The impact of Fc engineering on an anti-CD19 antibody: increased Fcγ receptor affinity enhances B-cell clearing in nonhuman primates

Blood ◽  
2009 ◽  
Vol 113 (16) ◽  
pp. 3735-3743 ◽  
Author(s):  
Jonathan Zalevsky ◽  
Irene W. L. Leung ◽  
Sher Karki ◽  
Seung Y. Chu ◽  
Eugene A. Zhukovsky ◽  
...  
Keyword(s):  
B Cell ◽  
Nk Cells ◽  
Binding Affinity ◽  
Effector Cell ◽  
Cell Depletion ◽  
B Cell Depletion ◽  
Fcγ Receptor ◽  
B Cell Malignancies ◽  
Cell Functions ◽  
The Impact

Abstract CD19, a B cell–restricted receptor critical for B-cell development, is expressed in most B-cell malignancies. The Fc-engineered anti-CD19 antibody, XmAb5574, has enhanced Fcγ receptor (FcγR) binding affinity, leading to improved FcγR-dependent effector cell functions and antitumor activity in murine xenografts compared with the non–Fc-engineered anti-CD19 IgG1 analog. Here, we use XmAb5574 and anti-CD19 IgG1 to further dissect effector cell functions in an immune system closely homologous to that of humans, the cynomolgus monkey. XmAb5574 infusion caused an immediate and dose-related B-cell depletion in the blood (to <10% of baseline levels) concomitant with a sustained reduction of natural killer (NK) cells. NK cells had fully recovered by day 15, whereas B-cell recovery was underway by day 57. B cells in secondary lymphoid tissues were depleted (to 34%-61% of vehicle), with involuted germinal centers apparent in the spleen. Anti-CD19 IgG1 had comparable serum exposure to XmAb5574 but demonstrated no B-cell depletion and no sustained NK-cell reduction. Thus, increasing FcγR binding affinity dramatically increased B-cell clearing. We propose that effector cell functions, possibly those involving NK cells, mediate XmAb5574 potency in cynomolgus monkeys, and that enhancing these mechanisms should advance the treatment of B-cell malignancies in humans.

Potent B-Cell Depletion by IMGN529, a CD37-Targeting Antibody-Maytansinoid Conjugate for the Treatment of B-Cell Malignancies,

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 3726-3726
Author(s):  
Jutta Deckert ◽  
Sharon Chicklas ◽  
Yong Yi ◽  
Min Li ◽  
Jan Pinkas ◽  
...  
Keyword(s):  
T Cells ◽  
B Cells ◽  
B Cell ◽  
Whole Blood ◽  
Cell Lymphoma ◽  
B Cell Lymphoma ◽  
Cell Depletion ◽  
B Cell Depletion ◽  
B Cell Malignancies

