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.

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 B Cell Depletion With an Anti-CD20 Antibody Enhances Alloreactive Memory T Cell Responses After Transplantation

2015 ◽  
Vol 16 (2) ◽  
pp. 672-678 ◽  
Author(s):  
J. Marino ◽  
J. T. Paster ◽  
A. Trowell ◽  
L. Maxwell ◽  
K. H. Briggs ◽  
...  
Keyword(s):  
T Cell ◽  
B Cell ◽  
T Cell Responses ◽  
Cell Depletion ◽  
B Cell Depletion ◽  
Memory T Cell ◽  
Cell Responses ◽  
Cd20 Antibody ◽  
Anti Cd20

GA101, a Novel Humanized Type II CD20 Antibody with Glycoengineered Fc and Enhanced Cell Death Induction, Exhibits Superior Anti-Tumor Efficacy and Superior Tissue B Cell Depletion In Vivo.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 2348-2348 ◽  
Author(s):  
Pablo Umana ◽  
Moessner Ekkehard ◽  
Bruenker Peter ◽  
Klingner Gabriele ◽  
Puentener Ursula ◽  
...  
Keyword(s):  
Cell Death ◽  
B Cells ◽  
Lymph Nodes ◽  
B Cell ◽  
Cell Depletion ◽  
Type Ii ◽  
B Cell Depletion ◽  
Cynomolgus Monkeys ◽  
High Affinity ◽  
Cd20 Antibody

Abstract GA101 is a novel monoclonal antibody of IgG1 type which binds with high affinity and selectivity to the extracellular domain of the human CD20 antigen on B cells. In contrast to rituximab which is a chimeric antibody and recognizes a type I epitope, GA101 is humanized and recognizes a type II epitope which is also localized in the extracellular loop of CD20. The recognition of the type II epitope together with a modification of the elbow hinge region results in enhanced direct non-caspase dependent cell death induction, and concomitant reduction in CDC upon binding to CD20. In addition, using GlycoMab technology, the Fc-region of GA101 was glycoengineered to contain bisected, afucosylated carbohydrates. As a result GA101 has increased affinity for the low and high affinity FcγRIIIa receptor expressed on natural killer cells, macrophages and monocytes. Consequently, GA101 mediated a 5–50 fold enhanced induction of effector cell mediated ADCC. In B-cell depletion assays with whole blood from healthy donors, an assay combining all mechanisms of action, GA101 was significantly more potent and efficacious in depleting B cells than rituximab. In preclinical NHL testing these properties translated into superior anti-tumoral efficacy of GA101 in direct comparison to rituximab against a number of aggressive NHL xenograft models. In cynomolgus monkeys the induction of B cell depletion mediated by GA101 and subsequent B cell recovery were investigated. GA101 induced complete, rapid and long-lasting B cell depletion both in peripheral blood and in lymphoid tissue e.g. spleen and lymph nodes. The efficacy of GA101 (10 and 30 mg/kg) at depleting B cells in different lymphoid tissues of cynomolgus monkeys was compared with that of rituximab (10 mg/kg) following 2 i.v. doses administered on days 0 and 7. Notably, GA101 showed statistically superior depletion of total B cells from lymph nodes compared to Rituximab from day 9 to 35 onwards with B cell numbers decreased by over 95%. These results demonstrated that GA101 was more efficacious at depleting B cells from lymph nodes and spleen of cynomolgus monkeys compared to rituximab. Compared to existing antibodies, GA101 constitutes the first type II CD20 antibody engineered for increased ADCC with significantly enhanced efficacy in a variety of preclinical models. Based on these data it is assumed that the combination of the recognition of a type II epitope together with improved ADCC potency might translate into superior efficacy in the clinical treatment of CD20 positive malignant diseases.

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.

Low doses of humanized anti-CD20 antibody, IMMU-106 (hA20), in refractory or recurrent NHL: Phase I/II results

2007 ◽  
Vol 25 (18_suppl) ◽  
pp. 8032-8032 ◽  
Author(s):  
F. Morschhauser ◽  
J. P. Leonard ◽  
L. Fayad ◽  
B. Coiffier ◽  
M. Petillon ◽  
...  
Keyword(s):  
Adverse Events ◽  
B Cell ◽  
Serum Levels ◽  
Cell Depletion ◽  
B Cell Depletion ◽  
Open Label ◽  
Clear Cut ◽  
Cd20 Antibody ◽  
Anti Cd20

