Irradiated NK-92 Targets AML Leukemic Stem Cells in Vivo and Gene-Modified CD16+NK-92 Mediates Antibody Dependent Cell Mediated Cytotoxicity (ADCC) Against CD123+ Cells

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1909-1909
Author(s):  
Brent A. Williams ◽  
Xing-Hua Wang ◽  
Sonam Maghera ◽  
Jeffrey V. Leyton ◽  
Raymond Reilly ◽  
...  
Keyword(s):  
Stem Cells ◽  
Treatment Group ◽  
Nk Cell ◽  
Xenograft Model ◽  
In Vitro Cytotoxicity ◽  
Class I ◽  
Leukemic Stem Cells ◽  
Nsg Mice ◽  
Dependent Cell

Abstract Abstract 1909 Introduction: Patients with acute myeloid leukemia (AML) in remission relapse frequently from residual leukemic stem cells (LSCs) that are CD34+CD38-CD123+. NK-92 is an infusible CD16- malignant NK cell line cytotoxic against AML and after irradiation for prevention of NK cell malignancy has minimal adverse events in Phase I trials. Here, we tested irradiated NK-92 (iNK-92) against primary AML in a NOD/SCID gamma null (NSG) xenograft model. To optimize killing of LSCs in vitro we utilized a gene modified CD16+NK-92 against the CD123+ leukemia cell line OCI/AML5 treated with and without an anti-CD123 monoclonal antibody (7G3) to facilitate antibody dependent cell mediated cytotoxicity (ADCC). Methods: NSG mice were irradiated with 225 or 325 cGy before infusion with primary AML blasts (1 or 3×10e6 cells). iNK-92 was started 1 or 10 days post AML infusion and given 1–3 times weekly (15 or 20×10e6 cells/dose) to a total dose of 60–75 ×10e6 cells/mouse. In vitro cytotoxicity was measured by the chromium release assay. OCI/AML5 or primary AML was pretreated with 7G3 or anti-Class I antibody respectively at 10 ug/ml 2 hours before ADCC assays. Results: We developed an NSG AML xenograft model using a CD34+CD38+ primary AML sample containing a small fraction of CD34+CD38- cells that were predominantly CD123+. 3×10e6 primary cells induced leukemia in NSG mice by 6 weeks and maintained comparable potency up to quaternary transplantations with a stable immunophenotype. In vitro cytotoxicity against LSCs was assessed by treating 1×10e6 first passage BM derived primary AML +/− 5×10e6 iNK-92 ×4 hours and injecting into 2 cohorts of 5 mice. At 6 weeks mice were sacrificed and bone marrow harvested. Average leukemic engraftment in the iNK-92 group (79.8, 3.48, 92.1, 81.3, 86.1, Av= 68.6%) was less than untreated AML inoculated group (95.0, 93.4, 19.4, 95, 97.3, Av=80.0%), but not statistically significant (p=0.62). Removing one poorly engrafted outlier mouse from each group yielded a higher engraftment in the control (Av=95.1%) versus the treatment group (Av=84.8%) and was significant (p=0.011). To test iNK-92 to treat engrafted leukemia, NSG mice were infused with 3×10e6 AML cells starting day 10 with 20×10e6 iNK-92 weekly ×6 doses. Survival was improved in the treatment group to near statistical significance (p=0.055), but all mice ultimately succumbed to disease. Addition of IL-2 to iNK-92 did not improve outcomes (p=0.13). 3×10e6 primary AML cells were also infused into 2 cohorts of 4 mice and treated +/− iNK-92 from day 2 and given 15×10e6 cells twice weekly to 75×10e6 total dose. BM (1×10e6 cells) from each of 4 primary recipients in control and treatment was serially transplanted 1:1 into four new NSG mice. BM engraftment occurred in all AML only cohort secondary mice (80.8, 93.3, 80.4, 96.4 Av=87.7%) while one mouse from iNK-92 group was leukemia free with engraftment at background levels of non-injected mice (96.4, 94.7, 1.8, 95.7 Av=72.2%). Proportion of LSCs in secondary transplanted mice was: AML (8.01, 9.48, 8.66, 5.25, Av=7.85%) and AML + iNK-92 (7.13, 3.46, 0.03, 4.0 Av=3.66%) which was statistically significant (p=0.05). CD16+NK-92 killed CD123+ OCI/AML5 cells at effector:target (E:T) ratios of 25:1, 10:1, 5:1 and 1:1 (% lysis +/−SD: 35.0 +/−4.0, 9.0+/−6.6, -2.0 +/−0.1, 1.7 +/−3.3) and was significantly enhanced (2–6x) when targets were coated with anti-CD123 mAb (% lysis +/−SD: 64.3 +/−3.1, 48.5 +/−4.1, 20.9 +/−0.1, 10.1+/−3.3). Further, CD16+NK-92 also killed primary AML at E:T ratios of 25:1, 10:1, 5:1 and 1:1 (% lysis +/−SD: 34.7 +/−4.6, 15.6 +/− 4.7, 11.5 +/− 2.0, 7.7 +/−1.6) which was significantly enhanced (2–3x) by coating with anti-Class I monoclonal antibodies (% lysis +/−SD: 64.8 +/−10.4, 31.1 +/− 8.9, 30.2 +/− 9.4, 23.9+/−2.8). Conclusion: iNK-92 reduces engraftment of AML and improves survival in a primary AML xenograft model. CD16+NK-92 cytotoxicity against primary AML is enhanced with anti-class I antibodies via ADCC, demonstrating that CD16+NK-92 can be redirected against bulk primary leukemia using a highly expressed cell surface marker. Finally, CD16+NK-92 cytotoxicity can be improved against OCI/AML5 with anti-CD123 antibodies via ADCC, providing the first proof-of-principle for the targeting of leukemic stem cells by combining humoral and cellular approaches. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Combinatorial immunotherapy of N-803 (IL-15 superagonist) and dinutuximab with ex vivo expanded natural killer cells significantly enhances in vitro cytotoxicity against GD2+ pediatric solid tumors and in vivo survival of xenografted immunodeficient NSG mice

