B cell-based therapies in CNS autoimmunity: differentiating CD19 and CD20 as therapeutic targets

HLA-transgenic mouse models to study autoimmune central nervous system diseases

It is known that certain human leukocyte antigen (HLA) genes are associated with autoimmune central nervous system (CNS) diseases, such as multiple sclerosis (MS), but their exact role in disease susceptibility and etiopathogenesis remains unclear. The best studied HLA-associated autoimmune CNS disease is MS, and thus will be the primary focus of this review. Other HLA-associated autoimmune CNS diseases, such as autoimmune encephalitis and neuromyelitis optica will be discussed. The lack of animal models to accurately capture the complex human autoimmune response remains a major challenge. HLA transgenic (tg) mice provide researchers with powerful tools to investigate the underlying mechanisms promoting susceptibility and progression of HLA-associated autoimmune CNS diseases, as well as for elucidating the myelin epitopes potentially targeted by T cells in autoimmune disease patients. We will discuss the potential role(s) of autoimmune disease-associated HLA alleles in autoimmune CNS diseases and highlight information provided by studies using HLA tg mice to investigate the underlying pathological mechanisms and opportunities to use these models for development of novel therapies.

Advancements and challenges in CAR T cell therapy in autoimmune diseases

Chimeric antigen receptor (CAR) T cells are highly effective at targeting and eliminating cells of the B cell lineage. CAR T cell therapy has become a standard-of-care treatment for patients with relapsed or refractory B cell malignancies. In addition, the administration of genetically modified T cells with the capacity to deplete B cells and/or plasma cells has tremendous therapeutic potential in autoimmune diseases. In the past few years, CD19-based and B cell maturation antigen (BCMA)-based CAR T cell therapies have been applied to various B cell-mediated autoimmune diseases including systemic lupus erythematosus, idiopathic inflammatory myopathy, systemic sclerosis, neuromyelitis optica spectrum disorder, myasthenia gravis and multiple sclerosis. The scientific rationale behind this approach is that deep depletion of B cells, including autoreactive B cell clones, could restore normal immune function, referred to as an immune reset. In this Review, we discuss important aspects of CAR T cell therapy in autoimmune disease, including considerations relating to patient selection, safety, efficacy and medical management. These considerations are based on the early experiences of CAR T cell therapy in autoimmune diseases, and as the field of CAR T cell therapy in autoimmune diseases continues to rapidly evolve, these issues will remain subject to ongoing refinement and adaptation.

Spatial Single Cell Profiling Using Imaging Mass Cytometry: Inflammatory Versus Penetrating Crohn's Disease

BACKGROUND AND AIMS

Fistula formation is a major complication in Crohn's disease [CD] and the role of the immune cell compartment remains to be elucidated. Thus, we compared the immune cell compartment of CD fistula to inflammatory CD colitis using imaging mass cytometry [IMC] and immunofluorescence.

METHODS

A 36-marker panel including structural, functional, and lineage markers for use in IMC was established. This panel was applied to analyse paraffin-embedded CD fistula tract [n = 11], CD colitis [n = 10], and colon samples from non-inflamed controls [n = 12]. Computational methods for cell segmentation, dimensionality reduction, and cell type clustering were used to define cell populations for cell frequency, marker distribution, and spatial neighbourhood analysis. Multiplex immunofluorescence was used for higher resolution spatial analysis.

RESULTS

Analysis of cell frequencies in CD fistulas compared to CD colitis and control colonic samples revealed a significant increase in neutrophils, effector cytotoxic T cells, and inflammatory macrophages in CD fistula samples, whereas regulatory T cells were decreased. Neutrophils in CD fistula expressed significantly more matrix metalloproteinase 9 [MMP9], correlating with extracellular matrix remodelling. Neighbourhood analysis revealed a strong association between MMP9+ neutrophils and effector cytotoxic T cells in both CD fistulas and colitis.

CONCLUSIONS

This study presents the first highly multiplexed single cell analysis of the immune cell compartment of CD fistulas and their spatial context. It links immune cell dynamics, particularly MMP9+ neutrophils, to extracellular matrix remodelling in CD fistulas, offering insights into the complex network of cellular interactions and potential therapeutic targets for CD complications.

[CAR T-cell therapy in rheumatology-What we know so far?]

Autoreactive B‑cells play a key role in the pathogenesis of autoimmune diseases, such systemic lupus erythematosus (SLE). An efficient depletion of B‑cells therefore plays a special role in autoimmune diseases, especially in cases with a severe course of the disease. Treatment with chimeric antigen receptor (CAR) T‑cells, which was originally developed for the treatment of B‑cell lymphomas and leukemias, provides the possibility to deplete B‑cells even in deep tissues. The initial results from case series with this procedure for SLE, myositis and systemic sclerosis were very positive. This review article gives an overview of the course, mechanism of action, results so far and the research agenda of CAR T‑cell therapy in autoimmune diseases.

Sequential immunotherapy: towards cures for autoimmunity

Despite major progress in the treatment of autoimmune diseases in the past two decades, most therapies do not cure disease and can be associated with increased risk of infection through broad suppression of the immune system. However, advances in understanding the causes of autoimmune disease and clinical data from novel therapeutic modalities such as chimeric antigen receptor T cell therapies provide evidence that it may be possible to re-establish immune homeostasis and, potentially, prolong remission or even cure autoimmune diseases. Here, we propose a 'sequential immunotherapy' framework for immune system modulation to help achieve this ambitious goal. This framework encompasses three steps: controlling inflammation; resetting the immune system through elimination of pathogenic immune memory cells; and promoting and maintaining immune homeostasis via immune regulatory agents and tissue repair. We discuss existing drugs and those in development for each of the three steps. We also highlight the importance of causal human biology in identifying and prioritizing novel immunotherapeutic strategies as well as informing their application in specific patient subsets, enabling precision medicine approaches that have the potential to transform clinical care.

Lymphoblastoid cell lines do not recapitulate physiological circulating B cell subtypes

Lymphoblastoid cell lines (LCLs) are immortalised peripheral B lymphocytes, transformed via infection with Epstein Barr virus (EBV). The use of LCLs to study B cell function remains controversial and core markers to define physiological B cell populations are not consistent between studies of physiological B cells and LCLs. A consensus on the nature of these commonly used cell lines has not been reached. Recently, a core set of markers to subtype peripheral B cells was proposed, addressing the lack of agreed markers for B cell characterisation. In this present study, the consensus panel was applied to describe the B cell subtypes in LCLs. We found that LCLs were generally not physiologically representative of B cells, with most cells harbouring marker combinations absent on peripheral B cells. Some B cell subtyping markers were fundamentally altered during EBV transformation to LCLs (e.g. CD19, CD21). Notably, most LCLs secreted IgG but the associated marker combinations were predominantly only present in vitro following EBV transformation. This study therefore informs interpretation of past investigations, and planning of future studies using LCLs, as these cells are unlikely to behave like their pre-transformed B cell subtype.

Chimeric antigen receptor T cell therapy for autoimmune disease

Infusion of T cells engineered to express chimeric antigen receptors (CARs) that target B cells has proven to be a successful treatment for B cell malignancies. This success inspired the development of CAR T cells to selectively deplete or modulate the aberrant immune responses that underlie autoimmune disease. Promising results are emerging from clinical trials of CAR T cells targeting the B cell protein CD19 in patients with B cell-driven autoimmune diseases. Further approaches are being designed to extend the application and improve safety of CAR T cell therapy in the setting of autoimmunity, including the use of chimeric autoantibody receptors to selectively deplete autoantigen-specific B cells and the use of regulatory T cells engineered to express antigen-specific CARs for targeted immune modulation. Here, we highlight important considerations, such as optimal target cell populations, CAR construct design, acceptable toxicities and potential for lasting immune reset, that will inform the eventual safe adoption of CAR T cell therapy for the treatment of autoimmune diseases.

Safety and efficacy of inebilizumab for the treatment of neuromyelitis optica spectrum disorder: end-of-study results from the open-label period of the N-MOmentum trial

BACKGROUND

Inebilizumab, an anti-CD19 B-cell-depleting antibody, demonstrated safety and efficacy in neuromyelitis optica spectrum disorder in the randomised controlled period of the N-MOmentum trial. Here, end-of-study data, including the randomised controlled period and open-label extension period, are reported.

