scholarly journals Targeting CD38high Acute Myeloid Leukaemia with "Affinity Optimized" Chimeric Antigen Receptor and Membrane Bound TRAIL Expressing Natural Killer Cells

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 5536-5536 ◽  
Author(s):  
Emma Nolan ◽  
Arwen Stikvoort ◽  
Mark Gurney ◽  
Nutsa Burduli ◽  
Lucy Kirkham-McCarthy ◽  
...  

Introduction: Chimeric Antigen Receptor (CAR) based cellular-immunotherapies have demonstrated significant clinical efficacy in haematological malignancies. However, the progress of cellular-immunotherapy for the treatment of Acute Myeloid Leukaemia (AML) has failed to gain momentum due to the lack of targetable tumour specific antigens. CD38 is a transmembrane glycoprotein expressed in lymphoid and myeloid cells with high expression in plasma B-cells, and is a well validated target for anti-CD38 therapy in Myeloma. A recent study has furthermore shown that a proportion of AML patients express CD38 on their leukemic blasts. TNF-related apoptosis-inducing ligand (TRAIL) receptor DR4 is another targetable antigen which has been shown to be expressed in 70% of AML patients. In this study, we investigate the therapeutic efficacy of "affinity-optimized" variant(s) of CD38 CAR and membrane bound TRAIL on NK-cell based platforms which can target AML blasts with high expression of CD38 (CD38high AML). The CAR variant is a CAR which binds with lower affinity to CD38 expressed on healthy immune cells such as CD38positive NK cells, while targeting CD38high AML. The membrane bound TRAIL variant (TRAIL4c9) is a mutant which binds with higher affinity to TRAIL-DR4 on AML cells, whilst avoiding binding to decoy receptors. We hypothesize that genetically modifying NK cells to express "affinity optimized" CD38 CARand/or TRAIL4c9 can effectively eliminate CD38high AML cells. Methods: AML cell lines THP-1, U937, and KG1a were immunophenotyped for CD38 and TRAIL-DR4 expression. Retrovirally transduced CD38 CAR-KHYG1 NK cells were used as immune effector cells and were co-cultured with AML cell lines in cytotoxicity assays. CD38low AML cell line KG1a was pre-treated with 10nM all-trans-retinoic acid (ATRA) to upregulate CD38 expression and were subsequently co-cultured with CD38 CAR-KHYG1 in cytotoxicity assays. CD38 CAR-KHYG1 was also co-cultured with n=4 patient derived AML cells in cytotoxicity assays. Using Maxcyte GT electroporation system primary donor derived IL-2 activated NK cells were either mock electroporated, or electroporated with TRAIL4c9 m-RNA orCD38 CAR m-RNA and subsequently co-cultured with THP-1 or ATRA pre-treated KG1a in a cytotoxicity assay. Expression of pro-apoptotic, anti-apoptotic and ligands for checkpoint inhibitory receptors was analysed by immunoblotting or flowcytometry. Results: Based on immunophenotyping, we classified AML cell lines as CD38high (THP-1), CD38moderate (U937) and CD38low (KG1a). CD38 CAR-KHYG1 was significantly more cytotoxic than MOCK KHYG1 against CD38high THP-1, at E:T ratios of 2.5:1, 5:1 and 10:1. CD38 CAR-KHYG1 were also more cytotoxic than MOCK KHYG1 against CD38moderate U937 at multiple E:T ratios; albeit the increase in cytotoxicity was at a much lower level in comparison to THP-1 (Fig 1a). Pre-treatment of CD38low KG1a cells with 10nM ATRA upregulated the cell surface expression of CD38, which were subsequently eliminated by CD38 CAR KHYG1 at E:T ratios of 2.5:1, 5:1 and 10:1. KG1a was intrinsically resistant to NK cells as compared to THP-1 and U937 (Fig 1b). This could partly be explained by the high intracellular expression of Bcl-xL, and higher cell surface expression of Nectin-1 and Sialic acid which are the ligands for checkpoint inhibitory receptors CD96 and Siglec-7/9 respectively on NK cell (Fig 1c). CD38 CAR-KHYG1 mounted a potent cytotoxic response against primary CD45intermediate AML blasts (n=4 patients) at multiple E:T ratios, and the extent of CAR induced cytotoxicity correlated with the cell surface CD38 expression on the primary AML blasts (R2=0.87) (Fig 1d,e). TRAIL4c9 or CD38 CAR m-RNA electroporated primary donor-derived NK cells were also potent in eliminating THP-1 and ATRA pre-treated KG1a at multiple E:T ratios (Fig 1f). This demonstrates the potential of therapeutically treating AML patients, with high CD38 expression, with a combination of NK cells expressing "affinity-optimized" CD38 CAR and membrane bound TRAIL variant. Conclusion: The study demonstrates the therapeutic potential of an "affinity-optimized" CD38 CAR NK cell-based therapy, which can potentially be combined with membrane bound TRAIL expressing NK cells to target CD38high AML. In patients with CD38low expressing AML blasts, patients could be pre-treated with ATRA followed by the combination therapy of CD38 CAR and TRAIL expressing NK cells. Disclosures Stikvoort: Onkimmune Ltd., Ireland: Research Funding. Kirkham-McCarthy:Onkimmune Ltd., Ireland: Research Funding. Van De Donk:Janssen Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Membership on an entity's Board of Directors or advisory committees; AMGEN: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene Corporation: Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Research Funding; Bayer: Membership on an entity's Board of Directors or advisory committees; Servier: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees. Mutis:Celgene: Research Funding; Janssen Pharmaceuticals: Research Funding; Amgen: Research Funding; BMS: Research Funding; Novartis: Research Funding; Aduro: Research Funding; Onkimmune: Research Funding. Sarkar:Onkimmune: Research Funding. O'Dwyer:Onkimmune: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; GlycoMimetics Inc: Research Funding; AbbVie: Consultancy; BMS: Research Funding.

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 3199-3199 ◽  
Author(s):  
Subhashis Sarkar ◽  
Sachin Chauhan ◽  
Arwen Stikvoort ◽  
Alessandro Natoni ◽  
John Daly ◽  
...  