2021 ◽  
Vol 9 (7) ◽  
pp. e002267
Author(s):  
Yaya Chu ◽  
Gaurav Nayyar ◽  
Susiyan Jiang ◽  
Jeremy M. Rosenblum ◽  
Patrick Soon-Shiong ◽  
...  
Keyword(s):  
Solid Tumors ◽  
Nk Cell ◽  
Ex Vivo ◽  
In Vitro Cytotoxicity ◽  
Event Free Survival ◽  
Free Survival ◽  
Nsg Mice ◽  
Ifn Γ

BackgroundChildren with recurrent and/or metastatic osteosarcoma (OS), neuroblastoma (NB) and glioblastoma multiforme (GBM) have a dismal event-free survival (<25%). The majority of these solid tumors highly express GD2. Dinutuximab, an anti-GD2 monoclonal antibody, significantly improved event-free survival in children with GD2+ NB post autologous stem cell transplantation and enhanced natural killer (NK) cell-mediated antibody-dependent cell cytotoxicity. Thus, approaches to increase NK cell number and activity, improve persistence and trafficking, and enhance tumor targeting may further improve the clinical benefit of dinutuximab. N-803 is a superagonist of an interleukin-15 (IL-15) variant bound to an IL-15 receptor alpha Su-Fc fusion with enhanced biological activity.MethodsThe anti-tumor combinatorial effects of N-803, dinutuximab and ex vivo expanded peripheral blood NK cells (exPBNK) were performed in vitro using cytoxicity assays against GD2+ OS, NB and GBM cells. Perforin and interferon (IFN)-γ levels were measured by ELISA assays. Multiple cytokines/chemokines/growth factors released were measured by multiplex assays. Human OS, GBM or NB xenografted NOD/SCID/IL2rγnull (NSG) mice were used to investigate the anti-tumor combinatorial effects in vivo.ResultsN-803 increased the viability and proliferation of exPBNK. The increased viability and proliferation are associated with increased phosphorylation of Stat3, Stat5, AKT, p38MAPK and the expression of NK activating receptors. The combination of dinutuximab and N-803 significantly enhanced in vitro cytotoxicity of exPBNK with enhanced perforin and IFN-γ release against OS, GBM and NB. The combination of exPBNK+N-803+dinutuximab significantly reduced the secretion of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), platelet-derived growth factor-BB (PDGF-BB), and stem cell growth factor beta (SCGF-β) from OS or GBM tumor cells. Furthermore, OS or GBM significantly inhibited the secretion of regulated on activation, normal T cell expressed and presumably secreted (RANTES) and stromal cell-derived factor-1 alpha (SDF-1α) from exPBNK cells (p<0.001) but significantly enhanced monokine induced by gamma interferon (MIG) secretion from exPBNK cells (p<0.001). N-803 combined with dinutuximab and exPBNK cells significantly extended the survival of OS, GBM or NB xenografted NSG mice.ConclusionsOur results provide the rationale for the development of a clinical trial of N-803 in combination with dinutuximab and ex vivo exPBNK cells in patients with recurrent or metastatic GD2+ solid tumors.

