Sustained improvement in rheumatoid arthritis following a protocol designed to deplete B lymphocytes

Non-TNF biologics and their biosimilars in rheumatoid arthritis

INTRODUCTION

Rheumatoid arthritis (RA) is a chronic inflammatory rheumatic disease that affects both the articular and extra-articular structures, leading to significant joint damage, disability and excess mortality. The treatment algorithm of RA has changed tremendously in the past 1-2 decades because of the emergence of novel biological therapies that target different mechanisms of action in addition to TNFα.

AREAS COVERED

This article summarizes the evidence and safety of the non-TNF biological DMARDs in the treatment of RA, including those that target B cells, T-cell co-stimulation, interleukin (IL)-6 and granulocyte-monocyte colony-stimulating factor (GM-CSF). The targeted synthetic DMARDs such as the Janus kinase inhibitors are not included. The availability of the less costly biosimilars has enabled more patients to receive biological therapy earlier in the course of the disease. The evidence for the non-TNF biosimilar compounds in RA is also reviewed.

EXPERT OPINION

There are unmet needs of developing novel therapeutic agents to enhance the response rate and provide more options for difficult-to-treat RA. These include the newer generation biologic and targeted synthetic DMARDs. A personalized treatment strategy in RA requires evaluation of the cellular, cytokine, genomic and transcriptomic profile that would predict treatment response to biologic or targeted DMARDs of different mechanisms of action.

B-cell depletion in autoimmune diseases

B cells have a pivotal function in the pathogenesis of autoimmune diseases, such as rheumatoid arthritis, multiple sclerosis and systemic lupus erythematosus. In autoimmune disease, B cells orchestrate antigen presentation, cytokine production and autoantibody production, the latter via their differentiation into antibody-secreting plasmablasts and plasma cells. This article addresses the current therapeutic strategies to deplete B cells in order to ameliorate or potentially even cure autoimmune disease. It addresses the main target antigens in the B-cell lineage that are used for therapeutic approaches. Furthermore, it summarises the current evidence for successful treatment of autoimmune disease with monoclonal antibodies targeting B cells and the limitations and challenges of these approaches. Finally, the concept of deep B-cell depletion and immunological reset by chimeric antigen receptor T cells is discussed, as well as the lessons from this approach for better understanding the role of B cells in autoimmune disease.

Pathophysiology and stratification of treatment-resistant rheumatoid arthritis

Early diagnosis and timely therapeutic intervention are clinical challenges of rheumatoid arthritis (RA), especially for treatment-resistant or difficult-to-treat patients. Little is known about the immunological mechanisms involved in refractory RA. In this review, we summarize previous research findings on the immunological mechanisms of treatment-resistant RA. Genetic prediction of treatment-resistant RA is challenging. Patients with and without anti-cyclic citrullinated peptide autoantibodies are considered part of distinct subgroups, especially regarding long-term clinical prognosis and treatment responses. B cells, T cells and other immune cells and fibroblasts are of pathophysiological importance and are associated with treatment responses. Finally, we propose a new hypothesis that stratifies patients with RA into two subgroups with distinct immunological pathologies based on our recent immunomics analysis of RA. One RA subgroup with a favorable prognosis is characterized by increased interferon signaling. Another subgroup with a worse prognosis is characterized by enhanced acquired immune responses. Increases in dendritic cell precursors and diversified autoreactive anti-modified protein antibodies may have pathophysiological roles, especially in the latter subgroup. These findings that improve treatment response predictions might contribute to future precision medicine for RA.

Therapeutic tactics for targeting B lymphocytes in autoimmunity and cancer

B lymphocytes have become a very popular therapeutic target in a number of autoimmune indications due to their newly appreciated roles, and approachability, in these diseases. Many of the therapies now applied in autoimmunity were initially developed to deplete malignant B cells. These strategies have also been found to benefit patients suffering from such autoimmune diseases as multiple sclerosis, type I diabetes, systemic lupus erythematosus, and rheumatoid arthritis, to name a few. These observations have supported the expansion of research addressing the mechanistic contributions of B cells in these diseases, as well as blossoming of therapeutics that target them. This review seeks to summarize cutting-edge modalities for targeting B cells, including monoclonal antibodies, bispecific antibodies, antibody-drug conjugates, chimeric antigen receptor-T cells, and small molecule inhibitors. Efforts to refine B-cell targeted therapy to eliminate only pathogenic autoreactive cells will be addressed as well as the potential for future B-cell-based cellular therapeutics. Finally, we also address approaches that seek to silence B-cell function without depletion.

Synthetically glycosylated antigens for the antigen-specific suppression of established immune responses

Inducing antigen-specific tolerance during an established immune response typically requires non-specific immunosuppressive signalling molecules. Hence, standard treatments for autoimmunity trigger global immunosuppression. Here we show that established antigen-specific responses in effector T cells and memory T cells can be suppressed by a polymer glycosylated with N-acetylgalactosamine (pGal) and conjugated to the antigen via a self-immolative linker that allows for the dissociation of the antigen on endocytosis and its presentation in the immunoregulatory environment. We show that pGal-antigen therapy induces antigen-specific tolerance in a mouse model of experimental autoimmune encephalomyelitis (with programmed cell-death-1 and the co-inhibitory ligand CD276 driving the tolerogenic responses), as well as the suppression of antigen-specific responses to vaccination against a DNA-based simian immunodeficiency virus in non-human primates. Our findings show that pGal-antigen therapy invokes mechanisms of immune tolerance to resolve antigen-specific inflammatory T-cell responses and suggest that the therapy may be applicable across autoimmune diseases.

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.

Aberrant pro-inflammatory responses of CD20+ T cells in experimental arthritis

CD20+ T cells comprise a highly inflammatory subset implicated in autoimmunity, including rheumatoid arthritis (RA). We sought to characterize the CD20+ T cell subset in the murine collagen-induced arthritis (CIA) model of RA and investigate the phenotype and functional relevance of CD3+CD20+ T cells in the lymph nodes and arthritic joints using flow cytometry and immunohistochemistry. We demonstrate that CD3+CD4+CD20+ and CD3+CD8+CD20+ T cells are expanded in the draining lymph nodes of CIA mice, produce increased levels of pro-inflammatory cytokines and are less susceptible to regulation by regulatory T cells. Notably, CD3+CD4+CD20+ and CD3+CD8+CD20+ T cells are enriched with CXCR5+PD-1+ T follicular helper cells and CXCR5-PD-1+ peripheral T helper cells, subsets of T cells implicated in promoting B-cell responses and antibody production within pathologically inflamed non-lymphoid tissues in RA. Our findings suggest CD20+ T cells are associated with inflammatory responses and may exacerbate pathology by promoting inflammatory B-cell responses.