Abstract Abstract 3726 CD37 is a B-cell surface antigen which is widely expressed on malignant B cells in non-Hodgkin's lymphoma (NHL) and chronic lymphocytic leukemia (CLL). In normal tissues CD37 expression is limited to blood cells and lymphoid tissues. This restricted expression profile makes CD37 an attractive therapeutic target for antibodies and antibody-drug conjugates. We developed a novel anti-CD37 antibody, K7153A, which provides a unique combination of functional properties: it demonstrated strong pro-apoptotic and direct cell killing activity against NHL cell lines and could mediate effector activity such as CDC and ADCC. The antibody-maytansinoid conjugate, IMGN529, was produced by conjugation of K7153A with the potent maytansinoid, DM1, via the non-cleavable linker, SMCC. The direct cytotoxic potency of the K7153A antibody was superior to that of the CD20-directed rituximab and was further enhanced with maytansinoid conjugation in IMGN529. In vivo, IMGN529 demonstrated better anti-tumor activity than the K7153A antibody in established subcutaneous follicular lymphoma (FL), diffuse large B-cell lymphoma (DLBCL), and CLL xenograft models in SCID mice. A single administration of IMGN529 showed similar or improved efficacy compared to anti-CD20 antibodies or standard chemotherapy where tested. Immunohistochemical (IHC) staining of formalin fixed paraffin-embedded (FFPE) NHL tissue sections was performed to evaluate CD37 expression. CD37 exhibited a similar prevalence to CD20 in subtypes of NHL such as FL, DLBCL, Burkitt's lymphoma (BL) and mantle cell lymphoma (MCL). B-cell depletion is an important measure of efficacy for targeted therapies, such as CD20-directed antibodies, in B-cell malignancies. CD37 expression in blood cells from healthy human donors was measured by quantitative flow cytometry in comparison to CD20. The greatest CD37 expression was found in B cells at approximately 77,000 antibodies bound per cell (ABC), which was similar to CD20 expression in B cells at 95,000 ABC. In other blood cell types CD37 staining was seen at low levels, about 2,000 – 5,000 ABC, in monocytes, NK cells and T cells. In vitro depletion experiments were performed with purified peripheral blood mononuclear cells (PBMCs) and with whole blood, both derived from several healthy donors. Cells were incubated for 1 hr with 10 μg/mL of either K7153A, IMGN529, CD37-targeting TRU-016, rituximab or the anti-CD52 antibody alemtuzumab, with cell depletion determined relative to counting beads by flow cytometry. The K7153A antibody and the IMGN529 conjugate efficiently and specifically depleted B-cells in a dose-dependent manner in the context of purified PBMCs and whole blood. With purified PBMCs, both K7153A and IMGN529 caused 50–60% depletion of B cells, with little to no depletion of T cells or monocytes. IMGN529 was more potent than rituximab, which led to 30–40% B-cell depletion, or TRU-016, which caused 20–30% B-cell depletion. IMGN529 also was more specific than alemtuzumab, which depleted T-cells and monocytes as well as B cells. With whole blood samples, both K7153A and IMGN529 resulted in 30–40% B-cell depletion with no effect on T cells, NK cells or monocytes. IMGN529 was again more potent than rituximab or TRU-016, which caused approximately 10% B-cell depletion, and was more specific than alemtuzumab, which depleted the majority of T cells in addition to 40% of B cells. IMGN529 embodies a unique B-cell targeted agent as it combines the intrinsic pro-apoptotic, CDC and ADCC activities of its anti-CD37 antibody component with the potent cytotoxic mechanism provided by the targeted delivery of its maytansinoid payload. It is highly active in vitro and in vivo against B-cell lymphoma and CLL cell lines. In addition, it mediates specific B-cell depletion in vitro that is greater than B-cell depletion by CD20-directed rituximab. Together, these findings indicate that IMGN529 is a promising therapeutic candidate for the treatment of B-cell malignancies. Disclosures: Deckert: ImmunoGen, Inc.: Employment. Chicklas:ImmunoGen, Inc.: Employment. Yi:ImmunoGen, Inc.: Employment. Li:ImmunoGen, Inc.: Employment. Pinkas:ImmunoGen, Inc.: Employment. Chittenden:ImmunoGen, Inc.: Employment. Lutz:ImmunoGen, Inc.: Employment. Park:ImmunoGen, Inc.: Employment.

scholarly journals Humoral and T-cell responses to SARS-CoV-2 vaccination in patients receiving immunosuppression

2021 ◽  
pp. annrheumdis-2021-220626
Author(s):  
Maria Prendecki ◽  
Candice Clarke ◽  
Helena Edwards ◽  
Stacey McIntyre ◽  
Paige Mortimer ◽  
...  
Keyword(s):  
T Cell ◽  
B Cell ◽  
T Cell Responses ◽  
T Cell Response ◽  
Cell Depletion ◽  
B Cell Depletion ◽  
Glomerular Diseases ◽  
Cell Responses ◽  
The Impact ◽  
Dose Vaccine