Selective Targeting of Leukemic Over Normal Stem Cells by the Serotonin Receptor Antagonist SB-216641

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 1884-1884
Author(s):  
Alissa R. Kahn ◽  
Kimberly A. Hartwell ◽  
Peter G. Miller ◽  
Benjamin L. Ebert ◽  
Todd R. Golub ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Cell Lines ◽  
Serotonin Receptor ◽  
Leukemic Cells ◽  
Leukemic Stem Cells ◽  
Nsg Mice ◽  
Cell Kill ◽  
Serotonin Receptor Antagonist

Abstract Abstract 1884 Acute myeloid leukemia (AML) is a common and aggressive hematologic malignancy affecting both children and adults which continues to have high mortality rates as well as high morbidity from toxic therapies. New treatments are needed to improve cure rates and decrease morbidity. A niche-based high throughput screen done in a murine system identified candidate small molecules potentially toxic to leukemic stem cells (LSCs) while sparing normal hematopoietic stem cells (HSCs) and bone marrow stroma (Hartwell KA, Miller, PG et al., in preparation). One such compound, SB-216641, demonstrated dose-dependent activity against leukemia in both a cell autonomous and non-autonomous manner, by modifying niche–based support. SB-216641 is a selective serotonin receptor antagonist specific for the 5-HT1B receptor, highlighting a pathway not previously investigated in the context of AML or leukemia stem cell biology. We examined the effects of this candidate small molecule on 7 human primary AML samples. CD34+ cells were isolated from these samples with immunomagnetic beads. Using the colony forming assay to assess kill of progenitor cells, all samples had ≥99% cell kill at 25 μM (10 times the IC-50 found in the murine system). We then assessed the compound's effect on LSCs using the cobblestone area forming cell (CAFC) assay, a standard in vitro stem cell assay. The leukemic cells were pulse treated for 18 hours and washed to remove residual SB-216641 prior to placement on MS-5 murine stroma and therefore only the direct effect on the leukemic cells was measured in this assay. CAFCs were read out at week 5, or week 2 when the sample was FLT3-ITD+ (Chung KY et al, Blood 2005, Vol 105, 77–84). We first tested five samples at 25 μM. All samples formed cobblestone areas in the control setting (46–200 CAFCs/106 cells plated). Four samples had no CAFC formation with SB-216641 and the remaining sample had >95% decrease in CAFC formation. We then performed serial dilutions using the CAFC assay in the human primary samples as well as in HSCs derived from cord blood to obtain the IC-50 for human AML and to ensure that our differential cell kill of LSCs versus normal HSCs held true in the human samples. IC-50 for the human primary leukemias was found to be 630 nanomolar and at 10 μM all leukemic samples were fully killed with 100% survival of normal human HSCs [see figure 1]. As a confirmatory study, using HL60 and U937 human AML cell lines transduced with GFP-luciferase, 500 cells were preincubated with SB-216641 at 25 μM or DMSO control and then injected IV into Nod Scid IL2R-gamma null (NSG) mice and imaged at 5 weeks. In both cell lines, the control mice had engraftment and the mice that received treated cells had no engraftment. HL60 cells were then preincubated with SB-216641 at lower doses (10 and 5 μM) and injected into NSG mice and imaged at 3 weeks. Again, the control mice had engraftment and the mice that received treated cells had no engraftment.Figure 1.Figure 1. 5-HT1B receptor antagonists have not previously been known to be active against AML or leukemic stem cells. Some hematopoietic cells including platelets express serotonin receptors and T-cells specifically have been found to express the 5-HT1b receptor. Selective 5-HT1B receptor antagonists have found to have apoptotic effects in vitro against cell lines of other cancers and may be involved in MAP kinase and P13K/Akt signaling pathways. SB-216641 is a highly promising compound which warrants further investigation. Its high toxicity to LSCs and sparing of normal HSCs make it appealing for possible clinical use in the future. Disclosures: No relevant conflicts of interest to declare.

scholarly journals KIR Expression on inVitro-Derived Natural Killer Cells Does Not Regulate Killing of Allogeneic Targets

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 3705-3705
Author(s):  
Yunzu Michele Wang ◽  
Huang Zhu ◽  
Alessa Ruiz-Cisneros ◽  
Naveen Heragu ◽  
Eivind Heggernes Ask ◽  
...  
Keyword(s):  
Stem Cells ◽  
Nk Cells ◽  
Genetic Background ◽  
Research Funding ◽  
Caspase 3 ◽  
Fas Ligand ◽  
Nk Cell ◽  
In Vitro Cytotoxicity ◽  
Hematopoietic Stem

