated with belimumab compared with placebo (geometric mean, 47 [95% CI, 25 to 88] vs. 103 [CI, 49 to 213] IU/mL; 70% greater reduction from baseline [CI, 46% to 84%]; P < 0.001). Belimumab reduced risk for severe flare (BILAG-2004 grade A) compared with placebo (hazard ratio, 0.27 [CI, 0.07 to 0.98]; log-rank P = 0.033), with 10 severe flares in the placebo group and 3 in the belimumab group. Belimumab did not increase incidence of serious adverse events. Belimumab significantly suppressed B-cell repopulation compared with placebo (geometric mean, 0.012 [CI, 0.006 to 0.014] vs. 0.037 [CI, 0.021 to 0.081] × 10⁹/L) at 52 weeks in a subset of patients (n = 25) with available data.

LIMITATIONS

Small sample size; biomarker primary end point.

CONCLUSION

Belimumab after rituximab significantly reduced serum IgG anti-dsDNA antibody levels and reduced risk for severe flare in patients with SLE that was refractory to conventional therapy. The results suggest that this combination could be developed as a therapeutic strategy.

PRIMARY FUNDING SOURCE

Versus Arthritis.

B cell depletion therapies in autoimmune disease: advances and mechanistic insights

In the past 15 years, B cells have been rediscovered to be not merely bystanders but rather active participants in autoimmune aetiology. This has been fuelled in part by the clinical success of B cell depletion therapies (BCDTs). Originally conceived as a method of eliminating cancerous B cells, BCDTs such as those targeting CD20, CD19 and BAFF are now used to treat autoimmune diseases, including systemic lupus erythematosus and multiple sclerosis. The use of BCDTs in autoimmune disease has led to some surprises. For example, although antibody-secreting plasma cells are thought to have a negative pathogenic role in autoimmune disease, BCDT, even when it controls the disease, has limited impact on these cells and on antibody levels. In this Review, we update our understanding of B cell biology, review the results of clinical trials using BCDT in autoimmune indications, discuss hypotheses for the mechanism of action of BCDT and speculate on evolving strategies for targeting B cells beyond depletion.

A reverse translational study on the effect of rituximab, rituximab plus belimumab, or bortezomib on the humoral autoimmune response in SLE

Objectives

SLE is a severe autoimmune disease characterized by autoreactive B cells and IC formation, which causes systemic inflammation. B cell–targeted therapy could be a promising treatment strategy in SLE patients; nevertheless, randomized clinical trials have not always been successful. However, some groups have demonstrated beneficial effects in severe SLE patients with off-label rituximab (RTX) with belimumab (BLM), or bortezomib (BTZ), which targeted different B cells subsets. This study assembled sera from SLE cohorts treated with RTX+BLM (n = 15), BTZ (n = 11) and RTX (n = 16) to get an in-depth insight into the immunological effects of these therapies on autoantibodies and IC formation.

Methods

Autoantibodies relevant for IC formation and the avidity of anti-dsDNA were determined by ELISA. IC-mediated inflammation was studied by complement levels and ex vivo serum-induced neutrophil extracellular trap formation.

Results

Reductions in autoantibodies were observed after all approaches, but the spectrum differed depending upon the treatment. Specifically, only RTX+BLM significantly decreased anti-C1q. Achieving seronegativity of ≥1 autoantibody, specifically anti-C1q, was associated with lower disease activity. In all SLE patients, the majority of anti-dsDNA autoantibodies had low avidity. RTX+BLM significantly reduced low-, medium- and high-avidity anti-dsDNA, while RTX and BTZ only significantly reduced medium avidity. IC-mediated inflammation, measured by C3 levels and neutrophil extracellular trap formation, improved after RTX+BLM and RTX but less after BTZ.

Conclusion

This study demonstrated the impact of different B cell–targeted strategies on autoantibodies and IC formation and their potential clinical relevance in SLE.

Safety and efficacy of belimumab after B cell depletion therapy in systemic LUPUS erythematosus (BEAT-LUPUS) trial: statistical analysis plan

Background

There is limited evidence that rituximab, a B cell depletion therapy, is an effective treatment for systemic lupus erythematosus (SLE). Data on the mechanisms of B cell depletion in SLE indicate that the combination of rituximab and belimumab may be more effective than rituximab alone. The safety and efficacy of belimumab after B cell depletion therapy in systemic LUPUS erythematosus (BEAT-LUPUS) trial aims to determine whether belimumab is superior to placebo, when given 4–8 weeks after treatment with rituximab. This article describes the statistical analysis plan for this trial as an update to the published protocol. It is written prior to the end of patient follow-up, while the outcome of the trial is still unknown.

Design and methods

BEAT-LUPUS is a randomised, double-blind, phase II trial of 52 weeks of belimumab versus placebo, initiated 4–8 weeks after rituximab treatment. The primary outcome is anti-dsDNA antibodies at 52 weeks post randomisation. Secondary outcomes include lupus flares and damage, adverse events, doses of concomitant medications, quality of life, and clinical biomarkers. We describe the trial’s clinical context, outcome measures, sample size calculation, and statistical modelling strategy, and the supportive analyses planned to evaluate for mediation of the treatment effect through changes in concomitant medication doses and bias from missing data.

