Sustained Depletion of B-Cells by a Humanized, Fc-Engineered Anti-CD20 Antibody, AME-133v, in Patients with Relapsed Follicular Lymphoma

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 4977-4977
Author(s):  
Jennifer Wayne ◽  
Kristen N. Ganjoo ◽  
Andres Forero ◽  
Brad Pohlman ◽  
Sven de Vos ◽  
...  
Keyword(s):  
Clinical Trials ◽  
B Cells ◽  
Phase I ◽  
Follicular Lymphoma ◽  
B Cell ◽  
Cell Depletion ◽  
B Cell Depletion ◽  
Cell Counts ◽  
Evaluable Population ◽  
Anti Cd20

Abstract Abstract 4977 Sustained Depletion of B-Cells by a Humanized, Fc-Engineered Anti-CD20 Antibody, AME-133v, in Patients with Relapsed Follicular Lymphoma J Wayne,1 K Ganjoo,2 A Forero,3 B Pohlman,4 S de Vos,5 S Carpenter,6 J Wooldridge,6 S Marulappa,1 V Jain11Mentrik Biotech, LLC, Dallas, TX, 2Standford University Medical Center, Stanford, CA, 3Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, AL,4Cleveland Clinic Taussig Cancer Institute, Cleveland, OH, 5David Geffen School of Medicine at University of California, Los Angeles, CA, 6Eli Lilly and Company, Indianapolis, Indiana Introduction AME-133v is a humanized anti-CD20 monoclonal antibody that has a 13 to 20-fold increase in binding affinity and approximately 6-fold more potent effector function in antibody-dependent cell-mediated cytotoxicity (ADCC) compared to rituximab. Phase I/II clinical trials of AME-133v in patients with relapsed follicular lymphoma have demonstrated an overall response rate of greater than 30% with a complete response rate of 16%. The extent and duration of depletion of CD19+ B-cells in peripheral blood was used as a surrogate of therapeutic levels of AME-133v. Analysis from the Phase I/II clinical trials is presented in this report. Methods CD-19 positive B-cells in peripheral blood were measured in 77 patients with relapsed follicular lymphoma enrolled in two phase I/II clinical trials of AME-133v. These studies assessed five different doses of AME-133v (from 2 mg/m2 to 375 mg/m2). AME-133v was administered intravenously four times at weekly intervals in both trials. Blood samples were taken at multiple time points throughout the trial and a central lab measured levels of circulating CD19+ B-cells using fluorescence-activated cell sorting (FACS). Results Excluding the four patients enrolled in the 2 mg/m2 dose cohort, depletion of peripheral B-cells occurred in all patients and was sustained over time (Table 1). Baseline levels of B-cell counts ranged from 4 × 103 to 1,187 × 103 cells/μL, with an average of 102 × 103 cells/μL and a median of 60 × 103 cells/μL. Within 24 hours of the first infusion, all patients had depletion of circulating B-cells; ninety-six percent of patients had less than 10 × 103 cells/μL and two patients had less than 20 × 103 cells/μL. Interestingly, AME-133v was effective at depleting B-cells even at doses as low as 7.5 mg/m2. To assess sustainability of B-cell depletion after four doses of AME-133v, CD19+ cell counts were evaluated at nine weeks after the fourth infusion and every three months thereafter. Complete depletion of CD19+ lymphocytes was sustained for nine weeks. At five months after the last infusion of AME-133v, nearly two-thirds of patients had no detectable circulating B-cells. Sustained B-cell depletion lasted for at least eight months following the last infusion in 63% of patients. Table 1. B-cell counts for all patients in 7.5, 30, 100 and 375 mg/m2 cohorts. Percentages are cumulative Time Point Cell Count (x 103 cells/μL) 0 < 1 2 to 10 11 to 30 31 to 50 < 100 Day 1 (24 hours after last infusion) 62 % 66 % 96 % 100 % 100% 100% Day 7 (day of infusion 2) 75% 80% 95% 97% 97% 98% Day 28 (1 week after last infusion) 78 % 87% 95% 98% 98% 100% Day 84 (9 weeks after last infusion) 78% 87% 91% 96% 96% 98% Day 174 (5 months after last infusion) 60% 60% 70% 86% 93% 100% Day 264 (8 months after last infusion) 26% 26% 41% 63% 81% 89% Day 354 (11 months after last infusion) 0% 0% 15% 40% 55% 80% DEMOGRAPHIC CHARACTERISTICS (EVALUABLE POPULATION) “\f C \l 1 Demographic and Disease Characteristics on evaluable population (N=30) Conclusion The rapid and sustained effect of AME-133v on B-cell depletion, even in low-affinity FcγRIIIa patients, indicates a potentially relevant biological activity of the antibody in treating B-cell non-Hodgkin lymphoma. Notably, this depletion occurred even at very low doses of drug administration and persisted over time. This may be related to its higher affinity for CD20, increased ADCC, or both. The sustained B-cell depletion may result in prolonged clinical response and might mitigate the need for maintenance therapy. A randomized trial is being planned to compare efficacy of AME-133v vs. rituximab. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Monitoring B-cell repopulation after depletion therapy in neurologic patients