Abstract Natural killer (NK) cells play an essential role in early innate killing of virally-infected and tumor targets. NK cell-mediated activity is regulated by a repertoire of activating and inhibitory receptors that recognize ligands on diseased, stressed, or tumor targets. Killer cell immunoglobulin-like receptors (KIRs) are a family of polymorphic receptors that can be inhibitory or activating based on their intracellular signaling motifs. Expression of certain KIR haplotypes plays a key role in survival and relapse prevention for patients with acute myelogenous leukemia (AML) who receive allogeneic hematopoietic cell transplantation. Therefore, KIR haplotypes are an important consideration in selecting allogeneic donors for patients with AML. However, it is unclear if KIRs play a role in adoptive transfer of NK cells that are becoming more routinely utilized to treat refractory AML and other malignancies. To better address this question we used umbilical cord blood to isolate both CD34+ hematopoietic stem cells and CD45+CD56+ NK cells (UCB-56-NK) from the same umbilical cord blood unit. The CD34+ hematopoietic stem cells were then differentiated in vitro into CD56+ NK cells (UCB-34-NK). Despite originating from the same donor and sharing the same genetic background, as well as comparable expression of Fas ligand, TRAIL, NKp46, NKp44, NKG2A, and NKG2D, the UCB-34-NK cells have characteristically low KIR expression, whereas the UCB-56-NK cells have high KIR expression. This phenotype was further confirmed by mass cytometric (CyTOF) analysis of UCB-56-NK cells and UCB-34-NKcells with a panel of 36 phenotypic and functional NK cell markers. This unique system allows us to study the role of KIR expression independent of any other variations in donor or cell characteristics. The cytotoxicity and NK cell activation of UCB-34-NK cells and UCB-56-NK cells are compared to control NK cells isolated from peripheral blood (PB-NK cells) with standard in vitro cytotoxicity assays against neuroblastoma lines with varying HLA genotypes and a control K562 leukemic targets. Our data demonstrates that there is no statistical difference in NK cytotoxicity and activation of UCB-34-NK cells and UCB-56-NK cells across a spectrum of target cell HLA types, despite the differences in KIR expression. For example, at effector to target (E:T) ratios of 1:5 and 1:20 against neuroblastoma line IMR32, UCB-34-NK cells (KIR-low) demonstrated 68.5% and 84.1% maximal Caspase 3/7 activation, compared to 81.3% and 89.6% by UCB-56-NK cells (KIR-high). Additionally, we have used human induced pluripotent stem cells to derive NK cells (iPSC-NK cells) that vary in KIR expression levels. These CD45+CD56+ iPSC-NKs are differentiated from the same well-established iPSC line in the laboratory and therefore again share the same genetic background, and they have similar NK cell surface receptor expression of Fas ligand, TRAIL, NKp46, NKp44, and NKG2D, but differ in levels of KIR expression. Again in vitro cytotoxicity against hematopoietic tumor targets such as K562 and MOLM13 do not demonstrate a significant difference in killing, despite these KIR differences. For example, in targeting erythroleukemia K562 cells, iPSC-NK cells with high levels of KIR expression at E:T ratios of 1:2.5, 1:5, and 1: 10 have Caspase 3/7 activation of 21.1%, 28.2%, and 41.0%, compared to 20.1%, 22.0%, and 31.2% by iPSC-NK cells with low KIR expression. Together, these studies demonstrate that in vitro-derived NK cells do not require KIR expression to become licensed for anti-tumor activity and these cells are able to kill tumor targets whether or not they express KIRs. These studies better enable use of these allogeneic NK cell populations for off-the-shelf NK cell-based therapies without the need to optimize for KIR profiles for patients of differing HLA haplotypes. Disclosures Malmberg: Fate Therapeutics Inc.: Consultancy, Research Funding. Kaufman:Fate Therapeutics: Consultancy, Research Funding.

scholarly journals Use of CD70 Targeted Chimeric Antigen Receptor (CAR) T Cells for the Treatment of Acute Myeloid Leukemia (AML)

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 4443-4443 ◽  
Author(s):  
Mark Leick ◽  
Irene Scarfò ◽  
Bryan D. Choi ◽  
Rebecca Larson ◽  
Amanda A Bouffard ◽  
...  
Keyword(s):  
Stem Cells ◽  
T Cells ◽  
Synergistic Activity ◽  
Leukemic Stem Cells ◽  
Cytotoxicity Assays ◽  
Car T Cells ◽  
Nsg Mice ◽  
Car T

