Killing Of Tumor Targets Research Articles

CAR-NK Cells Generated with mRNA-LNPs Kill Tumor Target Cells In Vitro and In Vivo.

Natural killer (NK) cells are cytotoxic lymphocytes that are critical for the innate immune system. Engineering NK cells with chimeric antigen receptors (CARs) allows CAR-NK cells to target tumor antigens more effectively. In this report, we present novel CAR mRNA-LNP (lipid nanoparticle) technology to effectively transfect NK cells expanded from primary PBMCs and to generate functional CAR-NK cells. CD19-CAR mRNA and BCMA-CAR mRNA were embedded into LNPs that resulted in 78% and 95% CAR expression in NK cells, respectively. BCMA-CAR-NK cells after transfection with CAR mRNA-LNPs killed multiple myeloma RPMI8226 and MM1S cells and secreted IFN-gamma and Granzyme B in a dose-dependent manner in vitro. In addition, CD19-CAR-NK cells generated with CAR mRNA-LNPs killed Daudi and Nalm-6 cells and secreted IFN-gamma and Granzyme B in a dose-dependent manner. Both BCMA-CAR-NK and CD19-CAR-NK cells showed significantly higher cytotoxicity, IFN-gamma, and Granzyme B secretion compared with normal NK cells. Moreover, CD19-CAR-NK cells significantly blocked Nalm-6 tumor growth in vivo. Thus, non-viral delivery of CAR mRNA-LNPs can be used to generate functional CAR-NK cells with high anti-tumor activity.

Largely preserved functionality after the combined loss of NKG2D, NCR1 and CD16 demonstrates the remarkable plasticity of NK cell responsiveness.

Natural killer (NK) cells play an important role in the early defense against tumors and virally infected cells. Their function is thought to be controlled by the balance between activating and inhibitory receptors, which often compete for the same ligands. Several activating receptors expressed on virtually all NK cells lack an inhibitory partner, most notably CD16, NCR1 and NKG2D. We therefore hypothesized that a signal through at least one of these receptors is always required for full NK cell activation. We generated animals lacking all three receptors (TKO) and analyzed their NK cells. In vitro, TKO NK cells did not show reduced ability to kill tumor targets but displayed hyperresponsiveness to NK1.1 stimulation. In vivo, TKO animals had a minor reduction in their ability to control non-hematopoietic tumors and cytomegalovirus infection, which was the result of reduced NK cell activity. Together, our findings show that activating NK cell receptors without an inhibitory partner do not provide a 'master' signal but are integrated in the cumulative balance of activating and inhibitory signals. Their activity is controlled through regulation of the responsiveness and expression of other activating receptors. Our findings may be important for future development of NK cell-based cancer immunotherapy.

Brief IL-12, IL-15, IL-18 activation drives the acquisition of two distinct memory-like NK cell states

Abstract IL-12/15/18 activation induces natural killer (NK) cell differentiation into cytokine-induced memory-like (ML) NK cells with enhanced IFNγ and killing of tumor targets that is antigen independent, rendering them distinct from conventional (cNK) and CMV-induced adaptive NK cells. In leukemia patients, ML NK cells have an excellent safety profile and 47% CR rate (PMID: 32826231). Despite their clinical promise, little is known about the biology underlying ML NK cells. Based on individual variability of human ML NK cell function, we hypothesized that ML NK cells manifest molecular heterogeneity. To this end, we applied Cellular Indexing of Transcriptomes and Epitopes by Sequencing (CITE-seq) to profile RNA and protein expression on the single-cell level, and evaluated NK cell function. Overnight IL-12/15/18 stimulation induced broad activation with distinct transcriptional programs evident in CD56 brightcompared to CD56 dimNK cells. In contrast, following in vitrodifferentiation for 7 days, IL-12/15/18 activated NK cells acquired a unique transcriptional and protein signature, and manifest one of two ML NK cell states (ML-1, ML-2), or remained similar to cNK cells. ML-1 was marked by increased activating receptor expression (NKp46, NKp30, NKp44) while ML-2 had increased expression of inhibitory receptors, CD25, HLA-DR, MKI67, and IFNG. In functional assays, ML-2 cells produced more IFNγ following cytokine stimulation than ML-1 cells. Further, ML-1 and ML-2 had divergent transcription factor profiles suggesting distinct mechanisms of regulation. Collectively, our findings reveal molecular and functional heterogeneity of ML NK cells, and investigations into ML subsets in patients receiving ML NK cell therapy are ongoing. AAI Intersect Fellowship for Computational Scientists & Immunologists (JAF, TAF, AAP), T32GM139799 (JAF), P50CA171963 (TAF, MMB-E), R01CA205239 (TAF), P30CA91842 (TAF)

Sensitizing solid tumors to respond to Cytokine-induced apoptosis and CAR T-cell therapy.

