Regeneration of B cell subsets after transient B cell depletion using anti-CD20 antibodies in rheumatoid arthritis

Should complete B cell depletion be maintained in patients treated long-term with rituximab for rheumatoid arthritis?

OBJECTIVE

To determine whether persistent complete B cell (BC) depletion was associated with a better clinical response in rheumatoid arthritis (RA) patients long-term treated with rituximab (RTX).

METHODS

We conducted a retrospective study including RA patients admitted for a new infusion between 2019 and 2021. The primary endpoint was the comparison of the mean disease activity score based on 28 joints (DAS28)-CRP at each of the four last infusion visits between patients with persistent complete BC depletion (mean CD19 counts <18/µl at each of the last four visits) or without persistent complete BC depletion (mean CD19 counts of the last four visits ≥18/µl). Secondary endpoints included DAS28, pain/fatigue visual analogue scale, CRP, gammaglobulins and the frequency of self-reported RA flares.

RESULTS

Of the 126 patients in maintenance therapy with RTX [exposure period: 76 (5) months, 14 (7) infusions received], 43 (34%) had persistent complete BC depletion at each of the four last infusions. The mean DAS28-CRP calculated at each of the four last infusion visits did not significantly differ according to persistence or not of complete BC depletion. This result remained unchanged after adjusting for antibody status, number of previous therapies, number of RTX infusion and cumulative RTX dose. All secondary outcomes were also not significantly different between the two groups.

CONCLUSION

Maintaining complete BC depletion does not appear to be a therapeutic target to achieve in RA patients in long-term maintenance therapy with RTX. There is a limited benefit of monitoring CD19 in RA patients long-term treated with RTX and having achieved low disease activity/remission.

Defects in B-lymphopoiesis and B-cell maturation underlie prolonged B-cell depletion in ANCA-associated vasculitis

OBJECTIVES

B-cell depletion time after rituximab (RTX) treatment is prolonged in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) compared with other autoimmune diseases. We investigated central and peripheral B-cell development to identify the causes for the defect in B-cell reconstitution after RTX therapy.

METHODS

We recruited 91 patients with AAV and performed deep phenotyping of the peripheral and bone marrow B-cell compartment by spectral flow and mass cytometry. B-cell development was studied by in vitro modelling and the role of BAFF receptor by quantitative PCR, western blot analysis and in vitro assays.

RESULTS

Treatment-naïve patients with AAV showed low transitional B-cell numbers, suggesting impaired B-lymphopoiesis. We analysed bone marrow of treatment-naïve and RTX-treated patients with AAV and found reduced B-lymphoid precursors. In vitro modelling of B-lymphopoiesis from AAV haematopoietic stem cells showed intact, but slower and reduced immature B-cell development. In a subgroup of patients, after RTX treatment, the presence of transitional B cells did not translate in replenishment of naïve B cells, suggesting an impairment in peripheral B-cell maturation. We found low BAFF-receptor expression on B cells of RTX-treated patients with AAV, resulting in reduced survival in response to BAFF in vitro.

CONCLUSIONS

Prolonged depletion of B cells in patients with AAV after RTX therapy indicates a B-cell defect that is unmasked by RTX treatment. Our data indicate that impaired bone marrow B-lymphopoiesis results in a delayed recovery of peripheral B cells that may be further aggravated by a survival defect of B cells. Our findings contribute to the understanding of AAV pathogenesis and may have clinical implications regarding RTX retreatment schedules and immunomonitoring after RTX therapy.

Zuberitamab, an innovative anti-CD20 monoclonal antibody, for patients with primary immune thrombocytopenia in China: a randomized, double-blind, placebo-controlled, phase 2 study

Background

Primary immune thrombocytopenia (ITP) is an autoimmune disease, and rituximab (RTX) induces long-term effect as second-line treatments. Zuberitamab is an innovative anti-CD20 monoclonal antibody, which was first developed in China and launched in diffuse large B lymphoma. This study aimed to investigate the safety, efficacy, and anticipated therapeutic dose of zuberitamab in Chinese ITP patients.

Methods

This randomised, double-blind, placebo-controlled, phase 2 study was conducted at 26 hospitals in China. Eligible patients were aged 18-70 years, had primary immune thrombocytopenia for more than 6 months, and did not respond or relapsed after previous treatment and had a pre-treatment platelet count of <30 × 109/L. Patients randomly received zuberitamab in a dose escalation (100/300/600 mg) or placebo once-weekly for 4 weeks and followed up to 24 weeks. The primary endpoint is the proportion of patients with a platelet count ≥50 × 109/L at week 8. Secondary endpoints include the proportion of patients with platelet counts ≥50 × 109/L or ≥100 × 109/L at least once within week 12/24, the proportion of patients experiencing platelets increased twice more than baseline as well as ≥30 × 109/L at least once during the treatment. Adverse events, pharmacokinetic, B cell depletion and immunogenicity were also assessed. This study is registered with https://www.chictr.org.cn/as ChiCTR2100050513.

Findings

From October 2021 to March 2023, 50 patients were screened for eligibility, of whom 32 patients were enrolled and randomly assigned to placebo (n = 4), zuberitamab 100 mg (n = 10), 300 mg (n = 8) and 600 mg (n = 10) groups. The primary endpoint (PLT ≥50 × 109/L at week 8) was achieved by 40% of patients in the 100 mg group, while none in the other groups. Within 12 weeks, the proportions of patients in each treatment group achieving at least one instance of platelet count ≥50 × 109/L or ≥100 × 109/L or an increase twice more than baseline as well as ≥30 × 109/L were (70%, 38%, 50%), (60%, 13%, 30%), and (80%, 50%, 70%) in zuberitamab 100/300/600 mg groups, respectively. By week 24, the proportions of patients achieving these secondary endpoints remained relatively stable or showed a mild increase of around 10%. The anticipated therapeutic dose of zuberitamab was 100 mg. The plasma concentration of zuberitamab showed an increasing trend with dose (100 mg-600 mg) and linear pharmacokinetic behavior. CD19+ B cells and CD20+ B lymphocytes rapidly declined to 0% within one week and consistently maintained reduced levels throughout the entire treatment phase in three groups. Adverse events occurred in all patients with most of them were mild to moderate, no severe infections occurred. A slight decrease in immunoglobulins was observed in the 600 mg group, but gradually recovered at week 20. Three patients (2 in 100 mg and 1 in 600 mg group) were tested positive for anti-zuberitamab antibodies. We also observed that women, disease duration <12 months, and MAIPA + patients may have higher response rates.

Interpretation

This study preliminarily confirmed that 100 mg zuberitamab was safe and effective in treating ITP and was recommended to support further investigation.

Funding

National Natural Science Foundation of China and Zhejiang Bioray Biopharmaceutical Co. Ltd.

Extended interval dosing with ocrelizumab in multiple sclerosis

BACKGROUND

This study investigates clinical and biomarker differences between standard interval dosing (SID) and extended interval dosing (EID) of ocrelizumab therapy in multiple sclerosis (MS).

METHODS

This is a prospective, double-arm, open-label, multi-center study in Denmark. Participants diagnosed with MS on ocrelizumab therapy >12 months were included (n = 184). Clinical, radiological, and blood-based biomarker outcomes were evaluated. MRI disease activity, relapses, worsening of neurostatus, and No Evidence of Disease Activity-3 (NEDA-3) were used as a combined endpoint.

RESULTS

Out of 184 participants, 107 participants received EID (58.2%), whereas 77 participants received SID (41.8%). The average extension was 9 weeks with a maximum of 78 weeks. When comparing EID to SID, we found higher levels of B-cells, lower serum concentrations of ocrelizumab, and similar levels of age-adjusted NFL and GFAP in the two groups. No difference in NEDA-3 between EID and SID was demonstrated (hazard ratio: 1.174, p = 0.69). Higher levels of NFL were identified in participants with disease activity. Body mass index correlated with levels of ocrelizumab and B-cells.

CONCLUSION

Extending one treatment interval of ocrelizumab on average 9 weeks and up to 78 weeks did not result in clinical, radiological, or biomarker evidence of worsening compared with SID.

Sensitive B-cell receptor repertoire analysis shows repopulation correlates with clinical response to rituximab in rheumatoid arthritis

BACKGROUND

Although B-cell depleting therapy in rheumatoid arthritis (RA) is clearly effective, response is variable and does not correlate with B cell depletion itself.

METHODS

The B-cell receptor (BCR) repertoire was prospectively analyzed in peripheral blood samples of twenty-eight RA patients undergoing rituximab therapy. Timepoints of achieved BCR-depletion and -repopulation were defined based on the percentage of unmutated BCRs in the repertoire. The predictive value of early BCR-depletion (within one-month post-treatment) and early BCR-repopulation (within 6 months post-treatment) on clinical response was assessed.

RESULTS

We observed changes in the peripheral blood BCR repertoire after rituximab treatment, i.e., increased clonal expansion, decreased clonal diversification and increased mutation load which persisted up to 12 months after treatment, but started to revert at month 6. Early BCR depletion was not associated with early clinical response but late depleters did show early response. Patients with early repopulation with unmutated BCRs showed a significant decrease in disease activity in the interval 6 to 12 months. Development of anti-drug antibodies non-significantly correlated with more BCR repopulation.

CONCLUSION

Our findings indicate that rather than BCR-depletion it is repopulation with unmutated BCRs, possibly from naïve B cells, which induces remission. This suggests that (pre-existing) differences in B-cell turnover between patients explain the interindividual differences in early clinical effect.