METHODS

In the double-blind, randomised, placebo-controlled, phase 2/3 N-MOmentum trial, adults aged 18 years and older with an neuromyelitis optica spectrum disorder diagnosis, Expanded Disability Status Scale score of 8·0 or less, and history of either at least one acute inflammatory attack requiring rescue therapy in the past year or two attacks requiring rescue therapy in the past 2 years, were recruited from 81 outpatient specialty clinics or hospitals in 24 countries. Eligible participants were randomly assigned (3:1), using a central interactive voice system or interactive web response system, and a permuted block randomisation scheme (block size of 4), to receive intravenous inebilizumab (300 mg) or identical placebo on days 1 and 15 of the randomised period, which lasted up to 197 days. Participants and all study staff were masked to treatment assignment. The primary endpoint of the randomised period of the trial was time to onset of adjudicated neuromyelitis optica spectrum disorder attack on or before day 197. Participants in the randomised controlled period who had an adjudicated attack, completed 197 days in the study, or were in the randomised controlled period when enrolment stopped, could voluntarily enter the open-label period. In the open-label period, participants either initiated inebilizumab if assigned placebo (receiving 300 mg on days 1 and 15 of the open-label period) or continued treatment if assigned inebilizumab (receiving 300 mg on day 1 and placebo on day 15, to maintain B-cell depletion and masking of the randomised controlled period). All participants subsequently received inebilizumab 300 mg every 6 months for a minimum of 2 years. The end-of-study analysis endpoints were time to adjudicated attack and annualised attack rate (assessed in all participants who received inebilizumab at any point during the randomised controlled period or open-label period [any inebilizumab population] and the aquaporin-4 [AQP4]-IgG seropositive subgroup [any inebilizumab-AQP4-IgG seropositive population]) and safety outcomes (in all participants who were exposed to inebilizumab, analysed as-treated). This study is registered with ClinicalTrials.gov, NCT02200770, and is now complete.

FINDINGS

Between Jan 6, 2015, and Sept 24, 2018, 467 individuals were screened, 231 were randomly assigned, and 230 received at least one dose of inebilizumab (n=174) or placebo (n=56). Between May 19, 2015, and Nov 8, 2018, 165 (95%) of 174 participants in the inebilizumab group and 51 (91%) of 56 in the placebo group entered the open-label period (mean age 42·9 years [SD 12·4], 197 [91%] of 216 were female, 19 [9%] were male, 115 [53%] were White, 45 [21%] were Asian, 19 [9%] were American Indian or Alaskan Native, and 19 [9%] were Black or African American). As of data cutoff for this end of study analysis (Dec 18, 2020; median exposure 1178 days [IQR 856-1538], total exposure of 730 person-years) 225 participants formed the any inebilizumab population, and 208 (92%) participants were AQP4-IgG seropositive. Overall, 63 adjudicated neuromyelitis optica spectrum disorder attacks occurred in 47 (21%) of 225 treated participants (60 attacks occurred in 44 [21%] of 208 in the AQP4-IgG seropositive subgroup); 40 (63%) of 63 attacks occurred in 34 (15%) of 225 treated participants during the first year of treatment. Of individuals who had an adjudicated attack while receiving inebilizumab, 36 (77%) of 47 were subsequently attack-free at the end of 4 years. Annualised attack rates decreased year-on-year, with end-of-study adjusted annualised attack rates being similar in the any inebilizumab-AQP4-IgG seropositive subgroup (0·097 [95% CI 0·070-0·14]) and any inebilizumab populations (0·092 [0·067-0·13]). Overall, 208 (92%) of 225 participants who received any inebilizumab had at least one treatment-emergent adverse event, the most frequent of which were urinary tract infection (59 [26%]), nasopharyngitis (47 [21%]), and arthralgia (39 [17%]). Infection rates did not increase over 4 years. Three (1%) of 225 participants in the any inebilizumab population died during the open-label period (one each due to a CNS event of unknown cause and pneumonia, respiratory insufficiency resulting from an neuromyelitis optica spectrum disorder attack and viral pneumonia related to COVID-19), all of which were deemed to be unrelated to treatment.

INTERPRETATION

Data from the end-of-study analysis of the N-MOmentum trial showed continued and sustained clinical benefits of long-term inebilizumab treatment in individuals with neuromyelitis optica spectrum disorder, which supports the role of inebilizumab as a CD19+ B-cell-depleting therapy in neuromyelitis optica spectrum disorder.

FUNDING

MedImmune and Viela Bio/Horizon Therapeutics, now part of Amgen.

Clinical and Immunological Impact of Ocrelizumab Extended Interval Dosing in Multiple Sclerosis: A Single-Center, Real-World Experience

Ocrelizumab (OCR), an anti-CD20 monoclonal antibody, is approved for treating relapsing remitting (RR) and primary progressive (PP) multiple sclerosis (MS). The standard interval dosing (SID) regimen requires intravenous infusions every six months. Experience of extended dosing due to COVID-19 pandemic-related issues suggests that this strategy may provide comparable efficacy while reducing treatment burden and healthcare costs. This study aimed to evaluate clinical effectiveness, changes in B- and T-cell count, and immunoglobulin dynamics associated with extended interval dosing (EID) of ocrelizumab in a real-world setting. We retrospectively included RRMS or PPMS patients treated with OCR that had already received two OCR cycles and with at least 6 months of follow up after the last infusion. EID was defined as a ≥4 weeks delay compared to SID. Clinical outcomes were occurrence of relapses, MRI activity, 6-months confirmed disability progression (CDP) and their combination (No Evidence of Disease Activity, NEDA-3). We also evaluated changes in CD19+ B cell count, CD4+ and CD8+ T cell count, immunoglobulin titers, and occurrence of hypogammaglobulinemia (hypo-Ig). Frequency tests, multivariate regression models, and survival analysis were applied as appropriate. We analyzed data on 93 subjects (75.3% RRMS) for a total of 389 infusions (272 SID, 117 EID). Clinical and MRI activity, CDP, and NEDA 3 did not significantly differ between EID and SID. EID was associated with lower rates of B-cell depletion. T-cell dynamics and incidence of hypo-Ig were comparable following EID and SID. Hypo-IgG at index infusion was associated with further occurrence of hypo-IgG; male sex and hypo-IgM at index infusion were independently associated with hypo-IgM. In conclusion, OCR EID does not impact MS clinical and radiological outcomes, although it interferes with B-cell dynamics. These findings provide support for a tailored schedule of OCR in MS.

Exploring the depths of IgG4: insights into autoimmunity and novel treatments

IgG4 subclass antibodies represent the rarest subclass of IgG antibodies, comprising only 3-5% of antibodies circulating in the bloodstream. These antibodies possess unique structural features, notably their ability to undergo a process known as fragment-antigen binding (Fab)-arm exchange, wherein they exchange half-molecules with other IgG4 antibodies. Functionally, IgG4 antibodies primarily block and exert immunomodulatory effects, particularly in the context of IgE isotype-mediated hypersensitivity reactions. In the context of disease, IgG4 antibodies are prominently observed in various autoimmune diseases combined under the term IgG4 autoimmune diseases (IgG4-AID). These diseases include myasthenia gravis (MG) with autoantibodies against muscle-specific tyrosine kinase (MuSK), nodo-paranodopathies with autoantibodies against paranodal and nodal proteins, pemphigus vulgaris and foliaceus with antibodies against desmoglein and encephalitis with antibodies against LGI1/CASPR2. Additionally, IgG4 antibodies are a prominent feature in the rare entity of IgG4 related disease (IgG4-RD). Intriguingly, both IgG4-AID and IgG4-RD demonstrate a remarkable responsiveness to anti-CD20-mediated B cell depletion therapy (BCDT), suggesting shared underlying immunopathologies. This review aims to provide a comprehensive exploration of B cells, antibody subclasses, and their general properties before examining the distinctive characteristics of IgG4 subclass antibodies in the context of health, IgG4-AID and IgG4-RD. Furthermore, we will examine potential therapeutic strategies for these conditions, with a special focus on leveraging insights gained from anti-CD20-mediated BCDT. Through this analysis, we aim to enhance our understanding of the pathogenesis of IgG4-mediated diseases and identify promising possibilities for targeted therapeutic intervention.

B-cell targeted therapies in autoimmune encephalitis: mechanisms, clinical applications, and therapeutic potential

Autoimmune encephalitis (AE) broadly refers to inflammation of the brain parenchyma mediated by autoimmune mechanisms. In most patients with AE, autoantibodies against neuronal cell surface antigens are produced by B-cells and induce neuronal dysfunction through various mechanisms, ultimately leading to disease progression. In recent years, B-cell targeted therapies, including monoclonal antibody (mAb) therapy and chimeric antigen receptor T-cell (CAR-T) therapy, have been widely used in autoimmune diseases. These therapies decrease autoantibody levels in patients and have shown favorable results. This review summarizes the mechanisms underlying these two B-cell targeted therapies and discusses their clinical applications and therapeutic potential in AE. Our research provides clinicians with more treatment options for AE patients whose conventional treatments are not effective.