Abstract Introduction: Multiple Myeloma (MM) is a clonal plasma cell malignancy typically associated with the high and uniform expression of CD38 transmembrane glycoprotein. Daratumumab is a humanized IgG1κ CD38 monoclonal antibody (moAb) which has demonstrated impressive single agent activity even in relapsed refractory MM patients as well as strong synergy with other anti-MM drugs. Natural Killer (NK) cells are cytotoxic immune effector cells mediating tumour immunosurveillance in vivo. NK cells also play an important role during moAb therapy by inducing antibody dependent cellular cytotoxicity (ADCC) via their Fcγ RIII (CD16) receptor. Furthermore, 15% of the population express a naturally occurring high affinity variant of CD16 harbouring a single point polymorphism (F158V), and this variant has been linked to improved ADCC. However, the contribution of NK cells to the efficacy of Daratumumab remains debatable as clinical data clearly indicate rapid depletion of CD38high peripheral blood NK cells in patients upon Daratumumab administration. Therefore, we hypothesize that transiently expressing the CD16F158V receptor using a "safe" mRNA electroporation-based approach, on CD38low NK cells could significantly enhance therapeutic efficacy of Daratumumab in MM patients. In the present study, we investigate the optimal NK cell platform for generating CD38low CD16F158V NK cells which can be administered as an "off-the-shelf"cell therapy product to target both CD38high and CD38low expressing MM patients in combination with Daratumumab. Methods: MM cell lines (n=5) (MM.1S, RPMI-8226, JJN3, H929, and U266) and NK cells (n=3) (primary expanded, NK-92, and KHYG1) were immunophenotyped for CD38 expression. CD16F158V coding m-RNA transcripts were synthesized using in-vitro transcription (IVT). CD16F158V expression was determined by flow cytometry over a period of 120 hours (n=5). 24-hours post electroporation, CD16F158V expressing KHYG1 cells were co-cultured with MM cell lines (n=4; RPMI-8226, JJN3, H929, and U266) either alone or in combination with Daratumumab in a 14-hour assay. Daratumumab induced NK cell fratricide and cytokine production (IFN-γ and TNF-α) were investigated at an E:T ratio of 1:1 in a 14-hour assay (n=3). CD38+CD138+ primary MM cells from newly diagnosed or relapsed-refractory MM patients were isolated by positive selection (n=5), and co-cultured with mock electroporated or CD16F158V m-RNA electroporated KHYG1 cells. CD16F158V KHYG1 were also co-cultured with primary MM cells from Daratumumab relapsed-refractory (RR) patients. Results: MM cell lines were classified as CD38hi (RPMI-8226, H929), and CD38lo (JJN3, U266) based on immunophenotyping (n=4). KHYG1 NK cell line had significantly lower CD38 expression as compared to primary expanded NK cells and NK-92 cell line (Figure 1a). KHYG1 electroporated with CD16F158V m-RNA expressed CD16 over a period of 120-hours post-transfection (n=5) (Figure 1b). CD16F158V KHYG1 in-combination with Daratumumab were significantly more cytotoxic towards both CD38hi and CD38lo MM cell lines as compared to CD16F158V KHYG1 alone at multiple E:T ratios (n=4) (Figure 1c, 1d). More importantly, Daratumumab had no significant effect on the viability of CD38low CD16F158V KHYG1. Moreover, CD16F158V KHYG1 in combination with Daratumumab produced significantly higher levels of IFN-γ (p=0.01) upon co-culture with CD38hi H929 cell line as compared to co-culture with mock KHYG1 and Daratumumab. The combination of CD16F158V KHYG1 with Daratumumab was also significantly more cytotoxic to primary MM cell ex vivo as compared to mock KHYG1 with Daratumumab at E:T ratio of 0.5:1 (p=0.01), 1:1 (p=0.005), 2.5:1 (p=0.003) and 5:1 (p=0.004) (Figure 1e). Preliminary data (n=2) also suggests that CD16F158V expressing KHYG1 can eliminate 15-17% of primary MM cells from Daratumumab RR patients ex vivo. Analysis of more Daratumumab RR samples are currently ongoing. Conclusions: Our study provides the proof-of-concept for combination therapy of Daratumumab with "off-the-shelf" CD38low NK cells transiently expressing CD16F158V for treatment of MM. Notably, this approach was effective against MM cell lines even with low CD38 expression (JJN3) and primary MM cells cultured ex vivo. Moreover, the enhanced cytokine production by CD16F158V KHYG1 cells has the potential to improve immunosurveillance and stimulate adaptive immune responses in vivo. Disclosures Sarkar: Onkimmune: Research Funding. Chauhan:Onkimmune: Research Funding. Stikvoort:Onkimmune: Research Funding. Mutis:Genmab: Research Funding; OnkImmune: Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Research Funding; Celgene: Research Funding; Novartis: Research Funding. O'Dwyer:Abbvie: Membership on an entity's Board of Directors or advisory committees; Celgene: Research Funding; BMS: Research Funding; Glycomimetics: Research Funding; Onkimmune: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding.


Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 138-138
Author(s):  
John Daly ◽  
Subhashis Sarkar ◽  
Alessandro Natoni ◽  
Robert Henderson ◽  
Dawn Swan ◽  
...  

Introduction: Evading Natural Killer (NK) cell-mediated immunosurveillance is key to the development of Multiple Myeloma (MM). Recent attention has focused on the role of hypersialylation in facilitating immune-evasion of NK cells. Abnormal cell surface sialylation is considered a hallmark of cancer and we have implicated hypersialylation in MM disease progression. Certain sialylated glycans can act as ligands for the sialic acid-binding immunoglobulin-like lectin (Siglec) receptors expressed by NK cells (Siglec-7 and Siglec-9). These ITIM motif-containing inhibitory receptors transmit an inhibitory signal upon sialic acid engagement. We hypothesized that desialylation of MM cells or targeted interruption of Siglec expression could lead to enhanced NK cell mediated cytotoxicity of MM cells. Methodology: MM cells were treated with the sialidase neuraminidase prior to co-culture with primary NK (PNK) cells. MM cells were treated with 300µM 3Fax-Neu5Ac (sialyltransferase inhibitor) for 3 days prior to co-cultures with PNK cells. PNK cells were expanded, IL-2 activated (500U/ml) overnight, or naïve (resting). Primary MM samples/MM cell lines were screened with Siglec-7/9 chimeras (10µg/ml). PNK (IL-2 activated) cells were stained with anti-Siglec-7 and anti-Siglec-9 antibodies. Siglec-7 was targeted for knockout (KO) using the CRISPR/Cas9 system, a pre-designed guideRNA and the MaxCyteGT transfection system. MM cells were treated with 10µg/ml of Daratumumab prior to co-culture with expanded PNK cells. Results: Using recombinant Siglec-7/9 chimeras a panel of MM cell lines (MM1S, RPMI-8226, H929, JJN3 and U266) were shown to express ligands for Siglec-7 and Siglec-9 (>85%, n=3). Primary MM cells isolated from BM of newly diagnosed (n=3) and relapsed patients (n=2) were also shown to express Siglec-7 ligands (72.5±17.5%, 36.5% respectively). PNK cells express Siglec-7 and Siglec-9 (94.3±3.3% and 61±8.8% respectively, n=6). Desialylation of the MM cell lines JJN3 and H929 using neuraminidase significantly enhanced killing of MM cells by healthy donor (HD) derived PNK cells (expanded, IL-2 activated and naïve, n=7) at multiple effector:target (E:T) cell ratios. Furthermore, de-sialylation of JJN3 and H929 using neuraminidase resulted in increased NK cell degranulation (CD107α expression), compared to a glycobuffer control (n=7). De-sialylation, using 300µM 3Fax-Neu5Ac, resulted in strongly enhanced killing of MM1S by expanded HD-derived PNK cells at multiple E:T ratios (n=5, p<0.01 at 0.5:1, p<0.001 at 1:1, p<0.01 at 2.5:1). Furthermore, CD38 expression on H929 MM cells significantly increased after treatment with 300µM 3Fax-Neu5Ac for 3 days (p<0.01, n=3). In a cytotoxicity assay, expanded PNK cell-mediated antibody dependent cellular cytotoxicity (ADCC) of H929 MM cells pre-treated with Daratumumab (anti-CD38 moAb) and 3Fax-Neu5Ac was significantly higher than H929 cells pre-treated with Dara (p<0.05 at 0.5:1, p<0.01 at 1:1) or 3Fax-Neu5Ac (p<0.01 at 0.5:1, p<0.01 at 1:1) alone (n=5). Using CRISPR/Cas9, over 50% complete KO of Siglec-7 was observed on expanded PNK cells, yet did not result in enhanced NK cell-mediated cytotoxicity against either H929 or JJN3 (n=7). Siglec-9 KO using CRISPR/Cas9 is ongoing. Discussion: Hypersialylation of MM cells facilitates immune evasion and targeted removal of sialic acid strongly enhances the cytotoxicity of NK cells against MM. However, to date the role of Siglecs remains inconclusive. Nevertheless, our data suggest that targeted desialylation is a novel therapeutic strategy worth exploring in MM. In particular, upregulation of CD38 provides a strong rationale for combinatory strategies employing targeted desialylation with CD38 moAbs such as Daratumumab, with the goal of maximizing ADCC. Disclosures Sarkar: Onkimmune: Research Funding. O'Dwyer:Onkimmune: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Research Funding; GlycoMimetics Inc: Research Funding; AbbVie: Consultancy.


Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 4064-4064
Author(s):  
Sun-Young Kong ◽  
Sabikun Nahar ◽  
Xian-Feng Li ◽  
Weihua Song ◽  
Yiguo Hu ◽  
...  

Abstract Abstract 4064 HM1.24, an immunological target highly expressed on majority of multiple myeloma (MM) cells, has not been effectively targeted with therapeutic monoclonal antibodies (mAbs). Recently, XmAb5592, a novel Fc-domain engineered humanized anti-HM1.24 mAb with specific Fc-domain modification, was shown to induce >10-fold antibody-dependent cellular cytotoxicity (ADCC) and antibody dependent cellular phagocytosis against MM cells, when compared with the humanized normal anti-HM1.24 IgG1 (XmAb5627) from which it is derived (ASH Abstract#609, 2009). Here we investigated whether XmAb5592, when combined with other anti-MM drugs, further enhanced ADCC against MM cell lines and primary patient MM cells using Calcein-AM release ADCC assays and flow cytometric analysis for cell membrane CD107a to specifically quantitate NK cell (CD56+CD3-) activation. Addition of lenalidomide (10 μ M) in standard ADCC assays increased XmAb5592 (0.1 μ g/ml)-induced cell lysis against MM1S, MM1R, and RPMI8226 cells in the presence of peripheral blood mononuclear cells (PBMCs) from normal donors (n=2). Specifically, XmAb5592 (0.01, and 0.1 μ g/ml) combined with lenalidomide (2.5, 5, 10 μ M), in the presence or absence of IL-2 (100 units/ml), synergistically induced NK-mediated RPMI8226 MM cell lysis, as evidenced by combination index (CI) < 1 (0.08-0.89). Pre-incubation of PBMCs with additional IL-2 (100 units/ml) enhanced even stronger XmAb5592-induced cytotoxicity against MM cells than pretreatment with lenalidomide alone. Lenalidomide also enhanced PBMC effectors to kill primary patient MM cells. Cell surface CD107a, as a functional marker for NK cell activation dependent on granzyme B secretion, was further determined following target myeloma cell incubation, with or without NK cells and in the presence of mAbs. NK cells were activated by as low as 0.001 μ g/ml of XmAb5592 only in the presence of MM1S tumor cells. In contrast, neither XmAb6166, an Fc-domain knockout of XmAb5592 without NK binding, nor XmAb4614, a similar Fc-engineered mAb targeting respiratory syncytial virus (RSV) antigen, induced any cell surface CD107a on NK cells incubated with MM cells. Specific XmAb5592-induced CD107a-dependent NK cell degranulation further correlated with IFNγ secretion (r=0.7, p=0.03). XmAb5592 induced > 10-fold more potent NK degranulation than XmAb5627, which significantly correlated with MM cell lysis by ADCC, even in the presence of bone marrow stromal cells (BMSCs). Moreover, no significant HM1.24 was expressed on NK cells stimulated with or without IFN-α, suggesting minimal NK toxicity. XmAb5592 more potently (>10-fold) than XmAb5627 induces homotypic aggregation and adhesion of NK cells, which was further enhanced by lenalidomide. Finally, minimal HM1.24 expression was confirmed on different PBMC subsets including CD15+ (PMN), CD19+ (B), CD14+ (MC), and CD3+ (T) cells. These results indicate that lenalidomide further potentiates XmAb5592-induced myeloma cell killing via NK-mediated ADCC, providing a rationale to combine both novel drugs to improve patient outcome in MM. Disclosures: Muchhal: Xencor Inc: Employment. Desjarlais:Xencor Inc: Employment. Richardson:Gentium: Membership on an entity's Board of Directors or advisory committees, Research Funding. Munshi:Millennium Pharmaceuticals: Honoraria, Speakers Bureau. Anderson:Millennium Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau.


Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 57-58
Author(s):  
Frank Cichocki ◽  
Ryan Bjordahl ◽  
Karrune Woan ◽  
Zachary Davis ◽  
Greg Bonello ◽  
...  