Discussion

The analysis will provide detailed information on the safety and effectiveness of belimumab. It will be implemented from July 2020 when patient follow-up and data collection is complete.

Trial registration

ISRCTN: 47873003. Registered on 28 November 2016.

EudracT: 2015-005543-14. Registered on 19 November 2018.

B Cell Therapy in Systemic Lupus Erythematosus: From Rationale to Clinical Practice

B cell hyperactivity and breach of tolerance constitute hallmarks of systemic lupus erythematosus (SLE). The heterogeneity of disease manifestations and relatively rare prevalence of SLE have posed difficulties in trial design and contributed to a slow pace for drug development. The anti-BAFF monoclonal antibody belimumab is still the sole targeted therapy licensed for SLE, lending credence to the widely accepted notion that B cells play central roles in lupus pathogenesis. However, more therapeutic agents directed toward B cells or B cell-related pathways are used off-label or have been trialed in SLE. The anti-CD20 monoclonal antibody rituximab has been used to treat refractory SLE during the last two decades, and the anti-type I IFN receptor anifrolumab is currently awaiting approval after one phase III clinical trial which met its primary endpoint and one phase III trial which met key secondary endpoints. While the latter does not directly affect the maturation and antibody production activity of B cells, it is expected to affect the contribution of B cells in proinflammatory cytokine excretion. The proteasome inhibitor bortezomib, primarily directed toward the plasma cells, has been used in few severe cases as an escape regimen. Collectively, current clinical experience and primary results of ongoing clinical trials prophesy that B cell therapies of selective targets will have an established place in the future personalized therapeutic management of lupus patients.

Long-term effects of combined B-cell immunomodulation with rituximab and belimumab in severe, refractory systemic lupus erythematosus: 2-year results

Background

Anti-CD20 B-cell depletion has not shown superior efficacy to standard immunosuppression in patients with systemic lupus erythematosus (SLE). Besides trial design, potential explanations are incomplete B-cell depletion in relation to substantial surges in B-cell-activating factor (BAFF). To improve B-cell targeting strategies, we conducted the first study in SLE patients aimed at investigating immunological effects and feasibility of combining rituximab (RTX; anti-CD20) and belimumab (BLM; anti-BAFF).

Methods

Reported is the long-term follow-up of a Phase 2 proof-of-concept study in 15 patients with SLE including 12 (80%) with lupus nephritis (LN).

Results

In 10/15 (67%) patients, a clinical response was observed by achievement of lupus low disease activity state, of which 8 (53%) continued treatment (BLM + ≤7.5 mg prednisolone) for the complete 2 years of follow-up. Five patients (33%) were referred to as ‘non-responders’ due to persistent LN, major flare or repetitive minor flares. Out of 12 LN patients, 9 (75%) showed a renal response including 8 (67%) complete renal responders. All anti-dsDNA⁺ patients converted to negative, and both anti-C1q and extractable nuclear antigen autoantibodies showed significant reductions. CD19⁺ B cells showed a median decrease from baseline of 97% at 24 weeks, with a persistent reduction of 84% up to 104 weeks. When comparing responders with non-responders, CD20⁺ B cells were depleted significantly less in non-responders and double-negative (DN) B cells repopulated significantly earlier.

Conclusions

Combined B-cell targeted therapy with RTX and BLM prevented full B-cell repopulation including DN B cells, with concomitant specific reduction of SLE-relevant autoantibodies. The observed immunological and clinical benefits in a therapy-refractory SLE population prompt further studies on RTX + BLM.

Characterization of concurrent target suppression by JNJ-61178104, a bispecific antibody against human tumor necrosis factor and interleukin-17A

Tumor necrosis factor (TNF) and interleukin (IL)-17A are pleiotropic cytokines implicated in the pathogenesis of several autoimmune diseases including rheumatoid arthritis (RA) and psoriatic arthritis (PsA). JNJ-61178104 is a novel human anti-TNF and anti-IL-17A monovalent, bispecific antibody that binds to both human TNF and human IL-17A with high affinities and blocks the binding of TNF and IL-17A to their receptors in vitro. JNJ-61178104 also potently neutralizes TNF and IL-17A-mediated downstream effects in multiple cell-based assays. In vivo, treatment with JNJ-61178104 resulted in dose-dependent inhibition of cellular influx in a human IL-17A/TNF-induced murine lung neutrophilia model and the inhibitory effects of JNJ-61178104 were more potent than the treatment with bivalent parental anti-TNF or anti-IL-17A antibodies. JNJ-61178104 was shown to engage its targets, TNF and IL-17A, in systemic circulation measured as drug/target complex formation in normal cynomolgus monkeys (cyno). Surprisingly, quantitative target engagement assessment suggested lower apparent in vivo target-binding affinities for JNJ-61178104 compared to its bivalent parental antibodies, despite their similar in vitro target-binding affinities. The target engagement profiles of JNJ-61178104 in humans were in general agreement with the predicted profiles based on cyno data, suggesting similar differences in the apparent in vivo target-binding affinities. These findings show that in vivo target engagement of monovalent bispecific antibody does not necessarily recapitulate that of the molar-equivalent dose of its bivalent parental antibody. Our results also offer valuable insights into the understanding of the pharmacokinetics/pharmacodynamics and target engagement of other bispecific biologics against dimeric and/or trimeric soluble targets in vivo.

