B-cell Repopulation Research Articles

Safety of Obinutuzumab in Children With Autoimmune Encephalitis and Early B-Cell Repopulation on Rituximab

BackgroundRituximab (RTX) resistance or early B-cells repopulation were observed in children but only few publications reported the use of Obinutuzumab and no recommendations were made concerning the dosage for children. MethodsThis study was a single-center retrospective cohort study of all the children followed-up in the Pediatric Neurology Department of Necker-Enfants malades Hospital in Paris, France, and treated with obinutuzumab, between November 1, 2019, and November 1, 2021. ResultsA total of eight children (three females, median age 4.5 years) were treated. Seven patients presented with autoimmune encephalitis and one with myeloradiculitis. The median delay of B-cell repopulation after a course of RTX was 87 days (range 41 to 160). A switch to obinutuzumab (anti-CD20) was performed for eight children. The median duration between the first RTX infusion and obinutuzumab administration was 6.6 months. The dosage regimen for obinutuzumab was one infusion of 1000 mg/1.73 m2, that is to say 580 mg/m2 (maximum 1000 mg/infusion), by extrapolation from the adult dosage. The median delay of B-cell repopulation after one course of obinutuzumab was 230 days (range 66 to 303 days) vs 87 days after one course of RTX (P < 0.01). None of the patients presented side effects with obinutuzumab treatment. All patients had a favorable evolution at the last-follow up. Median follow-up was 1.6 years. ConclusionsThis study reports the use of obinutuzumab in neurological inflammatory diseases in a pediatric population. Obinutuzumab seems to have a better biological efficacy than RTX with a longer time of B-cell repopulation.

Ocrelizumab B-cell repopulation-guided extended interval dosing versus standard dosing – similar clinical efficacy with decreased immunoglobulin M deficiency rates

BackgroundOcrelizumab (OCR) is a humanized anti-CD20 monoclonal antibody used in treatment of multiple sclerosis. The standard dosing (SD) regimen consists of OCR maintenance infusions every 6 months. In B-cell repopulation-guided extended interval dosing (EID), repeat infusions are delayed until there is evidence for B-cell repopulation. ObjectivesTo compare frequencies of ‘no evidence of disease activity’ (NEDA-3) and immunoglobulin G (hypo-IgG; <600 mg/dL) and M (hypo-IgM; <40 mg/dL) deficiencies in persons with multiple sclerosis (PwMS) treated with OCR B-cell repopulation-guided EID versus SD. MethodsTwo-center retrospective study comparing frequencies of NEDA-3 and hypo-IgG and hypo-IgM in PwMS treated with OCR B-cell repopulation-guided EID versus SD using a multivariate generalized linear model adjusted for age, sex, and treatment duration. ResultsA total of 112 OCR-treated PwMS were included (B-cell repopulation-guided EID n = 52; SD n = 60) with average infusion intervals of 319 (246–485) days (EID) and 184 (170–218) days (SD). There was no significant difference in NEDA-3 (EID: 47/52 [90.4 %]; SD: 50/60 [83.3 %]; p = 0.161) or hypo-IgG (EID: 1/52 [1.9 %]; SD: 4/60 [6.7 %]; p = 0.298) rates. Hypo-IgM was significantly less common in EID (EID: 9/52 [17.3 %] vs. SD: 34/60 [55 %]; p<0.001) upon assessment 1099 (475–1436) days (EID) and 980 (409–1846) days (SD) post-initiation of OCR. Hypo-IgM was associated with average infusion interval length (p = 0.005) and total number of OCR cycles (p = 0.003). ConclusionsOCR B-cell repopulation-guided EID may be a safe alternative to traditional SD with similar efficacy and significantly less hypo-IgM rates.

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

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. 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. 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. 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.

Sustained post-rituximab B-cell depletion is common in ANCA-associated vasculitis and is affected by sex and renal function.