Approximately 19,940 new cases of acute myeloid leukemia (AML) will be diagnosed in 2020 with an estimated 11,180 deaths, which has remained steady for 3 decades. We established that allogeneic natural killer (NK) cell infusions have an antileukemic effect and induce remission in 25-40% of relapsed/refractory AML patients. After hundreds of individual donor product infusions, we noted therapeutic limitations to include effector potency, cell numbers,persistence, specificity and exportability. To overcome these barriers, we developed a robust genetic editing and manufacturing platform for the uniform engineering and expansion of high-quality NK cells derived from induced pluripotent stem cells (iPSCs). This manufacturing system allows efficient production of iPSC-derived NK (iNK) cells engineered to enhance persistence and potency, and enables distribution of highly homogenous iNK cells to multiple clinical sites and multi-dosing to treat patients on-demand with advanced cancer. We hypothesized that iNK cells could be combined with the anti-CD38 monoclonal antibody daratumumab (dara) to directly target various tumors and harness their antibody-dependent cellular cytotoxicity (ADCC) potential. Previously, we reported on our ability to effectively target multiple myeloma with our FT538 program (the iNK defined below), now FDA approved for clinical trials. Here we discuss applying these same engineered iNK cells to specifically target and kill AML blasts induced to upregulate CD38 by retinoic acid exposure. We utilized iNK cells expressing a high-affinity, non-cleavable version of CD16 (the Fc receptor that mediates ADCC) termed hnCD16 alone or combined with CD38 knockout (KO) to prevent dara-mediated NK cell fratricide (Fig. 1A). CD38 KO iNK cells had intact calcium flux in response to ionomycin or CD16 crosslinking (Fig. 1B). Adding dara to peripheral blood NK cells or hnCD16 iNK cells triggered ADCC-mediated fratricide, while hnCD16/CD38 KO iNK cells that cannot be targeted by dara were unaffected (Fig 1C). CD38, expressed intracellularly and on the plasma membrane, functions as an NADase, degrading nicotinamide adenine dinucleotide (NAD+) into ADP-ribose and nicotinamide. Because NAD+ levels influence several key metabolic pathways, we assessed the impact of CD38 KO on iNK cell metabolism. We found that, relative to hnCD16 iNK cells, hnCD16/CD38 KO iNK cells had significantly higher intracellular NAD+, NADH, and ATP levels (Fig. 1D). Additionally, hnCD16/CD38 KO iNK cells exhibited elevated mitochondrial oxidative phosphorylation (Fig. 1E) and marked resistance to oxidative stress to hydrogen peroxide exposure (Fig. 1F). Together, these results demonstrate a significant enhancement of NK cell mitochondrial oxidative phosphorylation and redox homeostasis in iNK CD38 KO cells. To enhance hnCD16/CD38 KO iNK cells further, we incorporated a third modification consisting of an IL-15 receptor signaling complex (IL-15RF). This receptor complex is expressed on the cell surface and provides IL-15 signals required for NK cell survival and proliferation independent of exogenous cytokine. To determine the efficacy of hnCD16/CD38 KO/IL-15RF iNK cells combined with dara to target AML, we first assessed CD38 expression on THP-1 cells (an AML cell line) and primary AML blasts incubated with or without retinoic acid. We observed high CD38 expression on both THP-1 cells and primary AML cells further elevated with retinoic acid treatment (Fig. 1G). THP-1 and primary AML cells were labeled with CellTrace dye and used as targets for killing assays using hnCD16/CD38 KO/IL-15RF iNK cells. Compared to hnCD16/CD38 KO/IL-15RF iNK cells cultured with targets alone, adding dara led to higher target cell killing, especially after retinoic acid exposure (Fig. 1H). In 12-hour live imaging experiments testing iNK cell cytotoxicity against THP-1 cells, similar results were observed (Fig. 1I). Collectively, our results show that utilizing the iNK cell platform to uniformly express hnCD16 and IL15RF combined with complete CD38 KO is an effective strategy to promote effective ADCC against CD38+ cells in the absence of fratricide, and that CD38 KO reprograms NK cells for higher oxidative metabolic fitness for improved persistence and anti-tumor function. Furthermore, we have generated proof-of-concept data supporting triple gene-modified iNK cells combined with dara as a novel AML immunotherapy. Disclosures Cichocki: Fate Therapeutics, Inc: Consultancy, Patents & Royalties, Research Funding. Bjordahl:Fate Therapeutics: Current Employment. Bonello:Fate Therapeutics, Inc: Current Employment. Mahmood:Fate Therapeutics, Inc: Current Employment. Rogers:Fate Therapeutics, Inc: Current Employment. Ge:Fate Therapeutics, Inc: Current Employment. Lee:Fate Therapeutics, Inc.: Current Employment. Felices:GT Biopharma: Consultancy. Walcheck:Fate Therapeutics: Consultancy, Research Funding. Blazar:Fate Therapeutics Inc.: Research Funding; KidsFirst Fund: Research Funding; Magenta Therapeutics: Consultancy; Childrens' Cancer Research Fund: Research Funding; BlueRock Therapeutics: Research Funding; BlueRock Therapeuetic: Consultancy; Tmunity: Other: Co-founder. Valamehr:Fate Therapeutics, Inc: Current Employment, Current equity holder in publicly-traded company. Miller:GT Biopharma: Consultancy, Patents & Royalties, Research Funding; Onkimmune: Honoraria, Membership on an entity's Board of Directors or advisory committees; Nektar: Honoraria, Membership on an entity's Board of Directors or advisory committees; Fate Therapeutics, Inc: Consultancy, Patents & Royalties, Research Funding; Vycellix: Consultancy. OffLabel Disclosure: FT538 is a genetically modified induced pluripotent stem cell derived NK cell product that can be combined with daratumumab to target CD38 on AML after retinoid acid induction.


Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 3215-3215 ◽  
Author(s):  
Frank Cichocki ◽  
Karrune Woan ◽  
Cheng-Ying Wu ◽  
Bruce R. Blazar ◽  
Ryan Bjordahl ◽  
...  