B Cell Tetherin: A Flow Cytometric Cell-Specific Assay for Response to Type I Interferon Predicts Clinical Features and Flares in Systemic Lupus Erythematosus

OBJECTIVE

Type I interferon (IFN) responses are broadly associated with autoimmune diseases, including systemic lupus erythematosus (SLE). Given the cardinal role of autoantibodies in SLE, this study was undertaken to investigate whether the findings of a B cell-specific IFN assay correlate with SLE activity.

METHODS

B cells and peripheral blood mononuclear cells (PBMCs) were stimulated with type I IFN and type II IFN. Gene expression was analyzed, and the expression of pathway-related membrane proteins was determined. A flow cytometry assay for tetherin (CD317), an IFN-induced protein ubiquitously expressed on leukocytes, was validated in vitro and then clinically against SLE diagnosis, plasmablast expansion, and the British Isles Lupus Assessment Group (BILAG) 2004 score in a discovery cohort (n = 156 SLE patients, 30 rheumatoid arthritis [RA] patients, and 25 healthy controls). A second, longitudinal validation cohort of 80 SLE patients was also evaluated for flare prediction.

RESULTS

In vitro, a close cell-specific and dose-response relationship between type I IFN-responsive genes and cell surface tetherin was observed in all immune cell subsets. Tetherin expression on multiple cell subsets was selectively responsive to stimulation with type I IFN compared to types II and III IFNs. In patient samples from the discovery cohort, memory B cell tetherin showed the strongest associations with diagnosis (SLE:healthy control effect size 0.11 [P = 0.003]; SLE:RA effect size 0.17 [P < 0.001]), plasmablast numbers in rituximab-treated patients (R = 0.38, P = 0.047), and BILAG 2004. These associations were equivalent to or stronger than those for IFN score or monocyte tetherin. Memory B cell tetherin was found to be predictive of future clinical flares in the validation cohort (hazard ratio 2.29 [95% confidence interval 1.01-4.64]; P = 0.022).

CONCLUSION

Our findings indicate that memory B cell surface tetherin, a B cell-specific IFN assay, is associated with SLE diagnosis and disease activity, and predicts flares better than tetherin on other cell subsets or whole blood assays, as determined in an independent validation cohort.

Peripheral B Cell Subsets in Autoimmune Diseases: Clinical Implications and Effects of B Cell-Targeted Therapies

Antibody-secreting cells (ASCs) play a fundamental role in humoral immunity. The aberrant function of ASCs is related to a number of disease states, including autoimmune diseases and cancer. Recent insights into activated B cell subsets, including naïve B cell to ASC stages and their resultant cellular disturbances, suggest that aberrant ASC differentiation occurs during autoimmune diseases and is closely related to disease severity. However, the mechanisms underlying highly active ASC differentiation and the B cell subsets in autoimmune patients remain undefined. Here, we first review the processes of ASC generation. From the perspective of novel therapeutic target discovery, prediction of disease progression, and current clinical challenges, we further summarize the aberrant activity of B cell subsets including specialized memory CD11c^hiT-bet⁺ B cells that participate in the maintenance of autoreactive ASC populations. An improved understanding of subgroups may also enhance the knowledge of antigen-specific B cell differentiation. We further discuss the influence of current B cell therapies on B cell subsets, specifically focusing on systemic lupus erythematosus, rheumatoid arthritis, and myasthenia gravis.

Belimumab after B cell depletion therapy in patients with systemic lupus erythematosus (BEAT Lupus) protocol: a prospective multicentre, double-blind, randomised, placebo-controlled, 52-week phase II clinical trial

INTRODUCTION

Few treatment options exist for patients with systemic lupus erythematosus (SLE) who fail conventional therapy. Although widely used to treat lupus, the efficacy of B cell depletion therapy using rituximab has not been demonstrated in randomised clinical trials. Following rituximab, elevated levels of serum B cell activating factor (BAFF) have been associated with failure to remit or subsequent lupus relapse. The administration of belimumab, a monoclonal antibody specific for BAFF and approved for lupus therapy, could potentiate the efficacy of rituximab and enable longer periods of disease remission. The aim of this trial is to assess the safety and efficacy of belimumab following rituximab in patients with SLE.

METHODS AND ANALYSIS

BEAT Lupus is a double-blind, randomised, placebo controlled, phase II clinical trial. Patients with SLE commencing a treatment cycle of rituximab (two 1g infusions, 2 weeks apart) as standard of care will be randomised to receive belimumab or placebo, 4 to 8 weeks following the first rituximab infusion. Belimumab or placebo infusions are administered for 52 weeks. The primary outcome measure is anti-double stranded DNA (anti-dsDNA) antibody levels at 52 weeks. Secondary outcomes include measures of adverse events, lupus disease activity and cumulative steroid dose. The kinetics of B cell repopulation will be assessed in a subgroup of participants. Belimumab administration after rituximab may provide a novel therapeutic pathway for patients with active lupus if safety is demonstrated in this proof of concept study, and lower anti-dsDNA antibodies levels are achieved in those patients treated with belimumab compared with placebo.

