Induction of NK Cell Reactivity Against AML Cells by Fc-Engineered RANK-Ig Fusion Proteins.

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 2625-2625
Author(s):  
Tina Nuebling ◽  
Benjamin J Schmiedel ◽  
Miyuki Azuma ◽  
Pascal Schneider ◽  
Ludger Grosse-Hovest ◽  
...  
Keyword(s):  
Fusion Protein ◽  
Nk Cells ◽  
Fusion Proteins ◽  
Nk Cell ◽  
Conflicts Of Interest ◽  
Residual Disease ◽  
Target Antigen ◽  
Dependent Manner ◽  
Cell Reactivity ◽  
Allogenic Stem Cell Transplantation

Abstract Abstract 2625 NK cells are cytotoxic lymphocytes that play an important role in anti-tumor immunity. A clinically important feature of NK cells is their ability to mediate antibody-dependent cellular cytotoxicity (ADCC) upon application of anti-tumor antibodies. In acute myeloid leukemia (AML) NK cells largely contribute to the therapeutic efficacy allogenic stem cell transplantation (SCT). Recently we demonstrated that AML cells functionally express the TNF family member RANK ligand (RANKL) which impairs NK cell anti-leukemia reactivity (Schmiedel et al., ASH annual meeting 2011). Here we developed a strategy to combine blocking of the NK inhibitory effects of RANKL with targeting of AML cells for NK cell ADCC. To this end we generated fusion proteins consisting of the extracellular domain of RANK and a human IgG1 Fc part that was modified by amino acid exchange. Compared to wild type RANK-Fc fusion protein (RANK-Fc-WT), our mutant RANK-Fc-ADCC (S239D/I332E) displayed highly enhanced affinity to FcγRIIIa (CD16) on NK cells. Primary AML cells expressed substantial levels of RANKL in 53 of 78 (68%) investigated patient cases, and our RANK-Ig fusion proteins bound to AML cells in a target antigen-specific manner. Treatment with both RANK-Fc-WT and RANK-Fc-ADCC clearly reduced the release of RANKL-induced immunomodulatory factors like TNF, IL-6, IL-8 and IL-10 by AML cells. When the effects of the fusion proteins on NK cell ADCC were studied we found that treatment with RANK-Fc-WT only slightly enhanced NK cell reactivity against RANKL-positive patient AML cells. However, RANK-Fc-ADCC potently induced NK cell ADCC and cytokine production in response to AML targets in a target antigen-dependent manner due to the functional properties of its engineered Fc moiety. Taken together, our Fc-engineered RANK-Fc-ADCC fusion protein may serve to modulate the cytokine milieu involved in AML pathophysiology and target RANKL-expressing leukemia cells for NK anti-tumor reactivity. Thus, RANK-Fc-ADCC constitutes an attractive immunotherapeutic means for the treatment of AML, e.g. for elimination of minimal residual disease after conventional therapy including SCT. Disclosures: No relevant conflicts of interest to declare.

Bimodal Induction of NK Cell Reactivity Against Acute Myeloid (AML) and Chronic Lymphoid Leukemia (CLL) by Fc-Engineered GITR-Fc Fusion Proteins.

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 2143-2143
Author(s):  
Julia Steinbacher ◽  
Benjamin J Schmiedel ◽  
Antje Werner ◽  
Tina Nuebling ◽  
Corina Buechele ◽  
...  
Keyword(s):  
Fusion Protein ◽  
Nk Cells ◽  
Fusion Proteins ◽  
Nk Cell ◽  
Conflicts Of Interest ◽  
Combined Treatment ◽  
Leukemia Cells ◽  
Target Antigen ◽  
Dependent Manner ◽  
Allogenic Stem Cell Transplantation

