Phenotypic and functional changes of NK cells in patients with myelodysplastic syndrome and acute myeloid leukemia treated with hypomethylating drugs

Natural killer cells (NK cells) are cytotoxic lymphocytes that play a pivotal role in maintaining immunological surveillance and in developing an innate immune response. Since the discovery of NK cells in 1973, the mechanisms of their functioning have been studied in details, and there is currently no doubt that they play a special role in the process of recognition and destruction of transformed and malignant cells. Understanding the role of NK cells in antitumor immunity, on the one hand, leads to emergence of new immunotherapeutic strategies and, on the other hand, allows to adjust the existing treatment regimens for tumor diseases, in accordance with the principle of primum non nocere. Optimization of cancer therapy protocols executed in order to protect immune cells from death and functional impairment is an important problem that cannot be successfully resolved without regular aggregation of the results from disparate studies and critical analysis of the all accumulated data.The objective of this review is to create a relevant and holistic picture of changes in the phenotypic and functional characteristics of NK cells in patients with two related hematological diseases – myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). For the treatment of both illnesses, drugs from the group of hypomethylating agents are used, the acting mechanism of which, unlike classical cytostatic agents, is based on modulation of the tumor cell genes expression. All the cells of the body are being affected, including NK cells, since these drugs act nonspecifically. Such an interaction leads to a hypomethylation of NK cell DNA and changes the expression of functional receptors, which, in turn, provide the development of antitumor NK cell immune response.Of course, just the fact of changing gene expression in certain cells does not allow us to fully judge the drug’s impact on the state of immune system. Meanwhile, the origin of this change and its role are important in the context of the disease pathogenesis. Ultimately, a simple description of an increase or decrease in a single receptor expression is not illustrative, since it can lead to uncertain consequences. For this reason, the current review, in addition to describing the existing data on the changes of NK cell receptors expression under the influence of hypomethylating drugs, gives a special attention to critical analysis of functional characteristics of NK cells, including their cytotoxic activity aimed at malignant blast cells, being a determinant of clinical course in the described diseases.

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Tumor-Derived Microvesicles From Sera of Patients with Acute Myeloid Leukemia Suppresses NK Cell Cytotoxicity Via Transforming Growth Factor Beta-1.

Blood ◽

10.1182/blood.v114.22.2678.2678 ◽

2009 ◽

Vol 114 (22) ◽

pp. 2678-2678

Author(s):

Miroslaw J Szczepanski ◽

Marta E Szajnik ◽

Malgorzata Czystowska ◽

Magis Mandapathil ◽

Ann Welsh ◽

...

Keyword(s):

Acute Myeloid Leukemia ◽

Nk Cells ◽

Myeloid Leukemia ◽

Nk Cell ◽

Receptor Expression ◽

Cell Cytotoxicity ◽

Western Blots ◽

Cell Suppression ◽

Nk Cell Cytotoxicity ◽

Acute Myeloid

Abstract Abstract 2678 Poster Board II-654 Natural killer (NK) cell cytotoxicity in patients with acute myeloid leukemia (AML) is significantly decreased relative to that in normal controls (NC). However, the mechanisms responsible for low NK cell activity in AML are not known. We considered the possibility that tumor-cell-derived microvesicles (MV) mediate suppression of NK cells. MV originate from the endosomal compartment of activated normal and neoplastic cells. Evidence suggests that tumor-derived MV exert detrimental effects on cells of the immune system and may play a role in tumor progression. To determine their contribution to immune suppression in AML, MV were isolated from sera of patients newly diagnosed with AML prior to any treatment and used to evaluate MV-mediated NK cell suppression. The protein content of MV isolated using exclusion chromatography and ultracentrifugation from sera of 19 AML patients was significantly higher than that of MV isolated from sera of 25 NC (75μg±12/mL vs 1.2μg±0.4/mL, p<0.001 ). MV from AML patients were positive for membrane-associated TGFb-1 and FasL in Western blots, whereas no TGFb-1 or FasL was detected in MV from NC. For functional assays, NK cells sorted from peripheral blood of NC were cultured with MV isolated from sera of the AML patients. A significant decrease in NK cell cytotoxicity was observed after co-incubation with MV (2412 LU before vs 1640 LU after, p<0.002). Concomitantly, a decrease in the expression of the NK cell activating receptor, NKG2D, was observed (57% before vs 38% after, p<0.001). The addition of TGFb1-neutralizing antibody abrogated the effects of MV on the NK cell cytotoxicity and receptor expression. The increased levels in sera of AML patients of MV mediating potent NK cell suppression is likely to compromise anti-tumor immune responses. Therefore, modulation of the levels and functions of MV might provide new immunotherapeutic approaches in AML. Disclosures: No relevant conflicts of interest to declare.