Background: CAR-T cells have led to a revolution in the treatment of advanced hematologic malignancies. Since these cells target antigens that are expressed on the cellular surface, it is imperative that there is near ubiquitous tumor expression with minimal expression vital human tissues. Finding targets with these characteristics in myeloid malignancies has been challenging. Typical markers expressed on the surface of AML are also expressed on essential innate immune effector cells (e.g. neutrophils) which, if targeted, could lead to prolonged absence of this immune arm, which is not survivable or replaceable. Current approaches rely on the use of CAR-T cells against common myeloid targets (e.g. CD123, CD33) as an ablative strategy with a planned allogeneic stem cell transplant rescue to eradicate the CAR-T cells afterwards. These solutions have resulted in significant toxicity with several deaths resulting from CD123-targeted CAR-T cells. Another approach has involved gene editing donor progenitor cells to delete CD33, repopulation of the marrow with these CD33 negative cells, and then treatment with CD33-targeted CAR-T cells. (Kim, Cell 2018). However, this approach is challenging, costly, and genomic editing of stem cells remains a concern. CD70 is an immune checkpoint found on antigen presenting cells and activated T cells. Multiple studies have shown a strong degree of expression on AML blasts and leukemic stem cells, with minimal normal tissue expression (Perna, Cell 2017, Riether J Exp Med 2017). A Phase 1 study of a CD70 targeted antibody drug conjugate in combination with azacitidine (which has been shown to increase CD70 expression on leukemic stem cells) for untreated AML patients has shown impressive results (Blood 2018 132:2680, Blood 2017 130:2652). Based on these findings, we explored CD70-targeting CARs for the treatment of AML. Methods: Based on our success with a trimeric ligand-based CAR of another TNFα family member, APRIL, for multiple myeloma (Schmidt Blood 2018 132:2059), we generated monomeric and trimeric second-generation ligand-based CAR constructs to target CD70 on AML. In vitro effector function was compared by cytotoxic potency and cytokine production. In vivo anti-tumor efficiency was assessed in a xenograft mouse model of AML. Effect of surface CD70 expression on AML cell lines after co-culture with azacitidine was assessed. Results: CAR T cell manufacturing of both constructs was accomplished successfully (transduction efficiency 70-93%) from three different healthy donors with no apparent fratricide. CD70 CARs were efficacious in in vitro cytotoxicity assays targeting an AML cell line Molm13. Unexpectedly, monomeric CD70 targeted CAR-T cells were superior to trimeric in cytotoxicity assays and, thus, were carried forward for in vivo assays. Next, we treated NSG mice that had been engrafted with Molm13 and demonstrated a substantial dose-dependent therapeutic effect with prolonged survival of CAR treated mice compared to those treated with untransduced T-cells (UTD). Treated mice demonstrated a CAR-T robust expansion in the peripheral blood assessed by flow cytometry that was commensurate with individual animal treatment responses. Bone marrow from these mice revealed substantially reduced CD70 in all groups. Preliminary in vitro co-culture of AML cells with azacitidine showed increased CD70 expression. Conclusion: CD70 based CAR-T targeting of AML is effective in vitro and in vivo. Combination treatment with azacitidine may increase target antigen expression and lead to synergistic activity and represents a viable therapeutic strategy that warrants further investigation. Treatment of AML engrafted NSG mice with CD70 CAR-T cells in conjunction with azacitidine is ongoing. Disclosures Frigault: Xenetic: Consultancy; Novartis: Consultancy; Juno/Celgene: Consultancy; Foundation Medicine: Consultancy; Incyte: Consultancy; Nkarta: Consultancy; Kite/Gilead: Honoraria. Maus:INFO PENDING: Other: INFO PENDING.

NK-92 Preferentially Targets Acute Myeloid Leukemia Stem Cells

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 4300-4300
Author(s):  
Brent A. Williams ◽  
Bishoy Dief ◽  
Xing-Hua Wang ◽  
Armand Keating
Keyword(s):  
Stem Cells ◽  
Monoclonal Antibody ◽  
Cell Line ◽  
Cell Lines ◽  
Myeloid Leukemia ◽  
Nk Cell ◽  
Class I ◽  
Leukemic Stem Cells ◽  
Chromium Release ◽  
Acute Myeloid

