A Highly Efficient Method to Expand CD3-CD56+ NK Cells from Cord Blood Segments

Abstract Background: The infusion of in-vitro expanded cord blood derived CD3−CD56+ NK cells could potentially be used to enhance graft-vs-tumor effects following cord blood transplantation. In order to infuse NK cells derived from the same cord unit used during allogeneic transplantation, we sought to develop a highly efficient culture method to expand large numbers of NK cells in vitro from < 1 ml of cord blood. Methods: Immunomagnetic beads were used to deplete CD3+ T-cells from thawed cord blood. CD3 depleted mononuclear cells (<0.1% CD56+) were co-cultured with either irradiated EBV-LCL feeder cells or 41BB transduced K562 cells in X-VIVO 20, 10% human AB serum, and 500 IU/ml hrIL-2 for up to 47 days. Results: Day 12 EBV-LCL expanded NK cell cultures contained up to 90% CD3−CD56+ NK cells with less than 0.5% CD3+CD56+ cells. Expanded cord blood derived CD56+NK cells had similar expression of CD16, NKG2D, LFA-1, perforin, and granzymes A and B and had similar cytotoxic function as NK cells expanded from adult PBMC. Surface expression of NK cell TRAIL increased dramatically with in vitro expansion. By day 12, TRAIL surface expression by FACS was at similar levels observed on expanded adult NK cells, although expression gradually declined with prolonged cell culture; on days 12, 20, and 34, 89%, 57% and 11% of cord derived NK cells expressed TRAIL respectively. NK cell cultures expanded with 41BB-transduced APCs had a similar phenotype and cytotoxic function against K562 cells and renal cell carcinoma (RCC) cells as EBV-LCL expanded cells. Furthermore, NK cell cytotoxicity against RCC tumor targets treated with 10 nM bortezomib for 18 hrs (bortezomib upregulates RCC surface expression of DR5) was higher than untreated RCC cells confirming the functional cytolytic activity of TRAIL expressed on cord blood derived NK cells. We next evaluated the feasibility of expanding CD56+ NK cells from thawed segments attached to the umbilical cord blood units. TNC numbers of each segment ranged from 3–9 × 106 cells. Unmanipulated thawed segments were co-cultured with irradiated EBV-LCL feeder cells as described above. On Day 12, 43% of viable cells were CD3+, 21.5% were CD3+CD56+ and 36% were CD3− CD56+. CD3−CD56+ NK cells from thawed segments increased 200 – 300 fold with in vitro expansion when maintained in culture for 2–3 weeks (Table). To enrich for pure NK cell populations, subsequent expansions were performed on CD3 depleted cells pooled from three thawed segments stimulated with EBV-LCL; cultures on day 12 contained a pure population of CD3−CD56+ NK cells with virtually an identical phenotypic and cytotoxicity profile as NK cells expanded from larger aliquots taken directly from the thawed cord blood unit. By day 33, CD3−CD56+ NK cells expanded by up to 30,000 fold; in one experiment, 391 ×106 CD3-CD56+ NK cells were expanded from only 13,000 NK cells obtained from a pool of three thawed cord segments. Conclusions: In vitro-expansion of a pure population of CD3−CD56+ cells derived from cord blood can be achieved using EBV-LCL or 41BB transduced feeder cells. Expanded cells have increased NKG2D and TRAIL expression and enhanced TRAIL-mediated tumor cytotoxicity. Even with very low starting numbers of TNCs, substantial numbers of CD3+, CD3+56+ and CD3−CD56+ cells can be expanded in vitro from thawed segments using EBV-LCL feeder cells in advance of thawing of the cord unit. These methods are being optimized to allow for clinical scale expansion of NK cells from the same cord unit used for hematopoietic cell transplantation. Cell numbers after expansion of individual segments with EBV – LCL feeder cells Day 0 (×10e6) Day 16 (× 10e6) Fold expansion TNC 3–6 78–112 20–30 CD3+ 0.42–0.91 33–47 50–70 CD3+CD56- 0.015–0.032 16–24 700–1000 CD3-CD56+ 0.081–0.175 28–40 200–300 Cell numbers after CD3+ depletion of pooled segments and expansion with EBV – LCL feeder cells Day 0 (×10e6) Day 33 (× 10e6) Fold expansion TNC 4.16 401 96 CD3+ 0 0 - CD3+CD56- 0 0 - CD3-CD56+ 0.0132 391 29621

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A Phase II Trial of IPH2101 (anti-KIR mAb) in Smoldering Multiple Myeloma

Blood ◽

10.1182/blood.v118.21.2944.2944 ◽

2011 ◽

Vol 118 (21) ◽

pp. 2944-2944

Author(s):

Neha Korde ◽

Jane Trepel ◽

Mattias Carlsten ◽

Adriana Zingone ◽

Rene Costello ◽

...