Distribution of multi-level B cell subsets in thymoma and thymoma-associated myasthenia gravis

B-cell subsets in peripheral blood (PB) and tumor microenvironment (TME) were evaluated to determine myasthenia gravis (MG) severity in patients with thymoma-associated MG (TMG) and the distribution of B cells in type B TMG. The distribution of mature B cells, including Bm1-Bm5, CD19+ and CD20+ B cells and non-switched (NSMBCs) and switched (SMBCs) memory B cells, were determined in 79 patients with thymoma or TMG. Quantitative relationships between the T and TMG groups and the TMG-low and TMG-high subgroups were determined. NSMBCs and SMBCs were compared in TME and PB. Type B thymoma was more likely to develop into MG, with types B2 and B3 being especially associated with MG worsening. The percentage of CD19+ B cells in PB gradually increased, whereas the percentage of CD20+ B cells and the CD19/CD20 ratio were not altered. The (Bm2 + Bm2')/(eBm5 + Bm5) index was significantly higher in the TMG-high than in thymoma group. The difference between SMBC/CD19+ and NSMBC/CD19+ B cell ratios was significantly lower in the thymoma than TMG group. NSMBCs assembled around tertiary lymphoid tissue in thymomas of patients with TMG. Few NSMBCs were observed in patients with thymoma alone, with these cells being diffusely distributed. MG severity in patients with TMG can be determined by measuring CD19+ B cells and Bm1-Bm5 in PB. The CD19/CD20 ratio is a marker of disease severity in TMG patients. Differences between NSMBCs and SMBCs in PB and TME of thymomas can synergistically determine MG severity in patients with TMG.

In relapsed or refractory diffuse large B-cell lymphoma, CD19 expression by immunohistochemistry alone is not a predictor of response to loncastuximab tesirine

CD19-targeting treatments have shown promise in relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL). Loncastuximab tesirine (loncastuximab tesirine-lpyl [Lonca]) is a CD19-targeting antibody-drug conjugate indicated for R/R DLBCL after at least two systemic treatments. CD19 expression was evaluated in patients receiving Lonca in the LOTIS-2 clinical trial with available tissue samples obtained after last systemic therapy/before Lonca treatment. Lonca cytotoxicity was evaluated in a panel of six lymphoma cell lines with various CD19 expression levels. Quantitative systems pharmacology (QSP) modelling was used to predict Lonca responses. Lonca responses were seen in patients across all CD19 expression levels, including patients with low/no detectable CD19 expression and H-scores at baseline. Similarly, Lonca induced cytotoxicity in cell lines with different levels of CD19 expression, including one with very low expression. QSP modelling predicted that CD19 expression by immunohistochemistry alone does not predict Lonca response, whereas inclusion of CD19 surface density improved response prediction. Virtual patients responded to Lonca with estimated CD19 as low as 1000 molecules/cell of CD19, normally below the immunohistochemistry detection level. We found Lonca is an effective treatment for R/R DLBCL regardless of CD19 expression by immunohistochemistry. These results provide the basis for future studies addressing CD19-targeted agent sequencing.

Inebilizumab reduces neuromyelitis optica spectrum disorder risk independent of FCGR3A polymorphism

Inebilizumab, a humanized, glycoengineered, IgG1 monoclonal antibody that depletes CD19+ B-cells, is approved to treat aquaporin 4 (AQP4) IgG-seropositive neuromyelitis optica spectrum disorder (NMOSD). Inebilizumab is afucosylated and engineered for enhanced affinity to Fc receptor III-A (FCGR3A) receptors on natural killer cells to maximize antibody-dependent cellular cytotoxicity. Previously, the F allele polymorphism at amino acid 158 of the FCGR3A gene (F158) was shown to decrease IgG-binding affinity and reduce rituximab (anti-CD20) efficacy for NMOSD attack prevention. In contrast, our current findings from inebilizumab-treated NMOSD patients indicate similar clinical outcomes between those with F158 and V158 allele genotypes.

Tumor-Infiltrating Normal B Cells Revealed by Immunoglobulin Repertoire Clonotype Analysis Are Highly Prognostic and Crucial for Antitumor Immune Responses in DLBCL

PURPOSE

Tumor-infiltrating B lymphocytes (TIL-B) have demonstrated prognostic and predictive significance in solid cancers. In this study, we aimed to distinguish TIL-Bs from malignant B-cells in diffuse large B-cell lymphoma (DLBCL) and determine the clinical and biological significance.

EXPERIMENTAL DESIGN

A total of 269 patients with de novo DLBCL from the International DLBCL R-CHOP Consortium Program were studied. Ultra-deep sequencing of the immunoglobulin genes was performed to determine B-cell clonotypes. The frequencies and numbers of TIL-B clonotypes in individual repertoires were correlated with patient survival, gene expression profiling (GEP) data, and frequencies of DLBCL-infiltrating immune cells quantified by fluorescent multiplex IHC at single-cell resolution.

RESULTS

TIL-B abundance, evaluated by frequencies of normal B-cell clonotypes in the immunoglobulin repertoires, remarkably showed positive associations with significantly better survival of patients in our sequenced cohorts. DLBCLs with high versus low TIL-B abundance displayed distinct GEP signatures, increased pre-memory B-cell state and naïve CD4 T-cell state fractions, and higher CD4+ T-cell infiltration. TIL-B frequency, as a new biomarker in DLBCL, outperformed the germinal center (GC) B-cell-like/activated B-cell-like classification and TIL-T frequency. The identified TIL-B-high GEP signature, including genes upregulated during T-dependent B-cell activation and those highly expressed in normal GC B cells and T cells, showed significant favorable prognostic effects in several external validation cohorts.

CONCLUSIONS

TIL-B frequency is a significant prognostic factor in DLBCL and plays a crucial role in antitumor immune responses. This study provides novel insights into the prognostic determinants in DLBCL and TIL-B functions with important therapeutic implications.

Delving into Molecular Pathways: Analyzing the Mechanisms of Action of Monoclonal Antibodies Integrated in IMGT/mAb-DB for Myasthenia Gravis

BACKGROUND

Myasthenia Gravis (MG) is a rare autoimmune disease presenting with auto-antibodies that affect the neuromuscular junction. In addition to symptomatic treatment options, novel therapeutics include monoclonal antibodies (mAbs). IMGT®, the international ImMunoGeneTics information system®, extends the characterization of therapeutic antibodies with a systematic description of their mechanisms of action (MOA) and makes them available through its database for mAbs and fusion proteins, IMGT/mAb-DB.

METHODS

Using available literature data combined with amino acid sequence analyses from mAbs managed in IMGT/2Dstructure-DB, the IMGT® protein database, biocuration allowed us to define in a standardized way descriptions of MOAs of mAbs that target molecules towards MG treatment.

RESULTS

New therapeutic targets include FcRn and molecules such as CD38, CD40, CD19, MS4A1, and interleukin-6 receptor. A standardized graphical representation of the MOAs of selected mAbs was created and integrated within IMGT/mAb-DB. The main mechanisms involved in these mAbs are either blocking or neutralizing. Therapies directed to B cell depletion and plasma cells have a blocking MOA with an immunosuppressant effect along with Fc-effector function (MS4A1, CD38) or FcγRIIb engager effect (CD19). Monoclonal antibodies targeting the complement also have a blocking MOA with a complement inhibitor effect, and treatments targeting T cells have a blocking MOA with an immunosuppressant effect (CD40) and Fc-effector function (IL6R). On the other hand, FcRn antagonists present a neutralizing MOA with an FcRn inhibitor effect.

CONCLUSION

The MOA of each new mAb needs to be considered in association with the immunopathogenesis of each of the subtypes of MG in order to integrate the new mAbs as a viable and safe option in the therapy decision process. In IMGT/mAb-DB, mAbs for MG are characterized by their sequence, domains, and chains, and their MOA is described.

CAR T-cell therapy in autoimmune diseases

Despite the tremendous progress in the clinical management of autoimmune diseases, many patients do not respond to the currently used treatments. Autoreactive B cells play a key role in the pathogenesis of autoimmune diseases, such as systemic lupus erythematosus, rheumatoid arthritis, and multiple sclerosis. B-cell-depleting monoclonal antibodies, such as rituximab, have poor therapeutic efficacy in autoimmune diseases, mainly due to the persistence of autoreactive B cells in lymphatic organs and inflamed tissues. The adoptive transfer of T cells engineered to target tumour cells via chimeric antigen receptors (CARs) has emerged as an effective treatment modality in B-cell malignancies. In the last 2 years treatment with autologous CAR T cells directed against the CD19 antigen has been introduced in therapy of autoimmune disease. CD19 CAR T cells induced a rapid and sustained depletion of circulating B cells, as well as in a complete clinical and serological remission of refractory systemic lupus erythematosus and dermatomyositis. In this paper, we discuss the evolving strategies for targeting autoreactive B cells via CAR T cells, which might be used for targeted therapy in autoimmune diseases.