ETHICS AND DISSEMINATION

The protocol has been reviewed and approved by the Hampstead Research Ethics Committee - London (reference 16/LO/1024). Trial information is available at https://www.isrctn.com/ISRCTN47873003, and the results of this trial will be submitted for publication in relevant peer-reviewed journals. Key findings will also be presented at national and international conferences.

TRIAL REGISTRATION NUMBER

ISRCTN47873; date assigned to the registry: 28 November 2016. The stage is pre-results.

B Cell Abnormalities in Systemic Lupus Erythematosus and Lupus Nephritis-Role in Pathogenesis and Effect of Immunosuppressive Treatments

Abnormalities in B cells play pivotal roles in the pathogenesis of systemic lupus erythematosus (SLE) and lupus nephritis (LN). Breach in central and peripheral tolerance mechanisms generates autoreactive B cells which contribute to the pathogenesis of SLE and LN. Dysregulation of B cell transcription factors, cytokines and B cell-T cell interaction can result in aberrant B cell maturation and autoantibody production. These immunological abnormalities also lead to perturbations in circulating and infiltrating B cells in SLE and LN patients. Conventional and novel immunosuppressive medications confer differential effects on B cells which have important clinical implications. While cyclophosphamide and mycophenolate mofetil (MMF) showed comparable clinical efficacy in active LN, MMF induction was associated with earlier reduction in circulating plasmablasts and plasma cells. Accumulating evidence suggests that MMF maintenance is associated with lower risk of disease relapse than azathioprine, which may be explained by its more potent and selective suppression of B cell proliferation. Novel therapeutic approaches targeting the B cell repertoire include B cell depletion with monoclonal antibodies binding to cell surface markers, inhibition of B cell cytokines, and modulation of costimulatory signals in B cell-T cell interaction. These biologics, despite showing improvements in serological parameters and proteinuria, did not achieve primary endpoints when used as add-on therapy to standard treatments in active LN patients. Other emerging treatments such as calcineurin inhibitors, mammalian target of rapamycin inhibitors and proteasome inhibitors also show distinct inhibitory effects on the B cell repertoire. Advancement in the knowledge on B cell biology has fueled the development of new therapeutic strategies in SLE and LN. Modification in background treatments, study endpoints and selective recruitment of subjects showing aberrant B cells or its signaling pathways when designing future clinical trials may better elucidate the roles of these novel therapies for SLE and LN patients.

Moving Forward With Biologics in Lupus Nephritis

The majority of patients with systemic lupus erythematosus develop lupus nephritis (LN) which significantly contributes to increased risks of hospitalizations, ESRD, and death. Unfortunately, treatments for LN have not changed over the past 15 years. Despite continued efforts to elucidate the pathogenesis of LN, no new drugs have yet replaced the standard-of-care regimens of cyclophosphamide or mycophenolate mofetil plus high-dose corticosteroids. The significant limitations of standard-of-care are low complete response rates, risk of flares, and ongoing inflammation in the kidney leading to progressive renal dysfunction. Repeat and prolonged treatments are often needed to control disease, leading to a high level of severe side effects. The development of targeted drugs with better efficacy and safety are desperately needed. The rationale for targeting key immunologic pathways in LN continues to be strongly supported by basic and translational research and has generated the hope and excitement of testing these therapies in human LN. This review provides an overview of biologics studied to date in clinical trials of LN, discusses the potential reasons for their failure, and addresses the challenges moving forward.

Patterns of B Cell Repletion Following Rituximab Therapy in a Pediatric Rheumatology Cohort

Objective

To investigate the association between demographic characteristics, disease characteristics, the number of rituximab (RTX) rounds, and concurrent immunosuppression on B cell level repletion following RTX therapy.

Methods

A retrospective chart review of 112 children who met inclusion criteria and were treated with RTX at a single institution was performed. Demographic, clinical, and laboratory data were extracted and compared. CD19 levels were reviewed at 6 and 12 months post‐RTX with depletion defined as fewer than 10 cells/μL and complete repopulation to normal levels defined as 170 cells/μL or more.

Results

Among patients with CD19 levels, 48% of patients remained depleted at 6 months, 89% were repleted with 10 cells/μL or more by 12 months, and 46% remained below normal levels at 12 months following infusion. There was no significant association between the number of RTX rounds or underlying disease and persistent depletion below normal levels at 12 months following RTX infusion. Depletion at 6 months was associated with a 79% chance of persistent depletion below normal levels at 12 months. The association between concurrent cyclophosphamide (CYC) and repletion of 10 cells/μL or more at 6 (P = 0.091) and 12 months (P = 0.087) trended toward significance with no significant association between CYC and persistent depletion below normal levels.