Cytolytic effector lymphocytes must contend with unfavorable microenvironments when infiltrating sites of infection or malignancy. Tumor cells typically have high levels of oxidative stress and produce reactive oxygen species (ROS) that suppress the cytotoxic functions of both natural killer (NK) cells and CD8+ T cells. Levels of activated granulocytes that release ROS are also elevated in cancer patients. Free radicals, such as ROS, cause detrimental cellular effects including protein oxidation, lipid peroxidation and DNA damage. Chronic viral infections, including CMV, are also associated with increased oxidative stress. We hypothesized that adaptive NK cells, which arise specifically in response to CMV, could have properties that allow these cells to persist and retain function in high oxidative stress environments. Adaptive NK cells are present in the peripheral blood of many otherwise healthy CMV seropositive individuals and expand in response to CMV reactivation in hematopoietic cell transplant (HCT) patients. Mounting evidence suggests that CMV peptides presented by HLA-E on infected cells can trigger the expansion of adaptive NK cells expressing the activating receptor NKG2C. The majority of NKG2C-positive adaptive NK cells co-express the terminal maturation marker CD57. Work by our group and others has shown that adaptive NK cells exhibit enhanced antibody-dependent cellular cytotoxicity (ADCC) and interferon (IFN)-γ production relative to canonical NK cells, appear to persist long-term and have metabolic attributes similar to memory CD8+ T cells. We also reported clinical correlations between adaptive NK cell numbers and reduced relapse risk in HCT patients with hematologic malignancies. Here, we show that CD38 expression is markedly reduced on adaptive NK cells from CMV seropositive individuals. This observation was first made from analyses of RNA-seq data comparing adaptive and canonical NK cells and was validated by flow cytometry (Figure 1A). CD38 is expressed both intracellularly and on the plasma membrane and functions as an NADase, degrading nicotinamide adenine dinucleotide (NAD+) into ADP-ribose and nicotinamide. NAD+ is a necessary cofactor for the sirturin family of protein deacetylases, which protect against oxidative stress. We hypothesized that CD38 downregulation in adaptive NK cells could be associated with more resistance to oxidative stress-induced cell death through increased NAD+ levels and sirturin activity. To determine whether there was a connection between CD38 expression and resistance to oxidative stress, we isolated NK cells from the peripheral blood of CMV seropositive donors and cultured them overnight with or without 15 mM H2O2 (hydrogen peroxide), known to induce oxidative stress and cell death. We found that NKG2C+ adaptive NK cells were markedly more resistant to oxidative stress-induced cell death compared to NKG2C-negative canonical NK cells as determined by annexin V and a fixable amine-reactive dye (LIVE/DEAD) that can permeate damaged membranes of dead cells and react with interior amines (Figure 1B). Similar results were observed in assays where NK cells from CMV seropositive donors were co-cultured with neutrophils pre-activated with phorbol 12-myristate 13-acetate (PMA) to induce the release of reactive oxygen species. To determine whether CD38 expression is directly associated with the NK cell response to oxidative stress, we generated induced pluripotent stem cell (iPSC) lacking CD38 through CRISPR/Cas9 gene editing that were differentiated into NK cells and tested for their ability to resist oxidative stress-induced death. Compared to control iPSC-derived NK (iNK) cells that express high levels of CD38 (Figure 1C), a substantially larger percentage of CD38 knockout iNK cells were viable when cultured overnight with H2O2 (Figure 1D). Our results have implications for adoptive immunotherapy to treat patients with cancer where a major goal is to manufacture cytotoxic cells that can persist and function in a tumor environment that contains high levels of oxidative radicals. We are exploring other cell stressors of high translational relevance such as freeze/thaw stress in adaptive and CD38 knockout cells that will be critical for cell therapy platforms. Disclosures Cichocki: Fate Therapeutics, Inc: Research Funding. Blazar:Kamon Pharmaceuticals, Inc: Membership on an entity's Board of Directors or advisory committees; Five Prime Therapeutics Inc: Co-Founder, Membership on an entity's Board of Directors or advisory committees; Regeneron Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Magenta Therapeutics and BlueRock Therapeuetics: Membership on an entity's Board of Directors or advisory committees; Fate Therapeutics, Inc.: Research Funding; RXi Pharmaceuticals: Research Funding; Alpine Immune Sciences, Inc.: Research Funding; Abbvie Inc: Research Funding; Leukemia and Lymphoma Society: Research Funding; Childrens' Cancer Research Fund: Research Funding; KidsFirst Fund: Research Funding; Tmunity: Other: Co-Founder; BlueRock Therapeutics: Membership on an entity's Board of Directors or advisory committees. Bjordahl:Fate Therapeutics, Inc.: Employment. Valamehr:Fate Therapeutics, Inc: Employment. Miller:Fate Therapeutics, Inc: Consultancy, Research Funding; CytoSen: Membership on an entity's Board of Directors or advisory committees; OnKImmune: Membership on an entity's Board of Directors or advisory committees; Dr. Reddys Laboratory: Membership on an entity's Board of Directors or advisory committees; Moderna: Membership on an entity's Board of Directors or advisory committees; GT BioPharma: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. OffLabel Disclosure: NK cells


Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 3261-3261 ◽  
Author(s):  
Arwen Stikvoort ◽  
Subhashis Sarkar ◽  
Renée Poels ◽  
Niels WCJ van de Donk ◽  
Sonja Zweegman ◽  
...  

Abstract Chimeric Antigen Receptors (CARs) are engineered transmembrane proteins consisting of an antibody-derived antigen recognition domain linked to intracellular cell signaling domains. CAR engineered autologous T cells have been successful in the treatment of a variety of hematologic malignancies. However, several major caveats, including lack of universal donors, long manufacturing times, and absence of a donor in immunologically frail patients, have limited the successful translation of CAR-T cell based therapy to a larger pool of patients. A universal, easy to manufacture, "off the shelf" CAR-based product could potentially address these limitations and result in a lower cost of goods. Towards developing an "off the shelf" CAR-based therapy for Multiple Myeloma (MM), we explored the feasibility and preclinical efficacy of expressing CD38 CARs in KHYG-1 cells, a natural killer (NK) cell line, first established by Yagita et al from a patient with aggressive NK leukemia (Leukemia, 2000). To this end, we effectively transduced KHYG-1 cells with high-affinity CD38 CARs as well as our recently reported affinity-optimized CD38 CARs, which can readily target MM cells with high CD38 expression, while ignoring non-malignant cells with intermediate, low or no CD38 expression when brought to expression on T cells (Drent et al, Molecular Therapy 2017). Moreover, we assessed performance of first and second generation CARs, with co-stimulatory domains CD28 and 4-1BB, and found the combination of CD28/CD3ζ to lead to the best results. After expanding the CAR transduced KHYG-1 cells, we analyzed their phenotype and efficacy in MM by analyzing their cytotoxic activity against CD38+ and CD38- MM and AML cell lines (UM9/THP-1 and U266/HL60, respectively), and against primary MM cells. The CD38-CAR transduced KHYG-1 cells showed no phenotypic alterations, and at effector to target ratios as low as 1:1, induced a high cytotoxicity towards CD38+ cell lines as compared to mock or non-transduced KHYG-1, demonstrating the important contribution of the CD38 CAR on the KHYG-1 NK cell surface. CD38- cell lines were unaffected by both CD38-CAR transduced KHYG-1 cells and mock or non-transduced KHYG-1 cells, indicating the specificity towards CD38 of the CAR and thus the potential safety of the CD38-CAR KHYG-1 cell. Similarly, ex vivo assays using primary MM cells revealed superior cytotoxic activity of CD38-CAR KHYG-1 cells as compared to mock or non-transduced KHYG-1 cells (median 86,5% vs 14% at 1:1 E:T ratio, n=2, Figure 1A). Confirming our previous results we identified an affinity-optimized CD38-CAR which mediated strong primary MM cell cytotoxicity with little or no "off tumor" effect. Normal immune cells (B, T, monocytes), which were either CD38 negative or only intermediate positive, were unaffected (Figure 1B-D), suggesting the potential safety of the CAR-NK cell therapy for clinical applications. As clinical administration would require irradiation of CD38-CAR KHYG-1 cells, we tested the effect of irradiation on their proliferative and cytotoxicity potential. Irradiation with 10Gy, while drastically inhibiting proliferative activity and viability (50% survival after 3 days), did not affect cytotoxicity, suggesting that repeated administrations of irradiated, CD38-CAR transduced KYHG-1 cells may exert effective in vivo anti-tumor activity, which is currently being evaluated in appropriate in vivo models, specifically the humanized bone scaffold in vivo model published by Groen et al (Blood, 2012). In conclusion, we demonstrate that the incorporation of CAR technology into the immortal NK cell line KHYG-1 has enormous potential to become a safe and effective "off the shelf" therapy for MM. Disclosures Stikvoort: Onkimmune: Research Funding. Sarkar:Onkimmune: Research Funding. van de Donk:Amgen: Research Funding; Janssen Pharmceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Novartis: Research Funding; Bristol-Myers Squibb: Research Funding; Celgene: Research Funding. Zweegman:Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene Corp.: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding. O'Dwyer:Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Onkimmune: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Research Funding; Celgene: Research Funding; Glycomimetics: Research Funding; Abbvie: Membership on an entity's Board of Directors or advisory committees. Mutis:Gilead: Research Funding; Celgene: Research Funding; Novartis: Research Funding; OnkImmune: Research Funding; Genmab: Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding.


Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 34-35
Author(s):  
Minoru Kanaya ◽  
Camille Philippon ◽  
Artur Cieslar-Pobuda ◽  
Frank Cichocki ◽  
Michelle Saetersmoen ◽  
...  

Induced pluripotent stem cell (iPSC)-derived natural killer (iNK) cells offer a promising platform for off-the-shelf immunotherapy against cancer. A unique benefit of iPSC-derived immune effector cells is the possibility to perform multiple precision editing steps at the single cell level to achieve a homogenous effector cell population tailored to target a desired cancer type and equipped with selected functional properties. These functional edits are superimposed on the innate reactivity of NK cells to stress ligands and MHC downregulation (missing self). The ability of NK cells to sense missing self is based on a functional calibration to self MHC during a process termed NK cell education, the latter being critically dependent on signaling through inhibitory receptors, including CD94/NKG2A and killer cell immunoglobulin-like receptors (KIR). Whereas the process of NK cell differentiation into mature effector cells from iPSCs has been well characterized, the role of natural variation in inhibitory receptor expression and NK cell education remains poorly defined in iNK cells. We used mass cytometry to map the receptor repertoire in series of iNK cell lines and genetic edits thereof during differentiation and in vitro expansion (Figure 1A and B). Similar to peripheral blood NK cells, the receptor repertoire was diversified but genetically hardwired showing consistent patterns within each iNK cell line but with slight variation between genetically distinct lines. NKG2A was the dominantly expressed inhibitory receptor ranging from 13% to 87% with the highest expression in multi-edited iNK cell lines engineered to express a chimeric antigen receptor against CD19, a high affinity, non-cleavable FcγRIIIa receptor (CD16) and a recombinant IL15 signaling complex (CAR19-iNK cells). KIR expression was generally low in all tested iNK cell lines but increased gradually during culture and was further increased by genetic silencing of NKG2A receptors. Interestingly, silencing of NKG2A lead to increased levels of the activating receptor NKG2C. We monitored degranulation by iNK cell variants against K562 engineered to express varying levels of HLA-E as well as CD19+ Nalm-6 cells. Genetic silencing of ß2microglobulin (ß2m), associated with reduced levels of HLA-class I and HLA-E, led to dampened global functional responses in iNK cells, suggesting a positive impact of education during iNK cell differentiation and expansion (Figure 1C). Subset stratification revealed that NKG2A+ iNK cells showed superior functionality compared to NKG2A- iNK cells across all iNK cell lines tested, albeit less striking in CAR19-iNK cells that showed the highest overall natural cytotoxicity (Figure 1D). Knockdown of NKG2A led to a general reduction in functional capacity of NK92 cells (Figure 1E-F) and CAR19-iNK cells (Figure 1H), supporting a critical role for NKG2A-driven education in iNK cells. Given the superior functionality of NKG2A+ iNK cells, we next addressed whether this advantage was countered by expression of the check point ligand HLA-E during target cell interactions. Although we noted a slight inhibitory impact on natural cytotoxicity in NK cells isolated and expanded from peripheral blood (PB-NK) against K562 cells expressing physiological levels of HLA-E, this effect was completely overridden in iNK cells and did not interfere with NKG2A+ CAR-iNK cell recognition of HLA-E expressing CD19+ target cells (Figure 1G-H). Indeed, NKG2A+ CAR19-iNK showed superior degranulation against HLA-E expressing CD19+ Nalm-6 targets compared to CRISPR-edited NKG2A-/- CAR19-iNK cells (Figure 1I). Our results shed light on the regulatory gene circuits and cellular programs that determine functional potential in iPSC-derived NK cells products. Specifically, our results point to a crucial role for NKG2A-driven acquisition of a mature effector cell phenotype in combination with functional education through cognate ligands. Importantly, iNK cell education is operational during iNK cell differentiation and expansion without interfering with recognition of tumor targets expressing HLA-E. Figure 1 Disclosures Cichocki: Fate Therapeutics, Inc: Consultancy, Patents & Royalties, Research Funding. Mahmood:Fate Therapeutics, Inc: Current Employment. Gaidarova:Fate Therapeutics, Inc: Current Employment. Bjordahl:Fate Therapeutics: Current Employment. Chu:Fate Therapeutics, Inc: Current Employment. Groff:Fate Therapeutics, Inc: Current Employment. Denholtz:Fate Therapeutics, Inc: Current Employment. Miller:Fate Therapeutics, Inc: Consultancy, Patents & Royalties, Research Funding; Vycellix: Consultancy; Onkimmune: Honoraria, Membership on an entity's Board of Directors or advisory committees; Nektar: Honoraria, Membership on an entity's Board of Directors or advisory committees; GT Biopharma: Consultancy, Patents & Royalties, Research Funding. Lee:Fate Therapeutics, Inc.: Current Employment. Kaufman:Fate Therapeutics: Consultancy. Goodridge:Fate Therapeutics, Inc: Current Employment. Valamehr:Fate Therapeutics, Inc: Current Employment, Current equity holder in publicly-traded company. Malmberg:Fate Therapeutics: Consultancy, Patents & Royalties; Vycellix: Membership on an entity's Board of Directors or advisory committees.


Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 2408-2408
Author(s):  
William T. Johnson ◽  
Colleen Isabelle ◽  
Ashley N Vogel ◽  
Jonathan E Brammer ◽  
Amy E Boles ◽  
...  