A Proposed Approach to Screening and Surveillance Labs for Patients With Multiple Sclerosis on Anti-CD20 Therapy

Background

Anti-CD20 therapies have proven to be highly effective and safe therapies for multiple sclerosis (MS) and have had rapid uptake in the MS community. However, no clear consensus has arisen regarding an approach to screening or surveillance lab monitoring.

Recent Findings

Based on current evidence, for screening labs before anti-CD20 initiation, we propose checking liver function test (LFT), complete blood count with differential (CBC), absolute B-cell count, quantitative immunoglobulins, hepatitis B virus serologies, varicella zoster virus IgG, John Cunningham virus (JCV) status, and age-appropriate vaccination history. For surveillance monitoring in an otherwise asymptomatic individual, we propose biannual LFTs and CBC, quantitative immunoglobulins annually after year 3, absolute B-cell count at month 6 and in the setting of relapse, and JCV only if clinical or radiographic features of progressive multifocal leukoencephalopathy arise. For ublituximab, pregnancy testing is additionally recommended before each infusion.

Implications for Practice

We propose evidence-based screening and safety surveillance labs which take into account likelihood of changing management in an otherwise stable or asymptomatic individual.

B cell repopulation trajectory after rituximab treatment in autoimmune diseases: a longitudinal observational study

To investigate B-cell repopulation trajectory and the associated factors in patients with autoimmune diseases (AIDs) who underwent rituximab (RTX) treatment. This is a retrospective study in a large tertiary medical center. Kaplan-Meier analysis and Cox regression were used to investigate factors associated with B-cell repopulation. Latent class trajectory modeling (LCTM) was employed to identify distinct B-cell repopulation trajectory longitudinally. A total of 224 patients were included, with a cumulative follow-up time of 193.6 person-years. Patients with antineutrophil cytoplasm antibody-associated vasculitis (AAV), connective tissue disease, and IgG4-related disease exhibited significant differences in B-cell repopulation time (p = 0.0055 by log-rank test). Multivariate Cox regression identified that higher levels of IgA (HR 1.21, 95%CI 1.01-1.45, p = 0.040) and concurrent glucocorticoid use (HR = 0.37,95%CI 0.20-0.67, p = 0.001) were associated with B-cell repopulation. The cluster showing prolonged B-cell depletion, identified by LCTM, had lower proportions of male (27% vs. 48.5%, p = 0.033), smoke history (17.6% vs. 38.7%, p = 0.025), higher proportions of AAV (44.3% vs. 15.2%, p = 0.004), RTX dose (p = 0.042), history of cyclophosphamide use (70.4% vs. 48.5%, p = 0.003), meanwhile glucocorticoid use (94.8% vs. 72.7%, p = 0.001). The trajectory of B-cell repopulation after RTX infusion in AIDs was heterogeneous. Certain factors were associated with B-cell repopulation, and a specific cluster of patients demonstrated prolonged B-cell depletion after RTX treatment.

Identification of Covariates Modulating B-Cell Repopulation Kinetics in Subjects Receiving Rituximab Treatment

OBJECTIVE

B-cell depletion using the anti-CD20 monoclonal antibody rituximab is a cornerstone in the therapeutic concept of multiple autoimmune diseases. B-cell depletion is associated with a higher risk for severe infections, and the time span of B-cell repopulation differs greatly between individuals. Data on factors influencing B-cell repopulation kinetics are limited. This study aims to identify patient-specific and therapy-associated covariates that modulate B-cell repopulation.

METHODS

This single-center retrospective observational study presents data of 839 subjects receiving 2,017 courses of rituximab for autoimmune diseases. Assessed covariates are patient-specific factors (sex, age, kidney function, and underlying disease) and co-immunosuppression with common agents (azathioprine, cyclosporine A, cyclophosphamide, hydroxychloroquine, methotrexate, mycophenolate mofetil, tacrolimus, and corticosteroids). The primary end point is the time to B-cell repopulation (≥5/μl). The secondary end point is the time to B-cell reconstitution (≥50/μl). Multivariate time-to-event analysis and logistic regression models were applied to estimate the influence of covariates.

RESULTS

Age over 60 years (hazard ratio [HR] 0.71 for repopulation, P = 0.008), impaired kidney function (HR 0.72, P = 0.001), antineutrophil cytoplasmic antibody-associated vasculitis (HR 0.61, P < 0.001), solid organ transplantation (HR 0.4, P < 0.001), and co-immunosuppression with corticosteroids (HR 0.64, P < 0.001) or azathioprine (HR 0.49, P < 0.001) were associated with impaired B-cell repopulation and reconstitution. Effects of corticosteroids (P = 0.043) and azathioprine (P = 0.025) were dose dependent.

CONCLUSION

Prolonged rituximab dosing intervals may be effective to achieve B-cell depletion and reduce risk of infection in advanced age or patients with impaired kidney function. Co-medication with corticosteroids or azathioprine prolongs B-cell recovery, which may increase therapeutic effects but also the rate of adverse events.

Polyomavirus Wakes Up and Chooses Neurovirulence

JC polyomavirus (JCPyV) is a human-specific polyomavirus that establishes a silent lifelong infection in multiple peripheral organs, predominantly those of the urinary tract, of immunocompetent individuals. In immunocompromised settings, however, JCPyV can infiltrate the central nervous system (CNS), where it causes several encephalopathies of high morbidity and mortality. JCPyV-induced progressive multifocal leukoencephalopathy (PML), a devastating demyelinating brain disease, was an AIDS-defining illness before antiretroviral therapy that has "reemerged" as a complication of immunomodulating and chemotherapeutic agents. No effective anti-polyomavirus therapeutics are currently available. How depressed immune status sets the stage for JCPyV resurgence in the urinary tract, how the virus evades pre-existing antiviral antibodies to become viremic, and where/how it enters the CNS are incompletely understood. Addressing these questions requires a tractable animal model of JCPyV CNS infection. Although no animal model can replicate all aspects of any human disease, mouse polyomavirus (MuPyV) in mice and JCPyV in humans share key features of peripheral and CNS infection and antiviral immunity. In this review, we discuss the evidence suggesting how JCPyV migrates from the periphery to the CNS, innate and adaptive immune responses to polyomavirus infection, and how the MuPyV-mouse model provides insights into the pathogenesis of JCPyV CNS disease.

Human and mouse early B cell development: So similar but so different

Early B cell development in the bone marrow ensures the replenishment of the peripheral B cell pool. Immature B cells continuously develop from hematopoietic stem cells, in a process guided by an intricate network of transcription factors as well as chemokine and cytokine signals. Humans and mice possess somewhat similar regulatory mechanisms of B lymphopoiesis. The continuous discovery of monogenetic defects that impact early B cell development in humans substantiates the similarities and differences with B cell development in mice. These differences become relevant when targeted therapeutic approaches are used in patients; therefore, predicting potential immunological adverse events is crucial. In this review, we have provided a phenotypical classification of human and murine early progenitors and B cell stages, based on surface and intracellular protein expression. Further, we have critically compared the role of key transcription factors (Ikaros, E2A, EBF1, PAX5, and Aiolos) and chemo- or cytokine signals (FLT3, c-kit, IL-7R, and CXCR4) during homeostatic and aberrant B lymphopoiesis in both humans and mice.

Efficacy of Rituximab Outlasts B-Cell Repopulation in Multiple Sclerosis: Time to Rethink Dosing?

BACKGROUND AND OBJECTIVES

Patients with multiple sclerosis (PwMS) receiving extended dosing of rituximab (RTX) have exhibited no return of disease activity, which suggests that maintenance of deep depletion of circulating B cells is not necessary to maintain the efficacy of RTX in MS.

METHODS

This was a prospective monocentric observational study including all consecutive PwMS who started or continued RTX after 2019, when the medical staff decided to extend the dosing interval up to 24 months for all patients. Circulating B-cell subsets were monitored regularly and systematically in case of relapse. The first extended interval was analyzed.

RESULTS

We included 236 PwMS (81% with relapsing-remitting MS; mean [SD] age 43 [12] years; median [range] EDSS score 4 [0-8]; mean relapse rate during the year before RTX start 1.09 [0.99]; 41.5% with MRI activity). The median number of RTX infusions before extension was 4 (1-13). At the time of the analysis, the median delay in dosing was 17 months (8-39); the median proportion of circulating CD19+ B cells was 7% (0-25) of total lymphocytes and that of CD27+ memory B cells was 4% (0-16) of total B cells. The mean annual relapse rate did not differ before and after the extension: 0.03 (0.5) and 0.04 (0.15) (p = 0.51). Similarly, annual relapse rates did not differ before and after extension in patients with EDSS score ≤3 (n = 79) or disease duration ≤5 years (n = 71) at RTX onset. During the "extended dosing" period, MRI demonstrated no lesion accrual in 228 of the 236 patients (97%). Five patients experienced clinical relapse, which was confirmed by MRI. In these patients, the level of B-cell subset reconstitution at the time of the relapse did not differ from that for patients with the same extension window.

DISCUSSION

The efficacy of RTX outlasted substantial reconstitution of circulating B cells in PwMS, which suggests that renewal of the immune system underlies the prolonged effect of RTX in MS. These findings suggest that extended interval dosing of RTX that leads to a significant reconstitution of circulating B cells is safe in PwMS, could reduce the risk of infection, and could improve vaccine efficacy.

Engineering chimeric autoantibody receptor T cells for targeted B cell depletion in multiple sclerosis model: An in-vitro study

Background

Recent evidence suggests that B cells and autoantibodies have a substantial role in the pathogenesis of Multiple sclerosis. T cells could be engineered to express chimeric autoantibody receptors (CAARs), which have an epitope of autoantigens in their extracellular domain acting as bait for trapping autoreactive B cells. This study aims to assess the function of designed CAAR T cells against B cell clones reactive to the myelin basic protein (MBP) autoantigen.