Abstract Abstract 2143 NK cells play an important role in anti-tumor immunity and largely contribute to the efficacy of therapeutic strategies like allogenic stem cell transplantation in AML and application of Rituximab that induces antibody-dependent cellular cytotoxicity (ADCC) in CLL. Recently, we demonstrated that the TNF family member GITR ligand (GITRL) is expressed on leukemia cells in a high proportion of AML and CLL patients and impairs direct and Rituximab-induced reactivity of NK cells which constitutively express its counterpart GITR (e.g., Buechele et al., Leukemia 2012). Here we developed a strategy to reinforce NK anti-leukemia reactivity by combining disruption of NK-inhibitory GITR-GITRL interaction with induction of ADCC against the GITRL-expressing leukemia cells using GITR-Ig fusion proteins with modified Fc moieties. Fc parts were engineered by amino acid exchange as previously described (Lazar et al., PNAS 2006; Armour et al., Eur. J. Immunol. 1999). Compared to wild type GITR-Ig (GITR-Fc-WT), our mutants (S239D/I332E and E233P/L234V/L235A/deltaG236/A327G/A330S) displayed highly enhanced (GITR-Fc-ADCC) and abrogated (GITR-Fc-KO) affinity to the Fc(gamma)RIIIa receptor (CD16) expressed on NK cells, respectively. In functional analyses of NK cells and primary leukemia cells, GITR-Fc-KO, which does not induce ADCC, already increased NK reactivity due to disruption of GITR-GITRL interaction. Treatment with GITR-Fc-WT further enhanced NK reactivity due to modest induction of ADCC, while GITR-Fc-ADCC induced highly increased NK-mediated target cell lysis, degranulation and cytokine production in a target-antigen dependent manner. With CLL cells, combined treatment with GITR-Fc-ADCC fusion protein and Rituximab caused additive effects, resulting in significantly enhanced NK cell ADCC. Notably, the effects of our fusion proteins were observed both in an allogenic setting and when employing NK cells of patients with autologous leukemia cells as targets. Our results demonstrate that Fc-engineered GITR-Fc-ADCC fusion protein may combine both neutralization of the NK-inhibitoryeffects of GITR-GITRL interaction and targeting GITRL-expressing malignant cells for NK anti-tumor reactivity and thus constitute an attractive immunotherapeutic means for the treatment of AML and CLL. Disclosures: No relevant conflicts of interest to declare.

Induction of NK Cell Reactivity in Breast Cancer by Fc-Engineered NKG2D-Ig Fusion Proteins

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 253-253
Author(s):  
Stefanie Raab ◽  
Julia Steinbacher ◽  
Ludger Grosse-Hovest ◽  
Benjamin J Schmiedel ◽  
Alexander Steinle ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Nk Cells ◽  
Cancer Cells ◽  
Fusion Proteins ◽  
Breast Cancer Cells ◽  
Cell Activation ◽  
Nk Cell ◽  
Conflicts Of Interest ◽  
Clinical Success ◽  
Cell Reactivity

Abstract Abstract 253 NK cells are cytotoxic lymphocytes that play an important role in anti-tumor immunity. Their capability to mediate Fc-receptor dependent effector functions like antibody dependent cellular cytotoxicity (ADCC) largely contributes to the clinical success of anti-tumor antibodies like Herceptin (Trastuzumab®), which is approved for treatment of breast cancer displaying HER2/neu-overexpression. Notably, only about 20% of breast cancer patients show overexpression of HER2/neu. Moreover, this antigen is also expressed on healthy cells, and application of Herceptin is associated with side effects. In contrast, ligands of the activating immunoreceptor NKG2D (NKG2DL) are widely expressed on malignant cells, but generally absent on healthy tissues. We aimed to take advantage of the tumor-restricted expression of NKG2DL by using them as tumor-antigens for Fc-optimized NKG2D-Ig fusion proteins targeting breast cancer cells for NK cell ADCC and IFN-γ production. NKG2D-Ig fusion proteins with distinct modifications in their Fc portion were generated by amino acid exchange as previously described (Lazar 2006; Armour 1999). Compared to wildtype NKG2D-Fc (NKG2D-Fc-WT) or Herceptin, our mutants (S239D/I332E and E233P/L234V/L235A/ΔG236/A327G/A330S) displayed highly enhanced (NKG2D-Fc-ADCC) and abrogated (NKG2D-Fc-KO) affinity to the NK cell FcγRIIIa receptor (CD16), respectively. This resulted in lacking (NKG2D-Fc-KO) or highly enhanced (NKG2D-Fc-ADCC) NK cell activation. In cultures of NK cells and breast cancer cells, NKG2D-Fc-KO significantly reduced NK cell reactivity due to blockade of NKG2DL-mediated activating signals, while NKG2D-Fc-WT substantially enhanced NK reactivity by induction of ADCC and cytokine production. Notably, the effect of our NKG2D-Fc-ADCC by far exceeded that of NKG2D-Fc-WT and, in case of HER2/neu low targets, also that of Herceptin, resulting in potently enhanced NK anti-tumor reactivity. Together, our results demonstrate that Fc-engineered NKG2D-Fc-ADCC fusion proteins can effectively target NKG2DL-expressing cancer cells for NK anti-tumor reactivity. In line with the hierarchically organized potential of the various activating receptors governing NK reactivity and due to its highly increased affinity to CD16 NKG2D-Fc-ADCC potently enhances NK cell reactivity despite the inevitable reduction of activating signals upon binding to NKG2DL. Due to the tumor-restricted expression of NKG2DL, NKG2D-Fc-ADCC may thus constitute an attractive means for immunotherapy, especially of HER2/neu-low or -negative breast cancer. Disclosures: No relevant conflicts of interest to declare.