Abstract Chimeric antigen receptor (CAR) T-cells are T-cells engineered with synthetic receptors that directs their specificity and function toward an antigen of choice. This application has been highly successful in treating a variety of blood-borne cancers such as B-cell lymphomas. CAR T-cells against solid tumors have been less efficacious, potentially due to the resistance of tumor cells to T cell-mediated cytotoxicity. Current paradigm suggests that tumor cells are killed by perforin/granzyme-secreting CD8 cytotoxic T cells (CTLs). However, activated CD8 T cells also produce TNF and IFNg, two cytokines that have been reported to have anti-tumor function, but it is not clear whether these cytokines can directly kill tumor targets. It has been reported that defects in kinases in the TNFR1 signaling pathway can sensitize cells to TNF-induced death. Therefore, we hypothesize that by inactivating these kinases, we can sensitize solid tumors to killing by CD8 CAR T-cells producing TNF and IFNg. We intend to conduct proof-of-concept studies to show that sensitizing tumor cells to cytokine-mediated cytotoxicity will enhance the effectiveness of CAR T-cell therapy against solid tumors. Institutional Funding

Being (past and present) President of the ERS: interview about the role, perspectives on career development, and vision for the Society.

This article presents the views of the past and current Presidents of the ERS regarding their role, perspectives on career development and vision for the Society, along with important messages to inspire ECMs to build their own successful career. https://bit.ly/3kAvxIM.

Newly identified role for the transcription factor Foxp1 in natural killer cells

Abstract Natural killer (NK) cells are innate lymphocytes critical for defense against pathogenic microbes and tumors. To understand dysfunction of NK cells in disease and to facilitate effective use of NK cells as therapeutic agents in the clinic, there is a critical need to ascertain the molecular mechanisms that regulate acquisition of optimum functionality of these cells. The functional maturation of NK cells is controlled by an incompletely defined network of transcription factors, which was recently expanded to implicate numerous factors, including Foxp1, that have never been studied in these cells. We show that mice with conditional deletion of the transcription factor Foxp1 in the NK cell lineage have substantially reduced frequencies of NK cells. The remaining NK cells in these mice exhibit an immature phenotype with reduced capacity to kill tumor target cells. The identification of a role of Foxp1 in development of highly functional NK cells is significant for the development of new strategies to promote or engineer highly functional NK cells to treat patients with tumors or infections. Supported by R01 AI148080

γδ T cell costimulatory ligands in antitumor immunity.

Antitumor immunity relies on the ability of T cells to recognize and kill tumor targets. γδ T cells are a specialized subset of T cells that predominantly localizes to non-lymphoid tissue such as the skin, gut, and lung where they are actively involved in tumor immunosurveillance. γδ T cells respond to self-stress ligands that are increased on many tumor cells, and these interactions provide costimulatory signals that promote their activation and cytotoxicity. This review will cover costimulatory molecules that are known to be critical for the function of γδ T cells with a specific focus on mouse dendritic epidermal T cells (DETC). DETC are a prototypic tissue-resident γδ T cell population with known roles in antitumor immunity and are therefore useful for identifying mechanisms that may control activation of other γδ T cell subsets within non-lymphoid tissues. This review concludes with a brief discussion on how γδ T cell costimulatory molecules can be targeted for improved cancer immunotherapy.

Gda-201, a Novel Metabolically Enhanced Allogeneic Natural Killer (NK) Cell Product Yields High Remission Rates in Patients with Relapsed/Refractory Non-Hodgkin Lymphoma (NHL): 2-Year Survival and Correlation with Cytokine IL7

Gda-201, a Novel Metabolically Enhanced Allogeneic Natural Killer (NK) Cell Product Yields High Remission Rates in Patients with Relapsed/Refractory Non-Hodgkin Lymphoma (NHL): 2-Year Survival and Correlation with Cytokine IL7

A Novel TGF-β2/Interleukin Receptor Signal Conversion Platform That Protects CAR/TCR T Cells from TGF-β2-Mediated Immune Suppression and Induces T Cell Supportive Signaling Networks