Methods

T cells were transduced to express a CAAR consisting of MBP as the extracellular domain. experimental autoimmune encephalomyelitis (EAE) was induced by injecting MBP into mice. The cytotoxicity, proliferation, and cytokine production of the MBP-CAAR T cells were investigated in co-culture with B cells.

Results

MBP-CAAR T cells showed higher cytotoxic activity against autoreactive B cells in all effector-to-target ratios compared to Mock T cell (empty vector-transduced T cell) and Un-T cells (un-transduced T cell). In co-cultures containing CAAR T cells, there was more proliferation and inflammatory cytokine release as compared to Un-T and Mock T cell groups.

Conclusion

Based on these findings, CAAR T cells are promising for curing or modulating autoimmunity and can be served as a new approach for clone-specific B cell depletion therapy in multiple sclerosis.

Immune response after SARS-CoV-2 vaccination in patients with inflammatory immune-mediated diseases receiving immunosuppressive treatment

BACKGROUND

Real world data on the response to the SARS-CoV-2 vaccine in patients with immunomediated diseases (IMIDs) treated with immunesuppressants is of great interest because vaccine response may be impaired. The main aim was to study the humoral and cellular immune response after SARS-CoV-2 vaccination in patients with IMIDs treated with immunosuppressants. The secondary aim was to describe the frequency of SARS-CoV-2 infections after vaccination in these patients.

MATERIAL AND METHODS

This is an observational study including 86 patients with IMIDs. All patients were treated with biologic or targeted synthetic disease-modifying antirheumatic drugs [b/tsDMARDs: TNF inhibitors (TNFi), rituximab, anti-interleukin 6 receptor (anti-IL6R) or JAK inhibitors (JAKi)]. Demographic and clinical information were collected. After 4-6 weeks of 2nd and 3rd vaccine doses, humoral response was assessed using the Thermo Scientific ELiA SARS-CoV-2-Sp1 IgG Test. Also, in patients with serum SARS-CoV-2 antibody levels under 100UI/ml, cellular response was analyzed using the QuantiFERON SARS-CoV-2 Starter Pack.

RESULTS

A total of 86 patients under b/tsDMARDs and 38 healthy controls were included. Most patients received TNFi (45 with TNFi, 31 with rituximab, 5 with anti-IL6R and 5 with JAKi). SARS-CoV-2 antibodies (Ab) were present in an 86% of patients with IMIDs and in 100% healthy controls (p = 0.017). However, 12 (14%) patients had undetectable SARS-CoV-2 Ab levels, all treated with rituximab. In addition, SARS-CoV-2 Ab (IU/ml) were statistically lower in patients (Mdn (IQR): 59.5 (17-163) in patients vs 625 (405-932) in controls, p < 0.001). Patients treated with rituximab had lower Ab levels than those treated with TNFi and controls (p < 0.001). The cellular response to SARS-CoV-2 vaccine was evaluated in 30 patients. Eleven patients had a positive cellular response, being more frequent in patients treated with rituximab (p = 0.03). SARS-CoV-2 infection was reported in 43% of patients and 34% of controls after vaccination. Only 6 (7%) patients required hospitalization, most of whom treated with rituximab (67%).

CONCLUSION

SARS-CoV-2 antibody levels were lower in patients than in controls, especially in patients treated with rituximab. A cellular response can be detected despite having a poor humoral response. Severe infections in vaccinated patients with IMIDs are rare, and are observed mainly in patients treated with rituximab.

The predictive and prognostic value of peripheral blood antigen-specific memory B cells in phospholipase A2 receptor-associated membranous nephropathy

Background

Phospholipase A2 receptor-associated membranous nephropathy (PLA2R-MN) is an anti-PLA2R antibody (PLA2R-Ab) mediated autoimmune kidney disease. Although antibody titer correlates closely with disease activity, whether it can provide longer-term predictions on disease course and progression is unclear. Rituximab, a B-cell depletion therapy, has become the first-line treatment option for PLA2R-MN; however, the response to Rituximab varies among patients.

Methods

We developed a flow cytometry-based test that detects and quantifies PLA2R antigen-specific memory B cells (PLA2R-MBCs) in peripheral blood, the primary source for PLA2R-Ab production upon disease relapse. We applied the test to 159 blood samples collected from 28 patients with PLA2R-MN (at diagnosis, during and after immunosuppressive treatment, immunological remission, and relapse) to evaluate the relationship between circulating PLA2R-MBC levels and disease activity.

Results

The level of PLA2R-MBCs in healthy controls (n=56) is less than or equal to 1.5% of the total MBC compartment. High circulating PLA2R-MBC levels were detected in two patients post-Rituximab despite achieving immunologic and proteinuric remission, as well as in two patients with negative serum autoantibody but increasing proteinuria. Elimination of these cells with Rituximab improved clinical outcomes. Moreover, five patients exhibited elevated PLA2R-MBC levels before disease relapse, followed by a rapid decline to baseline when relapse became clinically evident. COVID-19 vaccination or SARS-CoV-2 infection significantly affected the dynamics of circulating PLA2R-MBCs.

Conclusions

This study suggests that monitoring PLA2R-MBC levels in patients with PLA2R-MN may help refine and individualize immunosuppressive therapy and predict disease course and progression. The technology and findings may also have broader applications in the clinical management of other autoimmune diseases.

Immune response to SARS-CoV-2 mRNA vaccination in multiple sclerosis patients after rituximab treatment interruption

Peripheral B cell depletion via anti-CD20 treatment is a highly effective disease-modifying treatment for reducing new relapses in multiple sclerosis (MS) patients. A drawback of rituximab (RTX) and other anti-CD20 antibodies is a poor immune response to vaccination. While this can be mitigated by treatment interruption of at least six months prior to vaccination, the timing to resume treatment while maintaining subsequent vaccine responses remains undetermined. Here, we characterized SARS-CoV-2 S-directed antibody and B cell responses throughout three BNT162b2 mRNA vaccine doses in RTX-treated MS patients, with the first two doses given during treatment interruption. We examined B-cell mediated immune responses in blood samples from patients with RTX-treated MS throughout three BNT162b2 vaccine doses, compared to an age- and sex-matched healthy control group. The first vaccine dose was given 1.3 years (median) after the last RTX infusion, the second dose one month after the first, and the third dose four weeks after treatment re-initiation. We analyzed SARS-CoV-2 S-directed antibody levels using enzyme-linked immunosorbent assay (ELISA), and the neutralization capacity of patient serum against SARS-CoV-2 S-pseudotyped lentivirus using luciferase reporter assay. In addition, we assessed switched memory (CD19+CD20+CD27+IgD-), unswitched memory (CD19+CD20+CD27+IgD+), naïve (CD19+CD20+CD27-IgD+), and double negative (DN, CD19+CD20+CD27-IgD-) B cell frequencies, as well as their SARS-CoV-2 S-specific (CoV+) and Decay Accelerating Factor-negative (DAF-) subpopulations, using flow cytometry. After two vaccine doses, S-binding antibody levels and neutralization capacity in SARS-CoV-2-naïve MS patients were comparable to vaccinated healthy controls, albeit with greater variation. Higher antibody response levels and CoV+-DN B cell frequencies after the second vaccine dose were predictive of a boost effect after the third dose, even after re-initiation of rituximab treatment. MS patients also exhibited lower frequencies of DAF- memory B cells, a suggested proxy for germinal centre activity, than control individuals. S-binding antibody levels in RTX-treated MS patients after two vaccine doses could help determine which individuals would need to move up their next vaccine booster dose or postpone their next RTX infusion. Our findings also offer first indications on the potential importance of antigenic stimulation of DN B cells and long-term impairment of germinal centre activity in rituximab-treated MS patients.

Vaccine-based clinical protection against SARS-CoV-2 infection and the humoral immune response: A 1-year follow-up study of patients with multiple sclerosis receiving ocrelizumab

Introduction

Given the varying severity of coronavirus disease 2019 (COVID-19) and the rapid spread of Severe-Acute-Respiratory-Syndrome-Corona-Virus-2 (SARS-CoV-2), vaccine-mediated protection of particularly vulnerable individuals has gained increasing attention during the course of the pandemic.

Methods

We performed a 1-year follow-up study of 51 ocrelizumab-treated patients with multiple sclerosis (OCR-pwMS) who received COVID-19 vaccination in 2021. We retrospectively identified 37 additional OCR-pwMS, 42 pwMS receiving natalizumab, 27 pwMS receiving sphingosine 1-phosphate receptor modulators, 59 pwMS without a disease-modifying therapy, and 61 controls without MS (HC). In OCR-pwMS, anti-SARS-CoV-2(S)-antibody titers were measured prior to the first and after the second, third, and fourth vaccine doses (pv2/3/4). The SARS-CoV-2-specific T cell response was analyzed pv2. SARS-CoV-2 infection status, COVID-19 disease severity, and vaccination-related adverse events were assessed in all pwMS and HC.

Results

We found a pronounced and increasing anti-SARS-CoV-2(S)-antibody response after COVID-19 booster vaccinations in OCR-pwMS (pv2: 30.4%, pv3: 56.5%, and pv4 90.0% were antibody positive). More than one third of OCR-pwMS without detectable antibodies pv2 developed positive antibodies pv3. 23.5% of OCR-pwMS had a confirmed SARS-CoV-2 infection, of which 84.2% were symptomatic. Infection rates were comparable between OCR-pwMS and control groups. None of the pwMS had severe COVID-19. An attenuated humoral immune response was not associated with a higher risk of SARS-CoV-2 infection.