Conclusion

RTX therapy for pediatric rheumatic diseases is well‐tolerated and results in variable repletion and normalization of B cell numbers at 6 and 12 months. B cell repletion in children is variable and independent of underlying disease and of the number of RTX infusions.

Autoantibodies to killer cell immunoglobulin-like receptor 3DL1 in patients with systemic lupus erythematosus

A genetic variant of the killer immunoglobulin-like receptor 3DL1 (KIR3DL1) has been found in patients with systemic lupus erythematosus (SLE). Herein, we investigated the presence of autoantibodies to KIR3DL1 in a cohort of patients with SLE. We tested sera from 28 patients with SLE, 11 patients with rheumatoid arthritis (RA) and 17 healthy control subjects for anti-KIR3DL1 activity by an enzyme-linked immunosorbent assay (ELISA) using recombinant KIR3DL1-enhanced green fluorescent protein (EGFP) and EGFP proteins. Anti-KIR3DL1 antibodies were detected in 22 (79%) of the 28 patients with SLE, whereas they were present in only three (27%) of the 11 patients with RA examined. Notably, 10 (91%) of the 11 samples from patients with SLE prior to therapy had anti-KIR3DL1 antibodies. None of the samples from healthy donors were positive for the antibodies. Here, we report the presence of anti-KIR3DL1 antibodies in the sera of patients with SLE for the first time. Anti-KIR3DL1 autoantibodies may be involved in the pathogenesis of autoimmune diseases.

CCR6+ Th cell distribution differentiates systemic lupus erythematosus patients based on anti-dsDNA antibody status

Background

Systemic lupus erythematosus (SLE) disease has been shown to be associated with the generation of multiple auto-antibodies. Among these, anti-dsDNA antibodies (anti-DNAs) are specific and play a pathogenic role in SLE. Indeed, anti-DNA⁺ SLE patients display a worse disease course. The generation of these pathogenic anti-DNAs has been attributed to the interaction between aberrant T helper (Th) cells and autoimmune B cells. Thus, in this study we have investigated whether CCR6⁺Th cells have the ability to differentiate SLE patients based on anti-DNA status, and if their distribution has any correlation with disease activity.

Methods

We recruited 25 anti-DNA⁺ and 25 anti-DNA⁻ treatment-naive onset SLE patients, matched for various clinical characteristics in our nested matched case-control study. CCR6⁺ Th cells and their additional subsets were analyzed in each patient by flow cytometry.

Results

Anti-DNA⁺ SLE patients specifically had a higher percentage of Th cells expressing CCR6 and CXCR3. Further analysis of CCR6⁺ Th cell subsets showed that anti-DNA⁺ SLE patients had elevated proportions of Th9, Th17, Th17.1 and CCR4/CXCR3 double-negative (DN) cells. However, the proportions of CCR6⁻ Th subsets, including Th1 and Th2 cells, did not show any association with anti-DNA status. Finally, we identified a correlation between CCR6⁺ Th subsets and clinical indicators, specifically in anti-DNA⁺ SLE patients.

Conclusions

Our data indicated that CCR6⁺ Th cells and their subsets were elevated and correlated with disease activity in anti-DNA⁺ SLE patients. We speculated that CCR6⁺ Th cells may contribute to distinct disease severity in anti-DNA⁺ SLE patients.

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.

Altered expression of signalling lymphocyte activation molecule receptors in T-cells from lupus nephritis patients-a potential biomarker of disease activity

Objectives. The aim was to investigate whether the signalling lymphocyte activation molecule (SLAM) signalling pathways contribute to LN and whether SLAM receptors could be valuable biomarkers of disease activity.

Methods. Peripheral blood mononuclear cells from 30National Research Ethics Service SLE patients with biopsy-proven LN were analysed by flow cytometry. Clinical measures of disease activity were assessed. The expression of the SLAM family receptors on T-cell subpopulations [CD4, CD8 and double negative (DN) T cells] was measured and compared between lupus patients with active renal disease and those in remission.

Results. The frequency of CD8 T cells expressing SLAMF3, SLAMF5 and SLAMF7 was significantly lower in LN patients who were in remission. In contrast, these subsets were similar in patients with active renal disease and in healthy individuals. Patients with active nephritis had an increased percentage of circulating monocytes, consistent with a potential role played by these cells in glomerular inflammation. Changes in the frequency of DN T cells positive for SLAMF2, SLAMF4 and SLAMF7 were observed in lupus patients irrespective of the disease activity. We detected alterations in the cellular expression of the SLAM family receptors, but these changes were less obvious and did not reveal any specific pattern. The percentage of DN T cells expressing SLAMF6 could predict the clinical response to B-cell depletion in patients with LN.

Conclusion. Our study demonstrates altered expression of the SLAM family receptors in SLE T lymphocytes. This is consistent with the importance of the SLAM-associated pathways in lupus pathogenesis.