ObjectiveThere is an urgent need to assess the impact of immunosuppressive therapies on the immunogenicity and efficacy of SARS-CoV-2 vaccination.MethodsSerological and T-cell ELISpot assays were used to assess the response to first-dose and second-dose SARS-CoV-2 vaccine (with either BNT162b2 mRNA or ChAdOx1 nCoV-19 vaccines) in 140 participants receiving immunosuppression for autoimmune rheumatic and glomerular diseases.ResultsFollowing first-dose vaccine, 28.6% (34/119) of infection-naïve participants seroconverted and 26.0% (13/50) had detectable T-cell responses to SARS-CoV-2. Immune responses were augmented by second-dose vaccine, increasing seroconversion and T-cell response rates to 59.3% (54/91) and 82.6% (38/46), respectively. B-cell depletion at the time of vaccination was associated with failure to seroconvert, and tacrolimus therapy was associated with diminished T-cell responses. Reassuringly, only 8.7% of infection-naïve patients had neither antibody nor T-cell responses detected following second-dose vaccine. In patients with evidence of prior SARS-CoV-2 infection (19/140), all mounted high-titre antibody responses after first-dose vaccine, regardless of immunosuppressive therapy.ConclusionSARS-CoV-2 vaccines are immunogenic in patients receiving immunosuppression, when assessed by a combination of serology and cell-based assays, although the response is impaired compared with healthy individuals. B-cell depletion following rituximab impairs serological responses, but T-cell responses are preserved in this group. We suggest that repeat vaccine doses for serological non-responders should be investigated as means to induce more robust immunological response.

IL-21 Improves Rituximab-Mediated B Cell Depletion.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 345-345
Author(s):  
Steven D. Hughes ◽  
Rafael A. Ponce ◽  
Cecile Krejsa ◽  
Werner Frings ◽  
Stephanie Bartsch ◽  
...  
Keyword(s):  
B Cells ◽  
Combination Therapy ◽  
B Cell ◽  
Nk Cells ◽  
Dose Regimen ◽  
Cell Depletion ◽  
Partial Recovery ◽  
B Cell Depletion ◽  
Phagocytic Cells ◽  
Cynomolgus Monkeys

Abstract IL-21 is a cytokine produced by activated CD4+ T cells that augments the growth, survival, and function of NK, T and phagocytic cells. IL-21 also plays an important role in regulating B cell proliferation and differentiation. In a previous study of cynomolgus monkeys treated with recombinant human IL-21, we demonstrated increased numbers of NK cells and phagocytic cells expressing Fcγ RI and III, enhancement of ex vivo antibody dependent cellular cytotoxicity (ADCC) activity, altered lymphocyte trafficking, and improved B cell depletion with subclinical doses of rituximab. The current study aimed to extend these findings to a clinically relevant rituximab dose regimen, and to evaluate the safety and tolerability of IL-21 administration in this setting. Three groups of cynomolgus monkeys (n=8) were treated by IV injection once weekly for four weeks with rituximab (10 mg/kg), concurrently with vehicle or IL-21 (0.3 or 1.5 mg/kg). Standard toxicology data were collected. The number and activation state of peripheral blood leukocyte subsets were determined by flow cytometry. Effects on B cells within spleen and lymph nodes were evaluated by immunohistochemistry. Co-administration of rituximab and IL-21 was well tolerated at both dose levels of IL-21 tested. The primary toxicological responses to the combination treatment were moderate anemia and thrombocytopenia, which were IL-21 dose dependent and similar in magnitude to those observed in previous IL-21 toxicology studies. In animals treated with rituximab alone, circulating B cells were depleted to a nadir 0.3–3 % of baseline on Day 11 of the study (Figure 1). In contrast, significantly lower B cell nadirs were observed following the first treatment with rituximab and IL-21 combination therapy (p< 0.01, ANOVA). In animals receiving the 1.5 mg/kg dose of IL-21, circulating B cells were depleted to a nadir 0 −1 % of baseline on Day 4, followed by partial recovery and further depletion to 0.3 – 2% of baseline on Day 11. More importantly, B cell recovery was significantly delayed in the group treated with rituximab and 1.5 mg/kg IL-21, compared to rituximab treatment alone (p< 0.05, ANOVA/PLSD). Thirty days following the fourth and final treatment, B cell numbers had recovered to only 6% of baseline, compared to 22% in the rituximab monotherapy treated group. Additionally, coadministration of IL-21 with rituximab increased circulating activated monocytes, granulocytes and NK cells compared with rituximab monotherapy. In conclusion, addition of IL-21 to a standard weekly, 4-dose regimen of IV rituximab was well-tolerated in cynomolgus monkeys and resulted in more complete, rapid and durable depletion of circulating CD20-expressing target cells. As depletion of B cells in this model serves as a surrogate for clearance of CD20-expressing malignant cells, these data support the evaluation of IL-21 and rituximab combination therapy in patients with advanced CD20 positive malignancies. Figure Figure