Fc-Engineered NKG2D-IgG1 Fusion Proteins Target Leukemia Cells for Antibody-Dependent Cellular Cytotoxicity (ADCC) of NK Cells

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 1537-1537 ◽  
Author(s):  
Julia Hilpert ◽  
Katrin Baltz-Ghahremanpour ◽  
Benjamin J Schmiedel ◽  
Lothar Kanz ◽  
Gundram Jung ◽  
...  
Keyword(s):  
Nk Cells ◽  
Fusion Proteins ◽  
Nk Cell ◽  
Conflicts Of Interest ◽  
Leukemia Cell ◽  
Leukemic Cells ◽  
Leukemia Cells ◽  
Target Cells ◽  
Cellular Cytotoxicity ◽  
Antibody Dependent Cellular Cytotoxicity

Abstract Abstract 1537 The capability of anti-tumor antibodies to recruit Fc-receptor (FcR) bearing effector cells like NK cells, a feature considered critical for therapeutic success, can be markedly improved by modifications of the human IgG1 part. At present, Fc-engineered antibodies targeting leukemia cells are yet not available. The various ligands of the NK cell-activating immunoreceptor NKG2D (NKG2DL) are generally absent on healthy cells but upregulated on malignant cells of various origins including leukemia. We aimed to take advantage of the tumor-restricted expression of NKG2DL by using them as target-antigens for Fc-optimized NKG2D-IgG1 fusion proteins targeting leukemia cells for antibody-dependent cellular cytotoxicity (ADCC) and IFN-g production of NK cells. NKG2D-IgG1 fusion proteins with distinct modifications in their Fc portion were generated as previously described (Lazar 2006; Armour 1999). Compared to wildtype NKG2D-Fc (NKG2D-Fc-WT), the mutants (S239D/I332E and E233P/L234V/L235A/DG236/A327G/A330S) displayed highly enhanced (NKG2D-Fc-ADCC) and abrogated (NKG2D-Fc-KO) affinity to the NK cell FcgRIIIa receptor but comparable binding to NKG2DL-expressing target cells. Functional analyses with allogenic NK cells and leukemia cell lines as well as primary leukemic cells of AML and CLL patients revealed that NKG2D-Fc-KO significantly (p<0.05, Mann-Whitney U test) reduced NK cytotoxicity and IFN-g production (about 20% and 30% reduction, respectively), which can be attributed to blockade of NKG2DL-mediated activating signals. Treatment with NKG2D-Fc-WT significantly (p<0.05, Mann-Whitney U test) enhanced NK reactivity (about 20% and 100% increase in cytotoxicity and cytokine production, respectively). The effects observed upon treatment with NKG2D-Fc-ADCC by far exceeded that of NKG2D-Fc-WT resulting in at least doubled NK ADCC and IFN-g production compared to NKG2D-Fc-WT. When applied in combination with Rituximab in analyses with CLL cells, a clear additive effect resulting in a more than four-fold increase of ADCC and FcgRIIIa-induced IFN-g production was observed. The NKG2D-Fc fusion proteins did not induce NK reactivity against healthy blood cells, which is in line with the tumor-restricted expression of NKG2DL. Of note, treatment with NKG2D-Fc-ADCC also significantly (p<0.05, Mann-Whitney U test) enhanced reactivity (up to 70% increase) of NK cells against NKG2DL-positive AML and CLL cells among patient PBMC in an autologous setting. Together, our results demonstrate that Fc-engineered NKG2D-Fc-ADCC fusion proteins can effectively target NKG2DL-expressing leukemia cells for NK anti-tumor reactivity. In line with the hierarchically organized potential of the various activating receptors governing NK reactivity and due to their highly increased affinity to the FcgRIIIa receptor, NKG2D-Fc-ADCC potently enhances NK anti-leukemia reactivity despite the inevitable reduction of activating signals upon binding to NKG2DL. Due to the tumor-restricted expression of NKG2DL, Fc-modified NKG2D-Ig may thus constitute an attractive means for immunotherapy of leukemia. Disclosures: No relevant conflicts of interest to declare.