Aiolos Overexpression in Systemic Lupus Erythematosus B Cell Subtypes and BAFF-Induced Memory B Cell Differentiation Are Reduced by CC-220 Modulation of Cereblon Activity

BAFF is a B cell survival and maturation factor implicated in the pathogenesis of systemic lupus erythematosus (SLE). In this in vitro study, we describe that soluble BAFF in combination with IL-2 and IL-21 is a T cell contact-independent inducer of human B cell proliferation, plasmablast differentiation, and IgG secretion from circulating CD27⁺ memory and memory-like CD27^-IgD^- double-negative (DN) B cells, but not CD27^-IgD⁺ naive B cells. In contrast, soluble CD40L in combination with IL-2 and IL-21 induces these activities in both memory and naive B cells. Blood from healthy donors and SLE patients have similar circulating levels of IL-2, whereas SLE patients exhibit elevated BAFF and DN B cells and reduced IL-21. B cell differentiation transcription factors in memory, DN, and naive B cells in SLE show elevated levels of Aiolos, whereas Ikaros levels are unchanged. Treatment with CC-220, a modulator of the cullin ring ligase 4-cereblon E3 ubiquitin ligase complex, reduces Aiolos and Ikaros protein levels and BAFF- and CD40L-induced proliferation, plasmablast differentiation, and IgG secretion. The observation that the soluble factors BAFF, IL-2, and IL-21 induce memory and DN B cell activation and differentiation has implications for extrafollicular plasmablast development within inflamed tissue. Inhibition of B cell plasmablast differentiation by reduction of Aiolos and Ikaros may have utility in the treatment of SLE, where elevated levels of BAFF and Aiolos may prime CD27⁺ memory and DN memory-like B cells to become Ab-producing plasmablasts in the presence of BAFF and proinflammatory cytokines.

From mechanism to therapies in systemic lupus erythematosus

PURPOSE OF REVIEW

Systemic lupus erythematosus (SLE) is a disabling and deadly disease. Development of novel therapies for SLE has historically been limited by incomplete understanding of immune dysregulation. Recent advances in lupus pathogenesis, however, have led to the adoption or development of new therapeutics, including the first Food and Drug Administration-approved drug in 50 years.

RECENT FINDINGS

Multiple cytokines (interferon, B lymphocyte stimulator, IL-6, and IL-17), signaling pathways (Bruton's Tyrosine Kinase, Janus kinase/signal transducer and activator of transcription), and immune cells are dysregulated in SLE. In this review, we cover seminal discoveries that demonstrate how this dysregulation is integral to SLE pathogenesis and the novel therapeutics currently under development or in clinical trials. In addition, early work suggests metabolic derangements are another target for disease modification. Finally, molecular profiling has led to improved patient stratification in the heterogeneous SLE population, which may improve clinical trial outcomes and therapeutic selection.

SUMMARY

Recent advances in the treatment of SLE have directly resulted from improved understanding of this complicated disease. Rheumatologists may have a variety of novel agents and more precise targeting of select lupus populations in the coming years.

Treatment of lupus nephritis: current paradigms and emerging strategies

PURPOSE OF REVIEW

Lupus nephritis is the most common organ-threatening manifestation of lupus and continues to result in end-stage renal disease. This review describes the contemporary treatment of lupus nephritis as well as emerging therapeutic strategies.

RECENT FINDINGS

Lupus nephritis management consists of an initial (induction) phase and a maintenance (extended) phase in which steroids are used in combination with another immunosuppressive medication. Current treatments are incompletely effective and associated with substantial toxicity. Despite disappointing results of several recent trials, novel therapies targeting diverse immunologic pathways are being actively studied in lupus nephritis. Two promising strategies include the use of B-cell depletion therapy and multitarget therapy with calcineurin inhibitors. In parallel with the conduct of these trials, there are ongoing efforts to improve trial design. Two recent studies of outcome measures reported that a level of proteinuria of less than 0.7-0.8 g at 12 months is most predictive of good long-term renal outcome, and that the inclusion of urine red blood cells worsens the predictive value of proteinuria alone.

SUMMARY

Improved understanding of lupus nephritis pathogenesis, development of novel therapies, and optimization of clinical trial design are leading the path forward for successful drug development in lupus nephritis. The ultimate goal of these efforts is to treat our patients in a more strategic, personalized manner that improves long-term outcomes.

Research and therapeutics-traditional and emerging therapies in systemic lupus erythematosus

This review summarizes traditional and emerging therapies for SLE. Evidence suggests that the heterogeneity of SLE is a crucial aspect contributing to the failure of large clinical trials for new targeted therapies. A clearer understanding of the mechanisms driving disease pathogenesis combined with recent advances in medical science are predicted to enable accelerated progress towards improved SLE diagnosis and personalized approaches to treatment.

Beyond pan-B-cell-directed therapy - new avenues and insights into the pathogenesis of SLE

New insights into the mechanisms of autoimmune diseases have been obtained not only from preclinical studies, but also from clinical trials of pan-B-cell-directed therapy. Overall, the results of these clinical trials suggest that more-specific approaches focusing on pathogenic B-cell functions, and perhaps sparing or even enhancing regulatory B-cell activity, might be attractive alternatives. Importantly, pathogenic B-cell subpopulations function within a network of cellular interactions, many of which might require additional interventions to restore immunologic balance and suppress autoimmune disease. Thus, approaches that simultaneously target innate immune cells as well as multiple nodes of T-cell and B-cell interactions might hold the promise of improved therapeutic efficacy. Interfering with B-cell intracellular signalling pathways, altering their intracellular metabolic pathways and perturbing transcription factors are additional options. This Review critically analyses these approaches, examines the role of cytokines and other functions of B-lineage cells separate from antibody secretion, and provides insights into the potential next generation of therapies targeting B-lineage cells.