Keyword(s):

Nk Cells ◽

Nk Cell ◽

K562 Cells ◽

In Vitro Studies ◽

Before And After ◽

Post Infusion ◽

Correlative Studies ◽

M Spike ◽

Cytotoxic Function

Abstract Abstract 2944 Emerging evidence suggests multiple myeloma (MM) may be susceptible to components of the innate immune system including natural killer (NK) cells. In vitro studies have shown that allogeneic and autologous NK cells have the ability to kill CD138-purified primary MM cells. A recent study focusing on allogeneic hematopoietic stem cell transplantation for MM showed recipients who lacked MHC class I ligands for donor KIR (so called KIR incompatible transplants) had markedly reduced relapse rates, indicating NK cell KIR may exert significant control over clinical NK cell-mediated anti-MM responses. In this two-stage phase II study, we evaluated the response rate, toxicity, pharmacokinetic parameters and biological activity of IPH2101 in smoldering myeloma (SMM). IPH2101 is a fully human IgG4 monoclonal antibody (mAb) that facilitates natural killer (NK) cell-mediated killing of myeloma cells by blocking the interaction of inhibitory killer cell immunoglobin (Ig)-like receptor (KIR) 2D on NK cells with their human leukocyte antigen-C (HLA-C) ligands on target cells. This interim analysis was planned when all patients in the first stage (n=9/21) were recruited. Nine SMM patients meeting eligibility criteria were prospectively enrolled (median 59 yrs; 8 males and 1 female). Patients received a single dose of IPH2101 1mg/kg by intravenous route every other month (for a total of 6 cycles). A pre-treatment bone marrow biopsy was obtained for confirmation of diagnosis and for correlative studies. Peripheral blood mononuclear cells were obtained on days 1, 8, 18, 22 for cycle one then monthly thereafter for subsequent cycles for correlative studies to assess KIR 2D blockade and the effects of mAb therapy on NK cytotoxic function against K562 cells and MM cells matched for recipient KIR ligands. Routine blood work, serum/urine protein electrophoresis and immunofixation, and serum free light chain assays were conducted monthly. At the end of study, a post-treatment bone marrow biopsy will be obtained for clinical evaluation and correlative studies. To date, of the 9 patients enrolled on trial, 1 patient has received 5 cycles, 2 patients have received 4 cycles, and 4 patients have received 2 cycles. After an average of 3 (range 2–5) cycles of IPH2101, no patients have yet achieved a 50% reduction of their baseline M-spike (target for the study). Toxicities have been minimal and no grade 3–4 toxicities have been observed to date. Occupancy of KIR2D by IPH2101 has been assessed on peripheral blood NK cells taken at baseline, 24 hrs after the first infusion, and prior to each subsequent infusion using a flow based KIR occupancy assay that measures the binding of a labeled immunofluorescent anti-KIR relative to standard fluorescent beads. The interim results are consistent with a very high KIR occupancy of >90% at 24 hr post the first infusion and the maintenance of a high level of occupancy of available IPH2101 binding sites at 2 months post-infusion. In vitro studies measuring the cytotoxic function of patient's NK cells against K562 cells and KIR ligand matched myeloma cells before and after IPH2101 treatment are ongoing and will be reported at the meeting. In conclusion, this first interim analysis based on 9 SMM patients treated with IPH2101 are consistent with a very high KIR2D occupancy on NK cells by this mAb up to 2 months post-infusion. To date, none of the patients treated have had 50% reduction of their baseline M-spike. mAb infusions have been well tolerated with no grade 3–4 toxicities observed to date. Updated clinical data and functional in vitro studies measuring the cytotoxic function of patient's NK cells before and after mAb therapy will be presented at the meeting. Disclosures: No relevant conflicts of interest to declare.

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Defective Triggering of NK Cells Results in Primary CLL Cells Resistance to Cytotoxicity,

Blood ◽

10.1182/blood.v118.21.3876.3876 ◽

2011 ◽

Vol 118 (21) ◽

pp. 3876-3876

Author(s):

Caroline Veuillen ◽

Jerome Rey ◽

Rémy Castellano ◽

Florence Orlanducci ◽

Françoise Mallet ◽

...

Keyword(s):