Abstract Introduction: Mature T-cell neoplasms (MTCN) are a heterogeneous and aggressive group of lymphoid neoplasms with very limited options for precision immunotherapy. Targeted immunotherapy with antibodies directed against surface markers on tumor cells has emerged as an effective treatment for B-cell neoplasms, but the development of immunotherapy strategies for MTCN has been much slower. CD38 is expressed at low levels in a subset of normal resting T-cells. Data on the frequency and level of CD38 expression is MTCN are lacking. Our goal was to study the expression and stability of CD38 on a spectrum of neoplastic T-cell populations and assess the potential anti-tumor effect of anti-CD38 monoclonal antibodies in combination with allogeneic natural killer (NK) cells in MTCN. Methods and results: We searched the Thomas Jefferson University Hospital (TJUH) pathology records for all cases of MTCN for which immune-phenotypical characterization of the neoplastic T-cell population by multi-color flow cytometry (FC) was available. CD38 expression was evaluated in cases where an abnormal T-cell population (defined as loss of one on more pan T-cell markers and/or a skewed CD4 to CD8 ratio). A total of 103 unique patients with MTCN were identified. Of these, 51 had at least one biopsy whereby tumor cells had an abnormal immunophenotype which could then be assessed for CD38 expression. CD38 was expressed to some extent in all but 2 cases with expression levels on peripheral T-cell lymphoma-not other specified (PTCL-NOS)(% Mean±SEM = 80.84±10.26, N=11), angioimmunoblastic T-cell lymphoma (AITL) (% Mean±SEM = 80.56±7.34, N=6), nodal PTCL with T follicular-helper (T FH) phenotype (% Mean±SEM = 55.00±12.72, N=7), anaplastic large cell lymphoma (ALCL) (% Mean±SEM = 77.38±10.75, N=3), large granular lymphocytic leukemia (LGLL) (% Mean±SEM = 80.27±7.49, N=4), T-cell prolymphocytic leukemia (T-PLL) (% Mean±SEM = 88.26±4.20, N=7), cutaneous T-cell lymphoma (CTCL) (% Mean±SEM = 49.52±14.77, N=7), adult T-cell leukemia/lymphoma (ATLL) (% Mean±SEM = 76.68±10.45, N=3), hepatosplenic T-cell lymphoma/monomorphic epitheliotropic intestinal T-cell lymphoma (HSTCL/MEITL) (% Mean±SEM = 75.00±11.37, N=3). The medians and ranges of the MFI of CD38 on CD38+ tumor cells were the following: PTCL-NOS 29.46 (3.1-115.62), AITL 13.64 (2.67-29.41), other PTCL-T FH 5.87 (0-48.67), ALCL 11.13 (3.6-11.28), LGL (13.52 (9.72-18.25), T-PLL 6.49 (3.09-18), CTCL 8.36 (0-116.75), ATLL 27.17 (3.54-60.5), HSTCL/MEITL 15.96 (6.96-167.85). We also measured surface expression of CD38 on the patient-derived MTCN cell lines HuT-78, HuT-102, Jurkat, H9, HH, and MOTN1, all of which expressed CD38, to determine which of these cell lines could be used for in vitro experiments. We next evaluated if the CD38 molecule is an effective target for antibody-mediated therapy in MTCN, by testing the ability of daratumumab (dara) to enhance antibody-dependent cellular cytotoxicity (ADCC) elicited by NK cells. For this, we purified normal NK-cells from TJUH Blood Bank leukoreduction filters and cultured with recombinant IL-15 for 48 hours prior to all experiment. T-cell lines and primary MTCN cells were treated with increasing concentrations (0.1 µg/mL - 2 µg/mL) of dara or isotype control. NK-cells were added at Effector:Target ratio of 5:1 and incubated for 4 hours at 37⁰ Celsius. Cytotoxicity was measured by LDH release assay. Dara induced significant cell lysis starting at doses as low as 0.1μg/mL in both T-cell lines and primary MTCN cells, reaching maximum cytotoxicity at 0.5-2μg/mL (mean±SEM cytotoxicity in isotype vs dara treated cells= 50.0±5.05% vs 97.5±2.5%, N=4, p-value=0.0002). The degree of ADCC induction also correlated with interferon-gamma (IFN-g) release by NK cells in vitro for both T-cell lines and primary MTCN cells. Conclusions: The majority of MTCN analyzed (N=49, 96%) showed any degree of CD38 expression by FC with a wide variation of intensity, including within the same subtype. Allogeneic NK cells efficiently elicited dara-mediated ADCC of tumor cells from all MTCN subtypes and produced abundant IFN-g. These data highlight the potential of targeting CD38 in MTCN with anti-CD38 antibodies and allogeneic NK cells. The strong CD38 expression observed in most tumor cells from ultra-rare and very aggressive subtypes of MTCL opens the door to much needed new treatment strategies. Disclosures Brammer: Celgene: Research Funding; Kymera Therapeutics: Consultancy; Seattle Genetics: Speakers Bureau. Chakravarti: Kiadis Pharma: Patents & Royalties. Porcu: Viracta: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Innate Pharma: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BeiGene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Incyte: Research Funding; Daiichi: Honoraria, Research Funding; Kiowa: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Spectrum: Consultancy; DrenBio: Consultancy.


Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 2316-2316
Author(s):  
Bethan Psaila ◽  
Nayla Boulad ◽  
Emily Leven ◽  
Naznin Haq ◽  
Christina Soo Lee ◽  
...  

Abstract The pathogenesis of immune thrombocytopenia (ITP) is multifactorial, with both cellular and humoural immune dysfunction. The role of NK cells has not been well defined in ITP but in other diseases NK cells have a role in rejecting “foreign” eg transplanted organ or tumor, and also acting against self as occurs in autoimmunity. NK cell activity is orchestrated by the balance of activating vs. inhibitory signalling, in particular via the killer cell immunoglobulin-like receptor (KIR) family of receptors. Significant variation exists in KIR allelic subtype and copy number for the KIR between individuals, and associations have been made with certain haplotypes and a number of autoimmune disorders including rheumatoid arthritis, scleroderma and diabetes. Previous reports have demonstrated a reduction in natural killer (NK) cell number and function in ITP and expression of inhibitory KIR genes is increased in patients in remission vs. active ITP. Methods To explore whether a particular KIR haplotype might predispose to ITP, and also affect response to ITP treatment, we performed KIR genotyping using the Invitrogen SSP kit on 92 patients attending a haematology centre in New York and compared the results to data from 213 controls taken from the USA Eastern Database. Genomic DNA was typed for the inhibitory KIR genes KIR2DL1, KIR2DL2, KIR2DL5A (alleles 001 and 002), KIR2DL5B (alleles 002-004, 06, and 007), KIR3DL1, KIR3DL3; the activating KIR genes KIR2DS1, KIR2DS2, KIR2DS3, KIR2DS4, KIR2DS5, KIR3DS1; the framework genes KIR2DL3, KIR2DL4, KIR3DL2, KIR3DP1; and the pseudogene KIR2DP1. The patients with ITP had been or were receiving treatment with IVIG (n=64), corticosteroids (72) and rituximab (37). Bleeding symptoms were recorded. Response to treatment was defined as complete - platelet count increase to > 100 x 109/mL; partial - platelet count increase to > 50 x 109/mL; or no response. For the purpose of analysis, PRs and CRs were combined. A comprehensive database allowed a logistic regression, assessing both responses to treatments, platelet counts, neutrophil counts, CRP, lymphocyte subsets and bleeding symptoms. Results The expression of two inhibitory KIR genes, 2DL1 and 3DL1, was significantly lower in the patients with ITP as compared to controls (87% 2DL1 and 87% 3DL1 compared to 99% in controls - P < 0.02). Response to rituximab was strongly related to KIR haplotype expression. 2DL1 expression was higher among nonresponders to Rituximab (100% of non responders compared to 82% of responders), whereas 2DL3 expression was significantly lower (79% compared to 90%) (P < 0.05, Figure 1B). Separately, patients with the 2DS3 allele, an activatory KIR, were 5.5 times more likely to have experienced significant bleeding. Conclusions Although these findings are preliminary and require further investigation, these data suggest that increased cytotoxic autoimmunity due to reduced KIR inhibition may be associated with the development of ITP and possibly contribute importantly to the pathogenesis. Anti-CD20 targeting therapy directed at B cells was strongly influenced by 2 different KIRs (1 upregulated and one down-regulated) emphasizing the potential role of NK cells in elimination of tissue-based (nodal) B cells. Finally a more pronounced clinical phenotype with a markedly higher incidence of severe bleeding associated with an increased activatory KIR expression demonstrates the role of NK cells in bleeding presumably via their effects on either endothelial cells or platelet function. These exciting findings will be pursued for confirmation in a larger number of patients. Disclosures: Bussel: Amgen: Family owns stock Other, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Cangene: Research Funding; Genzyme: Research Funding; GlaxoSmithKline: Family owns stock, Family owns stock Other, Membership on an entity’s Board of Directors or advisory committees, Research Funding; IgG of America: Research Funding; Immunomedics: Research Funding; Ligand: Membership on an entity’s Board of Directors or advisory committees, Research Funding; Eisai: Membership on an entity’s Board of Directors or advisory committees, Research Funding; Shionogi: Membership on an entity’s Board of Directors or advisory committees, Research Funding; Sysmex: Research Funding; Symphogen: Membership on an entity’s Board of Directors or advisory committees.


Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 407-407
Author(s):  
Frank Cichocki ◽  
Jode P Goodridge ◽  
Ryan Bjordahl ◽  
Svetlana Gaidarova ◽  
Sajid Mahmood ◽  
...  

Abstract Treatments for B-cell malignancies have improved over the past several decades with clinical application of the CD20-specific antibody rituximab and chimeric antigen receptor (CAR) T cells targeting CD19. Despite the success of these therapies, loss of CD20 after rituximab treatment has been reported in leukemia and lymphoma patients. Additionally, up to 50% of all patients receiving anti-CD19 CAR T-cell therapy relapse within the first year with many of those patients exhibiting CD19 loss. Thus, new therapeutic approaches are needed to address tumor antigen escape. Accordingly, we generated triple gene-modified iPSC-derived NK (iNK) cells, termed "iDuo" NK cells, tailored to facilitate multi-antigen targeting. The iPSC line was clonally engineered to express high-affinity, non-cleavable CD16a (hnCD16), an anti-CD19 CAR optimized for NK cell signaling, and a membrane-bound IL-15/IL-15R fusion (IL-15RF) molecule to enhance NK cell persistence (Fig. 1A). To model antigen escape, we generated CD19 knockout AHR77 lymphoma cells alongside wild type AHR77 cells (both CD20 +) as targets in cytotoxicity assays. Activated peripheral blood NK (PBNK) cells, non-transduced iNK cells, and iDuo NK cells were tested as effectors. Unlike PBNK cells or non-transduced iNK cells, iDuo NK cells efficiently eliminated wild type AHR77 cells with or without the addition of rituximab at all tested E:T ratios. Similarly, iDuo NK cells in combination with rituximab were uniquely able to efficiently eliminate CD19 KO AHR77 cells due to enhanced antibody-dependent cellular cytotoxicity (ADCC) driven by hnCD16 (Fig. 1B-E). Cytotoxicity mediated by iDuo NK cells was also evaluated using primary chronic lymphocytic leukemia (CLL) cells. Compared to expanded PBNK cells and non-transduced iNK cells, only iDuo NK cells (in the absence of rituximab) were able to kill primary CLL cells (Fig. 1F). Expression of IL-15RF by iDuo NK cells uniquely supports in vitro expansion without the need for cytokine supplementation. To determine whether IL-15RF supports in vivo persistence of iDuo NK cells, CD19 CAR iNK cells (lacking IL-15RF) and iDuo NK cells were injected into NSG mice without the addition of cytokines or CD19 antigen availability. iDuo NK cell numbers peaked within a week after injection and persisted at measurable levels for ~5 weeks, in marked contrast to CD19 CAR iNK cell numbers that were undetectable throughout (Fig. 1G). To evaluate the in vivo function of iDuo NK cells, NALM6 leukemia cells were engrafted into NSG mice. Groups of mice received tumor alone or were treated with 3 doses of thawed iDuo NK cells. iDuo NK cells alone were highly effective in this model as evidenced by complete survival of mice in the treatment group (Fig. 1H). To assess iDuo NK cells in a more aggressive model, Raji lymphoma cells were engrafted, and groups of mice received rituximab alone, iDuo NK cells alone, or iDuo NK cells plus rituximab. Mice given the combination of iDuo NK cells and rituximab provided extended survival compared to all other arms in the aggressive disseminated Raji lymphoma xenograft model (Fig. 1I). One disadvantage of anti-CD19 CAR T cells is their inability to discriminate between healthy and malignant B cells. Because NK cells express inhibitory receptors that enable "self" versus "non-self" discrimination, we reasoned that iDuo NK cells could have higher cytotoxicity against tumor cells relative to healthy B cells. To address this, we labeled Raji cells, CD19 + B cells from healthy donor peripheral blood mononuclear cells (PBMCs) and CD19 - PBMCs. Labeled populations of cells were co-cultured with iDuo NK cells, and specific killing was analyzed. As expected, iDuo NK cells did not target CD19 - PBMCs. Intriguingly, iDuo NK cells had much higher cytotoxic activity against Raji cells compared to primary CD19 + B cells, suggesting a preferential targeting of malignant B cells compared to healthy B cells. Together, these results demonstrate the potent multi-antigen targeting capability and in vivo antitumor function of iDuo NK cells. Further, these data suggest that iDuo NK cells may have an additional advantage over anti-CD19 CAR T cells by discriminating between healthy and malignant B cells. The first iDuo NK cell, FT596, is currently being tested in a Phase I clinical trial (NCT04245722) for the treatment of B-cell lymphoma. Figure 1 Figure 1. Disclosures Cichocki: Gamida Cell: Research Funding; Fate Therapeutics, Inc: Patents & Royalties, Research Funding. Bjordahl: Fate Therapeutics: Current Employment. Gaidarova: Fate Therapeutics, Inc: Current Employment. Abujarour: Fate Therapeutics, Inc.: Current Employment. Rogers: Fate Therapeutics, Inc: Current Employment. Huffman: Fate Therapeutics, Inc: Current Employment. Lee: Fate Therapeutics, Inc: Current Employment. Szabo: Fate Therapeutics, Inc: Current Employment. Wong: BMS: Current equity holder in publicly-traded company; Fate Therapeutics, Inc: Current Employment. Cooley: Fate Therapeutics, Inc: Current Employment. Valamehr: Fate Therapeutics, Inc.: Current Employment. Miller: Magenta: Membership on an entity's Board of Directors or advisory committees; ONK Therapeutics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Vycellix: Consultancy; GT Biopharma: Consultancy, Patents & Royalties, Research Funding; Fate Therapeutics, Inc: Consultancy, Patents & Royalties, Research Funding; Sanofi: Membership on an entity's Board of Directors or advisory committees; Wugen: Membership on an entity's Board of Directors or advisory committees.


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