Fc-Engineered RANK-Fc Fusion Proteins for Neutralization of Soluble RANKL and Induction of Antibody-Dependent Cellular Cytotoxicity (ADCC) Against Multiple Myeloma

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3039-3039
Author(s):  
Benjamin J Schmiedel ◽  
Carolin Scheible ◽  
Tina Baessler ◽  
Constantin M Wende ◽  
Stefan Wirths ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Nk Cells ◽  
Fusion Proteins ◽  
Nk Cell ◽  
Conflicts Of Interest ◽  
Soluble Form ◽  
Target Cells ◽  
Published Data ◽  
Cellular Cytotoxicity ◽  
Antibody Dependent Cellular Cytotoxicity

Abstract Abstract 3039 Bone resorption is commonly associated with aging, but also with certain cancers. Recent studies identified Receptor Activator of NF-κB (RANK) ligand (RANKL) and its receptors RANK and osteoprotegerin as key regulators of bone remodelling. Multiple myeloma (MM) disrupts the balance within this molecule system towards osteoclastogenesis and bone destruction. Neutralization of RANKL by the monoclonal antibody Denosumab (AMG162) is presently being evaluated for treatment of both non-malignant and malignant osteolysis. We found, in line with previously published data, that primary MM cells (9 of 10) express substantial levels of RANKL at the cell surface and that MM cells directly release RANKL in soluble form (sRANKL). Next we evaluated the possibility to combine neutralization of sRANKL with targeting of MM cells for antibody-dependent cellular cytotoxicity (ADCC) of NK cells utilizing RANK-Ig fusion proteins with modified Fc portions. Compared to wildtype RANK-Fc, our mutants (S239D/I332E and E233P/L234V/L235A/DG236/A327G/A330S) displayed highly enhanced (RANK-Fc-ADCC) and abrogated (RANK-Fc-KO) affinity, respectively, to the NK cell FcγRIIIa, but comparable capacity to neutralize RANKL in binding competition and osteoclast formation assays. Analyses with RANKL transfectants and RANKL-negative controls confirmed the high and lacking potential of the RANK-Fc-ADCC and the RANK-Fc-KO to induce NK ADCC, respectively, and ascertained that the RANK-Fc-ADCC specifically induced NK cell lysis of RANKL-expressing but not RANKL-negative target cells. Most notably, in cultures of NK cells with RANKL-expressing primary MM cells RANK-Fc-ADCC potently enhanced NK cell degranulation, cytokine release and MM cells lysis due to enhanced NK reactivity. Thus, our Fc-engineered RANK-Fc-ADCC fusion protein may both neutralize detrimental effects of sRANKL and enhance NK anti-tumor reactivity by targeting RANKL-expressing malignant cells thereby constituting an attractive immunotherapeutic means for treatment of MM. Disclosures: No relevant conflicts of interest to declare.

Induction of NK Cell Reactivity Against Myeloid Leukemia By a Novel Fc-Optimized CD133 Antibody

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 3793-3793 ◽  
Author(s):  
Kathrin Rothfelder ◽  
Samuel Koerner ◽  
Maya Andre ◽  
Julia Leibold ◽  
Philaretos Kousis ◽  
...  
Keyword(s):  
Nk Cells ◽  
Progenitor Cells ◽  
Myeloid Leukemia ◽  
Nk Cell ◽  
Conflicts Of Interest ◽  
Residual Disease ◽  
Ex Vivo ◽  
Leukemic Cells ◽  
Hematopoietic Progenitor Cells ◽  
Hematopoietic Progenitor

Abstract NK cells largely contribute to the success of monoclonal antibody (mAb) application in cancer due to their ability to mediate antibody-dependent cellular cytotoxicity (ADCC), a feature considered critical for therapeutic success. Up to now, no immunotherapeutic antibodies are available for the treatment of myeloid leukemias. Recently, we reported on the development of mAb targeting CD133, which is expressed on a wide variety of tumor cells (Koerner et al., Blood 2014 124:2309). Here we extend our analyses and provide further data on the preclinical characterization of an Fc-engineered CD133 mAb for the treatment of myeloid leukemia. Compared to two other anti-human CD133 mAb (clones AC133 and W6B3), which both bound to primary AML and CML cells in 15/25 and 7/10 cases, respectively, clone 293C3 recognized the leukemic cells in 22/25 AML cases and 7/10 CML cases. Based on these results, clone 293C3 was chosen to generate chimeric mAb with either a wildtype Fc part (293C3-WT) or a variant containing amino acid exchanges (S239D/I332E) to enhance affinity to the activating Fc receptor CD16 on NK cells (293C3-SDIE). Treatment with 293C3-SDIE resulted in significantly enhanced activation, degranulation and lysis of primary CD133-positive AML cells by NK cells in allogeneic and autologous experimental ex vivo settings as compared to its wildtype counterpart. Considering the expression of CD133 on healthy hematopoietic progenitor cells, we further performed colony forming unit assays with healthy bone marrow (BM) cells. In line with the observed lower expression levels of CD133 on healthy compared to malignant hematopoietic cells no relevant toxicity of 293C3-SDIE at the level of committed hematopoietic progenitor cells was observed. Moreover, 293C3-SDIE did not induce lysis of of healthy BM cells by allogeneic or autologous NK cells. In a NOD.Cg-Prkdcscid IL2rgtmWjl/Sz (NSG) xenotransplantation model, induction of ADCC by treatment with 293C3-SDIE resulted in the elimination of patient AML cells by NK cells from a matched human donor. Thus, 293C3-SDIE constitutes an attractive immunotherapeutic compound, in particular for the elimination of minimal residual disease in CD133 bearing leukemia in the context of allogenic SCT. Disclosures No relevant conflicts of interest to declare.