B Cells ◽

Nk Cells ◽

Nk Cell ◽

K562 Cells ◽

Surface Expression ◽

Resting Cells ◽

Nk Receptors ◽

Healthy Donors

Abstract Abstract 3876 Chronic lymphocytic leukemia (CLL) remains an incurable disease except after allogenic transplantation. Natural killer (NK) cells are one of the main effectors of immune surveillance involved in tumor control. Alterations of NK cells functions have been well characterized in myeloid malignancies. However the role of NK cells in immune escape of CLL in less known and controversial. Here we describe extensive phenotypic and functional characterization of NK cells and primary CLL cells and their interactions in vitro and in vivo. Twenty eight untreated CLL patients, twenty four age-matched healthy donors and ten AML patients were enrolled in the study. We have previously shown that expression and function of NK cell-triggering receptors is defective in AML. We then assessed the phenotypic and functional properties of NK cells from CLL patients. Unlike the results found in AML, no significant differences were observed in term of activating receptors, NKp46, DNAM-1, NKG2D, 2B4 and CD16. Only the natural cytotoxicity receptor (NCR) NKp30 was weakly decreased compared to healthy donors (p=0.0107). There wasn't any difference in the expression of inhibitory receptors CD158a, b, e, ILT2 and NKG2A. Looking at the spontaneous NK-mediated cytotoxicity, CLL NK cells displayed a cytolytic activity similar to that of healthy donors against K562 cell line. To further evaluate the functional consequences of the decreased expression of NKp30, mAb redirected killing assays was performed against P815 cell lines. The NK cells killing was slightly lower in CLL patients compared to healthy donors when anti-NKp30 was used although no difference could be observed with anti-NKp46 and anti-CD16. All these results supported that NK cells cytotoxicity should be effective in CLL. We then studied the susceptibility of CLL B cells to allogenic NK killing both in vitro and in vivo. Unlike AML cells and K562 cells, CLL cells were resistant to NK cytotoxicity mediated by resting cells. Exogenous stimulation of allogenic NK cells with IL2 and IL15 restored partially CLL killing, which was nevertheless still lower than AML blasts and K562 cells killing (p=0.0288 and <0.0001 respectively). Murine xenotransplantation model using NOD/SCID g null (NSG) mice allowed us to study the anti-leukemic capacity of purified NK cells after activation with IL2. We didn't observe any clearance of CLL cells after allogenic NK cell injection while CLL and NK cells were checked to be present in blood, bone marrow, spleen and liver. These experiments confirmed the CLL resistance to NK-mediated killing. To investigate the potential mechanisms of this resistance, we analyzed the surface expression of ligands for activating and inhibitory NK receptors on CLL cells. CLL cells displayed poor expression of ligands for activating NK receptors MICA/B, ULBP1-3, PVR, nectin-2 and CD54. Interestingly, this profile of surface expression was similar to that of normal B cells except a slight increase of ULBP3 expression on CLL cells. Regarding ligands for inhibitory NK receptors, HLA-class I molecules were significantly down-regulated while HLA-E tended to be up-regulated on CLL cells compared to normal B cells. Finally, we tested ADCC in order to overcome the resistance of CLL cells to NK killing: the presence of rituximab increased significantly CLL lysis. Of note, priming of NK cells with IL2+IL15 still increased CLL cytotoxicity (p<0.0001). Our findings demonstrate that primary CLL cells are resistant to NK mediated killing. This defect is mainly due to the lack of ligands for NK receptors on CLL cells surface leading to deficient triggering of NK cells. However NK cells of CLL patients are fully competent. Attempts to optimize NK cell therapy for treatment of CLL will require overcoming the low immunogenicity of B-CLL cells. Our xenograft model provides the tools for such preclinical development. Disclosures: No relevant conflicts of interest to declare.

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Cell Density of NK Cells during Ex Vivo Expansion Impacts NK Cell Surface TRAIL Expression

Blood ◽

10.1182/blood-2020-141487 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 5-6

Author(s):

Joseph A. Clara ◽

Robert Reger ◽

Mala Chakraborty ◽

Steven L Highfill ◽

Jianjian Jin ◽

...

Keyword(s):

Nk Cells ◽

Cell Density ◽

Nk Cell ◽

Ex Vivo ◽

Death Receptor ◽

Surface Expression ◽

Feeder Cells ◽

Trail Expression ◽

Cell Densities

Introduction Natural Killer (NK) cells are an emerging form of cancer immunotherapy currently being tested in clinical trials world-wide. NK cells are innate immune cells that can kill tumor cells via release of cytotoxic granules and via surface expression of the death receptor ligands tumor-related apoptosis-inducing ligand (TRAIL) and Fas ligand. We and others have recently shown that the proteasome inhibitor bortezomib sensitizes tumor cells to NK cell TRAIL-mediated killing by upregulation of death receptor 5. In a recent phase I NK cell dose-escalation study conducted at the NIH (NCT00720785) we have attempted to exploit TRAIL sensitization by administering ex vivo-expanded autologous NK cells to patients with solid tumors or hematologic malignancies that have been pretreated with bortezomib. Ex vivo cultures used to expand clinical grade NK cells for this trial utilize irradiated EBV-LCL feeder cells and IL-2 containing media which upregulates surface expression of TRAIL, substantially augmenting NK cell killing of bortezomib-treated tumors in vitro. Here we characterize the impact of specific expansion conditions used to generate high numbers of NK cells for clinical use on NK cell TRAIL expression. Methods To generate clinical grade ex vivo-expanded NK cells, we first isolated NK cells from patient apheresis products by CD3+ depletion followed by CD56+ selection, and stimulated these enriched NK cells with irradiated EBV-LCL feeder cells at a ratio of 1:10 in X-VIVO 20 supplemented with 10% inactivated human AB serum and recombinant human IL-2 (500 IU/ml). The clinical trial evaluated 8 escalating NK cell dose levels (Figure 1). Cohorts 1-4 received a single infusion of ex vivo-expanded NK cells on day 0 in a dose-escalating fashion (3-6 pts per cohort) and cohorts 5-7 received 1 x 108 NK cells/kg on day 0 and a second escalating dose of NK cells infused on day +5. A "closed bag" Baxter PL732 culture system was used for cohorts 1-7 which was later changed to a GREX500-CS (Wilson Wolf) system in cohorts 7-8. Using flow cytometry, we monitored surface expression of TRAIL on the day NK cells were harvested and infused fresh into patients. We also assessed TRAIL expression on NK cells from a single patient cultured at 6 different cell densities (range: 2.03-16.95 x 106/cm2) using culture conditions mimicking the phase I trial. Results A total of 137 NK cell cultures were harvested and administered fresh to 32 patients. NK cells on the day of harvest expanded a median of 198-fold, 895-fold, and 3637-fold on culture days 14-16, 19-22, and 24-27, respectively. NK cells at harvest contained a median of 99.7% CD3−/CD56+ NK cells, were 68.65% CD16+ and had a median of 88% viability. TRAIL was assessed by mean fluorescence intensity (MFI) with a median surface expression of of 1245 (range 132-4913) at the time of infusion (Figure 1). Expansions for cohort 8 generated 10-14 x109 (1 vessel) and 50-70 x109 NK cells (4-5 vessels) for fresh infusion, enough to support the target dose level of 1x108 (1st harvest) and 5x108 (2nd harvest) NK cells/kg. Remarkably, NK cells grown at higher cell density to reach the target cell numbers for cohort 8 exhibited substantially reduced TRAIL expression (median: 255, range 132-691). Subsequent experiments conducted on NK cells expanded in vitro for 14 days at different cell densities/concentrations showed TRAIL expression (MFI range: 319-1627) inversely correlated with both cell density and concentration (Figure 2). NK cells grown at the highest cell density (16.95 x 106/cm2) and concentration (4.23 x 106/mL) expressed the least amount of TRAIL (MFI 319), in contrast to those cultured at the lowest cell density (2.03 x 106/cm2) and concentration (0.51 x 106/mL), which demonstrated a TRAIL MFI of 1627. Conclusions Although ex vivo cultures using feeder cells make it possible to expand large numbers of NK cells for clinical use in humans, the higher concentrations and density of cells in these cultures reduce NK cell surface expression of TRAIL. In vitro, TRAIL expression appears to inversely correlate with cell density. These data highlight the need to avoid overly concentrating ex vivo expanded NK cells to maximize TRAIL surface expression as a method to potentiate the anticancer effects of adoptively infused NK cells. Disclosures No relevant conflicts of interest to declare.