Despite the increasing use of rituximab in anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), it remains unclear what the optimal dosing is, especially for maintenance of remission. A deeper understanding of post-rituximab B-cell repopulation patterns may aid better-tailored treatment. This is a monocentric, retrospective study including ANCA-positive AAV patients receiving a single course of rituximab induction. CD19+ B cells were longitudinally monitored with flow cytometry. B-cell repopulation was defined as CD19+ >10 cells/μL. Seventy-one patients were included, the majority with microscopic polyangiitis (75%), myeloperoxidase-ANCA positivity (75%) and with renal involvement (79%). During a median follow-up of 54months since the first rituximab infusion, 44 patients (62%) repopulated B cells, with a median time to repopulation of 39months (range 7-102). Patients experiencing B-cell depletion lasting longer than the overall median time to repopulation (39months) exhibited a lower risk of flare and higher risk of serious infection. In multivariate Cox regression, higher estimated glomerular filtration rate (eGFR) [hazard ratio (HR) 1.84, 95% confidence interval (CI) 1.13-2.98 per 30mL/min/1.73 m2 eGFR] and female sex (HR 2.70, 95% CI 1.37-5.31) were independent predictors of increased rate of B-cell repopulation. A subset of AAV patients develop sustained post-rituximab B-cell depletion, which associates with reduced risk of flare and increased risk of serious infection in the long term. Preserved renal function and female sex are associated with faster B-cell repopulation. These observations further highlight the need to personalize immunosuppression to improve clinical outcomes.

Transcriptome alterations in peripheral blood B cells of patients with multiple sclerosis receiving immune reconstitution therapy

BackgroundMultiple sclerosis (MS) is a chronic, inflammatory and neurodegenerative disease that leads to irreversible damage to the brain and spinal cord. The goal of so-called "immune reconstitution therapies" (IRTs) is to achieve long-term disease remission by eliminating a pathogenic immune repertoire through intense short-term immune cell depletion. B cells are major targets for effective immunotherapy in MS.ObjectivesThe aim of this study was to analyze the gene expression pattern of B cells before and during IRT (i.e., before B-cell depletion and after B-cell repopulation) to better understand the therapeutic effects and to identify biomarker candidates of the clinical response to therapy.MethodsB cells were obtained from blood samples of patients with relapsing–remitting MS (n = 50), patients with primary progressive MS (n = 13) as well as healthy controls (n = 28). The patients with relapsing MS received either monthly infusions of natalizumab (n = 29) or a pulsed IRT with alemtuzumab (n = 15) or cladribine (n = 6). B-cell subpopulation frequencies were determined by flow cytometry, and transcriptome profiling was performed using Clariom D arrays. Differentially expressed genes (DEGs) between the patient groups and controls were examined with regard to their functions and interactions. We also tested for differences in gene expression between patients with and without relapse following alemtuzumab administration.ResultsPatients treated with alemtuzumab or cladribine showed on average a > 20% lower proportion of memory B cells as compared to before IRT. This was paralleled by profound transcriptome shifts, with > 6000 significant DEGs after adjustment for multiple comparisons. The top DEGs were found to regulate apoptosis, cell adhesion and RNA processing, and the most highly connected nodes in the network of encoded proteins were ESR2, PHB and RC3H1. Higher mRNA levels of BCL2, IL13RA1 and SLC38A11 were seen in patients with relapse despite IRT, though these differences did not pass the false discovery rate correction.ConclusionsWe show that B cells circulating in the blood of patients with MS undergoing IRT present a distinct gene expression signature, and we delineated the associated biological processes and gene interactions. Moreover, we identified genes whose expression may be an indicator of relapse risk, but further studies are needed to verify their potential value as biomarkers.

#4183 A PHENOTYPIC DRIVEN RITUXIMAB MAINTENANCE APPROACH IS EFFECTIVE AND SAFE IN PATIENTS WITH ANCA ASSOCIATED VASCULITIS