Targeted Therapy for SLE-What Works, What Doesn't, What's Next

For many years, the failure of randomized controlled trials (RCTs) has prevented patients with systemic lupus erythematosus (SLE) from benefiting from biological drugs that have proved to be effective in other rheumatological diseases. Only two biologics are approved for SLE, however they can only be administered to a restricted proportion of patients. Recently, several phase II RCTs have evaluated the efficacy and safety of new biologics in extra-renal SLE and lupus nephritis. Six drug trials have reported encouraging results, with an improvement in multiple clinical and serological outcome measures. The possibility of combining B-cell depletion and anti-BLyS treatment has also been successfully explored.

Pathogenesis and treatment of Sjogren's syndrome: Review and update

Sjogren's syndrome (SS) is a chronic autoimmune disease accompanied by multiple lesions. The main manifestations include dryness of the mouth and eyes, along with systemic complications (e.g., pulmonary disease, kidney injury, and lymphoma). In this review, we highlight that IFNs, Th17 cell-related cytokines (IL-17 and IL-23), and B cell-related cytokines (TNF and BAFF) are crucial for the pathogenesis of SS. We also summarize the advances in experimental treatment strategies, including targeting Treg/Th17, mesenchymal stem cell treatment, targeting BAFF, inhibiting JAK pathway, et al. Similar to that of SLE, RA, and MS, biotherapeutic strategies of SS consist of neutralizing antibodies and inflammation-related receptor blockers targeting proinflammatory signaling pathways. However, clinical research on SS therapy is comparatively rare. Moreover, the differences in the curative effects of immunotherapies among SS and other autoimmune diseases are not fully understood. We emphasize that targeted drugs, low-side-effect drugs, and combination therapies should be the focus of future research.

Advancing Biologic Therapy for Refractory Autoimmune Hepatitis

Biologic agents may satisfy an unmet clinical need for treatment of refractory autoimmune hepatitis. The goals of this review are to present the types and results of biologic therapy for refractory autoimmune hepatitis, indicate opportunities to improve and expand biologic treatment, and encourage comparative clinical trials. English abstracts were identified in PubMed by multiple search terms. Full-length articles were selected for review, and secondary and tertiary bibliographies were developed. Rituximab (monoclonal antibodies against CD20 on B cells), infliximab (monoclonal antibodies against tumor necrosis factor-alpha), low-dose recombinant interleukin 2 (regulatory T cell promoter), and belimumab (monoclonal antibodies against B cell activating factor) have induced laboratory improvement in small cohorts with refractory autoimmune hepatitis. Ianalumab (monoclonal antibodies against the receptor for B cell activating factor) is in clinical trial. These agents target critical pathogenic pathways, but they may also have serious side effects. Blockade of the B cell activating factor or its receptors may disrupt pivotal B and T cell responses, and recombinant interleukin 2 complexed with certain interleukin 2 antibodies may selectively expand the regulatory T cell population. A proliferation-inducing ligand that enhances T cell proliferation and survival is an unevaluated, potentially pivotal, therapeutic target. Fully human antibodies, expanded target options, improved targeting precision, more effective delivery systems, and biosimilar agents promise to improve efficacy, safety, and accessibility. In conclusion, biologic agents target key pathogenic pathways in autoimmune hepatitis, and early experiences in refractory disease encourage clarification of the preferred target, rigorous clinical trial, and comparative evaluations.

Sarcoidosis and autoimmunity: In the depth of a complex relationship

Sarcoidosis is a chronic granulomatous disease that can virtually affect any organ. Its etiology is unknown, although it has been proposed that environmental or biological agents can act as triggers, ultimately leading to chronic inflammation in genetically predisposed individuals. The main component of sarcoid inflammation is represented by an exaggerated T- lymphocytic cellular response to a putative antigen that could not be efficiently cleared in the patient. However, several clinical and immunological observations, such as the association of sarcoidosis to autoimmune diseases or the presence of autoantibodies in the serum of patients with sarcoidosis, suggest that humoral-mediated immune response might also play a role in the pathogenesis of sarcoidosis. The aim of this review is to deepen the relationship between sarcoidosis and autoimmunity, by analyzing the most recent advances and proposing new fields of research.

Diagnosis and Management of a Chronic Lower-Limb Wound in a Patient with Felty Syndrome

ABSTRACT

The authors report the case of a 55-year-old patient with a chronic lower-limb wound thought to be secondary to vasculitis. This case illustrates the importance of maintaining a high index of suspicion for vasculitic ulcers in patients with autoimmune disease. Management considerations in this context are also discussed.

Differences in the Development of Adverse Infusion Reactions to Rituximab in Patients With Systemic Lupus Erythematosus, Rheumatoid Arthritis and Non-Hodgkin's Lymphoma-Enigma Variations

It has become clear that rituximab treatment is useful for both B-cell malignancies and autoimmune rheumatic diseases. However this treatment is associated with an increased risk of an allergic reaction. We have reviewed the frequency with which these reactions occur in these different conditions. They appear to be less frequent when rituximab is used to treat rheumatoid arthritis and systemic lupus perhaps because concomitant steroids are invariably given to these patients with the rituximab which is not necessarily the case with the treatment of B-cell malignancies.

Can we predict if patients with SLE will require more than one cycle of rituximab?

OBJECTIVE

To identify clinical and serological features that distinguish patients with SLE who require single as opposed to repeated rituximab (RTX) cycles.

METHODS

All 175 SLE patients followed up at University College Hospital from 2000 onwards were retrospectively reviewed. They were divided into a one-RTX-cycle group and a multiple-cycle group (2 or more cycles). Patients included had a follow-up of at least 3 years after their first RTX cycle, unless they needed a second infusion sooner.