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Direct Binding of Human NK Cell Natural Cytotoxicity Receptor NKp44 to the Surfaces of Mycobacteria and Other Bacteria

Infection and Immunity ◽

10.1128/iai.00870-07 ◽

2008 ◽

Vol 76 (4) ◽

pp. 1719-1727 ◽

Cited By ~ 91

Author(s):

Semih Esin ◽

Giovanna Batoni ◽

Claudio Counoupas ◽

Annarita Stringaro ◽

Franca Lisa Brancatisano ◽

...

Keyword(s):

Nk Cells ◽

Nk Cell ◽

Cell Subset ◽

Surface Expression ◽

Binding Assays ◽

Igg Antibody ◽

Direct Stimulation ◽

Activating Receptors ◽

Accessory Cells

ABSTRACT Our previous studies demonstrated that Mycobacterium bovis bacillus Calmette-Guérin (BCG) can directly interact with human NK cells and induce the proliferation, gamma interferon production, and cytotoxic activity of such cells without the need for accessory cells. Thus, the aim of the present study was to identify the putative receptor(s) responsible for the recognition of BCG by human NK cells and potentially involved in the activation of NK cells. To this end, we first investigated the surface expression of three NK cell-activating receptors belonging to the natural cytoxicity receptor (NCR) family on highly purified human NK cells upon in vitro direct stimulation with BCG. An induction of the surface expression of NKp44, but not of NKp30 or NKp46, was observed after 3 and 4 days of in vitro stimulation with live BCG. The NKp44 induction involved mainly a particular NK cell subset expressing the CD56 marker at high density, CD56bright. In order to establish whether NKp44 could directly bind to BCG, whole BCG cells were stained with soluble forms of the three NCRs chimeric for the human immunoglobulin G (IgG) Fc fragment (NKp30-Fc, NKp44-Fc, NKp46-Fc), followed by incubation with a phycoerythrin (PE)-conjugated goat anti-human IgG antibody. Analysis by flow cytometry of the complexes revealed a higher PE fluorescence intensity for BCG incubated with NKp44-Fc than for BCG incubated with NKp30-Fc, NKp46-Fc, or negative controls. The binding of NKp44-Fc to the BCG surface was confirmed with immunogold labeling using transmission electron microscopy, suggesting the presence of a putative ligand(s) for human NKp44 on the BCG cell wall. Similar binding assays performed on a number of gram-positive and gram-negative bacteria revealed a pattern of NKp44-Fc binding restricted to members of the genus Mycobacterium, to the mycobacterium-related species Nocardia farcinica, and to Pseudomonas aeruginosa. Altogether, the results obtained indicate, for the first time, that at least one member of the NCR family (NKp44) may be involved in the direct recognition of bacterial pathogens by human NK cells.

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Immunoselection by natural killer cells of PIGA mutant cells missing stress-inducible ULBP

Blood ◽

10.1182/blood-2005-03-1337 ◽

2006 ◽

Vol 107 (3) ◽

pp. 1184-1191 ◽

Cited By ~ 48

Author(s):

Nobuyoshi Hanaoka ◽

Tatsuya Kawaguchi ◽

Kentaro Horikawa ◽

Shoichi Nagakura ◽

Hiroaki Mitsuya ◽

...