Glucocorticoid-Induced TNFR-Related Protein (GITR) Ligand Mediates Tumor Immunoediting in Chronic Lymphocytic Leukemia and Impairs Direct and Rituximab-Induced NK Cell Anti-Leukemia Reactivity.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 4403-4403
Author(s):  
Corina Buechele ◽  
Tina Baessler ◽  
Benjamin J Schmiedel ◽  
Lothar Kanz ◽  
Helmut R Salih
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
Nk Cells ◽  
Tumor Immunity ◽  
Nk Cell ◽  
Conflicts Of Interest ◽  
Inhibitory Effect ◽  
Lymphocytic Leukemia ◽  
Cell Reactivity ◽  
Immune Effector ◽  
Ifn Γ

Abstract Abstract 4403 Members of the TNF/TNF receptor (TNFR) family of proteins govern differentiation, proliferation, activation, and death of both tumor and immune effector cells and thus play an important role in tumor immunoediting, the reciprocal interaction of tumor cells and anti-tumor immunity. Activation of the TNFR family member GITR has recently been shown to stimulate T cell-mediated anti-tumor immunity in mice. However, available data suggest that GITR mediates different effects in mice and men, and may impair anti-tumor immunity of human NK cells. Here we studied the expression and function of GITR ligand (GITRL) in patients with chronic lymphocytic leukemia (CLL) and the consequences of GITR-GITRL interaction for NK cell reactivity against CLL cells. Substantial GITRL expression was detected on primary B-CLL cells in 38 of 48 (79%) investigated patients. Upon interaction with its cognate receptor, GITRL induced the release of immunoregulatory cytokines like TNF by the leukemia cells, which demonstrated that CLL-expressed GITRL is functional and capable to transduce bidirectional signals. Moreover, disruption of GITR-GITRL interaction in cultures of allogenic NK cells with patient CLL cells by addition of blocking antibody caused a significant increase in NK cell granule mobilization, cytotoxicity and IFN-γ production. The inhibitory effect of tumor-expressed GITRL on the reactivity of human NK cells was also confirmed in cocultures of C1R lymphoma cells transfected to express GITRL with mock transfectants serving as control. In addition, blocking GITR-GITRL interaction also considerably augmented both antibody-dependent cellular cytotoxicity (ADCC) and antibody-induced IFN-γ production of NK cells in cultures with allogenic CLL cells upon Rituximab exposure. Of note, GITR blockade also significantly enhanced anti-leukemia reactivity of autologous NK cells among PBMC of B-CLL patients, and this reinforcement of NK cell effector functions was observed both regarding the direct and, more pronounced, Rituximab-induced anti-leukemia reactivity (both n=10, p<0.01, Student's T test). Thus, expression of functional GITRL by CLL cells potently influences tumor immunoediting and impairs anti-tumor immunity by diminishing both direct and Rituximab-dependent anti-leukemia reactivity of NK cells. Modulation of the GITR-GITRL system might therefore serve to enhance the efficacy of therapeutic approaches in CLL which, like Rituximab-induced ADCC or stem cell transplantation, rely on a sufficient NK cell anti-tumor response. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Immunocytokines with Target Cell-Restricted IL-15 Activity for Induction of NK Cell Reactivity Against Acute Myeloid Leukemia (AML)

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 731-731
Author(s):  
Bastian J. Schmied ◽  
Latifa Zekri ◽  
Martin Pflügler ◽  
Melanie Märklin ◽  
Lothar Kanz ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Nk Cells ◽  
Target Cell ◽  
Nk Cell ◽  
Target Antigen ◽  
Cytokine Release ◽  
Cell Reactivity ◽  
Flow Cytometric ◽  
Patent Applications ◽  
Xenotransplantation Model