8032 Background: An open-label, multicenter study has shown that the humanized anti-CD20 antibody, IMMU-106 (hA20), which has framework regions of epratuzumab, has a good safety and efficacy profile in NHL pts when administered once-weekly × 4 at different doses. The trial is now focused on confirming the efficacy of lower doses (80–120 mg/m2/wk × 4). Methods: A total of 68 pts (35 male, 33 female; age 34–84) received hA20 at 750 (N=3), 375 (N=27), 200 (N=11), 120 (N=21), or 80 mg/m2 (N=6). They had follicular (FL, N=47) or other (N=21) B-cell NHL, were predominantly stage III/IV (N=47) at study entry, and had received 1–8 prior treatments (median, 2), including 1 (N=40) or more (N=21) rituximab regimens (without progression within 6 months). Results: Sixty- six pts completed all 4 infusions; 1 pt progressed during treatment and withdrew, while another pt with hives and chills after prior rituximab discontinued treatment after a similar episode at 1st infusion. hA20 was generally well tolerated, with shorter infusion times (typically 2 h initially and 1 h subsequently) at lower doses. Drug-related adverse events were transient, Grade 1–2, most occurring only at 1st infusion, and there was no evidence of HAHA in 54 pts now evaluated. Mean antibody serum levels increased with dose and infusions; serum clearance at 375 mg/m2 appears similar to rituximab. Currently, 48 pts with at least 12 wks follow-up were evaluated by Cheson criteria: 32 FL pts had 15 (47%) OR's with 7 (22%) CR/CRu's, even after 2–4 prior rituximab-regimens, and 17 non-FL pts had 6 (38%) OR's, with 1 CRu in a marginal zone NHL pt. At a median follow-up of 11 mo., 9/21 pts with ORs are continuing responses, including 4 long-lived responses (15–20 mo). The evaluated pts include 17 pts at 120 mg/m2 who had 5 (29%) ORs with 3 (17%) CR/CRu's. Responses at 80 mg/m2 remain to be evaluated, but B-cell depletion occurs after the 1st infusion even at this low dose. Conclusions: hA20 appears well-tolerated, with no evidence of significant adverse events other than minor infusion reactions, even at short infusion times. B-cell depletion and responses have occurred at all doses evaluated, with no clear-cut evidence of a dose-response. As such, the study is continuing to confirm the efficacy of lower doses. No significant financial relationships to disclose.

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 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.

Rituximab-Relapsing Patients with Non-Hodgkins Lymphoma Respond Even at Lower Doses of Humanized Anti-CD20 Antibody, IMMU-106 (hA20): Phase I/II Results.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 2719-2719 ◽  
Author(s):  
Franck Morschhauser ◽  
John P. Leonard ◽  
Luis Fayad ◽  
Bertrand Coiffier ◽  
STephen J. Schuster ◽  
...  
Keyword(s):  
Adverse Events ◽  
B Cell ◽  
Post Treatment ◽  
Cell Depletion ◽  
B Cell Depletion ◽  
Open Label ◽  
Dose Escalation Study ◽  
Cd20 Antibody ◽  
Anti Cd20