RESULTS

A total of 131 patients were included; 44 (33.6%) received one cycle of RTX and 87 (66.4%) received two or more. The former were older at diagnosis (31.4 vs 21 years, P < 0.001) and at first RTX infusion (39.9 vs 29 years, P < 0.001). This group of patients had more organs/systems involved (P = 0.044), more leukopenia, lymphopenia and thrombocytopenia (P = 0.001, P < 0.0001 and P = 0.003, respectively) and lower C3 levels (P = 0.035). They also had fewer immunosuppressive drugs before RTX therapy compared with those who required multiple RTX cycles (P = 0.003). There was no statistical difference in either the clinical or serological response after the first RTX cycle between both groups. Furthermore, patients who had received more immunosuppressive treatments were more likely to require more than one cycle of RTX infusions (P = 0.007).

CONCLUSIONS

RTX is an effective option for SLE patients with severe flares. Patients who received more immunosuppressive drugs were more likely to receive more than one set of RTX infusions. This suggests that RTX is best used for SLE patients with no history of refractory disease.

Multifunctional, Multivalent PIC Polymer Scaffolds for Targeting Antigen-Specific, Autoreactive B Cells

Multivalent scaffolds that carry multiple molecules with immunophenotyping or immunomodulatory properties are invaluable tools for studying and modulating specific functions of human immune responses. So far, streptavidin–biotin-based tetramers have been widely used for B-cell immunophenotyping purposes. However, the utility of these tetramers is limited by their tetravalency, the inherent immunogenicity of streptavidin (a bacterial protein that can potentially be recognized by B cells), and the limited feasibility to functionalize these reagents. This has rendered tetramers suboptimal for studying rare, in particular, antigen-specific B-cell populations in the context of clinical applications. Here, we used polyisocyanopeptides (PICs), multivalent polymeric scaffolds functionalized with around 50 peptide antigens, to detect autoreactive B cells in the peripheral blood of patients with rheumatoid arthritis. To explore the potential immunomodulatory functionalities, we functionalized PICs with autoantigenic peptides and a trisaccharide CD22 ligand to inhibit autoreactive B-cell activation through interference with the B-cell receptor activation pathway, as evidenced by reduced phospho-Syk expression upon PIC binding. Given the possibilities to functionalize PICs, our data demonstrate that the modular and versatile character of PIC scaffolds makes them promising candidates for future clinical applications in B-cell-mediated diseases.

Inflammation and Bone Metabolism in Rheumatoid Arthritis: Molecular Mechanisms of Joint Destruction and Pharmacological Treatments

Rheumatoid arthritis (RA) is an inflammatory disease characterized by a variety of symptoms and pathologies often presenting with polyarthritis. The primary symptom in the initial stage is joint swelling due to synovitis. With disease progression, cartilage and bone are affected to cause joint deformities. Advanced osteoarticular destruction and deformation can cause irreversible physical disabilities. Physical disabilities not only deteriorate patients’ quality of life but also have substantial medical economic effects on society. Therefore, prevention of the progression of osteoarticular destruction and deformation is an important task. Recent studies have progressively improved our understanding of the molecular mechanism by which synovitis caused by immune disorders results in activation of osteoclasts; activated osteoclasts in turn cause bone destruction and para-articular osteoporosis. In this paper, we review the mechanisms of bone metabolism under physiological and RA conditions, and we describe the effects of therapeutic intervention against RA on bone.

Precision medicine in rheumatoid arthritis

Rheumatoid arthritis is an autoimmune disease that causes significant morbidity. Application of cellular profiling techniques such as single-cell transcriptomics and spatial transcriptomics has uncovered novel pathogenic cell types in RA joint tissues and revealed marked heterogeneity in the cellular composition among RA patients. Together, these insights provide exciting opportunities to translate discoveries into precision medicine in RA. The present review aims to highlight novel insights into RA pathology and discuss key steps needed to translate these discoveries into actionable changes in clinical practice. We review the efforts to identify surrogate biomarkers that could be used to predict RA synovial tissue phenotypes and the corresponding responses to therapy. Finally, we discuss the opportunity to develop novel patient-derived organoid systems as a platform for therapeutic target validation.

Rheumatoid arthritis: Evolving recognition of a common disease

Rheumatoid arthritis (RA) is a highly prevalent autoimmune disease and the most common form of autoimmune inflammatory arthritis. Studies of RA pathogenesis have contributed significantly to understanding the basis for complex immune-mediated disease, identified key steps in the development of autoimmune activation and joint damage in RA, and led to the development of targeted therapies that opened up the era biologic therapy. Current studies are linking differences in gene expression to abnormalities in cellular function that will help optimize therapy for individual patients and advance the goal of personalized medicine. Our evolving understanding and current important issues in RA are highlighted.

Activated Peripheral Blood B Cells in Rheumatoid Arthritis and Their Relationship to Anti-Tumor Necrosis Factor Treatment and Response: A Randomized Clinical Trial of the Effects of Anti-Tumor Necrosis Factor on B Cells

OBJECTIVE

B cells can become activated in germinal center (GC) reactions in secondary lymphoid tissue and in ectopic GCs in rheumatoid arthritis (RA) synovium that may be tumor necrosis factor (TNF) and lymphotoxin (LT) dependent. This study was undertaken to characterize the peripheral B cell compartment longitudinally during anti-TNF therapy in RA.

METHODS

Participants were randomized in a 2:1 ratio to receive standard dosing regimens of etanercept (n = 43) or adalimumab (n = 20) for 24 weeks. Eligible participants met the American College of Rheumatology 1987 criteria for RA, had clinically active disease (Disease Activity Score in 28 joints >4.4), and were receiving stable doses of methotrexate. The primary mechanistic end point was the change in switched memory B cell fraction from baseline to week 12 in each treatment group.

RESULTS

B cell subsets remained surprisingly stable over the course of the study regardless of treatment group, with no significant change in memory B cells. Blockade of TNF and LT with etanercept compared to blockade of TNF alone with adalimumab did not translate into significant differences in clinical response. The frequencies of multiple activated B cell populations, including CD21- double-negative memory and activated naive B cells, were higher in RA nonresponders at all time points, and CD95+ activated B cell frequencies were increased in patients receiving anti-TNF treatment in the nonresponder group. In contrast, frequencies of transitional B cells-a putative regulatory subset-were lower in the nonresponders.