Discussion

Additional COVID-19 vaccinations can boost the humoral immune response in OCR-pwMS and improve clinical protection against COVID-19. Vaccines effectively protect even OCR-pwMS without a detectable COVID-19 specific humoral immune response, indicating compensatory, e.g., T cell-mediated immunological mechanisms.

Off-Label Uses of Rituximab in Dermatology

Purpose of Review

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

Recent Findings

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

Summary

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

Immune response to SARS-CoV-2 vaccination in relation to peripheral immune cell profiles among patients with multiple sclerosis receiving ocrelizumab

BACKGROUND

Vaccination has proven to be effective in preventing SARS-CoV-2 transmission and severe disease courses. However, immunocompromised patients have not been included in clinical trials and real-world clinical data point to an attenuated immune response to SARS-CoV-2 vaccines among patients with multiple sclerosis (MS) receiving immunomodulatory therapies.

METHODS

We performed a retrospective study including 59 ocrelizumab (OCR)-treated patients with MS who received SARS-CoV-2 vaccination. Anti-SARS-CoV-2-antibody titres, routine blood parameters and peripheral immune cell profiles were measured prior to the first (baseline) and at a median of 4 weeks after the second vaccine dose (follow-up). Moreover, the SARS-CoV-2-specific T cell response and peripheral B cell subsets were analysed at follow-up. Finally, vaccination-related adverse events were assessed.

RESULTS

After vaccination, we found anti-SARS-CoV-2(S) antibodies in 27.1% and a SARS-CoV-2-specific T cell response in 92.7% of MS cases. T cell-mediated interferon (IFN)-γ release was more pronounced in patients without anti-SARS-CoV-2(S) antibodies. Antibody titres positively correlated with peripheral B cell counts, time since last infusion and total IgM levels. They negatively correlated with the number of previous infusion cycles. Peripheral plasma cells were increased in antibody-positive patients. A positive correlation between T cell response and peripheral lymphocyte counts was observed. Moreover, IFN-γ release was negatively correlated with the time since the last infusion.

CONCLUSION

In OCR-treated patients with MS, the humoral immune response to SARS-CoV-2 vaccination is attenuated while the T cell response is preserved. However, it is still unclear whether T or B cell-mediated immunity is required for effective clinical protection. Nonetheless, given the long-lasting clinical effects of OCR, monitoring of peripheral B cell counts could facilitate individualised treatment regimens and might be used to identify the optimal time to vaccinate.

Novel Therapies to Address Unmet Needs in ITP

Primary immune thrombocytopenia (ITP) is an autoimmune disorder that causes low platelet counts and subsequent bleeding risk. Although current corticosteroid-based ITP therapies are able to improve platelet counts, up to 70% of subjects with an ITP diagnosis do not achieve a sustained clinical response in the absence of treatment, thus requiring a second-line therapy option as well as additional care to prevent bleeding. Less than 40% of patients treated with thrombopoietin analogs, 60% of those treated with splenectomy, and 20% or fewer of those treated with rituximab or fostamatinib reach sustained remission in the absence of treatment. Therefore, optimizing therapeutic options for ITP management is mandatory. The pathophysiology of ITP is complex and involves several mechanisms that are apparently unrelated. These include the clearance of autoantibody-coated platelets by splenic macrophages or by the complement system, hepatic desialylated platelet destruction, and the inhibition of platelet production from megakaryocytes. The number of pathways involved may challenge treatment, but, at the same time, offer the possibility of unveiling a variety of new targets as the knowledge of the involved mechanisms progresses. The aim of this work, after revising the limitations of the current treatments, is to perform a thorough review of the mechanisms of action, pharmacokinetics/pharmacodynamics, efficacy, safety, and development stage of the novel ITP therapies under investigation. Hopefully, several of the options included herein may allow us to personalize ITP management according to the needs of each patient in the near future.

Early B cells repopulation in multiple sclerosis patients treated with rituximab is not predictive of a risk of relapse or clinical progression

BACKGROUND

It is currently unknown whether early B cell reconstitution (EBR) in MS patients under rituximab is associated with a risk of relapse or progression.

OBJECTIVES

Analyzing EBR in rituximab-treated patients and its putative association with clinical findings.

METHODS

Prospective lymphocytes immunophenotyping was performed in a monocentric cohort of MS patients treated by rituximab for 2 years. EBR was defined when B cells concentration was > 5 cells/mm3. B cell subsets were retrospectively associated with clinical data. Clinical and radiological monitoring included relapses, EDSS (Expanded Disability Status Scale), SDMT (Symbol Digit Modalities Test), and MRI.

RESULTS

182 patients were analyzed (61 remitting-relapsing and 121 progressive-active). 38.5% experienced EBR at least once, but very few (7/182) showed systematic reconstitution. Most patients remained stable upon treatment, regardless of the occurrence of EBR. Dynamics of B cell reconstitution featured increased naïve/transitional B cells, and decreased memory subsets. Homeostasis of the B cell compartment differed at baseline between patients experiencing or not EBR upon treatment. In patients with EBR, reciprocal dynamics of transitional and pro-inflammatory double-negative B cell subsets was associated with better response to rituximab treatment.

CONCLUSION

EBR is common in rituximab-treated MS patients and is not associated with clinical disease activity. EBR in the peripheral blood may reflect regulatory immunological phenomena in subgroup of patients.

Alterations in B- and circulating T-follicular helper cell subsets in immune thrombotic thrombocytopenic purpura

Abnormal B-cell phenotype in acute iTTP with decreased transitional and post–germinal center memory cells and increased plasmablasts.

Decreased total and PD1⁺ circulating T-follicular helper cells and changes in B-cell CD80 expression suggest altered B- and T-cell interactions.

T follicular helper (Tfh) cells regulate development of antigen-specific B-cell immunity. We prospectively investigated B-cell and circulating Tfh (cTfh) cell subsets in 45 patients with immune thrombotic thrombocytopenic purpura (iTTP) at presentation and longitudinally after rituximab (RTX). B-cell phenotype was altered at acute iTTP presentation with decreased transitional cells and post–germinal center (post-GC) memory B cells and increased plasmablasts compared with healthy controls. A higher percentage of plasmablasts was associated with higher anti-ADAMTS13 IgG and lower ADAMTS13 antigen levels. In asymptomatic patients with ADAMTS13 relapse, there were increased naïve B cells and a global decrease in memory subsets, with a trend to increased plasmablasts. Total circulating Tfh (CD4⁺CXCR5⁺) and PD1⁺ Tfh cells were decreased at iTTP presentation. CD80 expression was decreased on IgD⁺ memory cells and double-negative memory cells in acute iTTP. At repopulation after B-cell depletion in de novo iTTP, post-GC and double-negative memory B cells were reduced compared with pre-RTX. RTX did not cause alteration in cTfh cell frequency. The subsequent kinetics of naïve, transitional, memory B cells and plasmablasts did not differ significantly between patients who went on to relapse vs those who remained in remission. In summary, acute iTTP is characterized by dysregulation of B- and cTfh cell homeostasis with depletion of post-GC memory cells and cTfh cells and increased plasmablasts. Changes in CD80 expression on B cells further suggest altered interactions with T cells.

B Cell Characteristics at Baseline Predict Vaccination Response in RTX Treated Patients

Background

Vaccination is considered as most efficient strategy in controlling SARS-CoV-2 pandemic spread. Nevertheless, patients with autoimmune inflammatory rheumatic diseases receiving rituximab (RTX) are at increased risk to fail humoral and cellular responses upon vaccination. The ability to predict vaccination responses is essential to guide adequate safety and optimal protection in these patients.

Methods

B- and T- cell data before vaccination were evaluated for characteristics predicting vaccine responses in altogether 15 patients with autoimmune inflammatory rheumatic diseases receiving RTX. Eleven patients with rheumatoid arthritis (RA) on other therapies, 11 kidney transplant recipients (KTR) on regular immunosuppression and 15 healthy controls (HC) served as controls. A multidimensional analysis of B cell subsets via UMAP algorithm and a correlation matrix were performed in order to identify predictive markers of response in patients under RTX therapy.

Results

Significant differences regarding absolute B cell counts and specific subset distribution pattern between the groups were identified at baseline. In this context, the majority of B cells from vaccination responders of the RTX group (RTX IgG+) were naïve and transitional B cells, whereas vaccination non-responders (RTX IgG-) carried preferentially plasmablasts and double negative (CD27-IgD-) B cells. Moreover, there was a positive correlation between neutralizing antibodies and B cells expressing HLA-DR and CXCR5 as well as an inverse correlation with CD95 expression and CD21low expression by B cells among vaccination responders.

Summary

Substantial repopulation of the naïve B cell compartment after RTX therapy appeared to be essential for an adequate vaccination response, which seem to require the additional capability of antigen presentation and germinal center formation. Moreover, expression of exhaustion markers represent negative predictors of vaccination responses.

T and B lymphocyte dynamics after genetically-modified pig-to-baboon kidney xenotransplantation with an anti-CD40mAb-based immunosuppressive regimen

BACKGROUND

The aim was to monitor recovery of T/B lymphocytes in baboons after depletion by anti-thymocyte globulin (ATG) and anti-CD20mAb (Rituximab), followed by pig kidney transplantation and maintenance therapy with an anti-CD40mAb-based regimen.

METHODS

In baboons (n = 14), induction was with ATG and anti-CD20mAb, and maintenance with (i) anti-CD40mAb, (ii) rapamycin, and (iii) methylprednisolone. Follow-up was for 6 months, or until rejection or other complication developed. Baboon blood was collected at intervals to measure T/B cells and subsets by flow cytometry. In a separate study in baboons receiving the same immunosuppressive regimen (n = 10), the populations of T/B lymphocytes in PBMCs, lymph nodes, and spleen were examined.