2018 ◽  
Vol 5 (4) ◽  
pp. e463 ◽  
Author(s):  
Erik Ellwardt ◽  
Lea Ellwardt ◽  
Stefan Bittner ◽  
Frauke Zipp
Keyword(s):  
B Cells ◽  
B Cell ◽  
Cell Depletion ◽  
Close Monitoring ◽  
B Cell Depletion ◽  
Cell Recovery ◽  
Cell Counts ◽  
White Blood Cell Counts ◽  
Anti Cd20 ◽  
Cell Repopulation

ObjectiveTo determine the factors that influence B-cell repopulation after B-cell depletion therapy in neurologic patients and derive recommendations for monitoring and dosing of patients.MethodsIn this study, we determined the association of body surface area (BSA; calculated by body weight and height with the Dubois formula), sex, pretreatment therapy, age, CSF data, and white blood cell counts with the risk and timing of B-cell repopulation, defined as 1% CD19+ cells (of total lymphocytes), following 87 B cell–depleting anti-CD20 treatment cycles of 45 neurologic patients (28 women; mean age ± SD, 44.5 ± 15.0 years).ResultsPatients with a larger BSA had a higher probability to reach 1% CD19+ cells than those with a smaller BSA (p < 0.05) following B-cell depletion therapy, although those patients had received BSA-adapted doses of rituximab (375 mg/m2). Sex, pretreatment, age, CSF data, or absolute lymphocyte and leukocyte counts during treatment did not significantly influence CD19+ B-cell recovery in the fully adjusted models. Intraindividual B-cell recovery in patients with several treatment cycles did not consistently change over time.ConclusionsB-cell repopulation after depletion therapy displays both high inter- and intra-individual variance. Our data indicate that a larger BSA is associated with faster repopulation of B cells, even when treatment is adapted to the BSA. A reason is the routinely used Dubois formula, underestimating a large BSA. In these patients, there is a need for a higher therapy dose. Because B-cell count–dependent therapy regimes are considered to reduce adverse events, B-cell monitoring will stay highly relevant. Patients' BSA should thus be determined using the Mosteller formula, and close monitoring should be done to avoid resurgent B cells and disease activity.

scholarly journals B cell depletion with anti-CD20 mAb exacerbates anti-donor CD4+ T cell responses in highly sensitized transplant recipients

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Asuka Tanaka ◽  
Kentaro Ide ◽  
Yuka Tanaka ◽  
Masahiro Ohira ◽  
Hiroyuki Tahara ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
T Cell Responses ◽  
Cell Depletion ◽  
B Cell Depletion ◽  
Transplant Recipients ◽  
Cell Responses ◽  
Anti Cd20

AbstractPretransplant desensitization with rituximab has been applied to preformed donor-specific anti-human leukocyte antigen antibody (DSA)-positive recipients for elimination of preformed DSA. We investigated the impact of pretransplant desensitization with rituximab on anti-donor T cell responses in DSA-positive transplant recipients. To monitor the patients’ immune status, mixed lymphocyte reaction (MLR) assays were performed before and after desensitization with rituximab. Two weeks after rituximab administration, the stimulation index (SI) of anti-donor CD4+ T cells was significantly higher in the DSA-positive recipients than in the DSA-negative recipients. To investigate the mechanisms of anti-donor hyper responses of CD4+ T cells after B cell depletion, highly sensitized mice models were injected with anti-CD20 mAb to eliminate B cells. Consistent with clinical observations, the SI values of anti-donor CD4+ T cells were significantly increased after anti-CD20 mAb injection in the sensitized mice models. Adding B cells isolated from untreated sensitized mice to MLR significantly inhibited the enhancement of anti-donor CD4+ T cell response. The depletion of the CD5+ B cell subset, which exclusively included IL-10-positive cells, from the additive B cells abrogated such inhibitory effects. These findings demonstrate that IL-10+ CD5+ B cells suppress the excessive response of anti-donor CD4+ T cells responses in sensitized recipients.