Numerous immune-suppressive mechanisms exist within the tumor microenvironment that may hinder the efficacy of adoptively transferred T cells. One such mechanism is mediated by TGF-β, a cytokine secreted by tumor cells and infiltrating suppressive immune cells that directly inhibits effector T cell activity. Effector T cells express the TGF-β receptors TGFBR1 and TGFBR2, and exposure of T cells to TGF-β induces hetero-dimerization of these receptors and phosphorylation of the major TGF-β signal mediators SMAD2 and SMAD3. Phosphorylated SMAD proteins (pSMADs) induce a suppressive transcriptional program that ultimately leads to reduced cytokine production, reduced cytotoxicity, and a failure to proliferate in response to antigen stimulation. In several previous reports, a dominant negative receptor (DNR) version of TGFBR2, that does not contain signaling domains, was shown to protect T cells from the impacts of TGF-β by blocking the ability of TGF-β to induce pSMADs.Herein, we report the development of a novel TGF-β signal conversion platform that provides a T cell supportive signal upon exposure to TGF-β. This platform utilizes co-expression of chimeric variants of TGFBR2 and TGFBR1 where the TGF-β-binding domain of each receptor is fused to the transmembrane and intracellular signaling domains of a T cell stimulating interleukin receptor. The signaling domains of interleukin receptors that were chosen for this platform are naturally activated via cytokine-induced hetero-dimerization and induce STAT transcription factor signaling pathways beneficial to effector T cell function and persistence. Based on the ability of lentiviral vectors to express large and complex gene expression cassettes, we constructed single vectors encoding both chimeric TGF-β receptors (CTBR) in the context of either a CAR or transgenic TCR. This required expression of four unique proteins from a single lentiviral vector when CTBR was combined with a transgenic TCR consisting of unique alpha and beta chains.To demonstrate successful signal conversion, we evaluated the impact of TGF-β exposure on multiple functional attributes of CTBR expressing T cells, including gene expression, cytokine production, cytotoxicity, and metabolic function. As anticipated, the STAT signaling signature induced by a particular CTBR was predictive of the functional consequence of exposure to TGF-β. In the case of a CTBR based on IL-12 signaling domains (CTBR12) that strongly induced STAT4 phosphorylation, CTBR12 expressing T cells secreted significantly greater amounts of IFNγ than control T cells following activation in the presence of TGF-β. This result was consistent with IL-12-mediated STAT4 signaling, which induces IFNγ production in effector T cells. We next evaluated CTBR expressing T cells in a stringent serial re-stimulation assay in the presence of TGF-β but absence of exogenous IL-2 cytokine support. Antigen driven T cell expansion was severely limited by exposure to TGF-β in this assay, and either CAR or transgenic TCR expressing cells ultimately lost cytotoxic activity over time. T cells overexpressing the dominant negative TGF-β receptor failed to expand and clear tumor cells following multiple rounds of antigen-driven stimulation in the presence of TGF-β, recapitulating the impact of tumor-derived TGF-β on infiltrating lymphocyte function. On the other hand, CTBR expressing cells maintained their ability to expand and kill tumor targets in the presence of TGF-β.Together, these data demonstrate the successful development of a TGF-β signal conversion platform that transforms the inhibitory effects of TGF-β exposure into a STAT signal that supports T cell effector function. The specific impact on T cell function is dependent on the nature of the signaling domains utilized. This platform is relevant in the context of both CAR T cells and transgenic TCR T cells, and has the potential to produce superior T cell responses in the immunosuppressive tumor microenvironment. DisclosuresBoyerinas:bluebird bio: Employment, Equity Ownership. Miller:bluebird bio: Employment, Equity Ownership. Murray:bluebird bio: Employment, Equity Ownership. Evans:bluebird bio: Employment, Equity Ownership. Parsons:bluebird bio: Employment, Equity Ownership. Seidl:bluebird bio: Employment, Equity Ownership. Friedman:bluebird bio: Employment, Equity Ownership. Morgan:bluebird bio: Employment, Equity Ownership, Patents & Royalties.

Generation of Natural Killer Cells with Enhanced Function from a CRISPR/Cas12a-Edited Induced Pluripotent Stem Cell Line