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A phase I clinical trial testing the safety of IL-21-expanded, off-the-shelf, natural killer cells for relapsed/refractory acute myeloid leukemia and myelodysplastic syndrome.

Journal of Clinical Oncology ◽

10.1200/jco.2020.38.15_suppl.tps7562 ◽

2020 ◽

Vol 38 (15_suppl) ◽

pp. TPS7562-TPS7562

Author(s):

Sumithira Vasu ◽

Nidhi Sharma ◽

Lynn Odonnell ◽

Kevin Bosse ◽

Dean Anthony Lee

Keyword(s):

Clinical Trial ◽

Acute Myeloid Leukemia ◽

Myelodysplastic Syndrome ◽

Phase I ◽

Nk Cells ◽

Natural Killer ◽

Myeloid Leukemia ◽

Nk Cell ◽

Third Party ◽

Acute Myeloid

TPS7562 Background: Allogeneic transplantation (Allo-HCT) demonstrates the enduring and potent role of the immune system in the control and eradication of acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). However, patients with relapsed, refractory (R/R) disease or comorbidities are not eligible for Allo-HCT. We sought to develop an allogeneic Natural killer (NK) cell-based immunotherapy approach to induce remission for these patients. The efficacy of haploidentical NK cells expanded ex vivo using a K562 feeder-cell line transfected with IL-21 and 41BBL has been established in R/R AML patients. However, haploidentical donor-derived NK cell manufacturing exceeds three weeks with the possibility of fulminant malignancy rendering patients ineligible for cellular therapy. To address this limitation we established a third-party NK cell bank derived from KIR and HLA-mismatched ‘ideal’ donors that allows scalable, affordable mass-production of large numbers of NK cells suitable for banking and immediate ‘off-the-shelf’ (OTS) administration to a broad population of recipients. Methods: This phase I study follows a 3+3 design to investigate the safety of mIL-21-expanded, third-party, OTS NK cells for treatment of R/R AML and MDS patients. Patients aged ≥18 or ≤80 years are enrolled into two cohorts: those <60 years and able to tolerate intensive chemo will receive Fludarabine 30mg/m2/day (days -6 to -2) and Cytarabine 2g/m2/day (days -6 to -2). Patients >60 years or <60 years and unable/unwilling to tolerate intensive chemo will receive Fludarabine 30mg/m2/day (days -5 to -2) and Decitabine 20mg/m2/day (days -6 to -2). All patients subsequently receive a total of 6 infusions of NK cells administered thrice weekly for two weeks (between days 0-21) and will be followed up to day 56 from first NK cell infusion. Three NK cell dose-levels: 1x107, 3x107 and 1x108 cells/kg/dose will be explored to determine maximum tolerated dose (MTD). 3-18 patients/cohort/dose may be enrolled for MTD determination plus an additional 10 patients/dose in an expansion phase (maximum 28/cohort = 56 total subjects). Primary objective is to determine safety and feasibility of NK cell infusions. Secondary objectives will explore rates of remission PFS, overall survival and measurable residual disease negativity, cell counts, infectious complications, and patients proceeding to transplant. Enrollment in dose level 1 has started. Clinical trial information: NCT04220684 .

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PVRIG is a novel NK cell immune checkpoint receptor in acute myeloid leukemia

Haematologica ◽

10.3324/haematol.2020.258574 ◽

2020 ◽

pp. 0-0

Author(s):

Jessica Li ◽

Sarah Whelan ◽

Maya F. Kotturi ◽

Deborah Meyran ◽

Criselle D’Souza ◽

...