scholarly journals Effects of B Cell Depletion on Early Mycobacterium tuberculosis Infection in Cynomolgus Macaques

2016 ◽  
Vol 84 (5) ◽  
pp. 1301-1311 ◽  
Author(s):  
Jiayao Phuah ◽  
Eileen A. Wong ◽  
Hannah P. Gideon ◽  
Pauline Maiello ◽  
M. Teresa Coleman ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
B Cells ◽  
B Cell ◽  
Humoral Immunity ◽  
Nonhuman Primates ◽  
Acute Infection ◽  
Cell Depletion ◽  
B Cell Depletion ◽  
Content Type ◽  
The Impact

Although recent studies in mice have shown that components of B cell and humoral immunity can modulate the immune responses againstMycobacterium tuberculosis, the roles of these components in human and nonhuman primate infections are unknown. The cynomolgus macaque (Macaca fascicularis) model ofM. tuberculosisinfection closely mirrors the infection outcomes and pathology in human tuberculosis (TB). The present study used rituximab, an anti-CD20 antibody, to deplete B cells inM. tuberculosis-infected macaques to examine the contribution of B cells and humoral immunity to the control of TB in nonhuman primates during the acute phase of infection. While there was no difference in the overall pathology, disease profession, and clinical outcome between the rituximab-treated and untreated macaques in acute infection, analyzing individual granulomas revealed that B cell depletion resulted in altered local T cell and cytokine responses, increased bacterial burden, and lower levels of inflammation. There were elevated frequencies of T cells producing interleukin-2 (IL-2), IL-10, and IL-17 and decreased IL-6 and IL-10 levels within granulomas from B cell-depleted animals. The effects of B cell depletion varied among granulomas in an individual animal, as well as among animals, underscoring the previously reported heterogeneity of local immunologic characteristics of tuberculous granulomas in nonhuman primates. Taken together, our data clearly showed that B cells can modulate the local granulomatous response inM. tuberculosis-infected macaques during acute infection. The impact of these alterations on disease progression and outcome in the chronic phase remains to be determined.

scholarly journals Rituximab Treatment in Hepatitis C Infection: An In Vitro Model to Study the Impact of B Cell Depletion on Virus Infectivity

PLoS ONE ◽  
2011 ◽  
Vol 6 (9) ◽  
pp. e25789 ◽  
Author(s):  
Zania Stamataki ◽  
Samantha Tilakaratne ◽  
David H. Adams ◽  
Jane A. McKeating
Keyword(s):  
Hepatitis C ◽  
B Cell ◽  
In Vitro Model ◽  
Cell Depletion ◽  
Virus Infectivity ◽  
B Cell Depletion ◽  
Hepatitis C Infection ◽  
Vitro Model ◽  
The Impact

scholarly journals Obinutuzumab (GA101) Is Less Prone to Antagonism of Immune Effector Function By Ibrutinib Than Rituximab in Vitro and in Vivo

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 1765-1765 ◽  
Author(s):  
Sylvia Herter ◽  
Idit Sagiv-Barfi ◽  
Cariad Chester ◽  
Mohith Sadaram ◽  
Jonathan Hebb ◽  
...  
Keyword(s):  
B Cell ◽  
Whole Blood ◽  
Dose Range ◽  
Xenograft Model ◽  
Cell Depletion ◽  
B Cell Depletion ◽  
Immune Effector ◽  
The Impact