Keyword(s):

Membrane Proteins ◽

Nk Cells ◽

Natural Killer ◽

Blood Cells ◽

Cell Injury ◽

Nk Cell ◽

K562 Cells ◽

Cytotoxic Cells ◽

Immune Mediated

AbstractThe mechanism by which paroxysmal nocturnal hemoglobinuria (PNH) clones expand is unknown. PNH clones harbor PIGA mutations and do not synthesize glycosylphosphatidylinositol (GPI), resulting in deficiency of GPI-linked membrane proteins. GPI-deficient blood cells often expand in patients with aplastic anemia who sustain immune-mediated marrow injury putatively induced by cytotoxic cells, hence suggesting that the injury allows PNH clones to expand selectively. We previously reported that leukemic K562 cells preferentially survived natural killer (NK) cell-mediated cytotoxicity in vitro when they acquired PIGA mutations. We herein show that the survival is ascribable to the deficiency of stress-inducible GPI-linked membrane proteins ULBP1 and ULBP2, which activate NK and T cells. The ULBPs were detected on GPI-expressing but not on GPI-deficient K562 cells. In the presence of antibodies to either the ULBPs or their receptor NKG2D on NK cells, GPI-expressing cells were as less NK sensitive as GPI-deficient cells. NK cells therefore spared ULBP-deficient cells in vitro. The ULBPs were identified only on GPI-expressing blood cells of a proportion of patients with PNH but none of healthy individuals. Granulocytes of the patients partly underwent killing by autologous cytotoxic cells, implying ULBP-associated blood cell injury. In this setting, the lack of ULBPs may allow immunoselection of PNH clones.

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Human NK cell development in NOD/SCID mice receiving grafts of cord blood CD34+ cells

Blood ◽

10.1182/blood-2002-07-2024 ◽

2003 ◽

Vol 102 (1) ◽

pp. 127-135 ◽

Cited By ~ 30

Author(s):

Christian P. Kalberer ◽

Uwe Siegler ◽

Aleksandra Wodnar-Filipowicz

Keyword(s):

Cord Blood ◽

Nk Cells ◽

Scid Mouse ◽

Nk Cell ◽

Cell Development ◽

Scid Mice ◽

Differentiation Potential ◽

Ifn Γ

Abstract Definition of the cytokine environment, which regulates the maturation of human natural killer (NK) cells, has been largely based on in vitro assays because of the lack of suitable animal models. Here we describe conditions leading to the development of human NK cells in NOD/SCID mice receiving grafts of hematopoietic CD34+ precursor cells from cord blood. After 1-week-long in vivo treatment with various combinations of interleukin (IL)–15, flt3 ligand, stem cell factor, IL-2, IL-12, and megakaryocyte growth and differentiation factor, CD56+CD3- cells were detected in bone marrow (BM), spleen, and peripheral blood (PB), comprising 5% to 15% of human CD45+ cells. Human NK cells of NOD/SCID mouse origin closely resembled NK cells from human PB with respect to phenotypic characteristics, interferon (IFN)–γ production, and cytotoxicity against HLA class 1–deficient K562 targets in vitro and antitumor activity against K562 erythroleukemia in vivo. In the absence of growth factor treatment, CD56+ cells were present only at background levels, but CD34+CD7+ and CD34-CD7+ lymphoid precursors with NK cell differentiation potential were detected in BM and spleen of chimeric NOD/SCID mice for up to 5 months after transplantation. Our results demonstrate that limitations in human NK cell development in the murine microenvironment can be overcome by treatment with NK cell growth–promoting human cytokines, resulting in the maturation of IFN-γ–producing cytotoxic NK cells. These studies establish conditions to explore human NK cell development and function in vivo in the NOD/SCID mouse model. (Blood. 2003;102:127-135)

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Genetically Reengineered K562 Cells Significantly Expand Cord Blood (CB) Natural Killer (NK) Cells Ex-Vivo Expanded with Increased NK Cell Activation and Cytolytic Activity Both In-Vitro and In-Vivo: Potential Use In Adoptive Cellular Immunotherapy (ACI)

Blood ◽

10.1182/blood.v116.21.3928.3928 ◽

2010 ◽

Vol 116 (21) ◽

pp. 3928-3928

Author(s):

Michele Levin ◽

Janet Ayello ◽

Frances Zhao ◽

Andrew Stier ◽

Lauren Tiffen ◽

...

Keyword(s):