Abstract Background: An open-label, multicenter, dose-escalation study in patients with recurrent NHL was initially undertaken to establish the safety, tolerance, PK, and immunogenicity (HAHA) of humanized anti-CD20 antibody, IMMU-106 (hA20), administered once-weekly for 4 weeks at different doses. Additional patients have now been entered to confirm the efficacy of 120 and 375 mg/m2 dosing, and to determine the feasibility of using even lower hA20 doses. Methods: A total of 55 patients (23 male, 32 female; 51 Caucasian; 40–84 years old) received hA20 at 120 (N=21), 200 (N=6), 375 (N=25) or 750 mg/m2 (N=3). They had follicular (FL, N=37) or other (N=18) B-cell lymphomas, were predominantly stage III/IV (N=44) at study entry, and had received 1–7 prior treatments (median, 2), including 1 (N=34) or more (N=14) rituximab regimens (without progression within 6 months). Results: Fifty-two patients completed all 4 infusions, 2 are currently being treated, and one patient with hives and chills after prior rituximab discontinued treatment after similar NCI CTC v.3 grade 1–2 reactions at 1st hA20 infusion. hA20 was generally well tolerated with a median infusion time at the lowest dose of 120 mg/m2 of 2.2 h for 1st infusion and 1.2 h for subsequent infusions. Twenty-one patients had drug-related adverse events; these were all transient, mild-to-moderate (Grade 1–2) events, most occurring only at first infusion. No consistent pattern of abnormal laboratory changes occurred, and there was no evidence of immunogenicity in 29 patients now evaluated for HAHA. Mean antibody serum levels increased with dose and with repeated infusions, and limited post-treatment data indicate the serum clearance at 375 mg/m2 dosing is similar to rituximab. Even at 120 mg/m2, peripheral blood B-cell depletion occurred after the first infusion and persists after 4th infusion, with analysis continuing > 6 mo. Thirty-nine patients with at least 12 wks follow-up had one or more responses evaluated by Cheson criteria (Table), with all CR/CRu occurring in follicular lymphoma except for one patient with marginal zone lymphoma; 6 pts progressed by week 4. Of 18 pts with OR’s, 9 have continuing responses (median follow-up, 9 mos post-treatment), including 4 with long-lived responses (12–18 mos). Conclusions: hA20 is well tolerated, with no evidence of significant toxicity or pattern of adverse events other than minor infusion reactions, even at short infusion times. All dose levels studied so far, including the lowest dose of 120 mg/m2, resulted in B-cell depletion and objective responses (including CR/CRu), with no clear-cut evidence of dose response in efficacy. As such, further dose de-escalation is ongoing. Treatment Response hA20 Dose OR CR/CRu All patients (n = 39) 46% (18/39) 21% (8/39) 120 mg/m2 (n = 11) 36% (4/11) 27% (3/11) 200 mg/m2 (n = 6) 67% (4/6) 33% (2/6) 375 mg/m2 (n =19) 42% (8/19) 11% (2/19) 750 mg/m2 (n = 3) 67% (2/3) 33% (1/3)

A Glyco-Optimized Anti-CD20 Antibody from the Aquatic Plant Lemna: Comparison of Pharmacokinetics, B-Cell Depletion and Complement Activation with Rituxan® in Cynomolgus Monkeys

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 4977-4977
Author(s):  
John R Gasdaska ◽  
Jeff Regan ◽  
Steve Sherwood ◽  
Klaus-Peter Radtke ◽  
Bipin Dalmia ◽  
...  
Keyword(s):  
B Cell ◽  
Complement Activation ◽  
Aquatic Plant ◽  
Pharmacokinetic Profile ◽  
Cell Depletion ◽  
B Cell Depletion ◽  
Adcc Activity ◽  
Cd20 Antibody ◽  
Anti Cd20

Abstract Monoclonal antibodies represent one of the largest classes of drugs in preclinical and clinical development. For many antibodies, the structure and extent of the N-glycans on the Fc region of the heavy chain plays a significant role in their therapeutic function. A glyco-optimized version of the anti-CD20 antibody (rituximab) was expressed in the clonal aquatic plant Lemna. The optimized glycosylation was accomplished by co-expressing an interfering RNA (RNAi) construct targeting the endogenous alpha-1,3-fucosyltransferase and beta-1,2-xylosyltransferase genes (Cox et al., 2006). The resulting glyco-optimized rituximab contained a single major G0 N-glycan (lacking terminal galactose) without any detectable xylose or fucose. Previous in vitro cell-based studies have shown that the glyco-optimized rituximab had similar CD20 binding affinity and apoptotic effects as Rituxan® produced in mammalian cells but with significantly enhanced (up to 100- fold) antibody-dependent cellular cytotoxicity (ADCC). Enhanced ADCC activity was found for all FcgRIIIa-158 genotypes. Reported here are the results of expanded studies comparing Rituxan® with the Lemna–derived glyco-optimized rituximab. B-cell depletion was measured in genotyped human whole blood after ex vivo treatment with both anti-CD20 antibodies. Consistent with prior in vitro ADCC studies, glyco-optimized rituximab showed a significant increase in B-cell depletion for all FcgRIIIa-158 genotypes when compared to Rituxan®. To extend these findings to an in vivo setting, a comparative monkey study was conducted to evaluate: pharmacokinetic impact of the optimized glycans, B-cell depletion, and complement activation. The study design included two male Cynomologus monkeys per group in a dose-escalation scheme where each group received a single administration of two dose levels of either Rituxan® or glycooptimized rituximab. Results showed no difference between the two antibodies in clinical observations and pharmacokinetic profile. Overall the rate of depletion and recovery of the monkey B-cells between Rituxan® and glyco-optimized rituximab was similar with evidence of an increase in the initial rate of depletion with the glyco-optimized rituximab. The latter finding is not unexpected due to sequence differences between FcgRIIIa in humans and monkeys. Interestingly, 50% higher complement activation (as measured by serum levels of C3a,) was observed with Rituxan®. This is consistent with our previous observation that glyco-optimized rituximab had up to a ten-fold decrease in complement dependent cytotoxicity (CDC) in Raji cells compared to Rituxan®. These studies suggest that an optimized anti-CD20 antibody therapeutic can have a similar pharmacokinetic profile with enhanced ADCC activity and decreased CDC activity compared to Rituxan®. Confirmation that these differences will translate into improved efficacy with decreased side effects associated with CDC activity (Clark and Ledbetter, 2005) will require clinical research. Cox et al (2006). Nat. Biotech. 24: 1591–15197. Clark et al (2005). Ann. Rheum Dis. 64: 77–80.