A rat liver cell atlas reveals intrahepatic myeloid heterogeneity

The large size and vascular accessibility of the laboratory rat (Rattus norvegicus) make it an ideal hepatic animal model for diseases that require surgical manipulation. Often, the disease susceptibility and outcomes of inflammatory pathologies vary significantly between strains. This study uses single-cell transcriptomics to better understand the complex cellular network of the rat liver, as well as to unravel the cellular and molecular sources of inter-strain hepatic variation. We generated single-cell and single-nucleus transcriptomic maps of the livers of healthy Dark Agouti and Lewis rat strains and developed a factor analysis-based bioinformatics analysis pipeline to study data covariates, such as strain and batch. Using this approach, we discovered transcriptomic variation within the hepatocyte and myeloid populations that underlie distinct cell states between rat strains. This finding will help provide a reference for future investigations on strain-dependent outcomes of surgical experiment models.

The plethora of immunomodulatory drugs: opportunities for immune-mediated kidney diseases

In recent decades, insights into the molecular pathways involved in disease have revolutionized the treatment of autoimmune diseases. A plethora of targeted therapies have been identified and are at varying stages of clinical development in renal autoimmunity. Some of these agents, such as rituximab or avacopan, have been approved for the treatment of immune-mediated kidney disease, but kidney disease lags behind more common autoimmune disorders in new drug development. Evidence is accumulating as to the importance of adaptive immunity, including abnormalities in T-cell activation and signaling, and aberrant B-cell function. Furthermore, innate immunity, particularly the complement and myeloid systems, as well as pathologic responses in tissue repair and fibrosis, play a key role in disease. Collectively, these mechanistic studies in innate and adaptive immunity have provided new insights into mechanisms of glomerular injury in immune-mediated kidney diseases. In addition, inflammatory pathways common to several autoimmune conditions exist, suggesting that the repurposing of some existing drugs for the treatment of immune-mediated kidney diseases is a logical strategy. This new understanding challenges the clinical investigator to translate new knowledge into novel therapies leading to better disease outcomes. This review highlights promising immunomodulatory therapies tested for immune-mediated kidney diseases as a primary indication, details current clinical trials and discusses pathways that could be targeted in the future.

Proteolipid Protein-Induced Mouse Model of Multiple Sclerosis Requires B Cell-Mediated Antigen Presentation

The pathogenic role B cells play in multiple sclerosis is underscored by the success of B cell depletion therapies. Yet, it remains unclear how B cells contribute to disease, although it is increasingly accepted that mechanisms beyond Ab production are involved. Better understanding of pathogenic interactions between B cells and autoreactive CD4 T cells will be critical for novel therapeutics. To focus the investigation on B cell:CD4 T cell interactions in vivo and in vitro, we previously developed a B cell-dependent, Ab-independent experimental autoimmune encephalomyelitis (EAE) mouse model driven by a peptide encompassing the extracellular domains of myelin proteolipid protein (PLPECD). In this study, we demonstrate that B cell depletion significantly inhibited PLPECD-induced EAE disease, blunted PLPECD-elicited delayed-type hypersensitivity reactions in vivo, and reduced CD4 T cell activation, proliferation, and proinflammatory cytokine production. Further, PLPECD-reactive CD4 T cells sourced from B cell-depleted donor mice failed to transfer EAE to naive recipients. Importantly, we identified B cell-mediated Ag presentation as the critical mechanism explaining B cell dependence in PLPECD-induced EAE, where bone marrow chimeric mice harboring a B cell-restricted MHC class II deficiency failed to develop EAE. B cells were ultimately observed to restimulate significantly higher Ag-specific proliferation from PLP178-191-reactive CD4 T cells compared with dendritic cells when provided PLPECD peptide in head-to-head cultures. We therefore conclude that PLPECD-induced EAE features a required pathogenic B cell-mediated Ag presentation function, providing for investigable B cell:CD4 T cell interactions in the context of autoimmune demyelinating disease.

Leptomeningeal Metastasis: A Review of the Pathophysiology, Diagnostic Methodology, and Therapeutic Landscape

The present review aimed to establish an understanding of the pathophysiology of leptomeningeal disease as it relates to late-stage development among different cancer types. For our purposes, the focused metastatic malignancies include breast cancer, lung cancer, melanoma, primary central nervous system tumors, and hematologic cancers (lymphoma, leukemia, and multiple myeloma). Of note, our discussion was limited to cancer-specific leptomeningeal metastases secondary to the aforementioned primary cancers. LMD mechanisms secondary to non-cancerous pathologies, such as infection or inflammation of the leptomeningeal layer, were excluded from our scope of review. Furthermore, we intended to characterize general leptomeningeal disease, including the specific anatomical infiltration process/area, CSF dissemination, manifesting clinical symptoms in patients afflicted with the disease, detection mechanisms, imaging modalities, and treatment therapies (both preclinical and clinical). Of these parameters, leptomeningeal disease across different primary cancers shares several features. Pathophysiology regarding the development of CNS involvement within the mentioned cancer subtypes is similar in nature and progression of disease. Consequently, detection of leptomeningeal disease, regardless of cancer type, employs several of the same techniques. Cerebrospinal fluid analysis in combination with varied imaging (CT, MRI, and PET-CT) has been noted in the current literature as the gold standard in the diagnosis of leptomeningeal metastasis. Treatment options for the disease are both varied and currently in development, given the rarity of these cases. Our review details the differences in leptomeningeal disease as they pertain through the lens of several different cancer subtypes in an effort to highlight the current state of targeted therapy, the potential shortcomings in treatment, and the direction of preclinical and clinical treatments in the future. As there is a lack of comprehensive reviews that seek to characterize leptomeningeal metastasis from various solid and hematologic cancers altogether, the authors intended to highlight not only the overlapping mechanisms but also the distinct patterning of disease detection and progression as a means to uniquely treat each metastasis type. The scarcity of LMD cases poses a barrier to more robust evaluations of this pathology. However, as treatments for primary cancers have improved over time, so has the incidence of LMD. The increase in diagnosed cases only represents a small fraction of LMD-afflicted patients. More often than not, LMD is determined upon autopsy. The motivation behind this review stems from the increased capacity to study LMD in spite of scarcity or poor patient prognosis. In vitro analysis of leptomeningeal cancer cells has allowed researchers to approach this disease at the level of cancer subtypes and markers. We ultimately hope to facilitate the clinical translation of LMD research through our discourse.

Evaluation of BAFF, APRIL and CD40L in Ocrelizumab-Treated pwMS and Infectious Risk

BACKGROUND

The anti-CD20 monoclonal antibody ocrelizumab has been widely employed in the treatment of people with multiple sclerosis (pwMS). However, its B-cell-depleting effect may induce a higher risk of infectious events and alterations in the secretion of B-cell-activating factors, such as BAFF, APRIL and CD40L.

METHODS

The aim of this study was to investigate plasma BAFF, APRIL and CD40L levels and their relationship with infectious risk in ocrelizumab-treated pwMS at baseline (T0), at 6 months (T6) and at 12 months (T12) after starting the treatment. As a control group, healthy donors (HD) were enrolled too.

RESULTS

A total of 38 pwMS and 26 HD were enrolled. At baseline, pwMS showed higher plasma BAFF (p < 0.0001), APRIL (p = 0.0223) and CD40L (p < 0.0001) levels compared to HD. Compared to T0, plasma BAFF levels were significantly increased at both T6 and T12 (p < 0.0001 and p < 0.0001, respectively). Whereas plasma APRIL and CD40L levels were decreased at T12 (p = 0.0003 and p < 0.0001, respectively). When stratifying pwMS according to the development of an infectious event during the 12-month follow-up period in two groups-with (14) and without an infectious event (24)-higher plasma BAFF levels were observed at all time-points; significantly, in the group with an infectious event compared to the group without an infectious event (T0: p < 0.0001, T6: p = 0.0056 and T12: p = 0.0400). Conclusions: BAFF may have a role as a marker of immune dysfunction and of infectious risk.