Adoptive cell therapy using T cells to treat cancer is efficacious in a number of hematologic malignancies. Recently, natural killer (NK) cells have emerged as an alternative cell type for clinical utility given the low propensity for graft-versus-host disease, thereby making NK cells a potential off-the-shelf cell therapy. NK cells distinguish tumor from healthy tissue via multiple mechanisms, including recognition of stress ligands and loss of MHC class I expression. For instance, KIR mismatching enables allogenic NK cells to kill MHC-positive tumor cells similar to MHC-negative tumor cells. Effector function of allogeneic NK cells are typically diminished by limited functional persistence, as well as tumor-intrinsic immunosuppressive mechanisms, such as TGF-β, a pleiotropic cytokine that inhibits immune effector function. Gene editing, however, can overcome these biological limitations. We hypothesized that knockout of CISH, a negative regulator of IL-2/IL-15 signaling, would improve NK cell effector function, while knockout of the TGF-β receptor gene 2, TGFBR2, would render NK cells resistant to TGF-β mediated suppression. NK cells are typically isolated from either cord blood or peripheral blood of healthy donors but recent advances with induced pluripotent stem cells (iPSCs) allows a nearly unlimited supply of iPSC-derived natural killer cells (iNK). In this study, we used CRISPR/Cas12a to generate edited iPSC lines that were differentiated into CD56+ iNK cells. Specifically, we generated TGFβR2-/-, CISH-/-, and TGFβR2-/-/CISH-/- iPSC clones with bi-allelic gene disruption confirmed by next generation sequencing. Importantly, we also confirmed that the edited clones were pluripotent. In particular, a minimum of 3 clones from each genotype were differentiated to CD56+ iNK cells. After differentiation, >90% of the cells expressed CD56 for all genotypes. Additionally, we observed the expression of canonical natural killer cell markers such as CD16, NKG2A, KIRs, NKp46, NKp44, and NKp30 within this CD56+ population. We tested the effector function of TGFβR2-/-, CISH-/-, and TGFβR2-/-/CISH-/- iNKs in a variety of molecular and functional assays, including a spheroid killing assay and an in vitro serial killing assay. For example, we utilized a SK-OV-3 spheroid killing assay to determine the intrinsic ability for the iNK cells to kill tumor targets following the differentiation process. TGFβR2-/-, CISH-/-, and TGFβR2-/-/CISH-/- iNKs reduce the size of SK-OV-3 ovarian tumor spheroids more effectively than control iNK cells in the presence of exogenous TGF-β. In conclusion, we have established an iPSC editing platform that can generate a near infinite supply of natural killer cells with enhanced tumor killing function, paving the way for future off-the-shelf cell therapies for application to broad oncology indications. Disclosures Moon: Editas Medicine: Current Employment, Current equity holder in publicly-traded company. Chin:Editas Medicine: Current Employment, Current equity holder in publicly-traded company. Burden:Editas Medicine: Current Employment, Current equity holder in publicly-traded company. Sexton:Editas Medicine: Current Employment, Current equity holder in publicly-traded company. Wasko:Editas Medicine: Current Employment, Current equity holder in publicly-traded company. Nasser:Editas Medicine: Current Employment, Current equity holder in publicly-traded company. Antony:Editas Medicine: Current Employment, Current equity holder in publicly-traded company. Wong:Editas Medicine: Current Employment, Current equity holder in publicly-traded company. Borges:Editas Medicine: Current Employment, Current equity holder in publicly-traded company. Morgan:Editas Medicine: Current Employment, Current equity holder in publicly-traded company. Welstead:Editas Medicine: Current Employment, Current equity holder in publicly-traded company.

Results of a Phase 1 Trial of Gda-201, Nicotinamide-Expanded Allogeneic Natural Killer (NK) Cells in Patients with Refractory Non-Hodgkin Lymphoma (NHL) and Multiple Myeloma

Background: The innate capacity of natural killer (NK) cells to kill tumor targets has been translated into cancer immunotherapy. GDA-201 is a novel allogeneic NK cell product derived from NK cells from healthy donors, expanded ex-vivo with nicotinamide (NAM) and IL-15. We previously reported improved killing function, in vivo proliferation, organ trafficking, and augmented resistance against exhaustion in pre-clinical models. We conducted a phase 1 study of GDA-201 in combination with monoclonal antibodies to enhance NK cell targeting through antibody-dependent cellular cytotoxicity (ADCC). We now report safety data in patients (pts) with relapsed or refractory (R/R) non-Hodgkin lymphoma (NHL) and multiple myeloma (MM), and report efficacy outcomes in pts with NHL. Methods: Following donor apheresis, CD3-depleted mononuclear cells were cultured for 14-16 days with NAM (5mM) and IL-15 (20ng/ml), resulting in a 40-fold increase in NK cells and increased expression of CD62L from 2.9% to 21%. GDA-201 contained ~98% NK cells, and CD3 content was maintained at <0.5% (<5x105/kg/dose). Pts with R/R B-cell NHL or MM received lymphodepleting (LD) therapy with cyclophosphamide (400mg/m2 IV x 3d) and fludarabine (30 mg/m2 /d IV x 3d), followed by GDA-201 (days 0 and 2) and low-dose IL-2 (6 million units sc x 3 doses). Pts with NHL or MM received rituximab (375 mg/m2) or elotuzumab (10 mg/kg), respectively, x 3 weekly infusions. Results: 30 pts were enrolled:15 with NHL and 15 with MM, in 3 cohorts of escalating GDA-201 dose; 15 pts received the maximum target dose (median dose 12.4 [range 2.0-26.0] x 107 cells/kg). There were no dose limiting toxicities. The most common grade 3/4 adverse events were thrombocytopenia (n=9), hypertension (n=5), neutropenia (n=4), febrile neutropenia (n=4), and anemia (n=3). There were no neurotoxic events, confirmed cytokine release syndrome, graft versus host disease, or marrow aplasia. One patient died of E-coli sepsis. In pts with NHL, histologies included diffuse large B cell lymphoma (DLBCL) (de novo n=5, transformed n=3), follicular lymphoma (FL) (n=6), and mantle cell lymphoma (n=1). Median age was 64 (range 48-83 years). Pts had a median of 3 lines of prior therapy (range 1-8); most were multiply relapsed or refractory (n=2), and 87% had advanced stage. Median follow-up was 10.8 months (range 4.3-27.5 months). Ten pts had complete response (CR): 6/6 pts with FL and 4/8 with DLBCL; 1 pt had partial response (PR), and overall response rate in pts with NHL was 73.3%. Median duration of response was 8.7 months (range 4.3-25 months). Flow cytometry confirmed the persistence of GDA-201 in peripheral blood for 7-10 days (range 2-92% donor NK cells on day 7), as well as enhanced in vivo proliferation (median Ki 67 99%). Flow cytometry of biopsied tissues at day 4 demonstrated trafficking to bone marrow and lymph nodes. Four pts underwent re-treatment with GDA-201 without LD chemotherapy; GDA-201 cells were detectable in blood after the re-treatment and likely contributed to deepening of response in 2 patients. Post-GDA-201 therapy included allogeneic (n=2) and autologous (n=1) hematopoietic stem cell transplantation. One-year estimates of progression-free survival and overall survival were 66% (95% CI 36-84%) and 82% (95% CI 42-95%), respectively. Conclusions: Cellular therapy using GDA-201 with monoclonal antibodies to enhance ADCC was well-tolerated, and demonstrated significant clinical activity in heavily pretreated pts with advanced NHL. Data support the future testing of multiple infusions to potentially enhance anti-tumor effect. The omission of lymphodepleting chemotherapy is feasible and contributes to safety of this approach. Phase II studies in aggressive and indolent NHL cohorts are planned. Disclosures Bachanova: Incyte: Research Funding; FATE: Research Funding; Kite: Membership on an entity's Board of Directors or advisory committees; Karyopharma: Membership on an entity's Board of Directors or advisory committees; BMS: Research Funding; Gamida Cell: Membership on an entity's Board of Directors or advisory committees, Research Funding. McKenna:Gamida: Other: Cell Manufacturing; Fate Therapeutics: Other: Cell Manufacturing; Intima: Other: Cell Manufacturing; Magenta: Other: Cell Manufacturing. Janakiram:Takeda, Fate, Nektar: Research Funding. Simantov:Gamida Cell: Current Employment. Lodie:Gamida Cell: Current Employment. Miller:Vycellix: Consultancy; Nektar: Honoraria, Membership on an entity's Board of Directors or advisory committees; Onkimmune: Honoraria, Membership on an entity's Board of Directors or advisory committees; GT Biopharma: Consultancy, Patents & Royalties, Research Funding; Fate Therapeutics, Inc: Consultancy, Patents & Royalties, Research Funding.