Nk Cells ◽

Nk Cell ◽

Ex Vivo ◽

Granzyme B ◽

K562 Cells ◽

Cytolytic Activity ◽

Scid Mice ◽

Activation Marker

Abstract Abstract 3928 Background: NK cells play a role in reducing relapse in hematological malignancy following AlloSCT (Dunbar et al, Haematologica, 2008). NK cell limitations include lack of tumor recognition and/or limited numbers of viable and functional NK cells (Shereck/Cairo et al, Ped Bld Can, 2007). NK ACI provide safe and effective therapy against tumor relapse; yet NK cells are limited to specific cancer types and not all patients demonstrate optimal response (Ruggieri et al. Science, 2002; Ljunggren et al. Nat Rev Immuno, 2007). To circumvent these limitations, methods to expand and activate PBMNCs with genetically engineered K562 cells expressing membrane bound IL-15 and 41BB ligand (K562-mbIL15-41BBL [modK562]; Imai/Campana et al, Blood, 2005) have shown to significantly increase NK cells in number and maintain heterogeneous KIR expression (Fusaki/Campana et al BJH, 2009). We have shown that CB NK cells can be activated/expanded and exhibit enhanced cytolytic activity when cultured in a cytokines/antibody cocktail (Ayello/Cairo et al, BBMT, 2006; Exp Heme, 2009). Objective: To evaluate CBNK expansion, activation, cytolytic mechanism and function against Burkitt lymphoma (BL) tumor target and its influence on NK cell mediated in-vitro and in-vivo cytotoxicity in NOD-SCID mice following stimulation with modK562 cells (generously supplied by D.Campana, St Jude's Children's Hospital, Memphis, Tx). Methods: Following 100GY irradiation, modK562cells were incubated 1:1 with CBMNCs in RPMI+IL-2 (10IU/ml) for 7 days in 5%CO2, 37°C. NK activation marker (LAMP-1), perforin and granzyme B were determined by flow cytometry. Cytotoxicty was determined via europium assay at 20:1 E:T ratio with Ramos (BL) tumor targets (ATCC). The mammalian expression construct (ffLucZeo-pcDNA (generously supplied by L.Cooper, MD, PhD) was transfected to BL cells using lipofectin and selected by zeocin for stable transfection. Six week old NOD-SCID mice received 5×106 BL cells subcutaneously. Upon engraftment, xenografted NOD-SCID mice were divided in 5 groups: injected with PBS (control), BL only, 5×106 wildtype (WT) K562 expanded (E) CBNK cells, modK562 expanded (E) CB NK cells (5×106) and modK562 expanded (E) CBNK cells (5×107). Ex-vivo ECBNK cells were injected weekly for 5 weeks and xenografted NOD-SCID mice were monitored by volumetric measurement of tumor size (Tomayko/Reynolds, Can Chemother Pharmac, 1989), bioluminescent imaging (Inoue et al Exp Heme, 2007) and survival. The survival distribution for each group was estimated using the Fisher exact test. Results: On Day 0, NK cells (CD56+/3-) population was 3.9±1.3%. After 7 days, modK562 expanded CBNK cells was significantly increased compared to WTK562 and media alone (72±3.9 vs 43±5.9 vs 9±2.4%, p<0.01). This represented a 35-fold or 3374±385% increase of the input NK cell number. This was significantly increased compared to WTK562 (1771±300%, p<0.05). ModK562 ECBNK cells demonstrated increased perforin and granzyme B expression compared to WTK562 (42±1.5 vs 15±0.5%,p<0.001; 22±0.5 vs 11±0.3%,p<0.001, respectively). Cytotoxicity was against BL tumor targets was significantly increased (42±3 vs 18±2%,p<0.01), along with NK activation marker expression, CD107a (p<0.05). At 5 weeks, in-vivo studies demonstrated increased survival of NOD-SCID mice receiving both 5×106 and 5×107 modK562 ECBNK cells when compared to those with no treatment (p=0.05, p=0.0007, respectively). There was no difference in survival when comparing mice that received 5×106 vs 5×107 modK562 ECBNK cells (p=0.0894) at 5 weeks. Tumor volume of mice receiving either dose of modK562 ECBNK cells was significantly less than those receiving WTK562 ECBNK cells (1.92±0.57 and 0.37±0.05 vs 3.41±0.25, p=0.0096 and p=0.0001, respectively). Conclusions: CBMNCs stimulated and expanded with modK562 cells results in significant expansion of CBNK cells with enhanced in-vitro cytotoxicity, significant receptor expression of NK activation marker (LAMP-1), and perforin and granzyme B. Furthermore, modK562 ECBNK cells leads to increased survival and lower tumor burden of NOD-SCID mice xenografted with BL. Future directions include modK562 ECBNK cells to be genetically modified to express chimeric antigen receptor CD20 (MSCV-antiCD20-41BB-CD3 ζ) against CD20+ hematologic malignancies for future studies to evaluate whether targeting enhances in-vitro and in-vivo cytotoxicity. Disclosures: No relevant conflicts of interest to declare.

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Cord Blood Derived Natural Killer Cells Loaded with a Tetravalent Bispecific Antibody Construct (AFM13) As Off-the-Shelf Cell Therapy for CD30+ Malignancies

Blood ◽

10.1182/blood-2018-99-114954 ◽

2018 ◽

Vol 132 (Supplement 1) ◽

pp. 341-341

Author(s):

Lucila Kerbauy ◽

Mecit Kaplan ◽

Pinaki P Banerjee ◽

Francesca Lorraine Wei Inng Lim ◽

Ana Karen Nunes Cortes ◽

...