scholarly journals Sustained B cell depletion by CD19-targeted CAR T cells is a highly effective treatment for murine lupus

2019 ◽  
Vol 11 (482) ◽  
pp. eaav1648 ◽  
Author(s):  
Rita Kansal ◽  
Noah Richardson ◽  
Indira Neeli ◽  
Saleem Khawaja ◽  
Damian Chamberlain ◽  
...  
Keyword(s):  
Clinical Trials ◽  
T Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Cell Depletion ◽  
B Cell Depletion ◽  
Murine Lupus ◽  
Car T Cells ◽  
Car T

The failure of anti-CD20 antibody (Rituximab) as therapy for lupus may be attributed to the transient and incomplete B cell depletion achieved in clinical trials. Here, using an alternative approach, we report that complete and sustained CD19+ B cell depletion is a highly effective therapy in lupus models. CD8+ T cells expressing CD19-targeted chimeric antigen receptors (CARs) persistently depleted CD19+ B cells, eliminated autoantibody production, reversed disease manifestations in target organs, and extended life spans well beyond normal in the (NZB × NZW) F1 and MRLfas/fas mouse models of lupus. CAR T cells were active for 1 year in vivo and were enriched in the CD44+CD62L+ T cell subset. Adoptively transferred splenic T cells from CAR T cell–treated mice depleted CD19+ B cells and reduced disease in naive autoimmune mice, indicating that disease control was cell-mediated. Sustained B cell depletion with CD19-targeted CAR T cell immunotherapy is a stable and effective strategy to treat murine lupus, and its effectiveness should be explored in clinical trials for lupus.

Blinatumomab exposure and pharmacodynamic response in patients with non-Hodgkin lymphoma (NHL).

2013 ◽  
Vol 31 (15_suppl) ◽  
pp. 3051-3051 ◽  
Author(s):  
Youssef Hijazi ◽  
Matthias Klinger ◽  
Andrea Schub ◽  
Benjamin Wu ◽  
Min Zhu ◽  
...  
Keyword(s):  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Phase 1 ◽  
Cell Depletion ◽  
B Cell Depletion ◽  
Dose Requirement ◽  
Time Curve ◽  
Cell Counts ◽  
Dose Dependent

3051 Background: Blinatumomab (AMG 103) is an investigational, bispecific, T cell engaging (BiTE) antibody targeting CD19-expressing B cells. We describe the exposure-pharmacodynamic (PD) response of blinatumomab in patients with NHL, using a quantitative pharmacology approach. Methods: In a phase 1 study, 76 patients with NHL received blinatumomab by continuous intravenous infusion (cIV) at doses of 0.5 to 90 μg/m2/d in 4- or 8-week cycles. Pharmacokinetics (PK) was determined. PD responses evaluated included lymphocytes and cytokines measured during treatment, and sum of the products of the greatest diameters of tumor size in lymph nodes (SPD) at the end of treatment. Blinatumomab concentration at steady state (Css) and the cumulative area under the concentration (AUCcum)–time curve over the period before the evaluation of SPD were used to evaluate the exposure-SPD relationship. Results: Blinatumomab showed linear PK. Early PD responses were characterized by B cell depletion, T cell redistribution, and transient cytokine release. Following cIV at doses from 0.5 to 90 μg/m2/d, B cells declined at a first-order rate with a dose-dependent rate constant, ranging from 0.16 to 1.0 h-1. Complete B cell depletion was achieved within 48 hours at doses ≥5 μg/m2/d. A dose-independent decrease in T cell counts was observed within 24 hours after dosing, and T cells returned to baseline within 2 weeks of treatment. Cytokine elevation occurred in some patients and was dose-dependent. Blinatumomab exposure-SPD relationship was best described by an inhibitory Emax model (E = E0-(Imax*C)/(IC50+C)). According to the model estimation, a 50% reduction in SPD would be achieved when Css is 2141 pg/mL and AUCcum is 1381 h*μg/L, equivalent to a blinatumomab dose of 54 µg/m2/d given over 27 days. Conclusions: B lymphocytes were completely depleted from the circulation at blinatumomab doses ≥5 μg/m2/d. Depletion was faster at higher doses. Higher blinatumomab Css and AUCcum were associated with better tumor reduction. Tissue accessibility may explain the higher dose requirement for SPD reduction versus peripheral B cell depletion. The PK/PD model has utility for the design of future studies of blinatumomab in NHL. Clinical trial information: NCT00274742.