L’immunologie : les bases pour comprendre les traitements actuels et à venir: Immunology: The basis for understanding current and future treatments

AbstractThe immune system intergrate cells mainly present in lymphoid organs and tissues that react to modifications provided by the environment. They include cells including adaptive immunity (T and B cells) innate effectors and innate like effectors as well as soluble factors like cytokines and antibodies. This system acts differently in the different organs and tissues and upon environmental stress. Cancer induces also a modification of the homeostasis of the tissues. Immunology is a rapidly evolving science with important recent and not fully completed actors and functions.Various novel therapies rely on the immune system and have demonstrated their high effciency during the very last years. The first most recent waves of immunotherapies rely on the mechanisms of cosignaling but also genitically engeneered T cells prone to kill tumor targets as well as technological development using bispecific antibodies recognizing both tumor and an activating receptor on immune cells.The next steps will embrace various important mechanisms involved in the immune responses including cytokines, blockade of the inhibitory pathways in the tumor micro environment, innate and innate-like cells and vaccines.© 2020 SPLF. Published by Elsevier Masson SAS. All rights reserved.

A novel antibody-cell conjugation method to enhance and characterize cytokine-induced killer cells

BackgroundCytokine-induced killer (CIK) cells are an ex vivo–expanded cellular therapy product with potent anti-tumor activity in a subset of patients with solid and hematologic malignancies. We hypothesize that directing CIK cells to a specific tumor antigen will enhance CIK cell anti-tumor cytotoxicity. MethodsWe present a newly developed method for affixing antibodies directly to cell surface proteins. First, we evaluated the anti-tumor potential of CIK cells after affixing tumor-antigen targeting monoclonal antibodies. Second, we evaluated whether this antibody-conjugation method can profile the surface proteome of CIK cells. ResultsWe demonstrated that affixing rituximab or daratumumab to CIK cells enhances cytotoxic killing of multiple lymphoma cell lines in vitro. These ‘armed’ CIK cells exhibited enhanced intracellular signaling after engaging tumor targets. Cell surface proteome profiling suggested mechanisms by which antibody-armed CIK cells concurrently activated multiple surface proteins, leading to enhanced cytolytic activity. Our surface proteome analysis indicated that CIK cells display enhanced protein signatures indicative of immune responses, cellular activation and leukocyte migration. ConclusionsHere, we characterize the cell surface proteome of CIK cells using a novel methodology that can be rapidly applied to other cell types. Our study also demonstrates that without genetic modification CIK cells can be rapidly armed with monoclonal antibodies, which endows them with high specificity to kill tumor targets.