Keyword(s):

Acute Myeloid Leukemia ◽

Cell Surface ◽

Nk Cells ◽

Immune Checkpoint ◽

Myeloid Leukemia ◽

Cell Activation ◽

Nk Cell ◽

Blocking Antibody ◽

Poliovirus Receptor ◽

Acute Myeloid

This study explored the novel immune checkpoint poliovirus receptor-related immunoglobulin domain-containing (PVRIG) in acute myeloid leukemia (AML). We showed that AML patient blasts consistently expressed the PVRIG ligand (poliovirus receptor-related 2, PVRL2). Furthermore, PVRIG blockade significantly enhanced NK cell killing of PVRL2+, poliovirus receptor (PVR)lo AML cell lines, and significantly increased NK cell activation and degranulation in the context of patient primary AML blasts. However, in AML patient bone marrow, NK cell PVRIG expression levels were not increased. To understand how PVRIG blockade might potentially be exploited therapeutically, we investigated the biology of PVRIG and revealed that NK cell activation resulted in reduced PVRIG expression on the cell surface. This occurred whether NK cells were activated by tumour cell recognition, cytokines (IL-2 and IL-12) or activating receptor stimulation (CD16 and NKp46). PVRIG was present at higher levels in the cytoplasm than on the cell surface, particularly on CD56bright NK cells, which further increased cytoplasmic PVRIG levels following IL-2 and IL-12 activation. PVRIG was continually transported to the cell surface via the endoplasmic reticulum (ER) and Golgi in both unstimulated and activated NK cells. Taken together, our findings suggest that anti- PVRIG blocking antibody functions by binding to surface-bound PVRIG, which undergoes rapid turnover in both unstimulated and activated NK cells. We conclude that the PVRIGPVRL2 immune checkpoint axis can feasibly be targeted with PVRIG blocking antibody for NK-mediated immunotherapy of PVRL2+ AML.

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852 Trifunctional NKp46/CD16a-NK cell engager targeting CD123 overcomes acute myeloid leukemia resistance to ADCC

Journal for ImmunoTherapy of Cancer ◽

10.1136/jitc-2021-sitc2021.852 ◽

2021 ◽

Vol 9 (Suppl 3) ◽

pp. A893-A893

Author(s):

Laurent Gauthier ◽

Angela Virone-Oddos ◽

Jochen Beninga ◽

Benjamin Rossi ◽

...

Keyword(s):