Abstract Introduction: The efficacy of monoclonal antibodies (mAbs), which have substantially improved treatment options for cancer patients, largely relies on their ability to induce antibody-dependent cellular cytotoxicity (ADCC) of NK cells. Recently, we have introduced Fc-optimized (SDIE modification) antibodies targeting CD133 and CD135 (FLT3) with improved capacity to induce NK cell reactivity against AML cells (Koerner et al, Leukemia 2017; Hofmann et al, Leukemia 2012). Our FLT3 mAb termed FLYSYN is currently clinically evaluated in AML patients with minimal residual disease (NCT02789254). Notably, NK cell reactivity can be substantially increased by the cytokine IL-15, but clinical application of truly effective doses is currently prevented by substantial side effects due to unspecific immune activation (Conlon et al, JCO 2015). To overcome this limitation and to strengthen therapeutic efficacy, we fused our Fc-optimized CD133 and CD135 mAbs to an IL-15 mutant with abolished binding to IL-15 receptor α (IL-15Rα). The resulting modified immunocytokines (MIC) should substitute trans-presentation of IL-15 by binding to their target antigens on leukemic cells which facilitates stimulation of IL-15Rβ/γ on NK cells. Methods: Comparative analysis of MIC133/MIC135 binding to target cells, target antigen expression and induction of antigen shift was performed by flow cytometry using primary AML cells and target antigen transfected cell lines. NK cell activation was monitored by flow cytometric analyses of activation markers such as CD69 and CD25. Cytokine release, in particular that of IFN-γ, was measured by ELISA. Target cell killing in cocultures of healthy peripheral blood mononuclear cells (PBMC) with primary AML cells or target antigen transfected cell lines was studied by Europium, Xcelligence and flow cytometry based assays. Toxicity against healthy FLT3 expressing cells was studied by flow cytometric analysis of monocytes, dendritic cells and CD34+ cells within healthy PBMC or bone marrow. For in vivo analysis, MIC135 was tested in a NOD.Cg-Prkdc(scid)IL2rg(tmWjl)/Sz xenotransplantation model by inducing leukemia with primary AML cells and polyclonal NK cells as effector cells. Results: Functional analyses confirmed target antigen-restricted binding of MIC133/MIC135 with saturating doses reached at approximately 1µg/ml. FLT3 was found to be expressed on primary AML cells with significantly higher extent and to be less susceptible to antigen shift compared to CD133. Analysis of activation and cytokine release, the latter being particularly relevant for side effects, demonstrated that MIC proteins stimulate NK cells in a target cell-restricted manner and to a profoundly greater extent than their Fc-optimized counterparts without IL-15. In line, target cell killing induced by either MIC was clearly superior to that of the respective Fc-optimized CD133 and FLT3 mAbs as revealed by various experimental systems using primary AML cells. MIC135, which was chosen for further development due to its superior characteristics described above, did not induce unwanted effects against healthy FLT3 expressing cells and potently reduced leukemic burden in a NSG xenotransplantation model with primary AML and polyclonal NK cells. Conclusion: In summary, MIC stimulate NK cells in a target cell-restricted manner, clearly outperform Fc-optimized antibodies and thus constitute a promising treatment option for AML. Disclosures Jung: Several patent applications: Patents & Royalties: e.g. EP3064507A1. Salih:Several patent applications: Patents & Royalties: e.g. EP3064507A1.

4-1BB Ligand Mediates a “Vicious Cycle” of Immune Evasion Upon Reciprocal Interaction of Chronic Lymphocytic Leukemia and NK Cells

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 2416-2416
Author(s):  
Corina Buechele ◽  
Tina Baessler ◽  
Benjamin J Schmiedel ◽  
Lothar Kanz ◽  
Helmut R. Salih
Keyword(s):  
Chronic Lymphocytic Leukemia ◽  
Nk Cells ◽  
Immune Evasion ◽  
Nk Cell ◽  
Lymphocytic Leukemia ◽  
Antibody Treatment ◽  
Cell Reactivity ◽  
Allogenic Stem Cell Transplantation ◽  
Immunoregulatory Cytokines ◽  
Healthy Donors