Results of a Phase 1 Trial of Gda-201, Nicotinamide-Expanded Allogeneic Natural Killer Cells (NAM-NK) in Patients with Refractory Non-Hodgkin Lymphoma (NHL) and Multiple Myeloma (MM)

Background: NK cells have the capacity to kill tumor targets, representing a novel immunotherapeutic approach to cancer. We have shown promising clinical activity in AML with a previous NK cell preparation. Limitations of NK therapies have included specificity, persistence after infusion, and potential for maximal activity of NK cells in vivo. GDA-201 is a cellular product composed of natural killer (NK) cells from healthy donors expanded ex vivo with nicotinamide (NAM) and IL-15; this is a unique ex vivo activation strategy to induce persistence of potent anti-tumor activity. Prior in vitro studies and pre-clinical models demonstrated that NAM-exposed NK cells exhibited augmented resistance against exhaustion and improved killing function, proliferation, and organ retention. We now report safety and efficacy from a phase 1 clinical trial of GDA-201 in patients (pts) with relapsed or refractory (R/R) NHL or MM. Methods: Following donor apheresis, CD3-depleted mononuclear cells were cultured for 14-16 days with NAM (5mM) and IL-15 (20ng/ml), resulting in a 40-fold increase in NK cells and increased expression of CD62L from 2.9% to 21%. GDA-201 contained ~98% NK cells, and CD3 content was maintained at <0.5% (<5x105/kg/dose). Pts with R/R CD 20-positive NHL or refractory MM received cyclophosphamide (400mg/m2 IV x 3d) and fludarabine (30 mg/m2 /d IV x 3d), followed by two doses of GDA-201 (Days 0 and 2) and low-dose IL-2 (6 million units sc). Pts with NHL or MM received rituximab (375 mg/m2 x 4 weekly or elotuzumab (10 mg/kg x 3 weekly), respectively, to enhance NK cell targeting through antibody-dependent cellular cytotoxicity (ADCC). Results: 20 pts were enrolled: 7 with NHL (4 follicular, 2 transformed, 1 diffuse large cell lymphoma) and 13 with MM, in 3 cohorts of escalating GDA-201 dose; 11 pts received the maximum target dose (median 1.7 x 108 cells/kg, range 1.6-2.0 x 108 cells/kg). There were no dose limiting toxicities. The most common grade 3/4 adverse events were neutropenia and thrombocytopenia, febrile neutropenia (n=2), increased creatinine, hyponatremia, pulmonary edema; all events were transient. One pt had grade 2 cytokine release syndrome at day 18, presenting with fever, hypoxemia and hypotension, responding to tocilizumab; pt later died of E Coli sepsis. There were no neurotoxic events, GVHD or marrow aplasia. Among 7 NHL pts, there were 3 CR and 2 PR with overall response rate of 71%. Median duration of response was 12 months (CR patients) and 5 months (PR patients). Figure 1A illustrates a 57-year-old man with history of CLL and Richter's transformation (large cell lymphoma), pre- GDA-201 and 6 months post therapy; the pt had continued response with 80% tumor shrinkage at 6 months. In MM patients, 1 patient with extramedullary disease had CR and 4 had SD with median duration 2.5 months. In our previous study using overnight-activated NK cells, persistence 7 days after adoptive transfer was limited. Using GDA-201, flow cytometry confirmed persistence of donor NAM-NK in peripheral blood up to day 7-10 (day 7 range 2-55% donor NK cells; Figure 1B), as well as enhanced in vivo proliferation (median Ki67 99%). Conclusions: Cellular therapy using GDA-201 with monoclonal antibodies was safe, and demonstrated early evidence of clinical activity in heavily pre-treated pts with advanced NHL and MM. The recommended dose of GDA-201 for phase 2 is 2.0 x 108 cells/kg. The clinical responses showed that NK cell targeting through ADCC can be efficacious and increase response. Laboratory studies showed that GDA-201 had better persistence than observed in our previous studies using overnight activated cytokine alone stimulated NK cells. This study demonstrated that GDA-201 has an efficacy signal, and larger phase II studies are warranted. Disclosures Bachanova: Incyte: Research Funding; Gamida Cell: Research Funding; Novartis: Research Funding; GT Biopharma: Research Funding; Celgene: Research Funding; Kite: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees. McKenna:Fate Therapeutics: Research Funding; Magenta Therapeutics: Research Funding; CIBMTR BMT CTN (NIH): Other: Medical Monitor; Icahn School of Medicine, New York, New York: Consultancy; National Eye Institute (NIH): Other: DSMB (2); Gamida: Research Funding; NMDP: Other: Donor and Patient Safety Monitoring Advisory Group; Intima: Patents & Royalties: Royalities, Research Funding. Brachya:Gamida Cell: Employment, Equity Ownership. Peled:Gamida Cell: Employment, Equity Ownership. Miller:GT BioPharma: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; CytoSen: 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; Fate Therapeutics, Inc: Consultancy, Research Funding; OnKImmune: Membership on an entity's Board of Directors or advisory committees.