scholarly journals Anti-CD20-Mediated B Cell Depletion Is Associated with Reduced Osteoclastogenic Signals and Bone Mass Preservation: Clinical Observation in Patients with Follicular Lymphoma Supplemented By Animal Studies in a Murine Model

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 13-13
Author(s):  
Albert Kolomansky ◽  
Irit Kay ◽  
Nathalie Ben-Califa ◽  
Anton Gorodov ◽  
Zamzam Awida ◽  
...  
Keyword(s):  
Bone Mass ◽  
Follicular Lymphoma ◽  
B Cell ◽  
Cell Depletion ◽  
Control Group ◽  
Relative Reduction ◽  
B Cell Depletion ◽  
Mineral Density ◽  
Specific Antibodies ◽  
Anti Cd20

Background and aims: Immunotherapy with anti-CD20-specific antibodies (e.g. rituximab), has become the standard of care for B cell lymphoproliferative disorders and many autoimmune diseases. Despite previously demonstrated role for B cells in bone metabolism, the effect of anti-CD20-mediated B cell depletion on bone mass in human patients has not been thoroughly studied. For example, in rheumatological patients the effect of rituximab on bone mass yielded conflicting results, while in lymphoma patients it has not yet been described. Here, we describe the effect of treatment with anti-CD20-specific antibodies on bone mass in a cohort of patients with follicular lymphoma and propose a plausible mechanism using murine model. Methods: To assess the effect of rituximab on bone mass in lymphoma patients, we retrospectively studied the bone mass in patients with follicular lymphoma (FL) during the maintenance phase of chemoimunotherapy, i.e. when rituximab is administered as monotherapy. FL patients on no maintenance (historical controls) or patients with marginal zone lymphoma were include as a control group. Cross-sectional X-ray imaging (CT/PET-CT), performed at the completion of the induction phase and 6-12 months thereafter, were used to serially assess bone density. Wild-type female C57BL/6J mice and mouse anti-mouse CD20 antibody (Genentech) were used for the animal experimental system. Murine bone structure was assessed by the microCT method. Immunophenotyping of the bone marrow (BM), spleen and peripheral blood cells was performed. ELISA and "real-time" quantitative PCR were used to measure the levels of key mediators of bone remodeling, e.g. RANKL, OPG and TNFα. Standard osteoclastogenic assay was used to assesses the osteoclastogenic potential of BM cells. Results: Rituximab treatment prevented the decline in bone mass observed in patients who did not receive active maintenance therapy, both in the lumbar spine (-2.6% vs -8%) and femoral head (-0.5% vs -5.1%) (n=12 patients in each group, p&lt;0.05 for the comparisons in the control group, calculated by Wilcoxon matched-pairs signed rank test). Anti-CD20-mediated B cell depletion in mice led to a significant increase in bone mass as reflected by: 7.7% increase in bone mineral density (whole femur) and ~5% increase in cortical as well as trabecular tissue mineral density (n=17-21 mice in each group, p&lt;0.05). Mechanistically, treating mice with anti-CD20 antibodies significantly decreased the osteoclastogenic signals, including RANKL and TNFα, along with a substantial downregulation of RANK (the RANKL receptor). This correlated with nearly a 50% reduction in osteoclastogenic potential of BM cells derived from B-cell-depleted animals (p&lt;0.05). The decline in the RANKL output was observed both at the bone level (≈25% relative reduction in the mRNA levels), as measured in the whole bone and BM cells, as well as in the serum (18% relative reduction) of the anti-CD20-treated mice as compared to diluent-treated controls (p&lt;0.05 for all comparisons). No significant changes in the OPG levels were noted. Conclusions: While many lymphoma patients may suffer from bone loss due to advanced age and glucocorticoid administration, our data suggest additional favorable effect of anti-CD20 treatment in bone preservation. Importantly, our murine studies indicate that B cell depletion has a direct effect on bone remodeling, primarily by reducing the osteoclastogenic signals, thus potentially diminishing bone resorption. This novel unrecognized effect should be taken into consideration when maintenance treatment is considered. MM and DN contributed equally to this work. Figure Disclosures No relevant conflicts of interest to declare.