Abstract Abstract 2416 NK cells play an important role in tumor immunosurveillance. Their reactivity is governed by various immunoregulatory molecules, which influence both direct anti-tumor immunity and NK responses induced by therapeutic antibodies like Rituximab. Various members of the TNF/TNFR family modulate differentiation, proliferation, activation, and death of both tumor and immune effector cells including NK cells. Recently we reported that the TNFR family member 4-1BB/CD137 is expressed on human NK cells following activation. In contrast to the stimulatory role of its murine counterpart, we found that human 4-1BB impairs NK anti-tumor reactivity upon interaction with its ligand 4-1BBL expressed on blasts of a substantial proportion of acute myeloid leukemia patients (Blood 115: 3058-69; 2010). In addition, we found that expression of 4-1BBL is general feature of leukemic cells of chronic lymphocytic leukemia (CLL) patients causing impaired direct and Rituximab-induced NK cell reactivity (Blood 114: 279; 2009). Here we report that reverse signaling via 4-1BBL into CLL cells following interaction with 4-1BB, which is absent on NK cells of healthy donors, but expressed at substantial levels on NK cells of CLL patients, induced pronounced production of immunoregulatory cytokines like TNF, IL-6 and IL-8 by the CLL cells. Moreover, we found that sera of CLL patients contained elevated levels of these immunoregulatory cytokines as compared to healthy controls. When PBMC of healthy donors were exposed to supernatants of in vitro cultured CLL cells or sera from CLL patients, this resulted in pronounced 4-1BB expression on the NK cells. This effect could be prevented by addition of the TNF blocker Infliximab to patient sera. The 4-1BB expression induced by CLL sera resulted in impaired NK reactivity specifically against 4-1BBL-expressing targets as revealed by functional analyses with 4-1BBL transfectants and the respective mock-controls. Moreover, the induced 4-1BB expression also impaired NK cell reactivity against primary CLL cells constitutively expressing 4-1BBL, thus closing a cycle of immune evasion. Taken together, our data demonstrate that 4-1BBL enables CLL cells to evade NK anti-tumor reactivity, and disruption of the “vicious 4-1BB-4-1BBL cycle” in CLL - NK interaction e.g. by TNF- or 4-1BB-blockade may serve well to enhance NK reactivity in therapeutic strategies like antibody treatment or allogenic stem cell transplantation in CLL, which rely on sufficient NK cell function. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Development and Preclinical Characterization of an Fc-Optimized CD133 Antibody for Induction of NK Cell Reactivity Against Myeloid Leukemia

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 2309-2309 ◽  
Author(s):  
Samuel Koerner ◽  
Julia Leibold ◽  
Ludger Grosse-Hovest ◽  
Hans-Joerg Buehring ◽  
Gundram Jung ◽  
...  
Keyword(s):  
Nk Cells ◽  
Progenitor Cells ◽  
Myeloid Leukemia ◽  
Nk Cell ◽  
Conflicts Of Interest ◽  
Fc Receptor ◽  
Hematopoietic Progenitor Cells ◽  
Hematopoietic Progenitor ◽  
Allogenic Stem Cell Transplantation

Abstract NK cells are cytotoxic lymphocytes that play a major role in anti-tumor immunity and largely contribute to the efficacy of allogenic stem cell transplantation (SCT) in leukemia. Another clinically important feature of NK cells is their ability to mediate antibody-dependent cellular cytotoxicity (ADCC) upon application of monoclonal antibodies (mAb) like Rituximab, a feature considered critical for the therapeutic success of antibody treament. Modifications of the human IgG1 Fc-part in anti-tumor antibodies lead to markedly improved capability to recruit Fc-receptor bearing effector cells as highlighted by the improved clinical efficacy of the Fc-engineered CD20 antibody Ofatumumab as compared to its unmodified counterpart Rituximab in CLL. So far, no immunotherapeutic antibodies are available for the treatment of myeloid leukemias. Here we report on the development and preclinical characterization of an Fc-optimized mAb directed towards CD133, which is expressed on a wide variety of malignant cell types. As a first step we evaluated binding of three different mouse anti-human CD133 mAbs (clones AC133, W6B3 and 293C3) to 20 primary AML and 6 primary CML samples in order to identify a clone with optimal binding characteristics. AC133 and W6B3 comparably bound to the leukemic cells in 11/20 AML and 5/6 CML samples. In contrast, binding of 293C3 was observed in 18/20 AML cases and 5/6 CML cases. Thus, 293C3 recognizes a different epitope than the other two antibody clones, which is expressed in a high proportion of myeloid leukemia cases. Accordingly, 293C3 was selected for generating chimeric mAbs with either a wildtype Fc part (293C3-WT) or a variant containing distinct modifications (S239D/I332E) to enhance its affinity to the activating Fc receptor CD16 (293C3-SDIE). The binding specificity of 293C3-WT and 293C3-SDIE was validated by FACS in analyses with CD133 transfectants and mock controls. When comparing 293C3-WT and 293C3-SDIE with regard to their immunostimulatory properties, we found that already 293C3-WT induced NK cell ADCC against primary leukemia cells as revealed by analyses of degranulation and target cell lysis. These effects were by far exceeded by treatment with 293C3-SDIE, confirming the functional relevance of the SDIE modification in its Fc part. Notably, treatment with 293C3-SDIE also enhanced the reactivity of NK cells against CD133-positive AML cells in an autologous setting. Considering the expression of CD133, among others, on healthy hematopoietic progenitor cells, we further performed colony forming unit assays with healthy bone marrow cells, which did not reveal any toxicity of 293C3-SDIE at the level of committed hematopoietic progenitor cells. Thus, 293C3-SDIE constitutes an attractive immunotherapeutic compound which we envisage in particular for the elimination of minimal residual disease in CD133 bearing leukemia, especially in the context of allogenic SCT. Disclosures No relevant conflicts of interest to declare.