Targeting Immune-Related Molecules in Cancer Therapy: A Comprehensive In Vitro Analysis on Patient-Derived Tumor Models.

This study investigated the impact of immune-related pathway inhibition, among them indolamine 2,3-dioxygenase (IDO), alone and together with immune cells on growth and viability of colorectal cancer (CRC) cells. A panel of patient-derived CRC cell lines with different molecular characteristics (CpG island methylator phenotype, chromosomal, and microsatellite instability) was included. Initial phenotyping of CRC cell lines (n=17) revealed high abundance of immunosuppressive checkpoint-molecules in general, but an individual profile for IDO. Presence of immune-related molecules was independent of the molecular subtype. Selective treatment of CRC cell lines showing high or low IDO expression (n=2 cell lines each) was performed with single agents and combinations of Indoximod, Curcumin, and Gemcitabine with and without the addition of peripheral blood lymphocytes (PBL) in an allogeneic setting. All substances affected CRC cell growth in a cell line specific manner. The combination of Curcumin and Gemcitabine proved to be most effective in tumor cell elimination. Functional read-out analyses identified cellular senescence, after both single and combined treatment. Curcumin alone exerted strong cytotoxic effects by inducing early and late apoptosis. Necrosis was not detectable at all. Addition of lymphocytes generally boosted antitumoral effects of all IDO-inhibitors, with up to 80 % cytotoxicity for the Curcumin treatment. Here, no obvious differences became apparent between individual cell lines. Combined application of Curcumin and low-dose chemotherapy is a promising strategy to kill tumor target cells and to stimulate antitumoral immune responses.

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

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

Abstract 4939: Driving natural killer cell antigen-specific targeting of cancer via next generation trivalent molecules

Abstract Natural Killer (NK) cells are components of innate immune response that are involved in tumor surveillance and clearance. Due to their ability to lyse tumor targets without prior priming they have gained some notoriety in the tumor immunotherapy setting. Although NK cells sense malignant transformation of cells through a number of stochastic receptors they posses no clonotypic receptors to drive specific recognition of tumor antigens, somewhat limiting their therapeutic applications. In order to address the antigen specificity issue we generated molecules, termed Tri-Specific Killer Engagers (TriKEs), that contain three arms: one arm contains a single chain variable fragment (scFv) that binds a potent NK cell activating receptor (CD16); one arm contains an scFv that binds a tumor antigen; and one arm contains the cytokine IL-15 to drive NK cell priming, expansion and survival. Initial pre-clinical studies with these first generation molecules showed that we could use them to target hematological malignancies (via a CD33 binding arm) both in vitro and in vivo or solid malignancies (via an EpCAM binding arm) in vitro. However, to improve on this platform we altered the molecule by swapping out the anti-CD16 scFv arm with a humanized camelid single domain antibody against CD16 (termed cam16 henceforth). This second generation cam16 TriKE platform potently enhanced NK cell activation against tumor targets and induced far greater NK cell expansion when compared to the first generation TriKE. Using our bacterial expression system we generated and isolated cam16 TriKEs against a number of different tumor antigens (CD33, EpCAM, Mesothelin and ROR1) to display the ability of the second generation TriKE platform to target a variety of cancers. To test these molecules we used flow cytometry based NK cell activation assays, where NK cells co-cultured with tumor targets +/- cam16 TriKEs are evaluated for NK cell degranulation (by expression of surface CD107a) and NK cell inflammatory cytokine production (by expression of intracellular IFNγ). We also used a real-time imaging platform, the IncuCyte Zoom, to evaluate the ability of NK cells to kill tumor targets in the presence or absence of cam16 TriKEs over a 2-3 day period. Our data indicates that cam16 TriKEs drive NK cell specific degranulation, inflammation, and killing of AML (CD33), ovarian cancer (EpCAM and Mesothelin), lung cancer (Mesothelin and EpCAM) and sarcoma (ROR1) tumor targets in vitro. Furthermore cam16 TriKE in vivo efficacy could be seen in humanized mouse models using both luciferase-labeled cell lines and patient derived xenografts. Taken together, these findings clearly highlight the translational potential of cam16 TriKEs in the tumor immunotherapy setting. Citation Format: Martin Felices, Behiye Kodal, Alexander J. Lenvik, Brianna Ettestad, Laura Bendzick, Caitlin Ryan, Dawn K. Schirm, Ron McElmurry, Craig E. Eckfeldt, Melissa A. Geller, Todd R. Lenvik, Daniel A. Vallera, Jeffrey S. Miller. Driving natural killer cell antigen-specific targeting of cancer via next generation trivalent molecules [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4939.