Abstract Introduction: Kohrt et al., Blood, 2014 demonstrated that ibrutinib antagonizes ADCC function of rituximab in vitro in ADCC assays and in vivo in the DHL-4 xenograft model through inhibition of FcgammaR signaling in immune effector cells, possibly mediated by inhibition of ITK. Obinutuzumab (GA101) is a glycoengineered type II CD20 antibody that mediates higher direct cell death induction than rituximab, and by being glycoengineered mediates enhanced induction of ADCC and ADCP. Here we aimed to investigate the impact of ibrutinib on the immune effector function of obinutuzumab as compared to rituximab. Experimental methods: The impact of ibrutinib (dose range 30, 100, 300 ng/ml to cover Cmax and Ctrough in patients) on NK cell mediated ADCC induction by obinutuzumab and rituximab was investigated using SU-DHL4 and Z138 cells as targets in LDH and chromium release assays or measuring CD16 downmodulation and the degranulation marker CD107a. IFNg release as a surrogate for NK cell activation was investigated using DHL-4 target cells or an autologous in vitro system using leukemic cells derived from CLL/NHL patients. Depletion of CD19 positive B-cells was determined in whole blood from healthy volunteers in flow cytometry-based whole blood assay. In vivo the combination of obinutuzumab or rituximab (10 mg/kg once weekly for 3 weeks) with ibrutinib (25mg/kg BID days 14-28) was investigated in the DHL-4 xenograft model. Results: In ADCC assays, ibrutinib (dose range 30, 100, 300 ng/ml) resulted in a reduction of the ADCC potency of obinutuzumab and rituximab. However, at saturating antibody concentrations of 10 ug/ml, ADCC mediated by obinutuzumab was retained while ADCC mediated by rituximab was strongly reduced as measured by chromium release (Figure 1A). Interestingly, in the whole blood B cell depletion assay only little impact of ibrutinib on obinutuzumab-mediated B cell depletion in terms of EC50 and maximal killing was observed at clinically meaningful concentrations of ibrutinib (30, 100, 300 ng/ml), while the activity of rituximab could be completely abolished with 300 ng/ml ibrutinib (Figure 1B). Notably, control experiments using an effector dead version of obinutuzmab that cannot any longer mediate ADCC or ADCP demonstrate that the retained B cell depletion by obinutuzumab in presence of ibrutinib is not due to direct cell death induction, but also due to immune effector cell mediated function (ADCC and ADCP). In the DHL-4 xenograft model where ibrutinib as a single agent has no anti-tumoral efficacy, the combination resulted in a reduced anti-tumoral efficacy of rituximab, whereas efficacy of obinutuzumab was not affected (Figure 1C). Conclusions: Surprisingly, we found that the inhibitory effect of ibrutinib on the immune effector mediated activity of obinutuzumab is not observed when compared to rituximab. Most notably, ADCC at saturating antibody doses, whole blood B cell depletion and in vivo efficacy of obinutuzumab were retained in presence of clinically relevant concentrations of ibrutinib covering Cmax and Ctrough levels, whereas the activity of rituximab was almost completely abolished under these conditions. We hypothesize that the differential behavior of obinutuzumab and rituximab may be related to the enhanced FcgRIII affinity and stronger FcgRIII signaling activation mediated by obinutuzumab as a consequence of glycoengineering that may subsequently overwrite inhibitory effects of ibrutinib. While the clinical relevance of the observed preclinical antagonism for the combination of rituximab with ibrutinib still needs further clinical investigation, these preclinical data strongly support the clinical investigation of ibrutinib in combination with the glycoengineered Type II CD20 antibody obinutuzumab for the treatment of chronic lymphocytic leukemia and other B-cell malignancies. Figure 1 Figure 1. Disclosures Herter: Roche: Employment. Bacac:Roche: Employment. Umana:Roche: Employment. Klein:Roche: Employment, Equity Ownership, Patents & Royalties.