A Fc-Engineered RANK-Fc Fusion Protein Neutralizes Soluble RANK Ligand and Targets Malignant Hematopoietic Cells for NK Cell Reactivity.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 411-411
Author(s):  
Benjamin J Schmiedel ◽  
Tina Baessler ◽  
Carolin Scheible ◽  
Constantin M Wende ◽  
Miyuki Azuma ◽  
...  
Keyword(s):  
Fusion Protein ◽  
Nk Cells ◽  
Cytokine Production ◽  
Nk Cell ◽  
Target Cells ◽  
Cell Reactivity ◽  
Nk Cell Cytotoxicity ◽  
Student’S T ◽  
Negative Controls ◽  
Student’S T Test

Abstract Abstract 411 Bone resorption is commonly associated with aging, but also with certain cancers. Recent studies identified Receptor Activator of NFκB (RANK) ligand (RANKL) and its receptors RANK and osteoprotegerin (OPG) as key regulators of bone resorption. Multiple myeloma (MM) disrupts the balance within this molecule system, and severe bone destruction due to inappropriate osteoclastogenesis is a prominent feature of this disease. Besides MM cells, other malignant hematopoietic cells have also been found to express RANKL at the cell surface and to release this molecule in soluble form (sRANKL). Neutralization of RANKL using RANK-Fc fusion protein or monoclonal antibody (Denosumab/AMG162), which mimics the RANKL-neutralizing endogenous effects of osteoprotegerin, decreases osteolysis in multiple in vivo models and is presently being evaluated as a means to treat both non-malignant and malignant osteolysis. We here confirmed and extended previously published data and report that all investigated MM cell lines (n = 5) as well as primary leukemic cells of CLL patients (n = 12) displayed substantial levels of RANKL mRNA and surface expression. Moreover, we report that substantial levels of sRANKL can be detected in culture supernatants of MM and primary CLL cells, but not in supernatants of healthy PBMC. Next we engineered RANK-Fc fusion proteins with modified affinity to FcγR by mutating amino acids in the Fc portion as previously described (Lazar et al., PNAS 2006; Armour et al., Eur J Immunol 1999). Compared to wildtype RANK-Fc (RANK-Fc-wt), our mutants (S239D/I332E and E233P/L234V/L235A/DeltaG236/A327G/A330S) displayed highly enhanced and abrogated (RANK-Fc-ADCC+ and RANK-Fc-KO, respectively) affinity to FcγRIIIa expressed on NK cells, which play an important role in anti-tumor immunity due to their ability to lyse target cells directly and to mediate antibody-dependent cellular cytotoxicity (ADCC) upon application of therapeutic antibodies. The RANK-Fc-ADCC+ displayed similar capacitiy to neutralize sRANKL compared to the RANK-Fc-KO and the RANK-Fc-wt as revealed by binding competition assays. Next we cultured NK cells with L cells or P815 cells transfected to express RANKL and the parental, RANKL-negative controls in the presence or absence of the different RANK-Fc constructs. Addition of RANK-Fc-KO or RANK-Fc-wt did not substantially alter NK cell reactivity against the target cells. However, presence of the RANK-Fc-ADCC+ dramatically enhanced NK cell cytotoxicity and cytokine production in cultures with the RANKL-expressing target cells (increase from 20% to 89%, E:T ratio 30:1 and 12 pg/ml to 290 pg/ml respectively; both p<0.01, Student's t-test). Neither of the three RANK-Fc proteins altered NK cell cytotoxicity and cytokine production in cultures with the RANKL negative controls demonstrating that the RANK-Fc-ADCC+ specifically induced NK cell reactivity against RANKL-expressing malignant cells. Moreover, treatment with RANK-Fc-ADCC+ also significantly augmented NK cell anti-tumor reactivity in cultures with RANKL-expressing primary CLL cells of patients, and this was observed both in settings using allogenic NK cells and analyzing autologous NK cells among PBMC of the leukemia patients (both p<0.01, Student's t-test). Taken together, our Fc-engineered RANK-Fc-ADCC+ fusion protein may neutralize detrimental effects of sRANKL, can target RANKL-expressing malignant cells for NK cell anti-tumor reactivity and may thus constitute an attractive immunotherapeutic means for treatment of hematopoietic malignancies. Disclosures: No relevant conflicts of interest to declare.

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