Abstract Background and Aims Rituximab (RTX) has emerged as the first-line treatment to maintain remission in ANCA-Associated Vasculitis (AAV). However, the ideal strategy to RTX re-dosing is still unclear [1]. Method In this monocentric and retrospective study we evaluated the efficacy and safety of two RTX-based maintenance regimens in patients with AAV. Fixed-dose (FD) RTX dosing, consisting of at least 3 pre-emptive RTX administrations every 6 months, was preferred in patients judged to be at high relapse risk. Instead, a biomarker-guided on-demand (OD) RTX dosing strategy was preferred for patients deemed at lower risk of relapse; this consisted in RTX re-treatment only in case of B-cell repopulation or rise in ANCA titer. The single patient relapse risk was assessed according to the disease phenotype (granulomatous vs vasculitic), the ANCA specificity and the disease status (onset vs relapse). Relapses were defined as increase of disease activity requiring escalation of immunosuppression; major relapses were defined in case of life/organ-threatening manifestations. Results The study included 100 patients followed for a median of 24 months (IQR 20-30), 51% treated with an OD and 49% with a FD strategy. The main baseline characteristics of our cohort are shown in the Table; patients treated with a FD strategy were more often GPA, PR3-ANCA positive, with relapsing disease and ENT involvement and less frequent renal involvement. The FD group received a median of 4 (IQR 4-4) administrations of RTX for a median cumulative dose of 2 g (IQR 2-2). Only 6 (11.8%) patients in the OD group received RTX as maintenance therapy with a median of 1 (IQR 1-3) administration of RTX for a median cumulative dose of 0.75 g (IQR 0.5-1.75). Thirteen relapses occurred, 6 in the FD group and 7 in the OD one. Remission rates were comparable in the two cohorts, with respectively 87.6% and 85.9% of the patients in remission at 24 months (Figure 1 - panel A). No significant differences in remission rates across the 2 groups were observed after considering only major flares or after stratification according to clinical diagnosis (MPA/GPA) and ANCA specificity (Figure 1 - panel B to F). Ten and 20 severe infections (p = 0.383) and 3 and 1 cancer (p = 0.581) occurred respectively in the FD and OD group. Conclusion In our case series, a phenotypic-driven approach to RTX maintenance showed comparable efficacy and safety between fixed and on-demand dosing, despite different baseline characteristics between the two groups. These results suggest that personalizing RTX maintenance may be a feasible and safe strategy.

Tailoring Rituximab According to CD27-Positive B-Cell versus CD19-Positive B-Cell Monitoring in Neuromyelitis Optica Spectrum Disorder and MOG-Associated Disease: Results from a Single-Center Study.

B-cell-depleting agents have been widely used for neuromyelitis optica spectrum disorder (NMOSD) and MOG-associated diseases (MOGAD), but no consensus exists on the optimal dose and frequency of treatment administration. The aim of our study was to evaluate the effect of a Rituximab (RTX) personalized treatment approach based on CD27-positive B-cell monitoring on efficacy, safety, and infusion rates. This is a retrospective, uncontrolled, single-center study including patients with NMOSD and MOGAD treated with RTX at a tertiary multiple sclerosis center at the San Luigi University Hospital, Orbassano, Italy. All the patients were treated with RTX induction, followed by maintenance infusion at the dosage of 1000mg according to cell repopulation: initially according to total CD19-positive B-cell monitoring (>0.1% of lymphocytes), and subsequently according to CD27-positive B-cell repopulation (>0.05% of lymphocytes for the first 2years, and subsequently>0.1%). NMOSD and MOGAD activity was assessed as clinical or MRI activity. All patients were screened of the occurrence of severe adverse events (AEs). A total of 19 patients were included in the analysis. Median follow-up was 7.64years (range 3.09-16.25). The annualized relapse rate (ARR) 1year before RTX start was 2.37 [Standard deviation (SD), 1.34] and decreased to 0.08 (SD 0.11) in the subsequent years after RTX initiation. ARR did not differ before and after start of CD27 monitoring. Median inter-dose time was 8.80 (range 5.78-14.23) before CD27 monitoring and 15.93months (range 8.56-35.37) after CD27 monitoring (p<0.001). We observed no AEs. Our findings suggest that in our cohort CD27-positive B-cell-based RTX reinfusion regimen was able to reduce the number of RTX reinfusions relative to CD19-positive B-cell monitoring, with comparable efficacy and safety profile. In order to achieve an even more individualized and effective treatment, the FCGR3A genetic polymorphisms could be evaluated when assessing RTX efficacy.