RESULTS

After induction therapy, the total lymphocyte count and the absolute numbers of CD3⁺, CD4⁺, and CD8⁺T cells fell by >80%, and no CD22⁺B cells remained (all p < 0.001). T cell numbers began to recover early, but no CD22⁺B cells were present in the blood for 2 months. Recovery of both T and B cells remained at <30% of baseline (p < 0.001), even if rejection developed. At 6 months, effector memory CD8⁺T cells had increased more than other T cell subsets, but a greater percentage of B cells were naïve. In contrast to blood and spleen, T and B cells were not depleted in lymph nodes.

CONCLUSIONS

ATG and anti-CD20mAb effectively decreased T and B lymphocytes in the blood and, in the presence of anti-CD40mAb maintenance therapy, recovery of these cells was inhibited. The recovery of effector memory CD8⁺T cells may be detrimental to long-term graft survival.

A Personalized Rituximab Retreatment Approach Based on Clinical and B-Cell Biomarkers in ANCA-Associated Vasculitis

Background

Time to relapse after rituximab for the treatment of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is variable, and optimal retreatment strategy has remained unclear. In AAV following rituximab induction, the study objective was to evaluate clinical and B-cell predictors of relapse in order to develop a retreatment algorithm.

Methods

A retrospective observational study was conducted in 70 rituximab-treated ANCA-associated vasculitis patients followed up for over 10 years. Complete response (CR) was defined as Birmingham Vasculitis Activity Score v3.0 = 0. Retreatment was given on clinical relapse, defined as new features or worsening of persistent disease (not by biomarker status). Peripheral B-cell subsets were measured using highly sensitive flow cytometry. Predictors were tested using multivariable Cox regression.

Results

Median time to retreatment for cycles 1–5 were 84, 73, 67, 60, and 73 weeks. Over 467 patient-years follow-up, 158 relapses occurred in 60 patients; 16 (in 15 patients) were major (renal = 7, neurological = 4, ENT = 3, and respiratory = 2). The major-relapse rate was 3.4/100 patient-years. In multivariable analysis, concomitant immunosuppressant [HR, 0.48 (95% CI, 0.24–0.94)], achieving CR [0.24 (0.12–0.50)], and naïve B-cell repopulation at 6 months [0.43 (0.22–0.84)] were associated with longer time to relapse. Personalized retreatment using these three predictors in this cohort would have avoided an unnecessary fixed retreatment in 24% of patients. Area under the receiver operating characteristic for prediction of time to relapse was greater if guided by naïve B-cell repopulation than if previously evaluated ANCA and/or CD19⁺ cells return at 6 months had been used, 0.82 and 0.53, respectively.

Conclusion

Our findings suggest that all patients should be coprescribed oral immunosuppressant. Those with incomplete response or with absent naïve B cells should be retreated at 6 months. Patients with complete response and naïve repopulation should not receive fixed retreatment. This algorithm could reduce unnecessary retreatment and warrant investigation in clinical trials.

Immunosuppressive Therapy After Autologous Hematopoietic Stem Cell Transplantation in Systemic Sclerosis Patients-High Efficacy of Rituximab

Background

Systemic sclerosis (SSc) patients often need immunosuppressive medication (IS) for disease control. If SSc is progressive despite IS, autologous hematopoietic stem cell transplantation (aHSCT) is a treatment option for selected SSc patients. aHSCT is effective with good available evidence, but not all patients achieve a treatment-free remission after aHSCT. Thus far, data about the need of IS after aHSCT in SSc is not published. The aim of this study was to investigate the use of IS after aHSCT, its efficacy, and the occurrence of severe adverse events (SAEs).

Methods

Twenty-seven patients with SSc who had undergone aHSCT were included in this single-center retrospective cohort study. Clinical data, including IS, SAEs, and lung function data, were collected.

Results

Sixteen of 27 (59.3%) patients received IS after aHSCT. Methotrexate, rituximab, mycophenolate, cyclophosphamide, and hydroxychloroquine were most commonly used. The main reason for starting IS was SSc progress. Nine patients received rituximab after aHSCT and showed an improvement in modified Rodnan skin score and a stabilization of lung function 2 years after rituximab. SAEs in patients with IS after aHSCT (50.0%) were not more common than in patients without IS (54.6%). SAEs were mostly due to SSc progress, secondary autoimmune diseases, or infections. Two deaths after aHSCT were transplantation related and three during long-term follow-up due to pulmonary arterial hypertension.

Conclusion

Disease progression and secondary autoimmune diseases may necessitate IS after aHSCT in SSc. Rituximab seems to be an efficacious treatment option in this setting. Long-term data on the safety of aHSCT is reassuring.

Rituximab for the treatment of multiple sclerosis: a review

In the last decades, evidence suggesting the direct or indirect involvement of B cells on multiple sclerosis (MS) pathogenesis has accumulated. The increased amount of data on the efficacy and safety of B-cell-depleting therapies from several studies has suggested the addition of these drugs as treatment options to the current armamentarium of disease modifying therapies (DMTs) for MS. Particularly, rituximab (RTX), a chimeric monoclonal antibody directed at CD20 positive B lymphocytes resulting in cell-mediated apoptosis, has been demonstrated to reduce inflammatory activity, incidence of relapses and new brain lesions on magnetic resonance imaging (MRI) in patients with relapsing-remitting MS (RRMS). Additional evidence also demonstrated that patients with progressive MS (PMS) may benefit from RTX, which also showed to be well tolerated, with acceptable safety risks and favorable cost-effectiveness profile.Despite these encouraging results, RTX is currently approved for non-Hodgkin's lymphoma, chronic lymphocytic leukemia, several forms of vasculitis and rheumatoid arthritis, while it can only be administered off-label for MS treatment. Between Northern European countries exist different rules for using not licensed drug for treating MS. The Sweden MS register reports a high rate (53.5%) of off-label RTX prescriptions in relation to other annually started DMTs to treat MS patients, while Danish and Norwegian neurologists have to use other anti-CD20 drugs, as ocrelizumab, in most of the cases.In this paper, we review the pharmacokinetics, pharmacodynamics, clinical efficacy, safety profile and cost effectiveness aspects of RTX for the treatment of MS. Particularly, with the approval of new anti-CD20 DMTs, the recent worldwide COVID-19 emergency and the possible increased risk of infection with this class of drugs, this review sheds light on the use of RTX as an alternative treatment option for MS management, while commenting the gaps of knowledge regarding this drug.

Contribution of Dysregulated B-Cells and IgE Antibody Responses to Multiple Sclerosis

Multiple sclerosis (MS), a debilitating autoimmune inflammatory disease that affects the brain and spinal cord, causes demyelination of neurons, axonal damage, and neurodegeneration. MS and the murine experimental autoimmune encephalomyelitis (EAE) model have been viewed mainly as T-cell-mediated diseases. Emerging data have suggested the contribution of B-cells and autoantibodies to the disease progression. However, the underlying mechanisms by which dysregulated B-cells and antibody response promote MS and EAE remain largely unclear. Here, we provide an updated review of this specific subject by including B-cell biology and the role of B-cells in triggering autoimmune neuroinflammation with a focus on the regulation of antibody-producing B-cells. We will then discuss the role of a specific type of antibody, IgE, as it relates to the potential regulation of microglia and macrophage activation, autoimmunity and MS/EAE development. This knowledge can be utilized to develop new and effective therapeutic approaches to MS, which fits the scope of the Research Topic "Immune Mechanism in White Matter Lesions: Clinical and Pathophysiological Implications".

Revolution of Disturbed Bregs and Bmems Lymphocytes Homeostasis in Children With Chronic ITP After High-dose Dexamethasone Rescue Therapy

SUMMARY

Dexamethasone is approved as second-line therapy in pediatric chronic immune thrombocytopenic purpura (ITP). Several B-cell abnormalities have been described in ITP pathogenesis.This study assessed the effects of high-dose dexamethasone (HD-DXM) on the percentages and absolute counts of CD19+CD24hiCD38hi regulatory (Bregs) and CD19+CD27+ memory B lymphocytes (Bmems) in children with chronic ITP during active bleeding.The study was a prospective case-control, included 20 children with chronic ITP and uncontrolled bleeding. Children received a single daily dose of HD-DXM for 4 days. Blood samples were withdrawn from patients just before HD-DXM therapy and on day 5 to evaluate the platelet counts and flow cytometric analysis of Bregs and Bmem. The patients' platelet counts significantly increased after 5 days of the initiation of therapy (P=0.0001). Bmems percentage and absolute counts were significantly higher in patients before treatment (P=0.0007), and decreased after HD-DXM therapy (P=0.97) compared with the controls. Bregs percentage and absolute counts were significantly lower before treatment (P=0.0003) and increased after HD-DXM (P=0.003). There is a negative correlation between platelet counts and Bregs percentage and absolute count Bmems percentage before and after HD-DXM, whereas a positive correlation between platelets and Bregs before and after dexamethasone has been reported.

CONCLUSIONS

HD-DXM reestablishes the normal Bregs/Bmems balance. This finding discloses possible involvement of Bregs and Bmems in the pathogenesis of pediatric ITP and provides a novel vision for immune modulation and treatment perspectives.