25 Year Old Female Conceiving 6 Months After Last Dose of Rituximab: a Case Report

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 4924-4924 ◽  
Author(s):  
Lydia Y Cheung ◽  
Caroline Hamm ◽  
Michelle Suga ◽  
Mohammed Adie
Keyword(s):  
B Cell ◽  
Case Reports ◽  
Post Treatment ◽  
Cell Depletion ◽  
B Cell Depletion ◽  
Antibody Titres ◽  
Cd20 Antibody ◽  
Trimester Exposure ◽  
Anti Cd20

Abstract Abstract 4924 For female patients treated with rituximab, a monoclonal anti-CD20 antibody, it is recommended to wait 12 months post-treatment before pregnancy to avoid fetal B cell depletion. We report a case of a 25 year old female with a history of Grade II follicular lymphoma, Stage III who was treated with CHOP/R and maintenance rituximab therapy which was stopped when she expressed intentions for pregnancy. However, she conceives within only 6 months after her last dose of rituximab. This prompts questions of risks to the fetus. Rituximab is a monoclonal anti-CD20 antibody which targets and destroys normal and malignant CD20 positive B cells. As an IgG molecule, rituximab can cross the placenta, and has been documented to cause B cell depletion and immunosuppression in the fetus (McKeever et al, 2003). During treatment, high drug levels are detectable in the umbilical cord blood, and remains in the patient's blood between 3–6 months post-treatment (Pereg et al, 2007). The half life of rituximab varies with tumour burden and ranges from 3 – 19 days. B cell levels start to recover at 6 months post-treatment and are normal by 12 months. Hence, it is recommended by the manufacturer that pregnancies should be separated from rituximab use by a minimum of 12 months. Current literature regarding rituximab's safety in pregnancy is limited to animal studies and 10 case reports. When pregnant macaque cynomolgus females were exposed in 1st trimester, no teratogenic or embryotoxic effects were shown. There was a decrease in B cell levels but these were reversible by 179 days (McKeever et al., 2003). Among case reports, six involved women treated for hematological conditions. Of these cases, one was inadvertently exposed in 1st trimester and the fetus had B cell depletion that recovered to normal levels by 16 days (Kimby, 2004). All other cases were exposed in 2nd trimester of which two had transient B cell depletion that recovered by 4 months. All babies were healthy at birth, had normal antibody titres after their first vaccinations and normal childhood development at follow-up (Friedrich, 2006; Decker 2006). Four case reports involved rituximab use for non-hematological conditions; two cases of 1st trimester and two cases of 3rd trimester exposure. Only one 3rd trimester case reported transient fetal B cell depletion that recovered by 6 months (Klink, 2008). Again, all babies were healthy at birth and at follow-up, including normal antibody titres after vaccinations. From the cases reported, regardless of trimester exposure, the B cell depletion effect was only transient with no documented short-term or long-term effects on the baby's immune function and overall development. In this case, the patient stopped rituximab therapy 6 months prior to conception. There were no complications during pregnancy or delivery. Furthermore, a healthy baby boy was born at 42 weeks gestation with normal apgar scores, length at 75th percentile, and normal weight of 8 lbs 16 oz. Since the baby was clinically stable after delivery, B cell levels were not drawn. At 3 months old, the baby was healthy and had no difficulties with vaccinations to date. This is yet another case to add to the small literature base, and we hope it can help further inform the usage of rituximab during pregnancy. Disclosures: No relevant conflicts of interest to declare.

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