Abstract Abstract 4300 Introduction: Outcome of patients with acute myeloid leukemia (AML) remains poor because many relapse from residual leukemic stem cells (LSCs) enriched in the CD34+CD38- fraction of AML blasts. NK-92 is a human permanent natural killer (NK) cell line in phase I clinical trials for relapsed and refractory malignancies. We recently showed that NK-92 targets LSCs preferentially over bulk leukemia in the cell line KG1 (Cytotherapy. 2010 Mar 15). Here, we evaluate the action of NK-92 and another NK cell line, KHYG-1, against five AML cell lines and five primary AML samples by the chromium release and methylcellulose cytotoxicity assays to determine the mechanism of recognition and killing and the effect on leukemic stem cells. Results: Using a 4 hour chromium release assay (CRA), the highest effector:target (E:T) ratio tested (25:1) for NK-92 and KHYG-1 against cell line targets revealed % lysis as follows: K562: 81.2+/−5.4%; 82.2 +/−3.9%; KG1: 41.0+/−7.2%; 37.3% +/−3.6; OCI/AML2: 37.3+/−22.7%; 33.0+/−13.9%; OCI/AML3: 33.8+/−4.5%; 51.0+/− 6.8% and OCI/AML5: 99.0+/−4.9%; 52.9 +/− 5.6%, respectively. Killing by NK-92 and KHYG-1 was completely inhibited by calcium chelation using 4 mM EGTA for all cell lines tested. Blockade of class I HLA on target cells using 10 ug/ml of anti-class I monoclonal antibody did not affect killing by NK-92 and KHYG-1 except for a decrease in killing of OCI/AML5 by both NK-92 and KHYG-1 from 99.0 +/− 4.9% to 39.0 +/−3.2% and 52.9+/−5.6% to 19.6 +/− 6.25%, respectively. Blockade of NKG2D using 10 ug/ml of anti-NKG2D monoclonal antibody did not significantly affect killing of AML cell lines by NK-92 or KHYG-1. Five primary AML blast samples treated with NK-92 at 25:1 E:T yielded only slight to moderate degrees of cytotoxicity by CRA: 15.6 +/−12.7%, 42.3+/−3.6%, 29.8 +/−3.6%, 43.9 +/− 1.47%, 42.6 +/− 0.1%lysis. KHYG-1 at 25:1 E:T had minimal killing of this panel of AML blasts by CRA: 1.27 +/−21.9%, 9.8+/−2.2%, 5.2+/−2.5%, 17.1+/−2.8%, 8.5+/−3.3% lysis. Blockade of class I HLA did not affect killing of primary AML blasts by NK-92, but the fourth sample only was rendered more sensitive to killing by KHYG-1 from 17.1 +/−2.8% to 35.8 +/−1.2% lysis. Blockade of NKG2D with 10 ug/ml anti-NKG2D monoclonal antibody did not significantly affect killing of primary AML samples by NK-92 or KHYG-1. To further assess killing by NK-92 of LSCs from primary AML, we used a methylcellulose cytotoxicity assay (MCA) established previously by our lab. The MCA showed that NK-92 at 25:1 E:T eliminated clonogenic growth of 3/5 primary AML blast samples with minimal colony growth in 2/5 with % cytotoxicity of 100 +/−0%, 86.3 +/− 2.3%, 98.4 +/−2.8%, 100 +/− 0% and 100 +/−0%, demonstrating higher toxicity than obtained with the CRA. Primary AML derived CD34+CD38- sorted LSCs were more sensitive to killing than CD34+CD38+ blasts by NK-92 in a 4 hour CRA at 1:1 E:T: 58.9+/−11.5%, 20.3 +/−1.71%; 5:1: 78.3 +/−9.7%, 43.5+/−11.1% and 10:1: 72.9+/−5.6%, 38.5 +/−2.4% lysis. Summary and conclusion: We demonstrate cytotoxicity of NK-92 and KHYG-1 against a range of AML targets and show greater killing of primary AML blasts by NK-92. The mechanism of cytotoxicity for both cell lines is primarily by granule exocytosis and is NKG2D independent. Unexpectedly, blockade of class I HLA resulted in reduced killing of OCI/AML5 by both NK-92 and KHYG-1, suggesting the presence of an activating KIR receptor common to both cell lines. One of five primary AML samples had increased killing by KHYG-1, suggesting KIR mediated inhibition. Further assessment of NK-92 against LSCs by the MCA demonstrated greater cytotoxicity than with the CRA and indicated preferential killing of LSCs. This finding was confirmed using the CRA with sorted immunophenotypically defined CD34+CD38- LSCs and CD34+CD38+ blasts. Our findings support the use of NK-92 in the treatment of AML. Disclosures: No relevant conflicts of interest to declare.

Identification of Small Molecules Selectively Targeting Leukemic Stem Cells within Their Stromal Niche

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 413-413
Author(s):  
Alissa R. Kahn ◽  
Kimberly A. Hartwell ◽  
Peter G. Miller ◽  
Benjamin L. Ebert ◽  
Todd R. Golub ◽  
...  
Keyword(s):  
Stem Cells ◽  
Flow Cytometry ◽  
Cord Blood ◽  
Leukemic Cells ◽  
Leukemic Stem Cells ◽  
Minimal Toxicity ◽  
Nsg Mice ◽  
Cd34 Cells