Acute Myeloid Leukemia ◽

Antitumor Activity ◽

Nk Cells ◽

Myeloid Leukemia ◽

Nk Cell ◽

Ex Vivo ◽

Activating Receptors ◽

Acute Myeloid

BackgroundThere is a clear need for targeted therapies to treat acute myeloid leukemia (AML), the most common acute leukemia in adults. CD123 (IL-3 receptor alpha chain) is an attractive target for AML treatment.1 However, cytotoxic antibody targeting CD123 proved insufficiently effective in a combination setting in phase II/III clinical trials.2 T-cell engagers targeting CD123 displayed some clinical efficacy but were often associated with cytokine release syndrome and neurotoxicity.3 Interest in the use of NK cells for therapeutic interventions has increased in recent years, as a potential safer alternative to T cells. Several NK-cell activating receptors, such as CD16a, NKG2D, and the natural cytotoxicity receptors NKp30 and NKp46, can be targeted to induce antitumor immunity. We previously reported the development of trifunctional NK-cell engagers (NKCEs) targeting a tumor antigen on cancer cells and co-engaging NKp46 and CD16a on NK cells.4MethodsWe report here the design, characterization and preclinical development of a novel trifunctional NK cell engager (NKCE) targeting CD123 on AML cells and engaging the activating receptors NKp46 and CD16a on NK cells. The CD123 NKCE therapeutic molecule was engineered with humanized antibodies targeting NKp464 and CD123.5 We compared CD123-NKCE and a cytotoxic ADCC-enhanced antibody (Ab) targeting CD123, in terms of antitumor activity in vitro, ex vivo and in vivo. Pharmacokinetic, pharmacodynamic and safety profile of CD123-NKCE were evaluated in non-human primate (NHP) studies.ResultsThe expression of the high affinity Fc gamma receptor CD64 on patient-derived AML cells inhibited the ADCC of the Ab targeting CD123 in vitro and ex vivo, but not the antitumor activity of CD123-NKCE. CD123-NKCE had potent antitumor activity against primary AML blasts and AML cell lines, promoted strong NK-cell activation and induced cytokine secretion only in the presence of AML target cells. Its antitumor activity in mouse model was greater than that of the comparator antibody. Moreover, CD123-NKCE had strong and prolonged pharmacodynamic effects in NHP when used at very low doses, was well-tolerated up to high 3 mg/kg dose and triggered only minor cytokine release.ConclusionsThe data for activity, safety, pharmacokinetics, and pharmacodynamics provided here demonstrate the superiority of CD123-NKCE over comparator cytotoxic antibody, in terms of antitumor activity in vitro, ex vivo, in vivo, and its favorable safety profile, as compared to T-cell therapies. These results constitute proof-of-principle for the efficacy of CD123-NKCE for controlling AML tumors in vivo, and provide consistent support for their clinical development.ReferencesEhninger A, Kramer M, Rollig C, et al. Distribution and levels of cell surface expression of CD33 and CD123 in acute myeloid leukemia. Blood Cancer J 2014;4:e218.Montesinos P, Gail J Roboz GJ, et al. Safety and efficacy of talacotuzumab plus decitabine or decitabine alone in patients with acute myeloid leukemia not eligible for chemotherapy: results from a multicenter, randomized, phase 2/3 study. Leukemia 2021;35(1):62–74.Uy GL, Aldoss I, Foster MC, et al. Flotetuzumab as salvage immunotherapy for refractory acute myeloid leukemia. Blood 2021;137(6):751–762.Gauthier L, Morel A, Anceriz N, et al. Multifunctional natural killer cell engagers targeting NKp46 trigger protective tumor immunity. Cell 2019;177(7):1701–13.Jin L, Lee EM, Ramshaw HS, et al. Monoclonal antibody-mediated targeting of CD123, IL-3 receptor alpha chain, eliminates human acute myeloid leukemic stem cells. Cell Stem Cell 2009;5:31–42.

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Characterization of the DNAM-1, TIGIT and TACTILE Axis on Circulating NK, NKT-Like and T Cell Subsets in Patients with Acute Myeloid Leukemia

Cancers ◽

10.3390/cancers12082171 ◽

2020 ◽

Vol 12 (8) ◽

pp. 2171

Author(s):

Isabel Valhondo ◽

Fakhri Hassouneh ◽

Nelson Lopez-Sejas ◽

Alejandra Pera ◽

Beatriz Sanchez-Correa ◽

...

Keyword(s):

T Cells ◽

Acute Myeloid Leukemia ◽

T Cell ◽

Healthy Volunteers ◽

Nk Cells ◽

Myeloid Leukemia ◽

Cell Activation ◽

Nk Cell ◽

T Cell Subsets ◽

Acute Myeloid

Background: Acute myeloid leukemia (AML) remains a major clinical challenge due to poor overall survival, which is even more dramatic in elderly patients. TIGIT, an inhibitory receptor that interacts with CD155 and CD112 molecules, is considered as a checkpoint in T and NK cell activation. This receptor shares ligands with the co-stimulatory receptor DNAM-1 and with TACTILE. The aim of this work was to analyze the expression of DNAM-1, TIGIT and TACTILE in NK cells and T cell subsets in AML patients. Methods: We have studied 36 patients at the time of diagnosis of AML and 20 healthy volunteers. The expression of DNAM-1, TIGIT and TACTILE in NK cells and T cells, according to the expression of CD3 and CD56, was performed by flow cytometry. Results: NK cells, CD56− T cells and CD56+ T (NKT-like) cells from AML patients presented a reduced expression of DNAM-1 compared with healthy volunteers. An increased expression of TIGIT was observed in mainstream CD56− T cells. No differences were observed in the expression of TACTILE. Simplified presentation of incredibly complex evaluations (SPICE) analysis of the co-expression of DNAM-1, TIGIT and TACTILE showed an increase in NK and T cells lacking DNAM-1 and co-expressing TIGIT and TACTILE. Low percentages of DNAM-1−TIGIT+TACTILE+ NK cells and DNAM-1− TIGIT+TACTILE+ CD56− T cells were associated with a better survival of AML patients. Conclusions: The expression of DNAM-1 is reduced in NK cells and in CD4+ and CD8+ T cells from AML patients compared with those from healthy volunteers. An increased percentage of NK and T cells lacking DNAM-1 and co-expressing TIGIT and TACTILE is associated with patient survival, supporting the role of TIGIT as a novel candidate for checkpoint blockade.