B Cells in Primary Membranous Nephropathy: Escape from Immune Tolerance and Implications for Patient Management

Membranous nephropathy (MN) is an important cause of nephrotic syndrome and chronic kidney disease (CKD) in adults. The pathogenic significance of B cells in MN is increasingly recognized, especially following the discovery of various autoantibodies that target specific podocytic antigens and the promising treatment responses seen with B cell depleting therapies. The presence of autoreactive B cells and autoantibodies that bind to antigens on podocyte surfaces are characteristic features of MN, and are the result of breaches in central and peripheral tolerance of B lymphocytes. These perturbations in B cell tolerance include altered B lymphocyte subsets, dysregulation of genes that govern immunoglobulin production, aberrant somatic hypermutation and co-stimulatory signalling, abnormal expression of B cell-related cytokines, and increased B cell infiltrates and organized tertiary lymphoid structures within the kidneys. An understanding of the role of B cell tolerance and homeostasis may have important implications for patient management in MN, as conventional immunosuppressive treatments and novel B cell-targeted therapies show distinct effects on proliferation, differentiation and reconstitution in different B cell subsets. Circulating B lymphocytes and related cytokines may serve as potential biomarkers for treatment selection, monitoring of therapeutic response and prediction of disease relapse. These recent advances in the understanding of B cell tolerance in MN have provided greater insight into its immunopathogenesis and potential novel strategies for disease monitoring and treatment.

Rituximab for people with multiple sclerosis

BACKGROUND

Multiple sclerosis (MS) is the most common neurological cause of disability in young adults. Off-label rituximab for MS is used in most countries surveyed by the International Federation of MS, including high-income countries where on-label disease-modifying treatments (DMTs) are available.  OBJECTIVES: To assess beneficial and adverse effects of rituximab as 'first choice' and as 'switching' for adults with MS.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, CINAHL, and trial registers for completed and ongoing studies on 31 January 2021.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and controlled non-randomised studies of interventions (NRSIs) comparing rituximab with placebo or another DMT for adults with MS.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methodology. We used the Cochrane Collaboration's tool for assessing risk of bias. We rated the certainty of evidence using GRADE for: disability worsening, relapse, serious adverse events (SAEs), health-related quality of life (HRQoL), common infections, cancer, and mortality. We conducted separate analyses for rituximab as 'first choice' or as 'switching', relapsing or progressive MS, comparison versus placebo or another DMT, and RCTs or NRSIs.

MAIN RESULTS

We included 15 studies (5 RCTs, 10 NRSIs) with 16,429 participants of whom 13,143 were relapsing MS and 3286 progressive MS. The studies were one to two years long and compared rituximab as 'first choice' with placebo (1 RCT) or other DMTs (1 NRSI), rituximab as 'switching' against placebo (2 RCTs) or other DMTs (2 RCTs, 9 NRSIs). The studies were conducted worldwide; most originated from high-income countries, six from the Swedish MS register. Pharmaceutical companies funded two studies. We identified 14 ongoing studies. Rituximab as 'first choice' for relapsing MS Rituximab versus placebo: no studies met eligibility criteria for this comparison. Rituximab versus other DMTs: one NRSI compared rituximab with interferon beta or glatiramer acetate, dimethyl fumarate, natalizumab, or fingolimod in active relapsing MS at 24 months' follow-up. Rituximab likely results in a large reduction in relapses compared with interferon beta or glatiramer acetate (hazard ratio (HR) 0.14, 95% confidence interval (CI) 0.05 to 0.39; 335 participants; moderate-certainty evidence). Rituximab may reduce relapses compared with dimethyl fumarate (HR 0.29, 95% CI 0.08 to 1.00; 206 participants; low-certainty evidence) and natalizumab (HR 0.24, 95% CI 0.06 to 1.00; 170 participants; low-certainty evidence). It may make little or no difference on relapse compared with fingolimod (HR 0.26, 95% CI 0.04 to 1.69; 137 participants; very low-certainty evidence). The study reported no deaths over 24 months. The study did not measure disability worsening, SAEs, HRQoL, and common infections. Rituximab as 'first choice' for progressive MS One RCT compared rituximab with placebo in primary progressive MS at 24 months' follow-up. Rituximab likely results in little to no difference in the number of participants who have disability worsening compared with placebo (odds ratio (OR) 0.71, 95% CI 0.45 to 1.11; 439 participants; moderate-certainty evidence). Rituximab may result in little to no difference in recurrence of relapses (OR 0.60, 95% CI 0.18 to 1.99; 439 participants; low-certainty evidence), SAEs (OR 1.25, 95% CI 0.71 to 2.20; 439 participants; low-certainty evidence), common infections (OR 1.14, 95% CI 0.75 to 1.73; 439 participants; low-certainty evidence), cancer (OR 0.50, 95% CI 0.07 to 3.59; 439 participants; low-certainty evidence), and mortality (OR 0.25, 95% CI 0.02 to 2.77; 439 participants; low-certainty evidence). The study did not measure HRQoL. Rituximab versus other DMTs: no studies met eligibility criteria for this comparison. Rituximab as 'switching' for relapsing MS  One RCT compared rituximab with placebo in relapsing MS at 12 months' follow-up. Rituximab may decrease recurrence of relapses compared with placebo (OR 0.38, 95% CI 0.16 to 0.93; 104 participants; low-certainty evidence). The data did not confirm or exclude a beneficial or detrimental effect of rituximab relative to placebo on SAEs (OR 0.90, 95% CI 0.28 to 2.92; 104 participants; very low-certainty evidence), common infections (OR 0.91, 95% CI 0.37 to 2.24; 104 participants; very low-certainty evidence), cancer (OR 1.55, 95% CI 0.06 to 39.15; 104 participants; very low-certainty evidence), and mortality (OR 1.55, 95% CI 0.06 to 39.15; 104 participants; very low-certainty evidence). The study did not measure disability worsening and HRQoL.  Five NRSIs compared rituximab with other DMTs in relapsing MS at 24 months' follow-up. The data did not confirm or exclude a beneficial or detrimental effect of rituximab relative to interferon beta or glatiramer acetate on disability worsening (HR 0.86, 95% CI 0.52 to 1.42; 1 NRSI, 853 participants; very low-certainty evidence). Rituximab likely results in a large reduction in relapses compared with interferon beta or glatiramer acetate (HR 0.18, 95% CI 0.07 to 0.49; 1 NRSI, 1383 participants; moderate-certainty evidence); and fingolimod (HR 0.08, 95% CI 0.02 to 0.32; 1 NRSI, 256 participants; moderate-certainty evidence). The data did not confirm or exclude a beneficial or detrimental effect of rituximab relative to natalizumab on relapses (HR 1.0, 95% CI 0.2 to 5.0; 1 NRSI, 153 participants; very low-certainty evidence). Rituximab likely increases slightly common infections compared with interferon beta or glatiramer acetate (OR 1.71, 95% CI 1.11 to 2.62; 1 NRSI, 5477 participants; moderate-certainty evidence); and compared with natalizumab (OR 1.58, 95% CI 1.08 to 2.32; 2 NRSIs, 5001 participants; moderate-certainty evidence). Rituximab may increase slightly common infections compared with fingolimod (OR 1.26, 95% CI 0.90 to 1.77; 3 NRSIs, 5187 participants; low-certainty evidence). It may make little or no difference compared with ocrelizumab (OR 0.02, 95% CI 0.00 to 0.40; 1 NRSI, 472 participants; very low-certainty evidence). The data did not confirm or exclude a beneficial or detrimental effect of rituximab on mortality compared with fingolimod (OR 5.59, 95% CI 0.22 to 139.89; 1 NRSI, 136 participants; very low-certainty evidence) and natalizumab (OR 6.66, 95% CI 0.27 to 166.58; 1 NRSI, 153 participants; very low-certainty evidence). The included studies did not measure SAEs, HRQoL, and cancer.

AUTHORS' CONCLUSIONS

For preventing relapses in relapsing MS, rituximab as 'first choice' and as 'switching' may compare favourably with a wide range of approved DMTs. A protective effect of rituximab against disability worsening is uncertain. There is limited information to determine the effect of rituximab for progressive MS.  The evidence is uncertain about the effect of rituximab on SAEs. They are relatively rare in people with MS, thus difficult to study, and they were not well reported in studies. There is an increased risk of common infections with rituximab, but absolute risk is small.  Rituximab is widely used as off-label treatment in people with MS; however, randomised evidence is weak. In the absence of randomised evidence, remaining uncertainties on beneficial and adverse effects of rituximab for MS might be clarified by making real-world data available.

Immunosuppression in Rheumatologic and Auto-immune Disease

Many rheumatologic diseases are thought to originate in dysregulation of the immune system; lupus nephritis, for example, involves humoral immunity, while autoinflammatory diseases such as familial Mediterranean fever are caused by defects in innate immunity. Of note, this dysregulation may involve both upregulation of immune system components and aspects of immunodeficiency. Treatment of rheumatologic diseases thus requires a familiarity with a variety of immunosuppressive medications and their effects on immune system function.In many rheumatologic conditions, due to an incompletely elucidated mechanism of disease, immunosuppression is relatively broad in contrast to agents used, for example, in treatment of transplant rejection. Multiple immunosuppressive drugs may also be used in succession or in combination. As such, an understanding of the mechanisms and targets of immunosuppressive drugs is essential to appreciating their utility and potential adverse effects. Because of the overlap between therapies used in rheumatologic as well as other inflammatory disorders, some of these medications are discussed in other disease processes (e.g., Immunosuppression for inflammatory bowel disease) or in greater detail in other chapters of this textbook (corticosteroids, mTOR inhibitors, antiproliferative agents).