Trends and Predictors of Peripheral CD19+ B-cell Repopulation in Patients Treated with Ocrelizumab during COVID-19 Pandemic (P7-3.014)

<h3>Objective:</h3> To assess the predictors of B-cell repopulation in patients treated with ocrelizumab during COVID-19 pandemic. <h3>Background:</h3> Ocrelizumab (OCR) is used for multiple sclerosis (MS) administered every 6 months (SID). Peripheral CD19+ lymphocyte (CD19L) count is a surrogate marker of efficacy of OCR. B-cell repopulation (≥1% CD19L of total lymphocytes) is a potential biomarker to guide OCR extended interval dosing (EID) beyond 6 months. During COVID-19 pandemic, adjusted OCR treatment-cycle based on CD19L repopulation has been a strategy to minimize the risk of prolonged B-cell depletion associated higher potential complications of COVID. We studied the predictors of B-cell repopulation in patients treated with OCR. <h3>Design/Methods:</h3> Retrospective study of patients receiving OCR between 2020–2022 in whom CD19L counts were available &lt;30 days prior to next infusion. Data collected included age, gender, race, body mass index (BMI), MS subtype, prior immunosuppressive therapy, time-to-repopulation. Multiple linear regression was used to look for predictors of B-cell repopulation. <h3>Results:</h3> Total 248 patients (mean age 48±12.8 years; 172 female, 76 male) studied. Forty-five percent (111 patients) had CD19L repopulation, fifty-five percent (137 patients) had persistently low (&lt;1%) counts. Mean number of infusion cycles prior to CD19L repopulation was significantly longer in extended interval group (4.36±2.16 days vs. 2.33±2.04; p&lt;0.05). BMI and inter-infusion interval were predictors of repopulation (p&lt;0.001); age, race, gender, disease type, prior immunosuppressive therapy did not predict repopulation. All patients remained clinically stable. <h3>Conclusions:</h3> In this observational study of MS patients treated with OCR with standard or extended interval dosing, BMI and inter-infusion dosing interval were the only predictors of B-cell repopulation. The number of infusions prior to repopulation was higher in the extended dosing group. In the future, these data can be used to provide guidance on extending OCR dosing interval. <b>Disclosure:</b> Dr. Padron has nothing to disclose. Ms. Jimsheleishvili has nothing to disclose. Dr. Tornes has nothing to disclose. Dr. Delgado has received personal compensation in the range of $10,000-$49,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Novartis. The institution of Dr. Delgado has received research support from Novartis. The institution of Dr. Delgado has received research support from EMD Serono. The institution of Dr. Delgado has received research support from NIH/NINDS. Dr. Garg has nothing to disclose.

Effect of Previous Disease-Modifying Therapy on Treatment Effectiveness for Patients Treated With Ocrelizumab.

B cell-depleting antibodies were proven as effective strategy for the treatment of relapsing multiple sclerosis (RMS). The monoclonal antibody ocrelizumab was approved in 2017 in the United States and in 2018 in the European Union, but despite proven efficacy in randomized, controlled clinical trials, its effectiveness in the real-world setting remains to be fully elucidated. In particular, most study patients were treatment naive or switched from injectable therapies, whereas oral substances or monoclonal antibodies made up >1% of previous treatments. We evaluated ocrelizumab-treated patients with RMS enrolled in the prospective cohorts at the University Hospitals Duesseldorf and Essen, Germany. Epidemiologic data at baseline were compared, and Cox proportional hazard models were applied to evaluate outcomes. Two hundred eighty patients were included (median age: 37 years, 35% male patients). Compared with using ocrelizumab as a first-line treatment, its use as a third-line therapy increased hazard ratios (HRs) for relapse and disability progression, whereas differences between first- vs second-line and second- vs third-line remained smaller. We stratified patients according to their last previous disease-modifying treatment and here identified fingolimod (FTY) (45 patients, median age 40 years, 33% male patients) as a relevant risk factor for ongoing relapse activity despite 2nd-line (HR: 3.417 [1.007-11.600]) or 3rd-line (HR: 5.903 [2.489-13.999]) ocrelizumab treatment, disability worsening (2nd line: HR: 3.571 [1.013-12.589]; 3rd line: HR: 4.502 [1.728-11.729]), and occurrence of new/enlarging MRI lesions (2nd line: HR: 1.939 [0.604-6.228]; 3rd line: HR: 4.627 [1.982-10.802]). Effects were persistent throughout the whole follow-up. Neither peripheral B-cell repopulation nor immunoglobulin G levels were associated with rekindling disease activity. Our prospectively collected observational data suggest suboptimal effectiveness of ocrelizumab in patients switching from FTY compared with those switching from other substances or having been treatment naive. These findings support previous studies indicating abated effectiveness of immune cell-depleting therapies following FTY treatment in patients with RMS. This study provides Class IV evidence that for patients with RMS, previous treatment with FTY compared with previous treatment with other immunomodulating therapies decreases the effectiveness of ocrelizumab.