Abstract Abstract 413 Current therapies for acute myeloid leukemia (AML) are highly toxic, yet the relapse rate remains high. New therapies are needed to improve cure rates while decreasing toxicity. Because therapies may be affected by the tumor niche, we aimed to test new compounds on leukemic stem cells (LSCs) within their stromal microenvironment. A niche-based high throughput screen identified candidate small molecules potentially toxic to MLL-AF9 murine leukemic stem cells (LSCs) while sparing normal hematopoietic stem cells (HSCs) and bone marrow stroma (Hartwell et al, Blood 118, Abs 760, 2011.) Three such compounds, including a selective serotonin receptor antagonist highly specific for the 5-HT1B receptor, SB-216641, and two antihelminthics, parbendazole and methiazole, were found to be effective and selected for studies on human leukemias. We first examined SB-216641, studying the effects of this compound on 7 human primary AML samples. We began by assessing the compound's effect on LSCs using the week 5 cobblestone area forming cell (CAFC) assay, a standard in vitro stem cell assay. CD34+ cells were isolated with immunomagnetic beads. The leukemic cells were pulse treated for 18 hours and washed prior to placement on MS-5 murine stroma. We performed serial drug dilutions using the CAFC assay with the human primary samples as well as with HSCs derived from cord blood. All human leukemic samples formed cobblestone areas in the control setting (46-200 CAFCs/106 cells plated). IC50 for the human primary leukemia CAFCs was 630 nm, and at 10 μM all LSCs were killed while normal human HSCs had 100% survival. A combination of the AML cell line HL60 transduced with GFP-luciferase and normal cord blood CD34+ cells (1:200) were then pre-incubated overnight with SB-216641 at 5 and 10 μM and injected into Nod Scid IL2R-gamma null (NSG) mice. The control mice had leukemic engraftment by luciferase imaging and flow cytometry and the mice that received treated cells had no leukemic engraftment but normal multilineage engraftment of cord blood. Primary patient AML samples were also pre-incubated overnight with SB-216641 at 10 μM and injected into NSG mice. As shown by flow cytometry, control mice engrafted with leukemia and mice that received pre-treated cells had no engraftment following exposure to SB-216641. Finally, an in vivo study was completed on NSG mice injected intraperitoneally with 20 mg/kg/day beginning on day 1 or day 8 after inoculation with HL60 (500 cells). The mice were imaged at 2 and 3 week time points and both treatment groups had significantly less leukemia on imaging than the control group with minimal toxicity noted. Another specific 5-HT1B receptor antagonist, SB-224289, was found to have similar activity to SB-216641 against leukemic cells and to spare HSCs in preliminary studies. Similar CAFC studies with serial dilutions on primary AML samples were performed on the two anti-helminthic agents. IC50 for parbendazole was 1.25 μM and for methiazole 5 μM. As shown by luciferase imaging and flow cytometry, when injected with combined HL60 and cord blood pre-incubated overnight at 5 and 10 μM with each compound as described above, the control mice engrafted with leukemia and the mice that received treated cells had no leukemic engraftment but normal multilineage engraftment of cord blood. NSG mice were then injected with primary AML pretreated overnight with parbendazole at 10 μM. As shown by flow cytometry, control mice engrafted with leukemia and mice that received pre-treated cells had significantly lower engraftment following exposure to parbendazole (p = 0.01). Two new avenues of leukemia therapy were discovered warranting further investigation. SB-216641, an agent with a completely novel receptor target in leukemia therapy, has shown both in vitro success in human leukemia as well as preliminary success in vivo with minimal toxicity. We aim to move forward with this agent while also testing parbendazole in vivo, as this compound is already known to have good pharmacokinetics and minimal toxicity in animals. The high toxicity to LSCs and sparing of normal HSCs give both these agents an attractive profile for future clinical trials. Disclosures: Ebert: Genoptix: Consultancy; Celgene: Consultancy.

Assessment of antitumor function of NK cells expanded with exosomes from K562.mb21 cells.

2017 ◽  
Vol 35 (7_suppl) ◽  
pp. 132-132 ◽  
Author(s):  
Jeremiah Oyer ◽  
Sarah B. Gitto ◽  
Sara Khederzadeh ◽  
Kari Shaver ◽  
Dean A. Lee ◽  
...  
Keyword(s):  
Nk Cells ◽  
Cell Expansion ◽  
Nk Cell ◽  
Ex Vivo ◽  
K562 Cells ◽  
In Vitro Cytotoxicity ◽  
Feeder Cell ◽  
Nsg Mice

132 Background: NK cells can kill malignant cells to provide innate immunity against tumors. Due to their low abundance in blood, a focus is to expand NK cells ex vivo having enhanced anti-tumor cytotoxicity to be used as a treatment. Our group has pioneered a cell-free method using plasma membrane (PM) particles derived from K562 cells expressing 41BBL and membrane-bound IL-21 (K562.mb21) which were developed for NK cell expansion. Compared to feeder cell based methods for NK cell expansion, PM21-particles improve safety and allow for potential wide-spread dissemination, and also allows direct in vivo use. Exosomes, vesicles naturally secreted by cells, may yet be another novel feeder cell free way for NK cell expansion and may have further advantageous therapeutic dimensions. Methods: EX21-exosomes and PM21-particles were prepared from K562.mb21 cells and characterized by Nanosight and Western blot analysis. CD3-depleted PBMCs were cultured with EX21 for 14 days, NK cell amounts were monitored and media changed every 2-3 days. In vitro cytotoxicity against K562 cells were comparatively assessed for EX21-NK cells and PM21-NK cells. In vivo anti-tumor efficacy of EX21- and PM21-NK cells was assessed in NSG mice implanted ip with SKOV3_luc ovarian tumor cells (1 x 106 cells seeded for 4 days). SKOV3-bearing mice were treated with vehicle, or two doses of EX21-NK cells or PM21-NK cells (1 x 107, in 5 day intervals), and with or without in vivo administration of EX21 (10 µg, 3x/week) or PM21-particles (600 µg, 3x/week). All groups were injected ip with IL-2 (10 KU, 3x/week). Survival analysis was performed with a Log-rank (Mantel-Cox) test. Results: NK cells cultured with EX21 expanded 530 fold (344-710) over 14 days compared to 735 fold (667-802) in presence of PM21-particles. Treatment of SKOV3 engrafted NSG mice with NK cells, expanded with either EX21 or with PM21, allowed significant ( < 0.0001) increase in survival compared to untreated animals (41-44 vs 29 days post treatment). Ip delivery of EX21 to SKOV3 bearing mice had no effect on survival in either untreated control or EX21-NK cell treated groups. Conclusions: EX21 efficiently expands NK cells and EX21-NK cells have equal anti-tumor effect as PM21-NK cells, both in vitro and in vivo.