CONCLUSION

Overall, our results support the notion that peripheral blood B cell subsets are remarkably stable in RA and not differentially impacted by dual blockade of TNF and LT with etanercept or single blockade of TNF with adalimumab. Activated B cells do associate with a less robust response.

The Therapeutic Landscape of Rheumatoid Arthritis: Current State and Future Directions

Rheumatoid arthritis (RA) is a debilitating autoimmune disease with grave physical, emotional and socioeconomic consequences. Despite advances in targeted biologic and pharmacologic interventions that have recently come to market, many patients with RA continue to have inadequate response to therapies, or intolerable side effects, with resultant progression of their disease. In this review, we detail multiple biomolecular pathways involved in RA disease pathogenesis to elucidate and highlight pathways that have been therapeutic targets in managing this systemic autoimmune disease. Here we present an up-to-date accounting of both emerging and approved pharmacological treatments for RA, detailing their discovery, mechanisms of action, efficacy, and limitations. Finally, we turn to the emerging fields of bioengineering and cell therapy to illuminate possible future targeted therapeutic options that combine material and biological sciences for localized therapeutic action with the potential to greatly reduce side effects seen in systemically applied treatment modalities.

Long-term persistence of rituximab in patients with rheumatoid arthritis: an evaluation of the UCL cohort from 1998 to 2020

Objectives

B cell depletion therapy based on rituximab in patients with RA was pioneered at University College London Hospitals/University College London in 1998. The objective of this study was to evaluate long-term persistence of rituximab and identify factors associated with discontinuation of treatment.

Methods

Retrospective review of medical records from all rituximab-treated RA patients followed up in a dedicated clinic (1998–2020). Data collected included gender, disease duration, previous DMARDs, autoantibody status, age and concomitant therapy at first cycle, length of follow-up, and number of cycles. Drug survival and factors associated with drug discontinuation were analysed using Kaplan–Meier survival curves, log-rank test and Cox regression analysis.

Results

A total of 404 patients were included. Median disease duration and age at time of first rituximab cycle were 10 and 57 years, respectively. Median total follow-up was 55 months and median number of cycles five. 93.1% of patients were seropositive. Overall, 31.2% of patients stopped rituximab, with the largest reason for discontinuing being primary inefficacy (42.1%). Comparison of Kaplan–Meier curves showed that rituximab drug survival was lower in seronegative patients and in patients who had previously failed at least one biologic DMARD (bDMARD). Cox regression analysis revealed that rituximab discontinuation was associated with a greater number of previous bDMARDs.

Conclusion

Many patients with RA achieve good control of their disease with repeated cycles of rituximab treatment. The most common reasons for treatment discontinuation were either primary or secondary inefficacy. Patients who were seronegative and who had previously failed other bDMARDs were more at risk of drug discontinuation.

Rituximab - The first twenty years

It is now two decades since Rituximab was first used in the treatment of patients with systemic lupus erythematosus. There have been many challenges but in spite of failing to meet its primary endpoints in two clinical trials it is widely used for many aspects of lupus, its side-effects and the possibility that combining it with Benlysta may be of value. We also consider the proposal that it may provide a useful initial therapy. In this review, we consider the place of Rituximab in the treatment of lupus and anticipate how developments in fully-humanized anti-CD20 monoclonals may well extend the "therapeutic life" of B-cell depletion as a viable treatment option.

Anti-CD20 monoclonal antibodies in Systemic Lupus Erythematosus

Systemic Lupus Erythematosus (SLE) is an autoimmune inflammatory condition with a wide spectrum of disease manifestations and severities, resulting in significant morbidity and mortality. The aetiopathogenesis of SLE is complex. Young women and certain ethnicities are commonly affected, suggesting a significant hormonal and genetic influence. Diverse immunological abnormalities have been described. A characteristic abnormality is the presence of autoantibodies, implicating a central role for B cells in disease pathogenesis and/or perpetuation. Whilst conventional therapies have improved outcomes, a great unmet need remains. Recently, biological therapies are being explored. B-cell depletion therapy with rituximab has been in use off-label for nearly two decades. Inconsistent results between uncontrolled and controlled studies have raised doubts about its efficacy. In this review, we will focus on B cell abnormalities and the rationale behind B-cell depletion therapy with anti-CD20 monoclonal antibody (mAb), rituximab, will be explored including an evaluation of clinical and trial experience. Finally, we will discuss the mechanistic basis for considering alternative anti-CD20 mAbs.

Efficacy and safety results from a randomized double-blind study comparing proposed biosimilar ABP 798 with rituximab reference product in subjects with moderate-to-severe rheumatoid arthritis

BACKGROUND/OBJECTIVES

ABP 798 is a proposed biosimilar to the originator biologic rituximab, an anti-CD20 monoclonal antibody. This comparative clinical study evaluated the pharmacokinetics (PK), safety, and efficacy of ABP 798 versus rituximab reference product (RP) in patients with moderate-to-severe rheumatoid arthritis (RA).

METHODS

Adults with moderate-to-severe RA with an inadequate response or intolerance to other disease-modifying anti-rheumatic drugs including 1 or more tumor necrosis factor inhibitor therapies (n = 311) received ABP 798, US-sourced rituximab RP (rituximab US), or EU-sourced rituximab RP (rituximab EU) (1000 mg, 2 weeks apart). At week 24, ABP 798- or rituximab EU-treated subjects received a second dose of the same treatment, while rituximab US-treated subjects transitioned to receive ABP 798. The key efficacy endpoint was DAS28-CRP change from baseline at week 24. Other efficacy endpoints included DAS28-CRP at other time points; ACR20, ACR50, and ACR70 criteria; and hybrid ACR. The rituximab RP groups were pooled for all efficacy endpoints since PK equivalence had been established between rituximab US and rituximab EU.

RESULTS

Clinical equivalence between ABP 798 and rituximab RP was established as the 90% confidence interval for DAS28-CRP change from baseline at week 24 fell within the prespecified equivalence margin (- 0.6, 0.6). Safety and immunogenicity profiles of ABP 798 were comparable across treatment groups and not affected by single transition from RP to ABP 798.