B cell targeted therapies in inflammatory autoimmune disease of the central nervous system

Cumulative evidence along several lines indicates that B cells play an important role in the pathological course of multiple sclerosis (MS), neuromyelitisoptica spectrum disorders (NMOSD) and related CNS diseases. This has prompted extensive research in exploring the utility of targeting B cells to contain disease activity in these disorders. In this review, we first recapitulate the development of B cells from their origin in the bone marrow to their migration to the periphery, including the expression of therapy-relevant surface immunoglobulin isotypes. Not only the ability of B cells to produce cytokines and immunoglobulins seems to be essential in driving neuroinflammation, but also their regulatory functions strongly impact pathobiology. We then critically assess studies of B cell depleting therapies, including CD20 and CD19 targeting monoclonal antibodies, as well as the new class of B cell modulating substances, Bruton´s tyrosinekinase (BTK) inhibitors, in MS, NMOSD and MOGAD.

Targeting B Cells and Microglia in Multiple Sclerosis With Bruton Tyrosine Kinase Inhibitors: A Review

Importance

Currently, disease-modifying therapies for multiple sclerosis (MS) use 4 mechanisms of action: immune modulation, suppressing immune cell proliferation, inhibiting immune cell migration, or cellular depletion. Over the last decades, the repertoire substantially increased because of the conceptual progress that not only T cells but also B cells play an important pathogenic role in MS, fostered by the empirical success of B cell-depleting antibodies against the surface molecule CD20. Notwithstanding this advance, a continuous absence of B cells may harbor safety risks, such as a decline in the endogenous production of immunoglobulins. Accordingly, novel B cell-directed MS therapies are in development, such as inhibitors targeting Bruton tyrosine kinase (BTK).

Observations

BTK is centrally involved in the B cell receptor-mediated activation of B cells, one key requirement in the development of autoreactive B cells, but also in the activation of myeloid cells, such as macrophages and microglia. Various compounds in development differ in their binding mode, selectivity and specificity, relative inhibitory concentration, and potential to enter the central nervous system. The latter may be important in assessing whether BTK inhibition is a promising strategy to control inflammatory circuits within the brain, the key process that is assumed to drive MS progression. Accordingly, clinical trials using BTK inhibitors are currently conducted in patients with relapsing-remitting MS as well as progressive MS, so far generating encouraging data regarding efficacy and safety.

Conclusions and Relevance

While the novel approach of targeting BTK is highly promising, several questions remain unanswered, such as the long-term effects of using BTK inhibitors in the treatment of inflammatory CNS disease. Potential changes in circulating antibody levels should be evaluated and compared with B cell depletion. Also important is the potential of BTK inhibitors to enter the CNS, which depends on the given compound. Remaining questions involve where BTK inhibitors fit in the landscape of MS therapeutics. A comparative analysis of their distinct properties is necessary to identify which inhibitors may be used in relapsing vs progressive forms of MS as well as to clarify which agent may be most suitable for sequential use after anti-CD20 treatment.

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.

Repurposing MS immunotherapies for CIDP and other autoimmune neuropathies: unfulfilled promise or efficient strategy?

Despite advances in the treatment of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and other common autoimmune neuropathies (AN), still-many patients with these diseases do not respond satisfactorily to the available treatments. Repurposing of disease-modifying therapies (DMTs) from other autoimmune conditions, particularly multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOSD), is a promising strategy that may accelerate the establishment of novel treatment choices for AN. This approach appears attractive due to homologies in the pathogenesis of these diseases and the extensive post-marketing experience that has been gathered from treating MS and NMOSD patients. The idea is also strengthened by a number of studies that explored the efficacy of DMTs in animal models of AN but also in some CIDP patients. We here review the available preclinical and clinical data of approved MS therapeutics in terms of their applicability to AN, especially CIDP. Promising therapeutic approaches appear to be B cell-directed and complement-targeting strategies, such as anti-CD20/anti-CD19 agents, Bruton's tyrosine kinase inhibitors and anti-C5 agents, as they exert their effects in the periphery. This is a major advantage because, in contrast to MS, their action in the periphery is sufficient to exert significant immunomodulation.

Challenging Cases in Neuroimmunology

Neuroimmunology is rapidly evolving field extending from well-known, but incompletely understood conditions like multiple sclerosis, to novel antibody-mediated disorders, of which dozens have been described in the past 10 years. The ongoing expansion in knowledge needed to effectively diagnose and treat these patients presents myriad challenges for clinicians. Here, we discuss six informative cases from our institution. By highlighting these challenging cases, we hope to instill fundamental points on the nuances of diagnosis and management for conditions including tumefactive multiple sclerosis, antibody-mediated encephalitis, antiphospholipid antibody syndrome, neuromyelitis optica, and myelin oligodendrocyte glycoprotein IgG-associated disease.

Therapeutic antibodies for precise cancer immunotherapy: current and future perspectives

Antibodies, as one of the most important components of host adaptive immune system, play an important role in defense of infectious disease, immune surveillance, and autoimmune disease. Due to the development of recombinant antibody technology, antibody therapeutics become the largest and rapidly expanding drug to provide major health benefits to patients, especially for the treatment of cancer patients. Many antibody-based therapeutic strategies have been developed including monoclonal antibodies, antibody-drug conjugates, bispecific and trispecific antibodies and pro-antibodies with promising results from both clinical and pre-clinical trials. However, the response rate and side-effect still vary between patients with undefined mechanisms. Here, we summarized the current and future perspectives of antibody-based cancer immunotherapeutic strategies for designing next-generation drugs.

Detailed bladder cancer immunoprofiling reveals new clues for immunotherapeutic strategies

Objectives

Bladder cancer (BlCa) is the tenth most frequent malignancy worldwide and the costliest to treat and monitor. Muscle-invasive BlCa (MIBC) has a dismal prognosis, entailing the need for alternative therapies for the standard radical cystectomy. Checkpoint blockade immunotherapy has been approved for high-grade non-muscle-invasive BlCa (HG NMIBC) and metastatic disease, but its effectiveness in localised MIBC remains under scrutiny. Herein, we sought to characterise and compare the immune infiltrate of HG NMIBC and MIBC samples, including ICOS expression, a targetable immune checkpoint associated with regulatory T cell(T_regs)-mediated immunosuppression.

Methods

Immunohistochemistry for CD83, CD20, CD68, CD163, CD3, CD8, CD4, FoxP3/ICOS and PD-L1 was performed in HG NMIBC and MIBC samples (n = 206), and positive staining was quantified in the peritumoral and/or intratumoral tissue compartments with QuPath imaging software.

Results

CD20⁺ B cells, CD68⁺ and CD163⁺ tumor-associated macrophages were significantly increased in MIBCs and associated with poor prognosis. In turn, higher infiltration of T cells was associated with prolonged survival, with exception of the CD4⁺ helper subset. Intratumoral expression of CD3 and CD8 was independent prognostic factors for increased disease-free survival (DFS) in multivariable analysis. Remarkably, T_regs (FoxP3⁺/FoxP3⁺ICOS⁺) were found differentially distributed between tissue compartments. PD-L1 immunoexpression independently predicted a shorter DFS and associated with higher infiltration of FoxP3⁺ICOS⁺ T_regs.

Conclusions

Immune infiltrates of HG NMIBC and MIBC display significant differences that may help selecting patients for immunotherapies. Considering ICOS immunoexpression results, it might constitute a relevant therapeutic target, eventually in combination with anti-PD-1/PD-L1 therapies, for certain BlCa patient subsets.

Gut microbiome changes in anti-N-methyl-D-aspartate receptor encephalitis patients

Background

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is a type of autoimmune encephalitis. The underlying mechanism(s) remain largely unknown. Recent evidence has indicated that the gut microbiome may be involved in neurological immune diseases via the "gut-brain axis". This study aimed to explore the possible relationship between anti-NMDAR encephalitis and the gut microbiome.

Methods

Fecal specimens were collected from 10 patients with anti-NMDAR encephalitis and 10 healthy volunteers. The microbiome analysis was based on Illumina sequencing of the V3-V4 hypervariable region of the 16S rRNA gene. The alpha, beta, and taxonomic diversity analyses were mainly based on the QIIME2 pipeline.

Results

There were no statistical differences in epidemiology, medication, and clinical characteristics (except for those related to anti-NMDAR encephalitis) between the two groups. ASV analysis showed that Prevotella was significantly increased, while Bacteroides was reduced in the gut microbiota of the patients, compared with the controls. Alpha diversity results showed a decrease in diversity in the patients compared with the healthy controls, analyzed by the Shannon diversity, Simpson diversity, and Pielou_E uniformity based on the Kruskal–Wallis test (P = 0.0342, 0.0040, and 0.0002, respectively). Beta diversity analysis showed that the abundance and composition of the gut microbiota was significantly different between the two groups, analyzed by weighted and unweighted UniFrac distance (P = 0.005 and 0.001, respectively).