Glycolipid stimulation of invariant NKT cells mobilizes precursors of mature NK cells and potentiates their participation in immune surveillance against metastatic cancer.

Abstract Precursors of mature natural killer (pre-mNK) cells, initially called IFN-producing killer dendritic cells, have been recently characterized as a novel intermediate in NK cell differentiation. Typified by a unique B220+NK1.1+CD11c+MHCII+ phenotype, pre-mNK cells exhibit prolific anti-tumor cytotoxicity while retaining the ability to present antigens thereby activating neighbouring T cells. Invariant NKT (iNKT) cells are another population highlighted for their potential in anti-cancer immunity. They are activated very early and play an important role in transactivating downstream effectors, such as NK cells. The extent to which iNKT cells can activate pre-mNK cells is unknown. We hypothesized that iNKT cells are able to activate pre-mNK cells and potentiate their anti-tumor properties. Wildtype C57BL/6 mice were injected i.p. with the iNKT cell superagonist, α-galactosylceramide (αGC), and various lymphoid tissues were harvested after 5 days for phenotyping or cytotoxicity assays. We have shown, for the first time that iNKT cell activation via αGC results in robust expansion of pre-mNK cells in the spleen, lung and most notably, in the liver. These cells exhibited cytotoxic activity against YAC-1 thymoma and B16 melanoma cancer cells via the granule exocytosis pathway and significantly contributed to overall NK cytotoxic activity in vivo. The anti-cancer responses due to αGC activation have been well documented; however, the contribution of pre-mNK cells in these responses have never been shown. Our findings demonstrate that pre-mNK cells rapidly expand due to iNKT activation while retaining their capacity to kill tumor targets. This may suggest a novel mechanism of targeting pre-mNK cells in anti-cancer therapies.

Combination of NK Cells and Cetuximab to Enhance Anti-Tumor Responses in RAS Mutant Metastatic Colorectal Cancer.

The ability of Natural Killer (NK) cells to kill tumor targets has been extensively studied in various hematological malignancies. However, NK cell therapy directed against solid tumors is still in early development. Epidermal Growth Factor Receptor (EGFR) targeted therapies using monoclonal antibodies (mAbs) such as cetuximab and panitumumab are widely used for the treatment of metastatic colorectal cancer (mCRC). Still, the clinical efficacy of this treatment is hampered by mutations in RAS gene, allowing tumors to escape from anti-EGFR mAb therapy. It is well established that NK cells kill tumor cells by natural cytotoxicity and can in addition be activated upon binding of IgG1 mAbs through Fc receptors (CD16/FcγRIIIa) on their surface, thereby mediating antibody dependent cellular cytotoxicity (ADCC). In the current study, activated Peripheral Blood NK cells (PBNK) were combined with anti-EGFR mAbs to study their effect on the killing of EGFR+/- cancer cell lines, including those with RAS mutations. In vitro cytotoxicity experiments using colon cancer primary tumors and cell lines COLO320, Caco-2, SW620, SW480 and HT-29, demonstrated that PBNK cells are cytotoxic for a range of tumor cells, regardless of EGFR, RAS or BRAF status and at low E:T ratios. Cetuximab enhanced the cytotoxic activity of NK cells on EGFR+ tumor cells (either RASwt, RASmut or BRAFmut) in a CD16 dependent manner, whereas it could not increase the killing of EGFR- COLO320. Our study provides a rationale to strengthen NK cell immunotherapy through a combination with cetuximab for RAS and BRAF mutant mCRC patients.

NK cells are intrinsically functional in pigs with Severe Combined Immunodeficiency (SCID) caused by spontaneous mutations in the Artemis gene

We have identified Severe Combined Immunodeficiency (SCID) in a line of Yorkshire pigs at Iowa State University. These SCID pigs lack B-cells and T-cells, but possess Natural Killer (NK) cells. This SCID phenotype is caused by recessive mutations in the Artemis gene. Interestingly, two human tumor cell lines, PANC-1 and A375-SM, survived after injection into these SCID pigs, but, as we demonstrate here, these cells, as well as K562 tumor cells, can be lysed in vitro by NK cells from SCID and non-SCID pigs. NK cells from both SCID and non-SCID pigs required activation in vitro with either recombinant human IL-2 or the combination of recombinant porcine IL-12 and IL-18 to kill tumor targets. We also showed that SCID NK cells could be activated to produce perforin, and perforin production was greatly enhanced in NK cells from both SCID and non-SCID pigs after IL-2 cytokine treatment. While CD16+, CD172- NK cells constituted an average of only 4% in non-SCID pigs, NK cells averaged 27% of the peripheral blood mononuclear cell population in SCID pigs. We found no significant differences in killing activity per NK cell between SCID and non-SCID pigs. We conclude that survival of human cancer cells in these SCID pigs is not due to an intrinsic defect in NK cell killing ability.