2 grams versus 1 gram rituximab as maintenance schedule in multiple sclerosis, neuromyelitis optica spectrum disorders and related diseases: What B-cell repopulation data tell us.

Rituximab (RTX) is largely used as a long-term maintenance therapy in various inflammatory neurological diseases. Reducing the dose of maintenance therapy of RTX from 2 grams every 6 months (traditional regimen) to 1gram every 6 months (reduced regimen) is a widely applied practice, with the assumption that it decreases the risk of side effects while maintaining efficacy. In order to better describe the biological consequences of this strategy, we retrospectively compared, in a single center, the B-cell count after the traditional regimen and after the reduced regimen in patients who underwent both (n=161). The rate of patients with B-cell repopulation was not significantly different between traditional and reduced regimens (9.9% vs 15.6%, p=0.18). Among the 145 patients who did not have B-cell repopulation following the traditional regimen, B-cell repopulation following the reduced regimen occurred in only 16 cases (11.0%) and was usually slight: 11/16 patients had only 1% of CD19+ cells. These data emphasize the relevance of 1g of RTX as maintenance therapy and the fact that 2g of RTX is generally an overtreatment in inflammatory neurological diseases.

Peculiarities of vaccination in rituximab treated patients with rheumatoid arthritis: a review of clinical cases

Haroldas Jonas Bikelis1, Julija Mironova1,2 Irena Butrimienė2,3, 1Vilnius University, Faculty of Medicine, Vilnius, Lithuania 2Vilnius University Hospital Santaros Clinics, Centre of Rheumatology, Vilnius, Lithuania 3Vilnius University, Faculty of Medicine, Institute of Clinical Medicine, Clinic of Rheumatology, Orthopaedics Traumatology and Reconstructive Surgery, Vilnius, Lithuania Abstract Background. Rituximab is one of treatment options for patients with rheumatoid arthritis. It binds to CD20+ B cells and causes their depletion. Therefore, humoral immune response is dampened and COVID-19 vaccination strategy for such patients becomes complicated. Aim: to present clinical cases of patients with rheumatoid arthritis treated with rituximab and to review literature on the peculiarities of COVID-19 vaccination in such patients. Methods. A retrospective analysis of 5 clinical cases was performed to evaluate the peculiarities of COVID-19 vaccination in rituximab treated patients with rheumatoid arthritis. Patients written consents to use their medical data for scientific purposes were obtained. Case series. We present 5 clinical cases of patients with rheumatoid arthritis treated with rituximab in Vilnius University Hospital Santaros Clinics, Centre of Rheumatology during COVID-19 pandemic. Death due to COVID-19 of one patient was recorded. 2 of 4 patients had immune response to COVID-19 vaccine with normal repopulation of B lymphocytes. Remaining 2 patients did not exhibit immune response and did not have repopulated B cells. Conclusion. The patient data confirm, that rituximab treatment has been associated with a higher risk of worse COVID-19 course, complications and death. Therefore, such patients should be monitored according to the latest guidelines. Due to blunted humoral immune response to the vaccine in patients treated with rituximab and the variable B-cell repopulation timeframe it is advised to aim for individual COVID-19 vaccination strategy. Keywords: rituximab, COVID-19 vaccine, CD20+ B lymphocytes, humoral immune response, rheumatoid arthritis. Full article https://doi.org/10.53453/ms.2023.2.4

Ocrelizumab concentration and antidrug antibodies are associated with B-cell count in multiple sclerosis

BackgroundThe majority of patients with multiple sclerosis on ocrelizumab have B-cell depletion after standard interval dosing of 26 weeks. With B-cell-guided dosing patients receive their next dose when B-cell repopulation...