Conclusions

The abundance and evenness of bacterial distribution were significantly lower and jeopardized in patients with anti-NMDAR encephalitis than in healthy controls. Thus, our findings suggest that gut microbiome composition changes might be associated with the anti-NMDAR encephalitis. It could be a causal agent, or a consequence.

Normal B cell ranges in infants: A systematic review and meta-analysis

BACKGROUND

During the first year of life, B cell level is a valuable indicator of whether external factors, such as exposure to B cell depleting therapies, have an adverse impact on immune system development. However, there are no standard reference ranges of B cell levels in healthy infants by age.

OBJECTIVE

To estimate the normal range of B cell levels in infants, by age, during the first year of life, by pooling data from published studies.

METHODS

Studies reporting B cell levels measured using flow cytometry and CD19 markers in healthy infants were identified via a systematic literature review. Quality and feasibility assessments determined suitability for inclusion in meta-analyses by age group and/or continuous age. Means and normal ranges (2.5th-97.5th percentile) were estimated for absolute and percentage B cell levels. Sensitivity analyses assessed the impact of various assumptions.

RESULTS

Of 37 relevant studies identified, 28 were included in at least 1 meta-analysis. Means and normal ranges of B cell levels were found to be 707 (123-2324) cells/μL in cord blood, 508 (132-1369) cells/μL at age 0-1 month, 1493 (416-3877) cells/μL at age 1-6 months and 1474 (416-3805) cells/μL at age >6 months. The continuous age model showed that B cell levels peaked at week 26. Trends were similar for the percentage B cell estimates and in sensitivity analyses.

CONCLUSION

These meta-analyses provide the first normal reference ranges for B cell levels in infants, by week of age, during the first year of life.

Monoclonal Antibody Therapies Beyond Complement for NMOSD and MOGAD

Aquaporin-4 (AQP4)-IgG seropositive neuromyelitis optica spectrum disorders (AQP4-IgG seropositive NMOSD) and myelin oligodendrocyte glycoprotein (MOG)-IgG-associated disease (MOGAD) are inflammatory demyelinating disorders distinct from each other and from multiple sclerosis (MS).While anti-CD20 treatments can be used to treat MS and AQP4-IgG seropositive NMOSD, some MS medications are ineffective or could exacerbate AQP4-IgG seropositive NMOSD including beta-interferons, natalizumab, and fingolimod. AQP4-IgG seropositive NMOSD has a relapsing course in most cases, and preventative maintenance treatments should be started after the initial attack. Rituximab, eculizumab, inebilizumab, and satralizumab all have class 1 evidence for use in AQP4-IgG seropositive NMOSD, and the latter three have been approved by the US Food and Drug Administration (FDA). MOGAD is much more likely to be monophasic than AQP4-IgG seropositive NMOSD, and preventative therapy is usually reserved for those who have had a disease relapse. There is a lack of any class 1 evidence for MOGAD preventative treatment. Observational benefit has been suggested from oral immunosuppressants, intravenous immunoglobulin (IVIg), rituximab, and tocilizumab. Randomized placebo-controlled trials are urgently needed in this area.

Efficacy of Disease Modifying Therapies in Progressive MS and How Immune Senescence May Explain Their Failure

The advent of disease modifying therapies (DMT) in the past two decades has been the cornerstone of successful clinical management of multiple sclerosis (MS). Despite the great strides made in reducing the relapse frequency and occurrence of new signal changes on neuroimaging in patients with relapsing remitting MS (RRMS) by approved DMT, it has been challenging to demonstrate their effectiveness in non-active secondary progressive MS (SPMS) and primary progressive MS (PPMS) disease phenotypes. The dichotomy of DMT effectiveness between RRMS and progressive MS informs on distinct pathogeneses of the different MS phenotypes. Conversely, factors that render patients with progressive MS resistant to therapy are not understood. Thus far, age has emerged as the main correlate of the transition from RRMS to SPMS. Whether it is aging and age-related factors or the underlying immune senescence that qualitatively alter immune responses as the disease transitions to SPMS, that diminish DMT effectiveness, or both, is currently not known. Here, we will discuss the role of immune senescence on different arms of the immune system, and how it may explain relative DMT resistance.

Individualized regimen of low-dose rituximab monotherapy for new-onset AChR-positive generalized myasthenia gravis

BACKGROUND

Generalized AChR-MG is an archetype of B cell-mediated autoimmune disorders, and use of biologic agent rituximab (RTX) for B cell depletion is generally limited to immunosuppressive therapy-refractory cases. However, benefit of RTX monotherapy and individualized regimen with optimal dosage in early stage of new-onset generalized AChR-MG still remains to be elucidated. In this retrospective study, we explore the efficacy and safety of personalized regimen of 100 mg low-dose rituximab monotherapy in treating new-onset generalized AChR-MG.

METHODS

Thirteen new-onset generalized AChR-MG patients were enrolled for the study, initiating RTX treatment from November 2017 to August 2020. The individualized low-dose RTX monotherapy protocol consisted of 100 mg induction treatment weekly with no more than three circles, followed by reinfusion (100 mg once) sequentially according to whether achieving primary endpoint and peripheral CD19 + B-cell repopulation ≥ 1% of total lymphocytes at each visit (every 3 months). Outcome measures included MGFA-PIS Minimal Manifestation (MM) or better status (primary endpoint), changes in QMG, MMT, MG-ADL and MGQOL-15 scores (secondary endpoint), as well as cholinesterase inhibitors dosage.

RESULTS

All 13 patients achieved the primary endpoint in parallel with significant improvement of QMG, MMT, MG-ADL MGQOL-15 scores, and reduction of cholinesterase inhibitors dose. A total of 52 visits were performed during follow-up, and only 10 assessments presenting peripheral CD19 + B-cell repopulation (≥ 1%) without "MM or better status" were followed by RTX reinfusions (100 mg once) for clinical remission. The total dosage of RTX was only 346.15 ± 96.74 mg (including 269.23 ± 63.04 mg for induction and 76.92 ± 59.91 mg for reinfusion), which seemed to be much lower than those dosages used in new-onset generalized AChR-MG as described previously. Moreover, compared with patients without thymoma, thymectomy markedly delayed initiation of RTX for patients with thymoma (log-rank test, p = 0.0002), but the delaying treatments showed no influence on the time for achieving primary outcome (log-rank test, p = 0.2517).

CONCLUSION

Our study firstly showed that individualized regimen of low-dose RTX monotherapy is effective and safe for early treatment of new-onset generalized AChR-MG, and practicable for directing RTX reinfusion and withdrawal. Moreover, the monotherapy protocol was also indicated to be extensively applicable in both new-onset AChR-MG with thymoma (thymectomy) and without thymoma.

Prospects for CAR T cell immunotherapy in autoimmune diseases: clues from Lupus

INTRODUCTION

Medicine stands at the threshold of a new era heralded by the vast potential of cell engineering. Like advances made possible by genetic engineering, current prospects for purposeful control of cell functions through cell engineering may bring breakthroughs in the treatment of previously intractable diseases.

AREAS COVERED

Engineering of cytotoxic T cells for expression of chimeric antigen receptors (CARs) instructs them to attack and destroy malignant cells and thus provides an exciting new approach in oncology. A decade of practical experience and first-in-human trials encourage the search for new and broader uses of CAR technology, including in autoimmune diseases.

EXPERT OPINION

Systemic lupus erythematosus is an example of a broader category of autoimmune diseases, for which cell engineering will provide a powerful new therapeutic approach. This article describes different types of CAR T cell strategies that will provide new treatment options for patients with autoimmune diseases and replace conventional therapies.

Inebilizumab for treatment of neuromyelitis optica spectrum disorder in patients with prior rituximab use from the N-MOmentum Study

BACKGROUND

The B-cell-depleting agent rituximab (anti-CD20) was historically used to prevent attacks in neuromyelitis optica spectrum disorder (NMOSD). Inebilizumab, which targets and depletes CD19-expressing B cells, plasmablasts, and some plasma cells, received approval from the US Food and Drug Administration for treatment of NMOSD based on results from the randomized, placebo-controlled, phase 2/3 N-MOmentum trial. Because of their closely related mechanisms of action, consideration as to whether inebilizumab may be a suitable treatment option for patients with prior rituximab experience is important. This post hoc analysis of data from N-MOmentum assessed inebilizumab efficacy and tolerability in participants previously treated with rituximab.

METHODS

Adjudicated attacks, secondary efficacy outcomes, and treatment-emergent adverse events were assessed by prior rituximab use during a 6-month randomized control period and open-label period.