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Role of Glucocorticoid-Induced TNF-Related Protein (GITR) Ligand in the Interaction of Acute Myeloid Leukemia with NK Cells.

Blood ◽

10.1182/blood.v110.11.18.18 ◽

2007 ◽

Vol 110 (11) ◽

pp. 18-18

Author(s):

Matthias Krusch ◽

Katrin M. Baltz ◽

Tina Baessler ◽

Lothar Kanz ◽

Helmut R. Salih

Keyword(s):

Acute Myeloid Leukemia ◽

Nk Cells ◽

Myeloid Leukemia ◽

Map Kinases ◽

Nk Cell ◽

Immune Surveillance ◽

Related Protein ◽

Surface Receptors ◽

Enhanced Production ◽

Acute Myeloid

Abstract NK cells play an important role in the reciprocal interaction of tumor cells with the immune system and participate in the surveillance and eradication of hematological malignancies. The activity of NK cells is governed by a balance of activating and inhibitory surface receptors. Glucocorticoid-induced TNF-related protein (GITR) and its ligand (GITRL) are members of the TNF/TNF receptor (TNFR) superfamily, which mediates multiple cellular functions including proliferation, differentiation, and cell death. Recently we reported that NK cells express GITR while cancer cells express GITRL and GITR-GITRL interaction down regulates NK cell-mediated anti-tumor immunity (Baltz et al., FASEB J 2007). Here we demonstrate that GITRL is expressed on 6 of 7 investigated acute myeloid leukemia (AML) cell lines and on primary AML cells in 30 of 52 (59%) patients, while no GITRL expression was detected on CD34+ cells of healthy donors (n=5). GITRL expression was not restricted to a specific French-American-British (FAB) subtype, but was significantly (p<0.05, one-way ANOVA) associated with monocytic (FAB M4, M5) differentiation. In addition, no association with a particular cytogenetic abnormality or with expression of MHC class I was observed. Reverse signaling via GITRL led to phosphorylation of ERK and JNK resulting in significantly (p<0.05, Mann-Whitney U-test) enhanced production of IL-10 and TNF by patient AML cells (n=10). In line, specific inhibitors for JNK and ERK1/2 blocked the cytokine release by AML cells demonstrating that activation of MAP kinases is responsible for the production of the immunoregulatory cytokines following GITRL stimulation. Importantly, blocking GITR-GITRL interaction in cocultures of AML and NK cells significantly (both <0.05 Mann-Whitney U-test) increased cellular cytotoxicity about 70% and IFN-γ production about 60%, and this was due to restored NK cell NF-κB activity. Thus, GITRL substantially influences immunoediting by AML cells and enables the escape of AML cells from NK cell-mediated immune surveillance. The correlation found between GITRL expression and NK cell susceptibility may provide useful information for NK cell-based immunotherapy.

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Role of CD137/4-1BB and Its Ligand in the NK Cell Mediated Immune Surveillance of Acute Myeloid Leukemia.

Blood ◽

10.1182/blood.v110.11.880.880 ◽

2007 ◽

Vol 110 (11) ◽

pp. 880-880

Author(s):

Tina Baessler ◽

Matthias Krusch ◽

Katrin M. Baltz ◽

Benjamin J. Schmiedel ◽

Helga M. Schmetzer ◽

...

Keyword(s):