BAFF, involved in B cell activation through the NF-κB pathway, is related to disease activity and bone destruction in rheumatoid arthritis

B cell activating factor of TNF family (BAFF) is a member of TNF ligand superfamily and plays a key role in B cell homeostasis, proliferation, maturation, and survival. In this study, we detected BAFF level, the expressions of BAFF receptors and important molecules in NF-κB pathway in rheumatoid arthritis (RA) patients and analyzed the correlation between BAFF level and clinical variables, laboratory parameters or X-ray scores in order to elucidate the roles of BAFF in RA. A total of 50 RA patients and 50 healthy controls (HCs) were enrolled. We showed that the serum BAFF level in RA patients was significantly higher than that of HCs, and the percentages of B cell subsets (CD19⁺ B cells, CD19⁺CD27⁺ B cells, CD19⁺CD20⁺CD27⁺ B cells, and CD19⁺CD20^-CD27⁺ B cells) in the serum of RA patients were significantly increased compared with those of HCs. The percentages of CD19⁺BAFFR⁺ B cells, CD19⁺ BCMA⁺ B cells, and CD19⁺ TACI⁺ B cells in RA patients were significantly increased compared with those in HCs. The expression of important molecules in the NF-κB pathway (MKK3, MKK6, p-P38, p-P65, TRAF2, and p52) was significantly higher in RA patients than in HCs, but p100 level in RA patients was lower than that in HCs. The serum BAFF level was positively correlated with C-reactive protein, rheumatoid factor, disease activity score (in 28 joints), swollen joint counts, tender joint counts, and X-ray scores. When normal B cells were treated with BAFF in vitro, the percentages of the B cell subset and the expression of BAFF receptors were significantly upregulated. BAFF also promoted the expression of MKK3, MKK6, p-P38, p-P65, TRAF2, and p52. In conclusion, this study demonstrates that BAFF level is correlated with the disease activity and bone destruction of RA. BAFF is involved in the differentiation, proliferation, and activation of B cells in RA through NF-κB signaling pathway, suggesting that BAFF might be an ideal therapeutic target for RA.

Rituximab Therapy for Primary Sjögren's Syndrome

Primary Sjögren's syndrome (pSS) is a systemic autoimmune diseases of the connective tissues, characteristic of the presentation of keratoconjunctivitis sicca and xerostomia. A cardinal pathogenetic feature of SS is B-cell hyperactivity, which has invited efforts on optimal B-cell targeted therapy, whereas conventional corticosteroids and disease-modifying antirheumatic drugs (DMARDs) are restricted to symptomatic relief. As per the first EULAR recommendation for pSS patients published in 2020, regimens with monoclonal antibodies targeting B cells may be initiated in patients with severe, refractory systemic disease, notably rituximab (RTX), a mouse-derived monoclonal antibody that targets CD20 antigen and contributes to B-cell depletion. Nonetheless, the data available from clinical trials with RTX are often controversial. Despite the lack of promising results from two large RCTs, several positive clinical efficacies were demonstrated. This current review addressed the efficacy and safety of clinical trials available and elucidated the potential of RTX on the immune system, especially B and T cells. Furthermore, plausible explanations for the discrepancy in clinical data were also presented.

Ocrelizumab for the Treatment of Multiple Sclerosis: Safety, Efficacy, and Pharmacology

The success of selective B-cells depleting therapies, as the anti-CD20 antibodies, in patients with multiple sclerosis (MS) has confirmed that B-cells are critical in the immune pathogenesis of the disease. Ocrelizumab, a humanized monoclonal antibody that selectively targets CD20+ B-cells, profoundly suppresses acute inflammatory disease activity, representing a highly effective therapy for relapsing-remitting multiple sclerosis (RRMS). It is also the first proven therapy able to slow disability progression in primary progressive multiple sclerosis (PPMS), particularly in patients with signs of acute radiological activity before being enrolled. Effectiveness has widely been demonstrated in randomized clinical trials (RCTs), and recently confirmed in open-label extension trials. Here, we review the role of B-cells in MS, the mechanism of action of ocrelizumab, its pharmacokinetics and pharmacodynamics, and the clinical data supporting its use, as well as safety data. We focus on issues related to the maintenance of immunocompetence, essential to ensure an immune response to either a primary infection or a vaccination. Lastly, we discuss about the possible role of ocrelizumab as an exit strategy from natalizumab-treated patients at risk of developing multifocal progressive leukoencephalopathy. In view of using ocrelizumab chronically, collecting long-term safety data and finding strategies to minimize adverse events will be extremely relevant.

Rituximab-resistant splenic memory B cells and newly engaged naive B cells fuel relapses in patients with immune thrombocytopenia

Rituximab (RTX), an antibody targeting CD20, is widely used as a first-line therapeutic strategy in B cell-mediated autoimmune diseases. However, a large proportion of patients either do not respond to the treatment or relapse during B cell reconstitution. Here, we characterize the cellular basis responsible for disease relapse in secondary lymphoid organs in humans, taking advantage of the opportunity offered by therapeutic splenectomy in patients with relapsing immune thrombocytopenia. By analyzing the B and plasma cell immunoglobulin gene repertoire at bulk and antigen-specific single-cell level, we demonstrate that relapses are associated with two responses coexisting in germinal centers and involving preexisting mutated memory B cells that survived RTX treatment and naive B cells generated upon reconstitution of the B cell compartment. To identify distinctive characteristics of the memory B cells that escaped RTX-mediated depletion, we analyzed RTX refractory patients who did not respond to treatment at the time of B cell depletion. We identified, by single-cell RNA sequencing (scRNA-seq) analysis, a population of quiescent splenic memory B cells that present a unique, yet reversible, RTX-shaped phenotype characterized by down-modulation of B cell-specific factors and expression of prosurvival genes. Our results clearly demonstrate that these RTX-resistant autoreactive memory B cells reactivate as RTX is cleared and give rise to plasma cells and further germinal center reactions. Their continued surface expression of CD19 makes them efficient targets for current anti-CD19 therapies. This study thus identifies a pathogenic contributor to autoimmune diseases that can be targeted by available therapeutic agents.

Antigen Loss after Targeted Immunotherapy in Hematological Malignancies

Immunotherapy marked a milestone in cancer treatment and has shown unprecedented efficacy in a variety of hematological malignancies. Downregulation or loss of target antigens is commonly seen after immunotherapy, which often causes diagnostic dilemma and represents a key mechanism that tumor escapes from immunotherapy. The awareness of phenotypic changes after targeted immunotherapy is important to avoid misdiagnosis. Further understanding of the mechanisms of antigen loss is paramount for the development of therapeutic approaches that can prevent or overcome antigen escape in future immunotherapy.

A Milestone in Multiple Sclerosis Therapy: Monoclonal Antibodies Against CD20-Yet Progress Continues

Multiple sclerosis (MS), which is a chronic inflammatory disease of the central nervous system, still represents one of the most common causes of persisting disability with an early disease onset. Growing evidence suggests B cells to play a crucial role in its pathogenesis and progression. Over the last decades, monoclonal antibodies (mabs) against the surface protein CD20 have been intensively studied as a B cell targeting therapy in relapsing MS (RMS) as well as primary progressive MS (PPMS). Pivotal studies on anti-CD20 therapy in RMS showed remarkable clinical and radiological effects, especially on acute inflammation and relapse biology. These results paved the way for further research on the implication of B cells in the pathogenesis of MS. Besides controlling relapse development in RMS, ocrelizumab (OCR) also showed clinical benefits in patients with PPMS and became the first approved drug for this disease course. In this review, we provide an overview of the current anti-CD20 mabs used or tested for the treatment of MS-namely rituximab (RTX), OCR, ofatumumab (OFA), and ublituximab (UB). Besides their effectiveness, we also discuss possible limitations and safety concerns especially in regard to long-term treatment, both for this class of drugs overall as well as for each anti-CD20 mab individually. Additionally, we elucidate to what extent anti-CD20 therapy may alter the function of other immune cells, both directly or indirectly. Finally, we cover the current knowledge on repopulation of CD20+ cells after cessation of anti-CD20 treatment and discuss future aspirations towards alternative, further developed B cell silencing therapies.

Memory B Cells in Multiple Sclerosis: Emerging Players in Disease Pathogenesis

Multiple Sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system. Once thought to be primarily driven by T cells, B cells are emerging as central players in MS immunopathogenesis. Interest in multiple B cell phenotypes in MS expanded following the efficacy of B cell-depleting agents targeting CD20 in relapsing-remitting MS and inflammatory primary progressive MS patients. Interestingly, these therapies primarily target non-antibody secreting cells. Emerging studies seek to explore B cell functions beyond antibody-mediated roles, including cytokine production, antigen presentation, and ectopic follicle-like aggregate formation. Importantly, memory B cells (Bmem) are rising as a key B cell phenotype to investigate in MS due to their antigen-experience, increased lifespan, and rapid response to stimulation. Bmem display diverse effector functions including cytokine production, antigen presentation, and serving as antigen-experienced precursors to antibody-secreting cells. In this review, we explore the cellular and molecular processes involved in Bmem development, Bmem phenotypes, and effector functions. We then examine how these concepts may be applied to the potential role(s) of Bmem in MS pathogenesis. We investigate Bmem both within the periphery and inside the CNS compartment, focusing on Bmem phenotypes and proposed functions in MS and its animal models. Finally, we review how current immunomodulatory therapies, including B cell-directed therapies and other immunomodulatory therapies, modify Bmem and how this knowledge may be harnessed to direct therapeutic strategies in MS.

New Therapeutic Landscape in Neuromyelitis Optica

Purpose of review

This review discusses the current treatment trends and emerging therapeutic landscape for patients with neuromyelitis optica spectrum disorder (NMOSD).

Recent findings

Conventional immune suppressive therapies, such as B cell depletion, have been used for long-term treatment. However, the availability of recent FDA-approved and investigational drugs has made therapeutic choices for NMOSD more complex.