CONCLUSIONS

Clinical equivalence in terms of efficacy, safety, and immunogenicity was established between ABP 798 and rituximab RP in this comparative clinical trial in patients with moderate-to-severe RA. Key Points • ABP 798 provided similar efficacy as rituximab reference product (RP) in patients with moderate-severe rheumatoid arthritis. • The safety and immunogenicity profiles for ABP 798 were similar to those for the rituximab RP. • The single transition from rituximab RP to ABP 798 did not show differences in efficacy, safety, or immunogenicity.

Lessons for rituximab therapy in patients with rheumatoid arthritis

B-cell depletion therapy is an effective option for the treatment of rheumatoid arthritis but often does not result in complete B-cell depletion. Complete B-cell depletion after rituximab treatment is associated with clinical response, and this outcome leads to long-term maintenance of therapy. Low pretreatment plasmablast counts, concomitant treatment with disease-modifying antirheumatic drugs, no smoking exposure, the presence of anticitrullinated protein antibodies or rheumatoid factor, and a low interferon signature are all predictive of complete B-cell depletion and clinical response. Half of patients who initially show complete B-cell depletion and clinical response after rituximab treatment eventually lose responsiveness with further infusions. However three-quarters of these patients regain this outcome in their following treatment cycle, suggesting that loss of response is reversible and that patients can still benefit from rituximab retreatment. The efficacy of reduced doses of rituximab is being investigated, but preliminary results suggest that these strategies are best used for maintenance therapy, particularly in patients who suffer adverse events or who are at a high risk of infection. Infusion-related reactions are the most common adverse events associated with rituximab treatment, and monitoring of IgG concentrations is crucial, as low concentrations are correlated with an increased risk of infection.

Crohn's Disease Following Rituximab Treatment for Follicular Lymphoma in a Patient with Synchronous Gastric Signet Ring Cells Carcinoma: A Case Report and Literature Review

Recently, there have been a few reports of rituximab (RTX)-induced Crohn's disease, but there is no literature available on successful long-term treatment and the clinical outcome of this condition. We retrospectively analyzed the clinical data of a rare case of Crohn's disease induced by RTX administered as induction and prolonged maintenance therapy of a follicular lymphoma, diagnosed synchronously with a gastric signet ring cells carcinoma, treated at our hospital.

Rituximab use as induction therapy for lupus nephritis: a systematic review

OBJECTIVE

Rituximab (RTX) has important usage in rheumatoid arthritis and vasculitis. There remains a need for more, better, and safer treatments for patients with lupus nephritis (LN). RTX has been trialed in such patients without definitive conclusions about its effectiveness. As a role for RTX has not been clearly established for LN, we carried out a systematic review and analysis.

METHODS

We identified 31 studies of RTX for class I-VI LN, and assessed complete renal response (CRR) and partial renal response (PRR) using criteria including serum creatinine, proteinuria, and urinary sediment. Due to differences in the pediatric presentation of the disease, studies focusing on pediatric patients were excluded.

RESULTS

One randomized controlled trial (RCT) showed superiority of RTX+cyclophosphamide (CYC) versus CYC alone (64% vs. 21% CRR and 19% vs. 36% PRR). Six prospective and retrospective studies utilizing RTX monotherapy found 66% CRR or PRR in all patients. Eleven studies that investigated RTX in combination with CYC or mycophenolate mofetil (MMF) also found 66% CRR or PRR in all patients. In total, the CRR for Caucasian, East Asian, and Hispanic patients were 77%, 38%, and 28%, respectively.

CONCLUSIONS

RTX appeared to benefit certain LN patients, but most studies were not randomized or properly controlled, were heterogeneous in design, subjects, and LN types, and were not comparable, and must therefore be interpreted cautiously. RTX alone may not deplete B cells sufficiently for the perturbations of LN. In addition, RTX may induce responses differently among patients of different ethnic and racial backgrounds. Furthermore, there were wide variations in the baseline characteristics of the patients, namely LN class, time course of disease, age, and prior immunosuppressive use. We suggest a prospective RCT in patients aged 18-65 years with class IV LN. Ideally, the patients would not have received prior immunosuppression and would better represent different ethnicities. The treatment groups would be RTX, RTX+belimumab, CYC, and MMF groups, with pulse-dose steroids during induction followed by maintenance steroids and MMF. The CRR and PRR would be assessed at 12 and 24 months. This or a similar study might clarify RTX's role in the treatment of LN.

Update on immune-mediated therapies for myasthenia gravis

With the exception of thymectomy, immune modulatory treatment strategies and clinical trials in myasthenia gravis over the past 50 y were mainly borrowed from experience in other nonneurologic autoimmune disorders. The current experimental therapy paradigm has significantly changed such that treatments directed against the pathological mechanisms specific to myasthenia gravis are being tested, in some cases as the initial disease indication. Key advances have been made in three areas: (i) the expanded role and long-term benefits of thymectomy, (ii) complement inhibition to prevent antibody-mediated postsynaptic membrane damage, and (iii) neonatal Fc receptor (FcRn) inhibition as in vivo apheresis, removing pathogenic antibodies. Herein, we discuss these advances and the potential for these newer therapies to significantly influence the current treatment paradigms. While these therapies provide exciting new options with rapid efficacy, there are anticipated challenges to their use, especially in terms of a dramatic increase in cost of care for some patients with myasthenia gravis.

Cartilage-binding antibodies initiate joint inflammation and promote chronic erosive arthritis

BACKGROUND

Antibodies binding to cartilage proteins are present in the blood and synovial fluid of early rheumatoid arthritis patients. In order to develop animal models mimicking the human disease, we have characterized the arthritogenic capacity of monoclonal antibodies directed towards different joint proteins in the cartilage.