Acute Myeloid Leukemia ◽

Nk Cells ◽

Cell Lines ◽

Myeloid Leukemia ◽

Nk Cell ◽

Immune Surveillance ◽

Cell Reactivity ◽

Ifn Γ ◽

Tnfr Superfamily ◽

Acute Myeloid

Abstract NK cells play an important role in the reciprocal interaction of tumor cells with the immune system and participate in the surveillance and eradication of hematological malignancies including acute myeloid leukemia (AML). NK cell reactivity is governed by a balance of activating and inhibitory receptors including various members of the TNF receptor (TNFR) superfamily. The TNFR superfamily member CD137/4-1BB has been shown to stimulate proliferation and IFN-γ production, but not cytotoxicity of NK cells in mice. Surprisingly, yet nothing is known regarding the consequences of CD137-CD137 ligand (CD137L) interaction for NK cell reactivity in humans. In this study we demonstrate that CD56dimCD16+ but not CD56brightCD16− NK cells express CD137 upon stimulation with the activating cytokines IL-2 and IL-15 with peak expression between 48 and 60h. Furthermore, we found that 5 of 7 investigated AML cell lines and 16 of 51 (33%) primary AML cells of patients expressed substantial CD137L levels, while no CD137L expression was detected on CD34+ cells of healthy donors (n=5). CD137L expression was not restricted to a specific French-American-British (FAB) subtype, but was significantly (p<0.05, one-way ANOVA) associated with monocytic (FAB M4, M5) differentiation. In addition, no association with a particular cytogenetic abnormality or with expression of MHC class I was observed. Reverse signaling via CD137L into AML cells (n=10) significantly induced the release of the immunoregulatory cytokines IL-10 and TNF (both p<0.05, Mann-Whitney U-test). Surprisingly and in contrast to available data regarding the function of murine CD137, we found that in humans blocking CD137-CD137L interaction caused a significant increase in NK cell cytotoxicity and IFN-γ production about 50% (both p<0.05, Mann-Whitney U-test) in coculture assays with CD137L-expressing patient AML cells and AML cell lines. The inhibitory effect of CD137 on NK cell reactivity was further confirmed in cocultures of NK cells with CD137L-transfectants and by triggering CD137 with an agonistic monoclonal antibody. This indicates that CD137 mediates opposite effects in murine compared to human NK cells. Furthermore we conclude that CD137L expression substantially influences tumor immunoediting by AML cells and diminishes NK cell reactivity against AML.

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RANKL Expressed by Acute Myeloid Leukemia Cells Impairs NK Cell-Mediated Immune Surveillance

Blood ◽

10.1182/blood.v116.21.2164.2164 ◽

2010 ◽

Vol 116 (21) ◽

pp. 2164-2164

Author(s):

Benjamin J Schmiedel ◽

Constantin M Wende ◽

Tina Baessler ◽

Carolin Scheible ◽

Stefan Wirths ◽

...

Keyword(s):

Acute Myeloid Leukemia ◽

Nk Cells ◽

Myeloid Leukemia ◽

Nk Cell ◽

Conflicts Of Interest ◽

Immune Surveillance ◽

Surface Protein ◽

Leukemia Cells ◽

Acute Myeloid Leukemia Cells ◽

Acute Myeloid

Abstract Abstract 2164 NK cells play an important role in tumor immunosurveillance, especially of leukemia. Their reactivity is governed by various activating and inhibitory molecules expressed by their targets including multiple members of the TNF family. The TNF family member Receptor Activator of NF-κB ligand (RANKL) and its receptors RANK and osteoprotegerin (OPG) are key regulators of bone remodelling, but recently have also been shown to influence progression of hematopoetic malignancies. Here we studied the yet unkown role of the RANK/RANKL molecule system in NK cells and their reactivity against acute myeloid leukemia (AML). Primary leukemia cells from AML patients were found to substantially express RANKL mRNA and surface protein in 75% of the investigated cases (n=40). Reverse signaling via surface-expressed RANKL into AML blasts induced the release of soluble factors including the immunoregulatory cytokines TNF and IL-10, which impaired NK cell anti-tumor reactivity. Moreover, we observed upregulation of RANK on NK cells among PBMC of healthy donors upon exposure to IL-10. This was not caused by direct effects on NK cells, but was rather due to yet unidentified factors released by monocytes among the PBMC upon IL-10 exposure and could be prevented by the activating cytokine IL-2. Furthermore, functional experiments with NK cells and RANKL transfectants or RANKL-negative controls revealed that forward signaling into RANK-expressing NK cells by tumor-expressed RANKL also directly impaired NK cytotoxicity and IFN-γ production. In line, blocking RANK-RANKL interaction using anti-RANKL antibodies or RANK-Fc fusion protein increased cytotoxicity and cytokine production of allogenic NK cells in cultures with RANKL-positive primary AML cells. Our data indicate that RANKL expression enables immune evasion of leukemia cells both by directly inhibiting reactivity of RANK-expressing NK cells and by orchestrating a reciprocal interplay between AML cells, monocytes and NK cells resulting in an immunosuppressive cytokine milieu. Thus, therapeutic modulation of the RANK/RANKL system, e.g. with Denosumab/AMG162, which is presently being evaluated for treatment of both non-malignant and malignant osteolysis, holds promise to reinforce NK reactivity against hematopoietic malignancies. Disclosures: No relevant conflicts of interest to declare.