Indications and Safety of Rituximab in Pediatric Neurology: A 10-Year Retrospective Study

BackgroundRTX is used off-label in several neurological inflammatory diseases in adults children patients. We conducted a study to assess indications and safety of rituximab (RTX) for children and to identify risk factors for early B-cell repopulation. MethodsA single-center retrospective study of children treated with RTX for a neurological disease between May 31, 2010, and May 31, 2020, was performed. ResultsA total of 77 children (median age, 8.9 years) were included. RTX was mostly used as second-line therapy in all groups of diseases (68%). Median dose was 1500 mg/m2 for each patient. There were 13 clinical relapses (17%), 5 when B-cell depletion was complete. Adverse events were present in 6% of the cases. The factors influencing early B-cell repopulation were the recent infusion of intravenous Ig (P < 0.01) and the administration of less than 1500 mg/m2 during the first RTX treatment (P = 0.04). The median time to B-cell repopulation seemed to be shorter (160 vs 186 days) when patients had plasmapheresis even when a 48-hour delay was observed with RTX infusions. ConclusionsThis study confirms the good tolerance of RTX in the treatment of specific neurological disorders in a pediatric population. It also highlights risk factors for early B-cell repopulation and underlines the importance of B-cell monitoring.

Comparison of the efficacy and cost-effectiveness of an immunologically targeted low-dose rituximab protocol with the conventional rheumatoid arthritis protocol in severe pemphigus.

Various dosing protocols of rituximab have been used in pemphigus. B-cell repopulation following rituximab treatment can be considered a forerunner of clinical relapse. Immunologically guided dosing may remove the need for fixed timepoint maintenance dosing, hence being more cost-effective and perhaps safer. To compare the overall efficacy and cost-effectiveness of a low-dose rituximab regimen (500 mg, 2 weeks apart) with immunologically guided, ultralow-dose (200 mg) top-up infusions on immunological relapse vs. the use of a rheumatoid arthritis (RA) protocol with rituximab 500 mg repeat infusion to treat clinical relapse in severe pemphigus, over a 1-year period, METHODS: In total, 23 patients with severe pemphigus were randomized into Group A (RA protocol: 1000 mg given as two doses, 2 weeks apart) and Group B (low-dose rituximab 500 mg given as two doses, 2 weeks apart). Both groups also received short-term oral corticosteroids, and underwent clinical and immunological (3-monthly flow cytometry assessments of B-cell subtypes) monitoring. Group A received a top-up dose of rituximab 500 mg upon clinical relapse, while Group B received an ultralow top-up dose (200 mg) following detection of B-cell repopulation, which was intended to prevent clinical relapse. Outcome parameters [complete remission off treatment (CROT), relapse (clinical and immunological), total corticosteroid dose and direct cost of therapy] were compared. The mean ± SD time to CROT (Group A, 27.1 ± 1.6 weeks; Group B, 26 ± 1.2 weeks, P = 0.09) and the cumulative prednisolone dose (P = 0.28) were comparable between the two groups. In Group A, 3 of 9 (33.3%) patients had clinical relapse (mean ± SD time of 9.3 ± 0.4 months). In Group B, B-cell repopulation was seen in 10 of 11 (90.9%) patients within a mean time of 8.4 ± 2.4 months, and a single top-up dose of 200 mg successfully prevented clinical relapse. The overall cost of therapy was 37.4% cheaper in Group B. An immunologically guided low-dose rituximab regimen can be an equally effective but more affordable alternative to conventional rituximab regimens in pemphigus.

FC061: Renal Function is a Major Determinant of B-Cell Repopulation Following Rituximab Induction in Anca-Associated Vasculitis