METHODS

Purified antibodies specific to unmodified or citrullinated collagen type II (CII), collagen type XI (CXI), and cartilage oligomeric matrix protein (COMP) were produced as culture supernatant, affinity purified, pooled as antibody cocktails (Cab3 and Cab4), and injected intravenously into mice to induce arthritis. An adjuvant (lipopolysaccharide or mannan) was subsequently injected intraperitoneally on either day 5 or day 60 to enhance arthritis. Antibody binding and complement activation on the cartilage surface were analyzed by immunohistochemical methods. Bone erosions and joint deformations were analyzed by histological assessments, enzyme-linked immunosorbent assays, and micro-CT. Luminex was used to detect CII-triple helical epitope-specific antibody responses.

RESULTS

The new cartilage antibody cocktails induced an earlier and more severe disease than anti-CII antibody cocktail. Many of the mouse strains used developed severe arthritis with 3 antibodies, binding to collagen II, collagen XI, and cartilage oligomeric matrix protein (the Cab3 cocktail). Two new models of arthritis including Cab3-induced LPS-enhanced arthritis (lpsCAIA) and Cab3-induced mannan-enhanced arthritis (mCAIA) were established, causing severe bone erosions and bone loss, as well as epitope spreading of the B cell response. Cab4, with addition of an antibody to citrullinated collagen II, induced arthritis more efficiently in moderately susceptible C57BL/6 J mice.

CONCLUSIONS

The new mouse model for RA induced with cartilage antibodies allows studies of chronic development of arthritis and epitope spreading of the autoimmune response and bone erosion.

Exploration and Evaluation of Therapeutic Efficacy of Drug-Free Macromolecular Therapeutics in Collagen-Induced Rheumatoid Arthritis Mouse Model

Monoclonal antibodies (mAbs) against B cell antigens are extensively used in the treatment of rheumatoid arthritis (RA). The B cell depletion therapy prevents RA symptoms and/or alleviates existing inflammation. The previously established two-step drug-free macromolecular therapeutics (DFMT) is applied in the treatment of collagen-induced rheumatoid arthritis in a collagen-induced rheumatoid arthritis mouse model. DFMT is a B cell depletion strategy utilizing Fab' fragment of anti-CD20 mAb for biorecognition and receptor crosslinking to induce B cell apoptosis. DFMT is composed from two nanoconjugates: 1) bispecific engager, Fab'-MORF1 (anti-CD20 Fab' fragment conjugated with morpholino oligonucleotide MORF1), and 2) a crosslinking (effector) component P-(MORF2)X (N-(2-hydroxypropyl)methacrylamide copolymer grafted with multiple copies of complementary morpholino oligonucleotide MORF2). The absence of Fc fragment has the potential to avoid development of resistance and infusion-related reactions. DFMT produces B cell depletion, keeps the RA score low for more than 100 days, and shows minimal cartilage and bone erosion and inflammatory cell infiltration. Further improvements will be explored to optimize DFMT strategy in autoimmune disease treatment.

Unraveling the mysteries of plasma cells

Antibody-secreting plasma cells are the central pillars of humoral immunity. They are generated in a fundamental cellular restructuring process from naive B cells upon contact with antigen. This outstanding process is guided and controlled by a complex transcriptional network accompanied by a fascinating morphological metamorphosis, governed by the combined action of Blimp-1, Xbp-1 and IRF-4. The survival of plasma cells requires the intimate interaction with a specific microenvironment, consisting of stromal cells and cells of hematopoietic origin. Cell-cell contacts, cytokines and availability of metabolites such as glucose and amino acids modulate the survival abilities of plasma cells in their niches. Moreover, plasma cells have been shown to regulate immune responses by releasing cytokines. Furthermore, plasma cells are central players in autoimmune diseases and malignant transformation of plasma cells can result in the generation of multiple myeloma. Hence, the development of sophisticated strategies to deplete autoreactive plasma cells and myeloma cells represents a challenge for current and future research.

[Biologics in rheumatology]

BACKGROUND

Monoclonal antibodies and fusion proteins were introduced into clinical rheumatology 20 years ago. Nowadays they are an established component of modern internal medical practice.

OBJECTIVE

This article gives an overview of the breadth of biologics currently in clinical use.

MATERIAL AND METHODS

Evaluation of published approval studies and guideline recommendations, discussion of the immunological principles and targets in the treatment with biologics.

RESULTS

Monoclonal antibodies and fusion proteins for influencing cytokine signals, T‑cell costimulation and B‑cell function are the most important innovations in the treatment of rheumatological diseases. Nowadays they are indispensible for the treatment of moderate and severe disease courses of rheumatoid arthritis, spondylarthropathies and vasculitides.

CONCLUSION

Although a cure or permanent freedom from symptoms in rheumatological autoimmune diseases is still not possible, much more favorable disease courses with less long-term limitations can be achieved by the early administration of biologics.

Low-Dose Subcutaneous Anti-CD20 Treatment Depletes Disease Relevant B Cell Subsets and Attenuates Neuroinflammation

To explore the B cell depleting capacity of a low-dose (20 μg) subcutaneous mouse anti-CD20 antibody treatment on disease-relevant B cell populations within lymph nodes and the spleen. B cell depleting capacity was explored in healthy female C57BL/6 and BALB/c mice; following immune activation in two different mouse models: trinitrophenylated lipopolysaccharide model (thymus-independent response) and dinitrophenyl-keyhole limpet hemocyanin model (thymus-dependent response); and in a chronic neuroinflammation experimental autoimmune encephalomyelitis model. CD20 protein expression on B cell subpopulations was also studied. The subcutaneous anti-CD20 regimen resulted in rapid depletion of B cells in blood, lymph nodes and spleen. Low-dose subcutaneous treatment did not reduce antigen-specific immunoglobulin M and immunoglobulin G titers in all subgroups, and relatively spared splenic marginal zone (MZ) B cells in both T cell dependent and T cell independent B cell immunization models. Analysis of immune compartments during anti-CD20-modulated autoimmune neuroinflammation showed that the maximal B cell depletion was achieved within 2 days of treatment and was highest in the lymph node. Regardless of the tissues analyzed, low-dose subcutaneous treatment was characterized by rapid B cell repletion following treatment cessation. CD20 protein expression was consistent on all B cell subsets in blood, and was more pronounced in germinal center B cells of lymph nodes and MZ B-cells of the spleen. Low-dose subcutaneous anti-CD20 therapy effectively depleted B cells within lymphatic tissues and reduced the severity of neuroinflammation. These data suggest that subcutaneous anti-CD20 therapies can effectively target disease-relevant B cell populations, have shorter repletion kinetics and maintain vaccination responses, thereby achieving autoimmune amelioration without severely impacting immune surveillance functions. Graphical Abstract *p < 0.05; **p < 0.01. CD, cluster of differentiation; DNP-KLH, dinitrophenyl-keyhole limpet hemocyanin; EC50, concentration of a drug that gives half-maximal response; Ig, immunoglobulin; MZ, marginal zone; s.c., subcutaneous; SEM, standard error of mean; TNP-LPS, trinitrophenylatedlipopolysaccharide.