Summary

Recent randomized clinical trials have shown that eculizumab, inebilizumab, and satralizumab are efficacious therapies for AQP4 seropositive NMOSD. These therapies may not have the same benefit in patients with seronegative NMOSD, including MOG-associated disease, and further investigation is required in this population. Reliable biomarkers to guide therapy decisions are urgently needed. There is a plethora of promising investigational therapies currently in the pipeline with exciting and novel mechanisms of action.

The clinical efficacy of Rituximab administration in autoimmunity disorders, primary immunodeficiency diseases and malignancies

Rituximab (RTX), as a monoclonal antibody-based immunotherapeutic intervention targeting CD20 on B cells, has proven efficacy in the treatment of patients with some immune-mediated diseases. In the present review, we provided information on the immunobiological mechanisms of signaling for RTX and its clinical applications, according to the immune-pathophysiology involved in the microenvironment of multiple diseases. We highlighted combination therapy, dose schedules, and laboratory monitoring, as well as the associated common and rare side effects to avoid. We also discussed the efficacy and safety of RTX-based therapeutic strategies and whether RTX therapy can be used as a promising treatment regimen for autoimmune diseases, primary immunodeficiency diseases, and malignancies. Our review highlights and supports the importance of collaboration between basic medical researchers and clinical specialists when considering the use of RTX in the treatment of various immune-mediated disorders.

Safety and Efficacy of B-Cell Depletion with Rituximab for the Treatment of Systemic Sclerosis-associated Pulmonary Arterial Hypertension: A Multicenter, Double-Blind, Randomized, Placebo-controlled Trial

Rationale: Systemic sclerosis (SSc)-pulmonary arterial hypertension (PAH) is one of the most prevalent and deadly forms of PAH. B cells may contribute to SSc pathogenesis. Objectives: We investigated the safety and efficacy of B-cell depletion for SSc-PAH. Methods: In an NIH-sponsored, multicenter, double-blinded, randomized, placebo-controlled, proof-of-concept trial, 57 patients with SSc-PAH on stable-dose standard medical therapy received two infusions of 1,000 mg rituximab or placebo administered 2 weeks apart. The primary outcome measure was the change in 6-minute-walk distance (6MWD) at 24 weeks. Secondary endpoints included safety and invasive hemodynamics. We applied a machine learning approach to predict drug responsiveness. Measurements and Main Results: We randomized 57 subjects from 2010 to 2018. In the primary analysis, using data through Week 24, the adjusted mean change in 6MWD at 24 weeks favored the treatment arm but did not reach statistical significance (23.6 ± 11.1 m vs. 0.5 ± 9.7 m; P = 0.12). Although a negative study, when data through Week 48 were also considered, the estimated change in 6MWD at Week 24 was 25.5 ± 8.8 m for rituximab and 0.4 ± 7.4 m for placebo (P = 0.03). Rituximab treatment appeared to be safe and well tolerated. Low levels of RF (rheumatoid factor), IL-12, and IL-17 were sensitive and specific as favorable predictors of a rituximab response as measured by an improved 6MWD (receiver operating characteristic area under the curve, 0.88-0.95). Conclusions: B-cell depletion therapy is a potentially effective and safe adjuvant treatment for SSc-PAH. Future studies in these patients can confirm whether the identified biomarkers predict rituximab responsiveness. Clinical trial registered with www.clinicaltrails.gov (NCT01086540).

Association of Rituximab Use With Adverse Events in Children, Adolescents, and Young Adults

IMPORTANCE

Rituximab is among the most frequently used immunotherapies in pediatrics. Few studies have reported long-term adverse events associated with its use for children.

OBJECTIVE

To describe the use of rituximab and to assess whether its use is associated with short- or long-term adverse events, infections, or time to immune reconstitution in a diverse group of young people.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cohort study included 468 patients aged younger than 21 years who received rituximab for diverse indications between October 1, 2010, and December 31, 2017, at Texas Children's Hospital, a large pediatric referral hospital. Patterns of adverse events, infections, and immune recovery are described. Data analyses were conducted from December 2019 to June 2020.

EXPOSURE

One or more doses of rituximab.

MAIN OUTCOMES AND MEASURES

Adverse drug events (eg, anaphylaxis), incidence of mild and severe infections, and time to recovery of B lymphocyte subset counts and immunoglobulin levels. Survival models and logistic regression analyses and were used to identify associated risk factors of infectious and noninfectious adverse drug events.

RESULTS

We identified 468 patients receiving at least 1 dose of rituximab. The total follow-up time was 11 713 person-months. Of the 468 patients, 293 (62.6%) were female, the median (interquartile range) age at receipt of dose was 14.3 (9.9-16.8) years, and 209 (44.7%) were self-reported White Hispanic. Adverse events associated with rituximab infusion occurred in 72 patients (15.4%), and anaphylaxis occurred in 17 patients (3.6%). Long-term adverse events, such as prolonged neutropenia and leukoencephalopathy, were absent. Infections occurred in 224 patients (47.9%); 84 patients (17.9%) had severe infections, and 3 patients (0.6%) had lethal infections. Concurrent use of intravenous chemotherapy, treatment of systemic lupus erythematosus, neutropenia, and use of intravenous immunoglobulin were associated with increased risk of infection. Among 135 patients (28.8%) followed up to B cell count recovery, CD19+ or CD20+ cell numbers normalized in a median of 9.0 months (interquartile range, 5.9-14.4 months) following rituximab use; 48 of 95 patients (51%) evaluated beyond a year had low-for-age B cell counts. Recovery of CD27+ memory B cell number occurred in a median of 15.7 months (interquartile range, 6.0-22.7 months). Among patients with normal baseline values, low immunoglobulin G (IgG) levels developed in 67 of 289 patients (23.2%) and low IgM levels in 118 of 255 patients (40.8%); of these patients evaluated beyond 12 months from rituximab, 16 of 117 (13.7%) had persistently low IgG and 37 (33.9%) of 109 had persistently low IgM.

CONCLUSIONS AND RELEVANCE

Rituximab is well tolerated among young people and is associated with few serious adverse events, but infections are common, corresponding to a prolonged period of B cell count recovery often lasting for longer than a year. Further examination of strategies to prevent infections following rituximab should be pursued.

Evolving treatment modalities for immune thrombocytopenia in adults

The management of patients with relapsed or refractory immune thrombocytopenia (ITP) remains challenging for hematologists. While there are a multitude of drugs available, it is largely an individualized management based on patient preferences, side effects, previous treatment received, and responses to them, comorbidities and cost associated with the treatment. We hereby review the newer approaches in the treatment of ITP.

Comparison of the Efficacy and Safety of Anti-CD20 B Cells Depleting Drugs in Multiple Sclerosis

Rituximab, ocrelizumab, ofatumumab and ublituximab are disease modifying therapies (DMT) currently used in the treatment of multiple sclerosis (MS) or are in advanced stages of clinical trials. These monoclonal antibodies deplete B cells by targeting the cell surface protein CD20. This review highlights the similarities and major differences between the four agents. We summarize data from various clinical trials of each of these therapeutics and discuss their efficacy and safety. Additional considerations regarding the route of administration and cost are presented. Among the four therapeutics, only ocrelizumab is approved for primary progressive (PP) MS. Infusion/injection related reactions (IRRs) are the most common adverse events associated with all four therapeutics. In phase III trials of ocrelizumab and ofatumumab, the incidence of IRRs was lower with ofatumumab. Ofatumumab is unique among the four therapeutics due to its availability as a subcutaneous injection (SQ). Although SQ administration may be appealing for some patients it may raise concerns regarding medication compliance among physicians. Phase II trials studying ublituximab for the treatment of RMS yielded promising results. Phase III trials are currently comparing the efficacy of ublituximab to teriflunomide.

Immune Monitoring upon Treatment with Biologics in Sjögren's Syndrome: The What, Where, When, and How

Over the years, a wide variety of therapeutic antibodies has been successfully introduced in the auto-immunology clinic, and many more are on the way. Many of these treatments address either a pathogenic circulating molecule or a cell-bound molecule. Whereas addressing the former target results in neutralization of the soluble factor and binding to the latter target either inhibits cellular function or induces selective cell death. If this targeted molecule or cell is part of the immune system, this therapy evokes a state of immunodeficiency with infections as a possible consequence. Therefore, immune monitoring is needed to prevent such adverse side effects of immunotherapy. In this paper, different immunotherapies used in Sjögren's syndrome, as well as different approaches to monitoring the immune system, are discussed.

Clinical Perspectives on the Molecular and Pharmacological Attributes of Anti-CD20 Therapies for Multiple Sclerosis

Anti-CD20 therapies have demonstrated considerable efficacy in the treatment of relapsing multiple sclerosis, constituting a high-efficacy treatment approach for reducing relapse risk and mitigating disability progression. These therapies have been shown to strongly deplete circulating B cells and small subsets of CD3+ CD4 and CD8 T cells that express low levels of CD20. While the clinical profiles of the various anti-CD20 monoclonal antibodies used in treating multiple sclerosis are well-described in the literature, greater understanding of the implications of their distinct molecular and pharmacological attributes is needed. In this review, we focus on four anti-CD20 monoclonal antibodies-rituximab, ocrelizumab, ofatumumab, and ublituximab-that are currently used, approved, or in late-stage clinical development for the treatment of multiple sclerosis. We provide clinical perspectives on the potential implications of differences in molecular structures, target epitopes, dosing regimens, mechanisms and impact on B-cell depletion and reconstitution, immunogenicity, administration-related reactions, and infection risks.