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Over-Expression of CD200 In Acute Myeloid Leukemia Mediates the Expansion of Regulatory T-Lymphocytes and Directly Inhibits Natural Killer Cell Tumor Immunity

Blood ◽

10.1182/blood.v116.21.491.491 ◽

2010 ◽

Vol 116 (21) ◽

pp. 491-491 ◽

Cited By ~ 2

Author(s):

Steven J Coles ◽

Stephen Man ◽

Robert Hills ◽

Eddie CY Wang ◽

Alan Burnett ◽

...

Keyword(s):

Acute Myeloid Leukemia ◽

Nk Cells ◽

Tumor Immunity ◽

Myeloid Leukemia ◽

Nk Cell ◽

Cytolytic Activity ◽

Target Cells ◽

Over Expression ◽

Regulatory T Lymphocytes ◽

Acute Myeloid

Abstract Abstract 491 CD200 is a type-1 transmembrane glycoprotein which suppresses inflammatory and autoimmune responses by signalling through its cognate transmembrane receptor homologue (CD200R). Normally, CD200 expression is restricted to immune privileged sites where it enhances immune tolerance through mechanisms that include modulating the expansion of FOXP3+ regulatory T-lymphocytes (T-regs) and suppressing macrophage cytolytic activity. Furthermore, leukocyte associated CD200 has been reported to suppress Natural Killer (NK) cell activity in vivo. Pathologically, we have previously shown that CD200 over-expression on leukemic blasts in around 50% of acute myeloid leukemia (AML) patients is significantly associated with a poor overall survival (Tonks et al, Leukemia, 2007). Given the existing evidence that T-reg frequency and NK cell function influence blast clearance and long-term survival in AML, we investigated the possibility that CD200 expression in AML may be directly suppressing anti-tumor immunity in this disease. Here we present evidence that CD200+ AML can suppress host anti-tumor responses by augmenting the frequency of AML patient T-regs and by direct inhibition of NK cell anti-tumor activity. We also show that targeting the interaction between CD200 and its receptor might provide a new strategy for the treatment of AML. Bone marrow aspirates from 91 diagnostic AML patients were analysed by multiparameter flow cytometry for blast CD200 protein expression. We found that the level of blast CD200 expression directly correlated with an increased frequency of T-regs (CD4+CD25++FoxP3+; R=0.78, p=0.0008). Measuring 3H-thymidine incorporation, we show that T-regs isolated from AML patients by MACS® separation inhibited T-cell proliferation (induced by CD3 and CD28 stimulation) at ratios <0.1%, thus confirming that patients T-regs were functional. In contrast to T-regs, NK cell frequency (CD45+CD19−CD3−CD56+) did not correlate with the level of AML blast CD200 expression (R=0.15, p=0.851), however, NK cell subpopulation bivariate analysis using CD56 and CD16 demonstrated that the CD56dimCD16+ (the principle active NK population) was significantly reduced by over 50% in CD200+ AML patients (36±5% compared to 15±5%, p=0.009). Furthermore, CD200 expression on target cells appeared to have a direct effect on the cytotoxic activity of NK cells; co-culture of NK cells with CD200+ targets resulted in decreased CD107a expression (a marker for cytolytic granules) in NK cells (23±4% vs 12±5%, p=0.038) and decreased apoptosis of the target cells (19±1% vs 10±1%, p=0.041). Since CD200R was detected on NK cells in AML patients, it was likely that CD200 was having a direct effect on suppression of NK cytotoxicity. This was supported by the significant recovery of NK cytolytic activity against CD200+ blasts in the presence of a CD200 blocking antibody (5±1% vs 11±2% CD107a+ NK cells, p=0.046) whereas there was no change seen with CD200− blasts (19±4% vs 19±3%). In conclusion, these findings suggest that CD200 expression on leukemic blasts plays an influential role in suppressing anti-tumor immunity in AML patients through modulating the expansion of functionally suppressive T-regs and directly suppressing NK cell cytolytic activity. In this study blocking CD200 interaction with its receptor was able to recover a significant proportion of patient NK activity, making CD200 a potential therapeutic target for CD200+ AML. Disclosures: No relevant conflicts of interest to declare.