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 Increasing the efficacy of CD20 antibody therapy through the engineering of a new type II anti-CD20 antibody with enhanced direct and immune effector cell–mediated B-cell cytotoxicity

Blood ◽  
2010 ◽  
Vol 115 (22) ◽  
pp. 4393-4402 ◽  
Author(s):  
Ekkehard Mössner ◽  
Peter Brünker ◽  
Samuel Moser ◽  
Ursula Püntener ◽  
Carla Schmidt ◽  
...  
Keyword(s):  
Overall Survival ◽  
B Cell ◽  
Effector Cell ◽  
Antibody Therapy ◽  
Cell Depletion ◽  
Type Ii ◽  
B Cell Depletion ◽  
Immune Effector Cell ◽  
Immune Effector ◽  
Cd20 Antibody

AbstractCD20 is an important target for the treatment of B-cell malignancies, including non-Hodgkin lymphoma as well as autoimmune disorders. B-cell depletion therapy using monoclonal antibodies against CD20, such as rituximab, has revolutionized the treatment of these disorders, greatly improving overall survival in patients. Here, we report the development of GA101 as the first Fc-engineered, type II humanized IgG1 antibody against CD20. Relative to rituximab, GA101 has increased direct and immune effector cell-mediated cytotoxicity and exhibits superior activity in cellular assays and whole blood B-cell depletion assays. In human lymphoma xenograft models, GA101 exhibits superior antitumor activity, resulting in the induction of complete tumor remission and increased overall survival. In nonhuman primates, GA101 demonstrates superior B cell–depleting activity in lymphoid tissue, including in lymph nodes and spleen. Taken together, these results provide compelling evidence for the development of GA101 as a promising new therapy for the treatment of B-cell disorders.

The PI3K Delta Selective Inhibitor Idelalisib Minimally Interferes with Immune Effector Function and B Cell Depletion Mediated By Obinutuzumab (GA101) and Rituximab

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 3342-3342 ◽  
Author(s):  
Sylvia Herter ◽  
Adam Palazzo ◽  
Marina Bacac ◽  
Laura Grosmaire ◽  
Christian Frey ◽  
...  
Keyword(s):  
B Cell ◽  
Whole Blood ◽  
Nk Cell ◽  
Effector Function ◽  
Cell Depletion ◽  
B Cell Depletion ◽  
Immune Effector ◽  
Effector Cells ◽  
Immune Effector Function ◽  
The Impact

Abstract Introduction: Idelalisib is a highly selective oral inhibitor of the phosphoinositide 3-kinase delta (PI3Kδ) that is hyperactive in many B-cell malignancies and is critical for the activation, proliferation, survival and trafficking of B lymphocytes. Idelalisib is approved in the US for the treatment of chronic lymphocytic leukemia (CLL) in combination with rituximab and as monotherapy for patients with relapsed follicular B-cell non-Hodgkin lymphoma and small lymphocytic lymphoma who have received at least two prior systemic therapies. Obinutuzumab (GA101) is a glycoengineered type II, CD20 antibody that induces a high level of direct cell death. As a result of glycoengineering, obinutuzumab has increased affinity for FcγRIII on innate immune effector cells resulting in enhanced induction of ADCC and ADCP. Obinutuzumab has been approved for first line treatment of CLL patients in combination with chlorambucil in the US and Europe and is currently in pivotal clinical trials in indolent NHL and DLBCL. Previous work has shown the covalent BTK inhibitor ibrutinib can interfere with the immune effector function and ultimately in vivo efficacy of rituximab in preclinical models (Kohrt et al., Blood, 2014). As PI3K isoforms also play a role in immune effector cells and FcγR signaling we investigated the impact of PI3Kδ inhibition by the PI3Kδ selective inhibitor idelalisib on the immune effector function of obinutuzumab and rituximab. Experimental methods: The impact of idelalisib on NK cell mediated ADCC induction by obinutuzumab and rituximab was investigated in LDH release assays using WIL2-S, SU-DHL4 and Z138 target cells at plasma protein-binding adjusted clinically relevant concentrations mimicking exposure in patients. As a surrogate for NK cell activation CD16 levels and up-regulation of the degranulation marker CD107a were assessed by FACS. The impact on monocyte-derived macrophage mediated ADCP of WIL2-S cells was measured in a flow cytometry-based phagocytosis assay. Finally, depletion of CD19 positive B cells was determined in whole blood from healthy volunteers in flow cytometry-based whole blood assay. Results: In ADCC assays, no impact of idelalisib on ADCC at saturating concentration of obinutuzumab or rituximab (>1ug/ml) can be detected in LDH release assays with tumor cells targets (N=9 donors for WIL2-S, N>3 donors for SU-DHL-4 and Z138). Idelalisib did not alter obinutuzumab or rituximab ability to kill tumor cells by ADCC at low E:T ratio. Little to no increase of obinutuzumab or rituximab EC50 for LDH release, CD16 down regulation, or degranulation of NK cells could be detected depending on donor effector cells. ADCP assays were conducted with M2c polarized macrophages using WIL2-S as targets. Less than 30% inhibition of ADCP was observed in this assay at idelalisib concentration at protein binding-adjusted clinical Cmax. At idelalisib Cmax (4200 nM) the EC50 of obinutuzumab-mediated B cell depletion in healthy human whole blood was increased 3 to 5 times, whereas at Cmin (760 nM) idelalisib did not significantly influence obinutuzumab EC50 or maximal B cell depletion. Conclusions: PI3Kδ inhibition by idelalisib has minimal impact on the immune effector function of obinutuzumab (GA101) and rituximab as measured in NK cell-mediated ADCC, macrophage-mediated ADCP and whole blood B-cell depletion. Disclosures Herter: Roche: Employment. Palazzo:Gilead Sciences: Employment. Bacac:Roche: Employment. Grosmaire:Gilead Sciences: Employment. Frey:Gilead Sciences: Employment. Pflanz:Gilead Sciences: Employment. Liu:Gilead Sciences: Employment. Tannheimer:Gilead Sciences: Employment. Umana:Roche: Employment. Klein:Roche: Employment, Equity Ownership, Patents & Royalties. Queva:Gilead Sciences: Employment.