Keyword(s):

T Cell ◽

Cord Blood ◽

Nk Cells ◽

Natural Killer ◽

Research Funding ◽

Bispecific Antibody ◽

Nk Cell ◽

Ex Vivo

Abstract Chimeric antigen receptors to redirect T cell specificity against tumor antigens have shown remarkable clinical responses against CD19+ malignancies. However, the manufacture of an engineered autologous T cell product is expensive and cumbersome. Natural killer (NK) cells provide an alternative source of immune effectors for the treatment of cancer. NK cell cytolytic function can be directed towards specific targets by exploiting their ability to mediate antibody-dependent cellular cytotoxicity (ADCC) through the NK cell Fc receptor, CD16 (FcγRIIIa). AFM13 is a tetravalent bispecific antibody construct based on Affimed's ROCK™ platform. AFM13 is bispecific for CD30 and CD16A, designed for the treatment of CD30 expressing malignancies. It binds CD16A on the surface of NK cells, thus activating and recruiting them to CD30 expressing tumor cells and mediating subsequent tumor cell killing. Since autologous NK effector function is impaired in many patients with malignancies, we propose to overcome this by the use of allogeneic NK cells in combination with AFM13. Cord blood (CB) is a readily available ("off-the-shelf") source of allogeneic NK cells that can be expanded to large, highly functional therapeutic doses. The feasibility and safety of therapy with allogeneic ex vivo expanded CB-derived NK cells have been shown by our group and others. In this study, we hypothesized that we can redirect the specificity of NK cells against CD30+ malignancies by preloading ex vivo activated and expanded CB-derived NK cells with AFM13 prior to adoptive infusion. Briefly, mononuclear cells were isolated from fresh or frozen CB units by ficoll density gradient centrifugation. CD56+ NK cells were cultured with rhIL-12, rhIL-18 and rhIL-15 for 16 hrs, followed by ex vivo expansion with rhIL-2 and irradiated (100 Gy) K562-based feeder cells expressing membrane-bound IL-21 and CD137-ligand (2:1 feeder cell:NK ratio). After 14 days, NK cells were loaded with serial dilutions of AFM13 (0.1, 1, 10 and 100 mg/ml). After washing twice with PBS, we tested the effector function of AFM13-loaded NK-cells (AFM13-NK) compared to expanded CB-NK cells without AFM13 against Karpas-299 (CD30 positive) and Daudi (CD30 negative) lymphoma cell lines by 51Cr release and intracellular cytokine production assays. AFM13-NK cells killed Karpas-299 cells more effectively at all effector:target ratios tested than unloaded NK cells (Figure 1) and produced statistically more INFγ and CD107a (P=0.0034; P=0.0031 respectively, n=4). In contrast, AFM13-NK cells and unloaded NK cells exerted similar cytotoxicity against Daudi cells. Next, we established the optimal concentration of AFM13 for loading (determined to be 100 μg/ml) and the optimal incubation time to obtain maximal activity (1 h) in a series of in vitro experiments. We also confirmed that the activity of AFM13-NK cells against Karpas-299 cells remains stable for at least 72h post-wash (Figure 2). Additionally, we characterized the phenotype of AFM13-NK vs. unloaded NK cells by flow cytometry using monoclonal antibodies against 22 markers, including markers of activation, inhibitory receptors, exhaustion markers and transcription factors. Compared to unloaded NK cells, AFM13-NK cells expressed higher levels of CD25, CD69, TRAIL, NKp44, granzyme B and CD57, consistent with an activated phenotype. We next tested the in vivo anti-tumor efficacy of AFM13-NK cells in an immunodeficient mouse model of FFluc-Karpas-299. Briefly, six groups of NOD/SCID/IL2Rγc null mice (n=5 per group) were transplanted by tail-vein injection with 1 x 10e5 FFluc-transduced Karpas cells. Group 1 and 6 received tumor alone or tumor + AFM13 and served as a control. Groups 2-4 receive Karpas FFLuc with either expanded NK cells or AFM13-NK cells (NK cells loaded with AFM13) or expanded NK cells and AFM13 injected separately. Group 5 received AFM13-NK cells without tumor. Initial studies confirm the antitumor activity of AFM13-NK cells. In summary, we have developed a novel premixed product, comprised of expanded CB-NK cells loaded with AFM13 to 'redirect' their specificity against CD30+ malignancies. The encouraging in vitro and in vivo data observed in this study, provide a strong rationale for a clinical trial to test the strategy of an off-the-shelf adoptive immunotherapy with AFM13-loaded CB-NK cells in patients with relapsed/refractory CD30+ malignancies. Disclosures Champlin: Sanofi: Research Funding; Otsuka: Research Funding. Koch:Affimed GmbH: Employment. Treder:Affimed GmbH: Employment. Shpall:Affirmed GmbH: Research Funding. Rezvani:Affirmed GmbH: Research Funding.

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NF-kB c-Rel is dispensable for the development but is required for the cytotoxic function of NK cells

10.1101/2021.01.19.427356 ◽

2021 ◽

Author(s):

Y Vicioso ◽

K Zhang ◽

Parameswaran Ramakrishnan ◽

Reshmi Parameswaran

Keyword(s):

Nk Cells ◽

Nk Cell ◽

Granzyme B ◽

Conditional Knockout ◽

Cytotoxic Lymphocytes ◽

And Control ◽

Cytotoxic Function

AbstractNatural Killer (NK) cells are cytotoxic lymphocytes critical to the innate immune system. We found that germline deficiency of NF-kB c-Rel results in a marked decrease in cytotoxic function of NK cells, both in vitro and in vivo, with no significant differences in the stages of NK cell development. We found that c-Rel binds to the promoters of perforin and granzyme B, two key proteins required for NK cytotoxicity, and controls their transactivation. We generated a NK cell specific c-Rel conditional knockout to study NK cell intrinsic role of c-Rel and found that both global and conditional c-Rel deficiency leads to decreased perforin and granzyme B expression and thereby cytotoxic function. We also confirmed the role of c-Rel in perforin and granzyme B expression in human NK cells. c-Rel reconstitution rescued perforin and granzyme B expressions in c-Rel deficient NK cells and restored their cytotoxic function. Our results show a previously unknown role of c-Rel in transcriptional regulation of perforin and granzyme B expressions and control of NK cell cytotoxic function.