Circulating (CD3(-)CD19(+)CD20(-)IgD(-)CD27(high)CD38(high)) Plasmablasts: A Promising Cellular Biomarker for Immune Activity for Anti-PLA2R1 Related Membranous Nephropathy?

Membranous nephropathy (MN) is a kidney specific autoimmune disease mainly mediated by anti-phospholipase A2 receptor 1 autoantibody (PLA2R1 Ab). The adequate assessment of chimeric anti-CD20 monoclonal antibody, rituximab (RTX), efficacy is still needed to improve clinical outcome of patient with MN. We evaluated the modification of plasmablasts (CD3⁻CD19⁺CD20⁻IgD⁻CD27^highCD38^high), a useful biomarker of RTX response in other autoimmune diseases, and memory (CD3⁻CD19⁺CD20⁺IgD⁻CD27⁺CD38⁻) and naive (CD3⁻CD19⁺CD20⁺IgD⁺CD27⁻CD38^low) B cells by fluorescence-activated cell sorter analysis in PLA2R1 related MN in one patient during the 4 years of follow-up after RTX. RTX induced complete disappearance of CD19⁺ B cells, plasmablasts, and memory B cells as soon as day 15. Despite severe CD19⁺ lymphopenia, plasmablasts and memory B cells reemerged early before naive B cells (days 45, 90, and 120, resp.). During the follow-up, plasmablasts decreased more rapidly than memory B cells but still remained elevated as compared to day 0 of RTX. Concomitantly, anti-PLA2R1 Ab increased progressively. Our single case report suggests that, besides monitoring of serum anti-PLA2R1 Ab level, enumeration of circulating plasmablasts and memory B cells represents an attractive and complementary tool to assess immunological activity and efficacy of RTX induced B cells depletion in anti-PLA2R1 Ab related MN.

Success and failure of biological treatment in systemic lupus erythematosus: A critical analysis

Patients affected with systemic lupus erythematosus (SLE) still display increased mortality and decreased quality of life in respect to general population. The major determinant of poor long term prognosis is organ damage, which is predictive of more damage and death. Damage is in turn triggered by uncontrolled disease activity and especially by the long-standing corticosteroid use which often accompanies SLE patients over their disease course, owing both to the need of reaching disease remission and to the habit of keeping patients on a small steroid dose for an indefinite period of time. Hence, the need for new drugs and therapeutic strategies aiming at minimizing damage accrual through a better control of disease activity and a steroid-sparing potential is paramount. So far, however, the therapeutic strategy in SLE requires a multitarget approach which is not devoid of widespread immunesuppression. In fact, several studies have been carried out in recent years targeting both the adaptive and the innate immune system, the majority of which did not achieve their primary endpoint, being often divergent from successful clinical experience and thereby committing physician to off-label use of targeted therapies in face of refractory SLE manifestations. The study designs and the chosen endpoints were often blamed for inadequacy, being at least in part responsible for study failures. In this review, we go over major clinical trials conducted in SLE by analyzing any critical aspects related to study design, predefined endpoints and biological activity of novel compounds that may have hampered study outcome, despite the great effort of providing less toxic drugs within a targeted, pathogenic-based approach.

The BAFFling effects of rituximab in lupus: danger ahead?

Suboptimal trial design and concurrent therapies are thought to account for the unexpected failure of two clinical trials of rituximab in patients with systemic lupus erythematosus (SLE). However, in this Opinion article we propose an alternative explanation: that rituximab can trigger a sequence of events that exacerbates disease in some patients with SLE. Post-rituximab SLE flares that are characterized by high levels of antibodies to double-stranded DNA are associated with elevated circulating BAFF (B-cell-activating factor, also known as TNF ligand superfamily member 13B or BLyS) levels, and a high proportion of plasmablasts within the B-cell pool. BAFF not only perpetuates autoreactive B cells (including plasmablasts), particularly when B-cell numbers are low, but also stimulates T follicular helper (TFH) cells. Moreover, plasmablasts and TFH cells promote each others' formation. Thus, repeated rituximab infusions can result in a feedback loop characterized by ever-rising BAFF levels, surges in autoantibody production and worsening of disease. We argue that B-cell depletion should be swiftly followed by BAFF inhibition in patients with SLE.

Rituximab as maintenance therapy for ANCA associated vasculitis: how, when and why?

ANCA-associated vasculitides (AAV) are chronic autoimmune diseases characterized by inflammation and destruction of small vessels. Rituximab is now licensed for use as a remission-induction agent in the treatment of these disorders. During recent years, several non-controlled studies have suggested that rituximab may be of value in maintaining disease remission in AAV. In these series, 3 techniques have been tried: "watch-and-wait", repeated cycles in fixed intervals, or administration based on proposed biomarkers. More importantly, the results of the MAINRITSAN trial showed that this anti-CD20 agent is superior to azathioprine for preventing major relapses in AAV. This review summarizes current information regarding the effectiveness, timing, dosing, duration and safety of rituximab as a valid option for remission maintenance.