scholarly journals Comprehensive genetic and functional analysis of FcγRs in rituximab therapy for autoimmunity reveals a key role for FcγRIIIa on NK cells

2021 ◽  
Author(s):  
James I Robinson ◽  
Md Yuzaiful Md Yusof ◽  
Vinny Davies ◽  
Dawn Wild ◽  
Michael Morgan ◽  
...  
Keyword(s):  
B Cell ◽  
Clinical Response ◽  
Lupus Erythematosus ◽  
Killer Cell ◽  
Disease Status ◽  
Cell Depletion ◽  
B Cell Depletion ◽  
Patient Response ◽  
Functional Variants ◽  
The Impact

B cell depletion using rituximab is widely used to treat autoimmune diseases, but patient response varies. The efficacy of rituximab is limited by the efficiency of depletion. Strategies to improve response include altering rituximab dosing, switching anti-CD20-mAb, alternative B cell targets, or non-B cell targeted therapies. Implementing an appropriate strategy requires understanding of the mechanism(s) of resistance to depletion and, if this varies between individuals, a means to test for it. Rituximab kills B cells via a variety of Fcγ receptor (FcγR)-dependent mechanisms, including antibody-dependent cellular cytotoxicity (ADCC), as well as non-FcγR mechanisms. We conducted a longitudinal cohort study in rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) using two national registries. Qualitative and quantitative FCGR functional variants were measured using multiplexed ligation-dependent probe amplification, supplemented by novel FCGR2C assays. We provide consistent evidence that FCGR3A, specifically increased number of copies of the FCGR3A-158V allele, was the major FcγR gene associated with rituximab response, including clinical response in RA and SLE and depth of B cell depletion in the combined cohort. In SLE, we provide preliminary data suggesting increased FCGR2C ORF copies were also associated with improved clinical response. Furthermore, we demonstrated the impact of disease status and concomitant therapies on both natural killer cell FcγRIIIa expression and rituximab-induced ADCC; demonstrating increased FcγRIIIa expression and FCGR3A genotype were independently associated with clinical response and B cell depletion. Our findings highlight the importance of enhancing FcγR-effector functions, may help stratify patients, and support ongoing development of next-generation CD20 depleting therapeutics.

Sign in / Sign up

Export Citation Format

Share Document