Expression of CD20 after viral reactivation renders HIV-reservoir cells susceptible to Rituximab

The identification of exclusive markers to target HIV-reservoir cells will represent a significant advance in the search for therapies to cure HIV. Here, we identify the B lymphocyte antigen CD20 as a marker for HIV-infected cells in vitro and in vivo. The CD20 molecule is dimly expressed in a subpopulation of CD4-positive (CD4⁺) T lymphocytes from blood, with high levels of cell activation and heterogeneous memory phenotypes. In lymph node samples from infected patients, CD20 is present in productively HIV-infected cells, and ex vivo viral infection selectively upregulates the expression of CD20 during early infection. In samples from patients on antiretroviral therapy (ART) this subpopulation is significantly enriched in HIV transcripts, and the anti-CD20 monoclonal antibody Rituximab induces cell killing, which reduces the pool of HIV-expressing cells when combined with latency reversal agents. We provide a tool for targeting this active HIV-reservoir after viral reactivation in patients while on ART.

Here, the authors identify B lymphocyte antigen CD20 as a marker for HIV-infected T cells and provide evidence for the potential use of anti-CD20 antibodies in combination with latency reversing agents for depletion of viral reactivated CD4 T cells in patients on antiretroviral therapy.

Rituximab treatment for multiple sclerosis

Rituximab, a chimeric anti-CD20-antibody, attracts increasing attention as a treatment option for multiple sclerosis (MS). Apart from smaller controlled trials, an increasing number of studies in real-world populations indicate high efficacy based on clinical and neuroradiological outcomes for rituximab in relapsing-remitting MS patients. Additional evidence also demonstrates efficacy of rituximab with treatment of progressive MS phenotypes. In this topical review, we summarize and discuss current evidence on mechanisms of action, efficacy, safety, tolerance and other clinical aspects of rituximab in the treatment of MS. Finally, we will highlight current knowledge gaps and the need for comparative studies with other disease-modifying therapies in MS.

Imaging Mass Cytometry and Single-Cell Genomics Reveal Differential Depletion and Repletion of B-Cell Populations Following Ofatumumab Treatment in Cynomolgus Monkeys

Ofatumumab is the first, fully human, anti-CD20 monoclonal antibody in Phase 3 development for multiple sclerosis (MS). The study focused on changes in lymphocyte subsets in blood and lymphoid tissues and on potential novel biomarkers as a result of anti-CD20 antibody action in Cynomolgus monkeys treated with human equivalent doses of subcutaneous (s.c.) ofatumumab on Days 0, 7, and 14. Axillary lymph nodes (LNs) and blood samples were collected at various time points until Day 90. Lymphocyte subsets were quantified by flow cytometry, while morphological and immune cell changes were assessed by imaging mass cytometry (IMC), immunohistochemistry (IHC), in situ hybridization (ISH), and transcriptome analyses using single-cell methodology. Ofatumumab treatment resulted in a potent and rapid reduction of B cells along with a simultaneous drop in CD20⁺ T cell counts. At Day 21, IHC revealed B-cell depletion in the perifollicular and interfollicular area of axillary LNs, while only the core of the germinal center was depleted of CD20⁺CD21⁺ cells. By Day 62, the perifollicular and interfollicular areas were abundantly infiltrated by CD21⁺ B cells and this distribution returned to the baseline cytoarchitecture by Day 90. By IMC CD20⁺CD3⁺CD8⁺ cells could be identified at the margin of the follicles, with a similar pattern of distribution at Day 21 and 90. Single-cell transcriptomics analysis showed that ofatumumab induced reversible changes in t-distributed stochastic neighbor embedding (t-SNE) defined B-cell subsets that may serve as biomarkers for drug action. In summary, low dose s.c. ofatumumab potently depletes both B cells and CD20⁺ T cells but apparently spares marginal zone (MZ) B cells in the spleen and LN. These findings add to our molecular and tissue-architectural understanding of ofatumumab treatment effects on B-cell subsets.

Osteoimmunology

Bone is a crucial element of the skeletal-locomotor system, but also functions as an immunological organ that harbors hematopoietic stem cells (HSCs) and immune progenitor cells. Additionally, the skeletal and immune systems share a number of regulatory molecules, including cytokines and signaling molecules. Osteoimmunology was created as an interdisciplinary field to explore the shared molecules and interactions between the skeletal and immune systems. In particular, the importance of an inseparable link between the two systems has been highlighted by studies on the pathogenesis of rheumatoid arthritis (RA), in which pathogenic helper T cells induce the progressive destruction of multiple joints through aberrant expression of receptor activator of nuclear factor (NF)-κB ligand (RANKL). The conceptual bridge of osteoimmunology provides not only a novel framework for understanding these biological systems but also a molecular basis for the development of therapeutic approaches for diseases of bone and/or the immune system.

Rituximab-induced hypogammaglobulinemia in patients with neuromyelitis optica spectrum disorders

Objective

To evaluate the long-term effects of rituximab (RTX) on total and specific immunoglobulins (Igs) in patients with neuromyelitis optica spectrum disorders (NMOSDs).

Methods

Total IgG, IgA, and IgM levels were evaluated in 15 patients with NMOSDs treated with RTX (median follow-up 70 months). Anti-aquaporin 4 (AQP4)-IgG titration was performed on samples from 9 positive patients. Anti-tetanus (TET), anti-varicella-zoster virus (VZV), and anti-Epstein–Barr virus nuclear antigen (EBNA) IgGs were also tested in patients with NMOSDs and in 6 healthy controls (HCs).