RESULTS

Seventeen participants in N-MOmentum had prior rituximab use, of whom 13 were randomly assigned to the inebilizumab treatment group. Seven of these participants had breakthrough attacks prior to enrollment (annualized attack rate, 0.78 attacks/person-year) despite rituximab use. While they were receiving inebilizumab in the randomized control period, 1 of 13 participants with prior rituximab use had an attack (hazard ratio vs all placebo, 0.16; 95% confidence interval: 0.02 1.20; p = 0.07). Two additional participants with prior rituximab use experienced attacks on inebilizumab during the open-label period, with an overall annualized attack rate of 0.08 (95% confidence interval: 0.02 0.34) attacks/person-year. This annualized attack rate was similar to that of participants without prior rituximab use (0.10 [95% confidence interval: 0.07 0.15]). None of the 7 participants who experienced attacks while taking rituximab experienced an attack while receiving inebilizumab. Two (12%) participants with prior rituximab use experienced serious treatment-emergent adverse events related to inebilizumab, with serious or grade ≥3 infections occurring in 3 (18%) participants each. No deaths or opportunistic infections were reported in this cohort.

CONCLUSIONS

These findings support the efficacy of inebilizumab in participants with NMOSD who had previously been treated with rituximab. Infections occurred in nearly all study participants with prior rituximab exposure, highlighting a need for clinical vigilance in such individuals. Further studies are necessary to determine potential safety concerns of inebilizumab, including risk of infection, in rituximab-experienced patients. ClinicalTrials.gov identifier: NCT02200770.

nnResearch progress on B cells and thoracic aortic aneurysm/dissection

Thoracic aortic aneurysm/dissection (TAAD) is a rare cardiovascular disease characterized by acute onset, rapid progression and high morbidity and mortality. One of the crucial factors leading to TAAD is the inflammatory response, which is regulated by many immune cell subgroups, including B cells. Compared with normal aortic tissue, the number of B cells in the aortic tissue of TAAD patients is significantly higher. Activated B cells participate in the vascular immune inflammatory response by producing antibodies and inflammatory factors and activating the complement system. These effects can lead to collagen degradation and aortic wall remodeling, both of which are the main pathologic characteristics of TAAD. Therefore, B cells play a key role in the occurrence and development of TAAD. B cells can be divided into B1 cells, B2 cells and regulatory B cells, which have different mechanisms of action in TAAD. This article will review the role of B cells in TAAD from the perspective of three different subtypes of B cells.

Randomized Controlled Trials for Neuromyelitis Optica Spectrum Disorder: A Review of Trial Architecture

BACKGROUND

Neuromyelitis optica spectrum disorder (NMOSD) is a relapsing inflammatory disease that primarily affects the optic nerves and the spinal cord. Randomized controlled trials (RCTs) assessing treatments for NMOSD have only been performed in the past decade, and to date, there are 3 drugs approved by the US Food and Drug Administration (FDA) for antiaquaporin-4 immunoglobulin G seropositive NMOSD. This review assesses the characteristics and challenges of RCTs when evaluating treatments for NMOSD.

REVIEW SUMMARY

We conducted a review using the terms ("neuromyelitis optica" OR "NMO" OR "NMOSD") AND "clinical trial" in any language on March 28, 2021. Seven RCTs were included, and the trials' architecture was analyzed and synthesized. Overall, 794 subjects were randomized [monoclonal antibody intervention group, n= 493 (62.1%), placebo, n=196 (24.7%), and active control, n=105 (13.2%)]; 709 (89.3%) were females; and 658 (82.9%) were aquaporin-4 (AQP4) antibody seropositive. The primary outcome was time to relapse in 6/7 of the trials, and annualized relapse rate in the remaining one. Four RCTs used placebo in their design. Among the seven published RCTs, the trial design differed by the criteria used to define NMOSD relapse, selection of subjects, proportion of AQP4 immunoglobulin G seronegative patients, and baseline characteristics indicating NMO disease severity.

CONCLUSIONS

Ethical considerations for the use of placebo should change in light of the approval of 3 therapies for seropositive NMOSD. Remaining challenges for clinical trials in NMOSD include the assessment of long-term safety and efficacy, standardization of trial design and endpoints, and head-to-head study designs.

Long-term efficacy and safety of inebilizumab in neuromyelitis optica spectrum disorder: Analysis of aquaporin-4-immunoglobulin G-seropositive participants taking inebilizumab for ⩾4 years in the N-MOmentum trial

Background:

Efficacy and safety of inebilizumab for treatment of neuromyelitis optica spectrum disorder in adults seropositive for aquaporin-4 (AQP4)–immunoglobulin (Ig) G were demonstrated in the 28-week randomized controlled period of the N-MOmentum study.

Objective:

To assess efficacy and safety of long-term inebilizumab treatment.

Methods:

Post hoc analysis was performed in 75 AQP4–IgG–seropositive participants receiving inebilizumab for ⩾4 years in the randomized controlled period and open-label extension of the N-MOmentum study.

Results:

Eighteen attacks occurred in 13 participants during inebilizumab treatment (annualized attack rate, 0.052 attacks/person-year). Twelve attacks occurred during the first year of treatment, and two each occurred in years 2–4. Disability scores remained stable throughout ⩾4 years of treatment. Inebilizumab was well tolerated, with two (2.7%) serious treatment-emergent adverse events related to inebilizumab and no deaths. Immunoglobulin G levels decreased over time; however, correlation between severe infections and low IgG levels could not be determined because of their small numbers.

Conclusion:

These results from the N-MOmentum study continue to support use of inebilizumab for treatment of neuromyelitis optica spectrum disorder. Furthermore, the findings suggest that efficacy of inebilizumab may be enhanced after the first year of treatment, warranting additional long-term investigation.

Herpesviruses and the hidden links to Multiple Sclerosis neuropathology

Herpesviruses like Epstein-Barr virus, human herpesvirus (HHV)-6, HHV-1, VZV, and human endogenous retroviruses, have an age-old clinical association with multiple sclerosis (MS). MS is an autoimmune disease of the nervous system wherein the myelin sheath deteriorates. The most popular mode of virus mediated immune system manipulation is molecular mimicry. Numerous herpesvirus antigens are similar to myelin proteins. Other mechanisms described here include the activity of cytokines and autoantibodies produced by the autoreactive T and B cells, respectively, viral déjà vu, epitope spreading, CD46 receptor engagement, impaired remyelination etc. Overall, this review addresses the host-parasite association of viruses with MS.

[Treatment of antibody-mediated encephalomyelitis : Strategies for the treatment of neuromyelitis optica spectrum disorder and myelin oligodendrocyte glycoprotein antibody-associated disease]

BACKGROUND

Antibody-mediated encephalomyelitis, such as neuromyelitis optica spectrum disorder (NMOSD), myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD), and glial fibrillary acidic protein (GFAP) antibody-associated astrocytopathy belong to a group of newly described autoimmune diseases.

AIM

Presentation of the treatment of antibody-mediated encephalomyelitis with a focus on NMOSD and MOGAD.

METHODS

Selective literature search in PubMed taking the consultation version of the S2k guidelines of the German Society of Neurology (DGN) on the diagnosis and treatment of multiple sclerosis (MS), NMOSD and MOG IgG-associated diseases into account.

RESULTS

Acute relapses are treated with high-dose steroid pulse therapy or apheresis therapy (plasma exchange or immunoadsorption). It is crucial to start treatment as quickly as possible and apheresis therapy can also be used as first-line treatment under certain conditions. For prophylactic immunotherapy, steroids, classical immunosuppressants and monoclonal antibodies with specific mechanisms of action are used. Eculizumab, inebilizumab and satralizumab are the first drugs approved for NMOSD. Symptomatic treatment and neurorehabilitation are important complementary measures.

CONCLUSION

Treatment of antibody-mediated encephalomyelitis differs from treatment of multiple sclerosis and requires specific measures.

Effect of Ocrelizumab in Blood Leukocytes of Patients With Primary Progressive MS

OBJECTIVE

To analyze the changes induced by ocrelizumab in blood immune cells of patients with primary progressive MS (PPMS).

METHODS

In this multicenter prospective study including 53 patients with PPMS who initiated ocrelizumab treatment, we determined effector, memory, and regulatory cells by flow cytometry at baseline and after 6 months of therapy. Wilcoxon matched paired tests were used to assess differences between baseline and 6 months' results. p Values were corrected using the Bonferroni test.