Abstract BACKGROUND AND AIMS Rituximab is increasingly used to induce and maintain remission in ANCA-associated vasculitis (AAV). However, it remains unclear what the optimal dosing regimen is, especially in the setting of maintenance. Clinical trials have shown that vasculitis flares are unlikely as long as B-cell depletion in peripheral blood is sustained, with some evidence supporting a rituximab redosing strategy guided by B-cell-count monitoring. A better understanding of B-cell kinetics following rituximab treatment can facilitate personalized treatment approaches. This study aims to (1) describe B-cell repopulation in AAV patients treated with rituximab induction, and (2) identify clinical features predictive of B-cell repopulation. METHOD This is a single-centre, retrospective study, including AAV patients on no baseline immunosuppression who were treated with rituximab induction between December 2009 and March 2018 in the Nephrology Unit of Spedali Civili, Brescia. Only patients with available longitudinal B-cell monitoring for at least 6 months following rituximab were considered. B-cell counts were determined as CD19 + cells in peripheral blood using flow cytometry (Beckman Coulter Navios©). B-cell repopulation following rituximab was defined as CD19 + cell count &amp;gt;10 cells/μL, with a documented CD19 + count ≤ 10 cells/μL within the preceding year. For each patient, CD19 + cell counts were followed up to the earliest event among the following: (1) B-cell repopulation, (2) retreatment with rituximab or other induction agents, or (3) most recent observation available. Estimated glomerular filtration rate (eGFR) was calculated using the CKD-EPI equation. Flares were defined as active disease retreated with rituximab or cyclophosphamide and classified as major if one or more major items of the BVAS score v3 were present. Predictors of time to B-cell repopulation were assessed using uni- and multivariate analysis with log-rank test and Cox proportional hazards regression, respectively. RESULTS The study cohort included 64 patients. The main clinical characteristics are summarized in Table 1. During a median follow-up of 33.4 months (range 7.5–101.7 months), B-cell repopulation was observed in 36 patients (56.2%). Median time from rituximab induction to B-cell repopulation was 39.8 months [95% confidence interval (95% CI) 33.8–69.7]. Gender, ANCA subtype, rituximab dose, steroid pulses, plasma exchange and methotrexate/azathioprine maintenance were not significantly associated with time to B-cell repopulation. In contrast, B-cell repopulation was significantly slower in patients who were older (median time to repopulation 51.6 months in patients ≥ mean age of 66.8 years old versus 33.9 months in &amp;lt; mean age; P = 0.044), who had microscopic polyangiitis (median 51.6 months), as opposed to granulomatosis with polyangiitis (median 33.9 months; P = 0.012) and who had lower eGFR at the time of rituximab (69.7 months in eGFR &amp;lt; median of 18.3 mL/min/1.73 m2 versus 28.4 months in eGFR ≥ median; P = 0.001, Figure 1). Of these three predictors, only eGFR remained significantly associated with time to B-cell repopulation in a multivariate Cox regression model (hazard ratio for B-cell repopulation in eGFR ≥ median: 2.74, 95% CI 1.31–5.72). During sustained B-cell depletion, six vasculitis flares were observed, of which one was major (rise in creatinine &amp;gt; 30%) and the rest were minor (n = 4 worsening of urine abnormalities, n = 1 retro-orbital pain). CONCLUSION A substantial proportion of AAV patients treated with a single course of rituximab shows sustained B-cell depletion. Renal function emerged as the main independent predictor of B-cell repopulation, with delayed B-cell repopulation in people with kidney impairment. Only one major vasculitis flare was observed during sustained B-cell depletion. These data support the idea that longitudinal monitoring of B-cell counts can be a useful biomarker to guide rituximab dosing for maintenance in AAV, especially in patients with kidney impairment.

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

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 100mg low-dose rituximab monotherapy in treating new-onset generalized AChR-MG. 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 100mg induction treatment weekly with no more than three circles, followed by reinfusion (100mg once) sequentially according to whether achieving primary endpoint and peripheral CD19 + B-cell repopulation ≥ 1% of total lymphocytes at each visit (every 3months). 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. 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 (100mg once) for clinical remission. The total dosage of RTX was only 346.15 ± 96.74mg (including 269.23 ± 63.04mg for induction and 76.92 ± 59.91mg 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). 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.

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

BackgroundTime 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.MethodsA 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.ResultsMedian 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.ConclusionOur 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.

Humoral responses to SARS-CoV-2 vaccination in rituximab-treated patients depend on peripheral B cell re-population rather than the timings of the dosing

Introduction: Previous exposure to Rituximab affects the immunogenicity of vaccination including that against coronavirus disease (COVID-19). However, dynamics of the effect of rituximab on vaccination are not well understood. This study aims to assess the role of timing of vaccine dosing and B-cell repopulation on vaccine seroconversion.Methods: Autoimmune rheumatic disease (AIRD) patients treated with rituximab who had completed two doses of COVID-19 vaccination were enrolled. Peripheral B-cell counts were estimated along with the titer of immunoglobulin G antibody-directed against the receptor-binding domain of spike1 protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Antibody titers of participants were compared against B-cell re-population.Results: Out of the 33 participants with available prevaccination B-cell counts, 11 did not have any detectable peripheral B cells before vaccination, and out of these patients, only 1 developed antibodies postvaccination, whereas, of the remaining 22, 18 (81.8%) had a positive seroconversion. Although all patients who had received the last dose of Rituximab at least 1 year before vaccination had antibodies, there was no direct correlation between time from the last dose and antibody positivity. B-cell re-population was strongly associated with seroconversion (P = 0.0001).Conclusion: In rituximab-treated patients, humoral responses to SARS-CoV-2 vaccination depend on peripheral B-cell re-population rather than the timing of the vaccination postrituximab infusion.