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Transfer of Ex Vivo Expanded NK and γδT Cells from Untouched Posttransplant PBMCs to Clear Minimal Residual Disease in Acute Myeloid Leukemia

Blood ◽

10.1182/blood.v124.21.5294.5294 ◽

2014 ◽

Vol 124 (21) ◽

pp. 5294-5294

Author(s):

Patrick Schlegel ◽

Chihab Klose ◽

Christina Kyzirakos ◽

Ursula J.E. Seidel ◽

Kai Witte ◽

...

Keyword(s):

Cell Culture ◽

Acute Myeloid Leukemia ◽

Nk Cells ◽

Cell Expansion ◽

Myeloid Leukemia ◽

Nk Cell ◽

Residual Disease ◽

Cell Transfer ◽

Minimal Residual ◽

Acute Myeloid

Abstract GMP-grade NK cell expansion for clinical purpose has been demonstrated feasible and safe. Here we share our pilot data on posttransplant immunotherapy with ex vivo expanded NK cells to treat minimal residual disease in a pediatric patient with posttransplant relapsed myeloid leukemia. Our patient, a 13 year old boy who underwent 2nd allogeneic stem cell transplantation (haploidentical stem cell transplantation from his mother) due to posttransplant relapsed acute myeloid leukemia. After the 2nd haploidentical stem cell transplantation (SCT) minimal residual disease (MRD) was detected by multiparameter flow cytometry and by two molecular markers CALM-AF10 fusion transcript and a NRAS-mutation. For posttransplant compassionate use immunotherapy by NK cell transfer, NK cells were expanded from untouched isolated PBMCs of the patient post 2nd haploidentical SCT. GMP-grade expansion of the NK cells was done under static conditions in our GMP-facility. Isolated PBMCs were pooled with 100Gy irradiated K562mb15 4-1BBL feeder cells (kindly provided by Dario Campana) in a proportion of 1:20 (NK to K562mb15 4-1BBL). PBMCs and K562mb15 4-1BBL were seeded in conventional cell culture flasks (175cm2) at a density of 1.1E6 cells/ml. Cell culture media contained RPMI1640 supplemented with 10% AB-human serum, 1% L-glutamine and 100IU Proleukine® IL2/ml. Cell culture was monitored daily for cell number, white blood cell differentiation, pH of the cell culture, glucose metabolism, lactate production and microbial sterility testing at the beginning and the end of the expansion period. The cell product was harvested on day 15-17. Fresh isolated PBMCs and the expanded NK cell product were characterized by flow cytometry. NK cells were expanded >1000 fold (3.1 and 3.4 log-fold) in 14-17 days. The product contained a total number of 9.8E9 and 19.9E9 cells, which was 328 and 665E6/kgBW. The expansion protocol supports NK and γδ T cell expansion whereas the number of αβ T cells stays stable. Cytotoxicity assay against various targets revealed excellent cellular cytotoxicity and antibody dependent cellular cytotoxicity. To prevent relapse in our patient with posttransplant MRD positivity, NK cells from the patient post 2nd haploidentical SCT were expanded for cellular immunotherapy. 2 weeks post 1st NK cell transfer (day +170) the patient achieved complete MRD response in the bone marrow. Unfortunately the patient showed detectable MRD one month later. Therefore another NK cell expansion and transfer was done. 2 weeks post 2nd NK cell transfer (day +232) the patient again achieved complete MRD response in the bone marrow and is in complete molecular remission ever since (day +340). The NK cell products were tolerated well. Transient coughing and temporary increase of temperature were registered. Both, in vitro and in vivo effect of the NK cell product were documented. Clinical use of expanded and activated NK cells and γδ T cells can induce molecular remission in posttransplant MRD positive acute myeloid leukemia. Disclosures No relevant conflicts of interest to declare.

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