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Promising Preliminary Activity of Optimized Affinity, CD38 CAR NK Cells Generated Using a Non-Viral Engineering Approach in Gene Edited Cord Blood Derived NK Cells for the Treatment of Multiple Myeloma

Blood ◽

10.1182/blood-2021-151379 ◽

2021 ◽

Vol 138 (Supplement 1) ◽

pp. 4793-4793

Author(s):

Rohit Duggal ◽

Sumit Sen Santara ◽

Myra Gordon ◽

Aoife Kilgallon ◽

David Hermanson ◽

...

Keyword(s):

Multiple Myeloma ◽

Cell Surface ◽

Cord Blood ◽

Nk Cells ◽

Nk Cell ◽

Surface Expression ◽

Cell Surface Expression ◽

Feeder Layer ◽

Guide Rnas ◽

Rnp Complex

Abstract CD38 is a multifunctional cell surface protein that is frequently overexpressed on malignant plasma cells as well as on immune suppressive cells within the tumor microenvironment and constitutes a validated immunotherapeutic target in the treatment of multiple myeloma (MM). At ONK Therapeutics we are developing a gene edited, cord blood-derived NK (CBNK) cell product targeting CD38 for treatment of patients with relapsed and/or refractory MM. The product will be generated using a workflow shown in Figure 1A. This involves starting with cord blood that is processed for NK expansion using a clinically validated, Epstein Barr Virus-transformed lymphoblastoid cell line (EBV-LCL) feeder layer. The NK cells would undergo genetic engineering that involves gene editing followed by a non-viral chimeric antigen receptor (CAR) introduction process mediated by the TcBuster (TcB) DNA transposon system (Biotechne). This is followed by a second round of expansion on the EBV-LCL feeder layer resulting in a characterized NK cell product that can then be cryopreserved. In order to develop protocols for optimizing the best transfection efficiencies using the Maxcyte ATx instrument, GFP mRNA (TriLink) was used for transfecting CBNK cells using different electroporation programs. High transfection efficiency was obtained using all programs (Figure 1B.), with the best from program NK4. Since the product employs an optimized affinity second generation anti CD38 CAR (Stikvoort et al., Hemasphere 2021) which could also target CD38 expressed on neighbouring activated NK cells, it is imperative to knock out (KO) the cell surface expression of CD38 on the CAR-NK cells. To achieve this we carried out CRISPR Cas9 based KO studies of CD38 (Figure 1C. left top), using guide RNAs targeting CD38 (Synthego) in the form of a ribonucleoprotein (RNP) complex with Cas9. CBNK cells were transfected using the Maxcyte ATx instrument and CD38 cell surface expression monitored. As shown in Figure 1C. (left top), complete CD38 KO was achieved 11 days post transfection. ONK Therapeutics is actively involved in targeting and downregulating the negative regulator of cytokine signalling, cytokine inducible SH2-containing protein (CIS), which is encoded by the CISH gene, as part of their CBNK products. It has been demonstrated that in addition to facilitating greater cytokine signalling, CISH KO also confers greater metabolic capacity to NK cells resulting in their increased persistence (Daher et al., Blood 2021). Therefore, ONK Therapeutics have evaluated CISH KO in CBNK cells (Figure 1C, top right) using the same scheme that was used for the CD38 KO. Guide RNAs in the form of a RNP complex with Cas9 (Synthego) were transfected into CBNK cells and intracellular CIS protein levels monitored over time. Almost complete KO was attained by 9 days post transfection. In order to dial in CISH KO as part of the product, we further carried out a simultaneous KO of CD38 and CISH, in addition to individual KO of CD38 or CISH (Fig 1C, bottom). Simultaneous multiplexing of the CD38 and CISH KOs resulted in efficient double KO (DKO) . The extent of knock down leading to KO in the DKO setting was very similar to that of individual gene KOs. We then introduced the anti CD38 CAR as part of a transposon that could be transposed by TcB transposase in CBNK cells. After DKO of CD38 and CISH in CBNK cells, the transposon DNA and mRNA for transposase were electroporated. CAR expression was detected 4-5 days post transposition (Figure 1D) with more than 50% of cells expressing the anti CD38 CAR. These CAR expressing CBNK cells were then tested for functionality in a co-culture kill assay against the CD38 positive MM cell line, RPMI8226, which was engineered to express firefly luciferase. In a 4 hour killing assay, robust killing of the RPMI8226 cells was achieved by the CAR-CBNK cells with an EC 50 ten times lower (more potent) than that of mock electroporation control CBNK cells. To our knowledge this is the first successful expression of an anti CD38 CAR in cord-derived NK cells, and with a double CD38/CISH KO, using non-viral CAR insertion approaches. Current work is focusing on designing and developing a manufacturing-ready workflow for this potential product and further examining the effects of CAR NK cell activity in a DKO setting where both KOs contribute to improved metabolism and potentially NK cell persistence, as well as exploring the added benefit of a DR5 TRAIL variant to enhance cytotoxicity. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

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