scholarly journals The Influence of B Cell Depletion Therapy on Naturally Acquired Immunity to Streptococcus pneumoniae

2021 ◽  
Vol 11 ◽  
Author(s):  
Giuseppe Ercoli ◽  
Elisa Ramos-Sevillano ◽  
Rie Nakajima ◽  
Rafael Ramiro de Assis ◽  
Algis Jasinskas ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
B Cells ◽  
B Cell ◽  
Respiratory Infections ◽  
Serum Levels ◽  
Cell Depletion ◽  
B Cell Depletion ◽  
Protein Antigens ◽  
Antibody Recognition ◽  
Anti Cd20

The anti-CD20 antibody Rituximab to deplete CD20+ B cells is an effective treatment for rheumatoid arthritis and B cell malignancies, but is associated with an increased incidence of respiratory infections. Using mouse models we have investigated the consequences of B cell depletion on natural and acquired humoral immunity to Streptococcus pneumoniae. B cell depletion of naïve C57Bl/6 mice reduced natural IgM recognition of S. pneumoniae, but did not increase susceptibility to S. pneumoniae pneumonia. ELISA and flow cytometry assays demonstrated significantly reduced IgG and IgM recognition of S. pneumoniae in sera from mice treated with B cell depletion prior to S. pneumoniae nasopharyngeal colonization compared to untreated mice. Colonization induced antibody responses to protein rather than capsular antigen, and when measured using a protein array B cell depletion prior to colonization reduced serum levels of IgG to several protein antigens. However, B cell depleted S. pneumoniae colonized mice were still partially protected against both lung infection and septicemia when challenged with S. pneumoniae after reconstitution of their B cells. These data indicate that although B cell depletion markedly impairs antibody recognition of S. pneumoniae in colonized mice, some protective immunity is maintained, perhaps mediated by cellular immunity.

HuMax-CD20 Fully Human Monoclonal Antibody in Follicular Lymphoma. First Human Exposure: Early Results of an Ongoing Phase I/II Trial.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1400-1400 ◽  
Author(s):  
Anton Hagenbeek ◽  
Torben Plesner ◽  
Jan Walewski ◽  
Andrzej Hellmann ◽  
Brian K. Link ◽  
...  
Keyword(s):  
B Cells ◽  
Adverse Events ◽  
B Cell ◽  
Cell Count ◽  
Peripheral Blood ◽  
Tumor Response ◽  
Cell Depletion ◽  
B Cell Depletion ◽  
Cell Counts ◽  
Grade 3