RESULTS

Ocrelizumab reduced the numbers of naive and memory B cells (p < 0.0001) and those of B cells producing interleukin (IL)-6, IL-10, granulocyte-macrophage colony-stimulating factor (GM-CSF), and tumor necrosis factor-alpha (TNFα) (p < 0.0001 in all cases). By contrast, the proportions of plasmablasts and B cells producing GM-CSF and TNFα increased significantly, suggesting the need for treatment continuation. We also observed a decrease in CD20+ T-cell numbers (p < 0.0001) and percentages (p < 0.0001), and a clear remodeling of the T-cell compartment characterized by relative increases of the naive/effector ratios in CD4+ (p = 0.002) and CD8+ (p = 0.002) T cells and relative decreases of CD4+ (p = 0.03) and CD8+ (p = 0.004) T cells producing interferon-gamma. Total monocyte numbers increased (p = 0.002), but no changes were observed in those producing inflammatory cytokines. The immunologic variations were associated with a reduction of serum neurofilament light chain (sNfL) levels (p = 0.008). The reduction was observed in patients with Gd-enhanced lesions at baseline and in Gd- patients with baseline sNfL >10 pg/mL.

CONCLUSIONS

In PPMS, effector B-cell depletion changed T-cell response toward a low inflammatory profile, resulting in decreased sNfL levels.

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.

New progress in the treatment of neuromyelitis optica spectrum disorder with monoclonal antibodies (Review)

Neuromyelitis optica spectrum disorder (NMOSD) is a group of immune-mediated inflammatory demyelinating diseases mainly affecting the central nervous system. It is characterized by high risk of relapse and progression to disability. The frequent recurrences of neuromyelitis optica spectrum disorder often exacerbate the neurological dysfunction and severely affect the patient's quality of life. Conventional treatments for neuromyelitis optica spectrum disorder, including acute treatment and sequential therapy, aim to decrease the degree of disability and recurrences. In recent years, new monoclonal antibodies have yielded encouraging results. The present review discusses the research status and recent progress in the treatment of NMOSD with monoclonal antibodies.

Cerebrospinal fluid CD20 positive B-cell expansion in a case of anti-NMDAR encephalitis

Anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis is a potentially fatal autoimmune encephalitis with a strong B-cell response. We measured the proportion of CD20 positive and CD19 positive B-cells in the CSF from a case of severe anti-NMDAR encephalitis. The proportion of CD20 positive B-cells in the CSF was 15.0%, higher than CD19 positive B cells (10.1%), and higher than that seen in non-inflammatory neurological disorders (<1%). After the treatments of steroids, intravenous immunoglobulin and rituximab to eliminate B-cells, she recovered. These findings further support the use of rituximab that targets CD20 positive B-cells in anti-NMDAR encephalitis.

Emerging Targeted Therapies for Neuromyelitis Optica Spectrum Disorders

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune, inflammatory disorder of the central nervous system that typically presents with recurrent episodes of optic neuritis, longitudinally extensive myelitis, brainstem, diencephalic, and cerebral syndromes. Up to 80% of NMOSD patients have a circulating pathogenic autoantibody that targets the water channel aquaporin-4 (AQP4-IgG). The discovery of AQP4-IgG transformed our understanding of the pathogenesis of the disease and its possible treatment targets. Monoclonal antibodies targeting terminal complement (eculizumab), CD19 (inebilizumab), and the interleukin-6 receptor (satralizumab) have demonstrated efficacy in NMOSD attack prevention in recent phase 3 trials and have gained subsequent regulatory approval in the USA and other countries. We aim to review the evidence supporting the efficacy of these new drugs.

TCDD attenuates EAE through induction of FasL on B cells and inhibition of IgG production

Previously we demonstrated that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) suppressed experimental autoimmune encephalomyelitis (EAE), a model to study multiple sclerosis (MS), through induction of regulatory T cells (Tregs) and suppression of effector T cell function in the spleen. Since B cells and specifically regulatory B cells (Bregs) have been shown to be so critical in the pathology associated with EAE and MS, we wanted to determine whether TCDD could also induce Bregs. We specifically hypothesized that a Fas ligand (FasL)+ Breg population would be induced by TCDD in EAE thereby triggering apoptosis in Fas-expressing effector T cells as one mechanism to account for inhibition of T cell function by TCDD. TCDD (0.1-2.5 μg/kg/day administered orally for 12 days) modestly increased the percentage of FasL + B cells in the spleen and spinal cord in TCDD-treated EAE mice. However, we did not detect significant increases in percentages of FasL + B cells using TCDD in vitro in mouse splenocytes or human peripheral blood mononuclear cells (PBMCs). Part of the modest effect by TCDD was likely related to the localized expression of FasL; for instance, in the spleen, FasL was more highly expressed by IgM^hiIgD^lo marginal zone (MZ) B cells, but IgM^loIgD^hi follicular (FO) B cells were more responsive to TCDD. Consistent with our observation of modest upregulation of FasL, we also observed modest changes in mitochondrial membrane potential in T cells co-cultured with isolated total B cells or IgM-depleted (i.e., FO-enriched) B cells from TCDD-treated EAE mice. These data suggest that while small microenvironments of apoptosis might be occurring in T cells in response to TCDD-treated B cells, it is not a major mechanism by which T cell function is compromised by TCDD in EAE. TCDD did robustly suppress IgG production systemically and in spleen and spinal cord B cells at end stage disease. Thus, these studies show that TCDD's primary effect on B cells in EAE is compromised IgG production but not FasL + Breg induction.

Review of approved NMO therapies based on mechanism of action, efficacy and long-term effects

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Neuromyelitis optica (NMO - including NMO spectrum disorders [NMOSD]) is a devastating disease.

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Up until recently, there was no proven agent to treat to prevent relapses.

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We now have three agents indicated for the treatment of NMO.

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We might suggest the following sequence – 1st line using eculizumab for rapid efficacy and stabilization without effect on the acquired immune system followed by satrilizumab (long term immunomodulation).

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Reserve inebilizumab (immunosuppressant) for breakthrough disease and salvage the severe with AHSCBMT.

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In NMO, control the complement, transition to modulation, and reserve suppression – and salvage the severe with AHSCBMT.

Importance

Neuromyelitis optica (NMO - including NMO spectrum disorders [NMOSD]) is a devastating disease. Eighty-three percent of patients with transverse myelitic (TM) attacks and 67% of patients with optic neuritis (ON) attacks have no or a partial recovery.

Observations

Up until recently, there was no proven agent to treat to prevent relapses. The neuro-immunological community had a dearth of indicated agents for NMOSD. We now have three agents indicated for the treatment of NMO including (eculizumab [Soliris®]), an anti-C5 complement inhibitor, satralizumab (ENSRYNG®), a monoclonal antibody against the IL-6 receptor (IL-6R) that blocks B cell antibody production and inebilizumab (Uplinza®), a monoclonal antibody that binds to the B-cell surface antigen CD19 with subsequent B and plasmablast cell lymphocytolysis with decreasing antibody production. Autologous hematopoietic stem cell bone marrow transplantation (AHSCBMT) has also been used. How do we sequence NMO therapies with the understanding of the acuteness and severity of the disease, the individual mechanism of action (MOA) and rapidity of onset of action, onset of efficacy and long-term safety of each agent?

Conclusions and Relevance

We might suggest the following sequence – 1st line using eculizumab for rapid efficacy and stabilization without effect on the acquired immune system followed by satrilizumab (long term immunomodulation). Reserve inebilizumab (immunosuppressant) for breakthrough disease and salvage the severe with AHSCBMT. In NMO, control the complement, transition to modulation, and reserve suppression – and salvage the severe with AHSCBMT.

Aberrant Phenotypes in Acute Myeloid Leukemia and Its Relationship with Prognosis and Survival: A Systematic Review and Meta-Analysis

Background: The aim of this review was to evaluate the influence of aberrant phenotypes in prognosis and survival in acute myeloid leukemia (AML) patients by multiparametric flow cytometry. Materials and Methods: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, a review of PubMed, Scopus, Science Direct and Web of Science was carried out through 1998 to 2016, conducted by two reviewers independently, evaluating titles, abstracts and full-texts of the selected studies. Results: Ten studies were included on this review, in which the aberrant phenotype expression of 17 markers were detected in AML patients. From these, 11 aberrant phenotypes were associated with prognosis, which eight had shown negative impact on prognosis: CD7, CD56, CD15, CD2, CD3, CD90low, CD123high, CD117high, and three others were associated with good prognosis: CD19, CD98high and CD117+/CD15+. Meta-analysis showed that aberrant expression of CD56 as a poor prognostic marker with unfavorable outcomes is implicated in decreased overall survival in AML patients in 28 months (95% CI: 0.62 to 0.92). Conclusion: This was observed when there was association between CD56 expression and other prognostic factors, influencing on patients' management care and treatment.