Dual B cell immunotherapy is superior to individual anti-CD20 depletion or BAFF blockade in murine models of spontaneous or accelerated lupus

Objective

To determine whether a combination of B cell depletion and BAFF blockade is more effective than monotherapy in treating models of spontaneous or accelerated systemic lupus erythematosus (SLE) in (NZB × NZW)F1 mice.

Methods

Clinical parameters such as disease progression–free survival, proteinuria, and renal injury were assessed in models of spontaneous, interferon-α (IFNα)–accelerated, or pristane-accelerated lupus in (NZB × NZW)F1 mice. Treatment arms included anti-CD20 (B cell depletion), B lymphocyte stimulator receptor 3 fusion protein (BR-3-Fc) (BAFF blockade), the combination of anti-CD20 and BR-3-Fc, isotype control, or cyclophosphamide. In models of spontaneous, IFNα-accelerated, or pristane-accelerated lupus, mice were treated for 24 weeks, 8 weeks, or 12 weeks, respectively. Peripheral and resident B cell subsets and various autoantibodies were examined.

Results

Compared to B cell depletion or BAFF blockade alone, combined therapy significantly improved disease manifestations in all 3 lupus models. In addition, marginal zone B cells, plasmablasts, and circulating and tissue plasma cells were decreased more effectively. Dual B cell immunotherapy also reduced multiple classes of pathogenic autoantibodies, consistent with its observed effectiveness in reducing immune complex–mediated renal injury.

Conclusion

Dual immunotherapy via B cell depletion and BAFF blockade is more efficacious than single agent immunotherapy in murine SLE models, and this combination treatment is predicted to be an effective strategy for immunotherapy in human SLE.

Restoring the balance: immunotherapeutic combinations for autoimmune disease

Autoimmunity occurs when T cells, B cells or both are inappropriately activated, resulting in damage to one or more organ systems. Normally, high-affinity self-reactive T and B cells are eliminated in the thymus and bone marrow through a process known as central immune tolerance. However, low-affinity self-reactive T and B cells escape central tolerance and enter the blood and tissues, where they are kept in check by complex and non-redundant peripheral tolerance mechanisms. Dysfunction or imbalance of the immune system can lead to autoimmunity, and thus elucidation of normal tolerance mechanisms has led to identification of therapeutic targets for treating autoimmune disease. In the past 15 years, a number of disease-modifying monoclonal antibodies and genetically engineered biologic agents targeting the immune system have been approved, notably for the treatment of rheumatoid arthritis, inflammatory bowel disease and psoriasis. Although these agents represent a major advance, effective therapy for other autoimmune conditions, such as type 1 diabetes, remain elusive and will likely require intervention aimed at multiple components of the immune system. To this end, approaches that manipulate cells ex vivo and harness their complex behaviors are being tested in preclinical and clinical settings. In addition, approved biologic agents are being examined in combination with one another and with cell-based therapies. Substantial development and regulatory hurdles must be overcome in order to successfully combine immunotherapeutic biologic agents. Nevertheless, such combinations might ultimately be necessary to control autoimmune disease manifestations and restore the tolerant state.

Human T-follicular helper and T-follicular regulatory cell maintenance is independent of germinal centers

The monoclonal anti-CD20 antibody rituximab (RTX) depletes B cells in the treatment of lymphoma and autoimmune disease, and contributes to alloantibody reduction in transplantation across immunologic barriers. The effects of RTX on T cells are less well described. T-follicular helper (Tfh) cells provide growth and differentiation signals to germinal center (GC) B cells to support antibody production, and suppressive T-follicular regulatory (Tfr) cells regulate this response. In mice, both Tfh and Tfr are absolutely dependent on B cells for their formation and on the GC for their maintenance. In this study, we demonstrate that RTX treatment results in a lack of GC B cells in human lymph nodes without affecting the Tfh or Tfr cell populations. These data demonstrate that human Tfh and Tfr do not require an ongoing GC response for their maintenance. The persistence of Tfh and Tfr following RTX treatment may permit rapid reconstitution of the pathological GC response once the B-cell pool begins to recover. Strategies for maintaining remission after RTX therapy will need to take this persistence of Tfh into account.

CD20+ B cell depletion in systemic autoimmune diseases: common mechanism of inhibition or disease-specific effect on humoral immunity?

Autoimmunity remains a complex physiologic deviation, enabled and perpetuated by a variety of interplayers and pathways. Simplistic approaches, targeting either isolated end-effectors of more centrally placed interactors of these mechanisms, are continuously tried in an effort to comprehend and halt cascades with potential disabling and deleterious effects in the affected individuals. This review focuses on theoretical and clinically proved effects of rituximab-induced CD20+ B cell depletion on different systemic autoimmune diseases and extrapolates on pathogenetic mechanisms that may account for different interindividual or interdisease responses.