Abstract HuMax-CD20 is a fully human monoclonal IgG1 antibody targeting a unique extracellular epitope of the CD20 molecule on B-cells. HuMax-CD20 stops growth of engrafted B-cell tumors in SCID mouse tumor models more efficiently than Rituximab®, and i.v. infusion of HuMax-CD20 in cynomolgus monkeys has led to profound, long lasting, dose-dependent B-cell depletion. A total of 40 patients with CD20+ relapsed or refractory follicular non-Hodgkin’s lymphoma grade I-II will be enrolled in this open-label, dose-escalating, international, multi-center clinical trial. Cohorts of 10 patients will receive i.v. infusions at doses of either 300, 500, 700 or 1000 mg once weekly for 4 weeks. The patients are followed for 12 months. Patients receive oral acetaminophen and i.v. antihistamin before infusion. In case of adverse events of CTC grade 3 or higher, i.v. glucocorticosteroids are given. The endpoints are CT scan verified tumor response according to the Cheson criteria, B-cell depletion in peripheral blood and lymph nodes, time to next anti-lymphoma treatment, duration of response, BCL2 conversion, pharmacokinetics, and adverse events. Tumor and bone marrow biopsies and CT scans are assessed centrally. The first 17 patients treated with HuMax-CD20 are the subject of this report. Mean age is 60 years. In the 300 mg group all 10 patients have received all 4 infusions. Seven patients have been enrolled in the 500 mg group; three of them have received 4 infusions, two have received 3 infusions, and two patients have received 2 infusions. Baseline B-cell count was in the range of 11-382 x 106 cells per L with a median of 114 x 106. One week after the first infusion the median B-cell count available in 16 patients was 8 x 106 cells per L with a range of 0–19 x 106. In six of the 16 patients no B-cells were detected. B-cell counts measured one week after the 4th infusion are available for 10 patients. Eight patients had no detectable B-cells, one patient had 11 x 106 and one had 34 x 106 cells per L. B-cell counts eight weeks after the 4th infusion are available for two patients. No B-cells were detectable in these two patients. No dose limiting toxicity has been reported with administration of 300 or 500 mg. One serious adverse event assessed as not related to HuMax-CD20 has been reported in the 300 mg group. Infusion related adverse events have primarily been seen during the first infusion of HuMax-CD20. The events have, as expected, predominantly been signs and symptoms of cytokine release, e.g. pruritus, dyspnoea, rigors/chills, nausea, hypotension, urticaria, fatigue, fever and rash. In 15 of the 17 patients, 51 adverse events have been reported. Nine adverse events were CTC grade 3, 16 were grade 2, and 26 events were grade 1. In conclusion, this analysis based on preliminary data for the first 17 patients treated with HuMax-CD20 demonstrated significant depletion of peripheral blood B-cells and a favorable safety profile. An updated report of results for all 40 patients including preliminary tumor response data will be presented.

scholarly journals Successful Clearance of 300 Day SARS-CoV-2 Infection in a Subject with B-Cell Depletion Associated Prolonged (B-DEAP) COVID by REGEN-COV Anti-Spike Monoclonal Antibody Cocktail

Viruses ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1202
Author(s):  
Arnaud C. Drouin ◽  
Marc W. Theberge ◽  
Sharon Y. Liu ◽  
Allison R. Smither ◽  
Shelby M. Flaherty ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Follicular Lymphoma ◽  
B Cell ◽  
Rescue Therapy ◽  
Health Care Team ◽  
Cell Depletion ◽  
B Cell Depletion ◽  
Virus Clearance ◽  
Anti Cd20 ◽  
Antibody Cocktail

A 59-year-old male with follicular lymphoma treated by anti-CD20-mediated B-cell depletion and ablative chemotherapy was hospitalized with a COVID-19 infection. Although the patient did not develop specific humoral immunity, he had a mild clinical course overall. The failure of all therapeutic options allowed infection to persist nearly 300 days with active accumulation of SARS-CoV-2 virus mutations. As a rescue therapy, an infusion of REGEN-COV (10933 and 10987) anti-spike monoclonal antibodies was performed 270 days from initial diagnosis. Due to partial clearance after the first dose (2.4 g), a consolidation dose (8 g) was infused six weeks later. Complete virus clearance could then be observed over the following month, after he was vaccinated with the Pfizer-BioNTech anti-COVID-19 vaccination. The successful management of this patient required prolonged enhanced quarantine, monitoring of virus mutations, pioneering clinical decisions based upon close consultation, and the coordination of multidisciplinary experts in virology, immunology, pharmacology, input from REGN, the FDA, the IRB, the health care team, the patient, and the patient’s family. Current decisions to take revolve around patient’s follicular lymphoma management, and monitoring for virus clearance persistence beyond disappearance of REGEN-COV monoclonal antibodies after anti-SARS-CoV-2 vaccination. Overall, specific guidelines for similar cases should be established.

scholarly journals The Innate Mononuclear Phagocyte Network Depletes B Lymphocytes through Fc Receptor–dependent Mechanisms during Anti-CD20 Antibody Immunotherapy

2004 ◽  
Vol 199 (12) ◽  
pp. 1659-1669 ◽  
Author(s):  
Junji Uchida ◽  
Yasuhito Hamaguchi ◽  
Julie A. Oliver ◽  
Jeffrey V. Ravetch ◽  
Jonathan C. Poe ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Effector Cell ◽  
Fc Receptor ◽  
Cell Depletion ◽  
B Cell Depletion ◽  
Antibody Immunotherapy ◽  
Cd20 Antibody ◽  
Anti Cd20 ◽  
Cd20 Antibodies