Results

RTX reduced total IgG by 0.42 g/L per year, IgA by 0.08 g/L per year, and IgM by 0.07 g/L per year. Hypogammaglobulinemia (hypo-IgG) (IgG < 7 g/L) developed in 11/15 patients. Severe hypo-IgG (IgG < 4 g/L) was found in 3/15 patients, of whom 2 patients developed serious infectious complications. In group analysis, anti-AQP4 IgG titers were reduced by RTX over time, and a significant correlation between anti-AQP4 IgG titers and total IgG levels was found. The effects of RTX were observed on pathogen-specific IgGs as well. In particular, the levels of anti-TET IgG in patients were significantly lower than those in HCs. The half-life of anti-TET IgG was reduced by about 50% in patients compared with the general population.

Conclusions

Long-term RTX treatment is associated with the risk of hypo-Ig and reduction of anti-TET protection in patients with NMOSDs. Results obtained in this study suggest the importance of monitoring total and specific Ig levels before and during treatment with anti-CD20 drugs to prevent hypo-Ig–related complications and to optimize clinical management.

Bone Loss in Rheumatoid Arthritis: Basic Mechanisms and Clinical Implications

Patients with rheumatoid arthritis (RA) have historically developed progressive damage of articular bone and cartilage, which correlates with disability over time. In addition, these patients are prone to periarticular and systemic bone loss, carrying additional morbidity. In contrast to what is seen in many other rheumatic diseases, the impact of inflammation on bone in RA is uniquely destructive. Loss of articular bone (erosions) and periarticular bone (demineralization) is a result of excessive bone resorption and markedly limited bone formation. There has been tremendous progress in preventing net bone loss in RA with the advent of disease-modifying agents, including biologic agents and small molecules, that both limit inflammation and may have a direct impact on the prevention of cytokine- and antibody-driven osteoclastogenesis. However, repair of existing bone erosions, although feasible, is observed infrequently. Lack of repair is a consequence of suppression of osteoblast function and bone formation by some of the same mechanisms that promote osteoclastogenesis and bone resorption. As new agents are introduced to control inflammation in RA, and novel mechanisms to target synovitis are identified, it may be possible in the future to fully repair damaged bone.

Rheumatoid Arthritis: A Novel Approach in Diagnosis and Treatment

The rheumatoid arthritis is chronic disease with progressive course and deteriorations of joints as well as other organs. The pathogenesis of rheumatoid arthritis is characterized with chronic synovitis and inflammation. The main roles in development of rheumatoid arthritis have auto-reactive T cells and inflammatory cytokines, especially tumor necrosis factor α, interleukin 1 and interleukin 6. The management of rheumatoid arthritis has evolved significantly in the past twenty years, especially with introduction new diagnostic criteria by European League for Rheumatoid Arthritis which are very sensitive for early arthritis. The main goal of treating rheumatoid arthritis is to start with therapy in the phase of the disease when destruction of joints can still be prevented. Therapeutic strategies for rheumatoid arthritis involve wide palette of different drugs which can be divided into conventional and biological Disease Modifying Anthirheumatic Drugs. The use of methotrexate in combination with biological drugs provide targeting not only structural changes in rheumatoid arthritis but also and immunological pathways in development of rheumatoid arthritis. These drugs synergistically provide clinical remission and low activity of rheumatoid arthritis in the majority of patients. The uses of biological drugs are limited due their high costs or safety profile. In order to reduce costs and toxicity in the treatment of rheumatoid arthritis, new treat- to –target concept is established. The new class of drugs which modulate signal pathways and activity of tyrosine kinase are under investigations in post marketing surveys in patients with rheumatoid arthritis as in efficacy as in safety issues.

Next-generation anti-CD20 monoclonal antibodies in autoimmune disease treatment

The clinical success of anti-CD20 monoclonal antibody (mAb)-mediated B cell depletion therapy has contributed to the understanding of B cells as major players in several autoimmune diseases. The first therapeutic anti-CD20 mAb, rituximab, is a murine-human chimera to which many patients develop antibodies and/or experience infusion-related reactions. A second generation of anti-CD20 mAbs has been designed to be more effective, better tolerated, and of lower immunogenicity. These include the humanized versions: ocrelizumab, obinutuzumab, and veltuzumab, and the fully human, ofatumumab. We conducted a literature search of relevant randomized clinical trials in the PubMed database and ongoing trials in Clinicaltrials.gov. Most of these trials have evaluated intravenous ocrelizumab or subcutaneous ofatumumab in rheumatoid arthritis, multiple sclerosis, or systemic lupus erythematosus. Understanding how newer anti-CD20 mAbs compare with rituximab in terms of efficacy, safety, convenience, and cost is important for guiding future management of anti-CD20 mAb therapy in autoimmune diseases.

Osteoimmunology: The Conceptual Framework Unifying the Immune and Skeletal Systems

The immune and skeletal systems share a variety of molecules, including cytokines, chemokines, hormones, receptors, and transcription factors. Bone cells interact with immune cells under physiological and pathological conditions. Osteoimmunology was created as a new interdisciplinary field in large part to highlight the shared molecules and reciprocal interactions between the two systems in both heath and disease. Receptor activator of NF-κB ligand (RANKL) plays an essential role not only in the development of immune organs and bones, but also in autoimmune diseases affecting bone, thus effectively comprising the molecule that links the two systems. Here we review the function, gene regulation, and signal transduction of osteoimmune molecules, including RANKL, in the context of osteoclastogenesis as well as multiple other regulatory functions. Osteoimmunology has become indispensable for understanding the pathogenesis of a number of diseases such as rheumatoid arthritis (RA). We review the various osteoimmune pathologies, including the bone destruction in RA, in which pathogenic helper T cell subsets [such as IL-17-expressing helper T (Th17) cells] induce bone erosion through aberrant RANKL expression. We also focus on cellular interactions and the identification of the communication factors in the bone marrow, discussing the contribution of bone cells to the maintenance and regulation of hematopoietic stem and progenitors cells. Thus the time has come for a basic reappraisal of the framework for understanding both the immune and bone systems. The concept of a unified osteoimmune system will be absolutely indispensable for basic and translational approaches to diseases related to bone and/or the immune system.