Long-term immunological consequences of anti-CD20 therapies on humoral responses to COVID-19 vaccines in multiple sclerosis: an observational study.

Background:Anti-CD20 therapies induce pronounced B-cell depletion and blunt humoral responses to vaccines. Recovery kinetics of anti-CD20 therapy-mediated cellular and humoral effects in people with multiple sclerosis (pwMS) are poorly defined.Objective:To investigate the duration of the anti-CD20 treatment-induced effects on humoral responses to COVID-19 vaccines.Methods:This retrospective observational study included pwMS who had discontinued anti-CD20 therapy for ⩾12 months and remained without immunomodulation. We retrieved demographics and laboratory parameters including B-cell counts and immunoglobulin (IgG, IgM, IgA) levels prior to anti-CD20 commencement (baseline) and longitudinally after anti-CD20 treatment discontinuation from electronic medical records. Humoral responses to SARS-CoV-2 vaccines were compared with a population of 11 pwMS with ongoing anti-CD20 medication (control cohort).Results:A total of 24 pwMS had discontinued anti-CD20 therapy for a median of 34 months (range: 16–38 months). Antibody responses to COVID-19 vaccines were available in 17 (71%). Most individuals (n = 15, 88%) elicited a measurable antibody response [mean: 774 BAU/ml (±SD 1283 BAU/ml)] to SARS-CoV-2 immunization on average 22 months (range: 10–30 months) from the last anti-CD20 infusion, which was higher compared with the population with ongoing anti-CD20 therapy (n = 11, mean: 12.36 ± SD 11.94 BAU/ml; p < 0.00001). Significantly increased antibody levels compared with the control cohort were found among pwMS who were vaccinated >18 months after treatment discontinuation (19–24 months: n = 2, p = 0.013; 25–36 months: n = 9; p < 0.001). The interindividual kinetics for B-cell reconstitution were heterogeneous and mean B-cell counts approached normal ranges 18 months after treatment discontinuation. There was no correlation of B-cell repopulation and vaccine responses. Mean total IgG, IgM, and IgA levels remained within the reference range.Conclusion:Anti-CD20-induced inhibition of humoral responses to COVID-19 vaccines is transient and antibody production was more pronounced >18 months after anti-CD20 treatment discontinuation. The immunological effect on B-cell counts appears to wane by the same time.

CD19 B cell repopulation after ocrelizumab, alemtuzumab and cladribine: Implications for SARS-CoV-2 vaccinations in multiple sclerosis

BackgroundOcrelizumab maintains B-cell depletion via six-monthly dosing. Whilst this controls relapsing multiple sclerosis, it also inhibits seroconversion following SARS-CoV-2 vaccination unlike that seen following alemtuzumab and cladribine treatment. Emerging reports suggest that 1–3% B-cell repopulation facilitates seroconversion after CD20-depletion. ObjectiveTo determine the frequency of B-cell repopulation levels during and after ocrelizumab treatment. MethodsRelapse data, lymphocyte and CD19 B-cell numbers were obtained following requests to clinical trial data-repositories. Information was extracted from the phase II ocrelizumab extension (NCT00676715) trial and the phase III cladribine tablet (NCT00213135) and alemtuzumab (NCT00530348/NCT00548405) trials obtained clinical trial data requests ResultsOnly 3–5% of people with MS exhibit 1% B-cells at 6 months after the last infusion following 3–4 cycles of ocrelizumab, compared to 50–55% at 9 months, and 85–90% at 12 months. During this time relapses occurred at consistent disease-breakthrough rates compared to people during standard therapy. In contrast most people (90–100%) exhibited more than 1% B-cells during treatment with either cladribine or alemtuzumab. ConclusionsMost people demonstrate B cell repletion within 3 months of the last treatment of alemtuzumab and cladribine. However, few people repopulate peripheral B-cells with standard ocrelizumab dosing. Controlled studies are warranted to examine a view that delaying the dosing interval by 3–6 months may allow more people to potentially seroconvert after vaccination.