scholarly journals Combinatorial Natural Killer Cell–based Immunotherapy Approaches Selectively Target Chordoma Cancer Stem Cells

2021 ◽  
Vol 1 (3) ◽  
pp. 127-139
Author(s):  
Austin T.K. Hoke ◽  
Michelle R. Padget ◽  
Kellsye P. Fabian ◽  
Anjali Nandal ◽  
Gary L. Gallia ◽  
...  
Keyword(s):  
Stem Cells ◽  
Cancer Stem Cells ◽  
Nk Cells ◽  
Nk Cell ◽  
Killer Cell ◽  
Flow Cytometric Analysis ◽  
In Vitro Cytotoxicity ◽  
Programmed Death ◽  
Tumor Types

Chordoma is a rare tumor derived from notochord remnants that has a propensity to recur and metastasize despite conventional multimodal treatment. Cancer stem cells (CSC) are implicated in chordoma's resistant and recurrent behavior; thus, strategies that target CSCs are of particular interest. Using in vitro cytotoxicity models, we demonstrated that anti-programmed death ligand 1 (anti–PD-L1; N-601) and anti-EGFR (cetuximab) antibodies enhanced lysis of chordoma cells by healthy donor and chordoma patient NK cells through antibody-dependent cellular cytotoxicity (ADCC). Treatment of NK cells with an IL15 superagonist complex (N-803) increased their cytotoxicity against chordoma cells, which was further enhanced by treatment with N-601 and/or cetuximab. PD-L1–targeted chimeric antigen receptor NK cells (PD-L1 t-haNKs) were also effective against chordoma cells. CSCs were preferentially vulnerable to NK-cell killing in the presence of N-601 and N-803. Flow cytometric analysis of a chordoma CSC population showed that CSCs expressed significantly more NK-activating ligand B7-H6 and PD-L1 than non-CSCs, thus explaining a potential mechanism of selective targeting. These data suggest that chordoma may be effectively targeted by combinatorial NK cell–mediated immunotherapeutic approaches and that the efficacy of these approaches in chordoma and other CSC-driven tumor types should be investigated further in clinical studies. Significance: Combinatory immunotherapy using NK-mediated approaches demonstrates robust antitumor activity in preclinical models of chordoma and selectively targets chordoma CSCs.

scholarly journals RTID-07. HUMAN PLACENTAL HEMATOPOIETIC STEM CELL DERIVED NATURAL KILLER CELLS (CYNK-001) FOR TREATMENT OF RECURRENT GLIOBLASTOMA

2020 ◽  
Vol 22 (Supplement_2) ◽  
pp. ii194-ii195
Author(s):  
Nazanin Majd ◽  
Maha Rizk ◽  
Solveig Ericson ◽  
Kris Grzegorzewski ◽  
Sharmila Koppisetti ◽  
...  
Keyword(s):  
Cell Therapy ◽  
Nk Cells ◽  
Natural Killer ◽  
Nk Cell ◽  
In Vitro Cytotoxicity ◽  
Orthotopic Mouse Model ◽  
Hematopoietic Stem ◽  
Dismal Prognosis

Abstract Glioblastoma (GBM) is the most aggressive primary brain tumor with dismal prognosis. Recent advances of immunotherapy in cancer have sparked interest in the use of cell therapy for treatment of GBM. Active transfer of Natural Killer (NK) cells is of particular interest in GBM because NK cells are capable of exerting anti-tumor cytotoxicity without the need for antigen presentation and sensitization, processes that are impaired in GBM. CYNK-001 is an allogeneic, off-the-shelf product enriched for CD56+/CD3- NK cells expanded from placental CD34+ cells manufactured by Celularity. Here, we demonstrate in vitro cytotoxicity of CYNK-001 against several GBM lines and its in vivo anti-tumor activity in a U87MG orthotopic mouse model via intracranial administration resulting in 94.5% maximum reduction in tumor volume. We have developed a phase I window-of-opportunity trial of CYNK-001 in recurrent GBM via intravenous (IV) and intratumoral (IT) routes. In the IV cohort, subjects receive cyclophosphamide for lymphodepletion followed by 3-doses of IV CYNK-001 weekly. In the IT cohort, subjects undergo placement of an IT catheter with an ommaya reservoir followed by 3-doses of IT CYNK-001 weekly. Patients are monitored for 28-days after last infusion for toxicity. Once maximum safe dose (MSD) is determined, patients undergo IV or IT treatments at MSD followed by surgical resection and the tumor tissue will be analyzed for NK cell engraftment and persistence. We will utilize a 3 + 3 dose de-escalation design (maximum n=36). Primary endpoint is safety and feasibility. Secondary endpoints are overall response rate, duration of response, time to progression, progression free survival and overall survival. Main eligibility criteria include age ≥18, KPS ≥60, GBM at first or second relapse with a measurable lesion on ≤2mg dexamethasone. This is the first clinical trial to investigate CYNK-001 in GBM and will lay the foundation for future NK cell therapy in solid tumors.

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