Anti-CD20 antibody immunotherapy effectively treats non-Hodgkin's lymphoma and autoimmune disease. However, the cellular and molecular pathways for B cell depletion remain undefined because human mechanistic studies are limited. Proposed mechanisms include antibody-, effector cell–, and complement-dependent cytotoxicity, the disruption of CD20 signaling pathways, and the induction of apoptosis. To identify the mechanisms for B cell depletion in vivo, a new mouse model for anti-CD20 immunotherapy was developed using a panel of twelve mouse anti–mouse CD20 monoclonal antibodies representing all four immunoglobulin G isotypes. Anti-CD20 antibodies rapidly depleted the vast majority of circulating and tissue B cells in an isotype-restricted manner that was completely dependent on effector cell Fc receptor expression. B cell depletion used both FcγRI- and FcγRIII-dependent pathways, whereas B cells were not eliminated in FcR common γ chain–deficient mice. Monocytes were the dominant effector cells for B cell depletion, with no demonstrable role for T or natural killer cells. Although most anti-CD20 antibodies activated complement in vitro, B cell depletion was completely effective in mice with genetic deficiencies in C3, C4, or C1q complement components. That the innate monocyte network depletes B cells through FcγR-dependent pathways during anti-CD20 immunotherapy has important clinical implications for anti-CD20 and other antibody-based therapies.

B-Cell Depletion Using IgG1 Anti-CD20 Spares MZ B Cells and Promotes Tolerance to Human FVIII In a Murine Model of Hemophilia A

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 2206-2206
Author(s):  
Ai-Hong Zhang ◽  
Jonathan Skupsky ◽  
David W. Scott
Keyword(s):  
B Cells ◽  
B Cell ◽  
Hemophilia A ◽  
Tolerance Induction ◽  
Cell Depletion ◽  
High Dose ◽  
Marginal Effect ◽  
B Cell Depletion ◽  
Significant Difference ◽  
Anti Cd20

Abstract Abstract 2206 Preventing and reversing inhibitor formation remains one of the major challenges for hemophilia A therapy. Anti-CD20 mAb (Rituximab) has been reported to be beneficial for hemophilia A patients who failed immune tolerance induction (ITI). However, the evaluation of anti-CD20 therapy often is complicated in the clinical setting by concomitant use of other immune modulating drugs, such as hydrocortisone and IVIG. In this study, we tested the effect of B-cell depletion per se on tolerance induction to FVIII in a mouse model of hemophilia A. Two subclasses of anti-mouse CD20 monoclonal antibodies with differential effects were used. We previously showed that IgG1 anti-CD20 selectively depleted follicular (FO) B cells and spared marginal zone (MZ) B cells, while IgG2a anti-CD20 efficiently depleted both. In FVIII primed mice (inhibitor titer = 30.7 ± 4.8 BU/ml), a single dose of IgG1 anti-CD20 pretreatment prevented the increase in inhibitor formation in the majority of treated mice given daily, high dose FVIII i.v. injection as a model for ITI. Surprisingly, only a marginal effect was achieved when we repeated the same protocol using IgG2a anti-CD20 for B-cell depletion, which efficiently depletes both FO and MZ B cells. To examine tolerance to FVIII, we re-challenged the treated mice with 2 μg FVIII intraperitoneally three months after the initiation of B cell depletion using IgG1 anti-CD20 when the number of peripheral B cells had recovered 60 % or more. The inhibitor titers remained significantly lower in the IgG1 anti-CD20 group after this FVIII boost injection (60.9 ± 33.2 versus 190.3 ± 33.5 BU/ml in control IgG1 group; p = 0.02). Importantly, after the mice were subcutaneously challenged with an unrelated antigen, OVA in CFA, there was no significant difference in anti-OVA IgG titers between the two groups. Taken together, these results suggested that selectively depletion of FO B cells by IgG1 subtype anti-CD20 mAb treatment may facilitate the tolerance induction to FVIII. (Supported by NIH R01 HL061883 and a fellowship from the American Heart Association) Disclosures: No relevant conflicts of interest to declare.

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