Chimeric Antigen Receptor NK Cells Research Articles

A new vision of the efficacy of both CAR-NK and CAR-T cells in treating cancers and autoimmune diseases.

Chimeric Antigen Receptor (CAR) based therapies are becoming increasingly important in treating patients. CAR-T cells have been shown to be highly effective in the treatment of hematological malignancies. However, harmful therapeutic barriers have been identified, such as the potential for graft-versus-host disease (GVHD), neurotoxicity, and cytokine release syndrome (CRS). As a result, CAR NK-cell therapy is expected to be a new therapeutic option. NK cells act as cytotoxic lymphocytes, supporting the innate immune response against autoimmune diseases and cancer cells by precisely detecting and eliminating malignant cells. Genetic modification of these cells provides a dual approach to the treatment of AD and cancer. It can be used through both CAR-independent and CAR-dependent mechanisms. The use of CAR-based cell therapies has been successful in treating cancer patients, leading to further investigation of this innovative treatment for alternative diseases, including AD. The complementary roles of CAR T and CAR NK cells have stimulated exploration in this area. Our study examines the latest research on the therapeutic effectiveness of these cells in treating both cancer and ADs.

Abstract P20: Anti-CD123 CAR NK cells and cam161533 Trispecific Killer Engager have synergistic activity against Acute Myeloid Leukemia

Abstract P20: Anti-CD123 CAR NK cells and cam161533 Trispecific Killer Engager have synergistic activity against Acute Myeloid Leukemia

Chimeric Antigen Receptor T Cell and Chimeric Antigen Receptor NK Cell Therapy in Pediatric and Adult High-Grade Glioma—Recent Advances

High-grade gliomas (HGG) account for approximately 10% of central nervous system (CNS) tumors in children and 25% of CNS tumors in adults. Despite their rare occurrence, HGG are a significant clinical problem. The standard therapeutic procedure in both pediatric and adult patients with HGG is the surgical resection of the tumor combined with chemotherapy and radiotherapy. Despite intensive treatment, the 5-year overall survival in pediatric patients is below 20–30%. This rate is even lower for the most common HGG in adults (glioblastoma), at less than 5%. It is, therefore, essential to search for new therapeutic methods that can extend the survival rate. One of the therapeutic options is the use of immune cells (T lymphocytes/natural killer (NK) cells) expressing a chimeric antigen receptor (CAR). The objective of the following review is to present the latest results of preclinical and clinical studies evaluating the efficacy of CAR-T and CAR-NK cells in HGG therapy.

Cytokine Modification of Adoptive Chimeric Antigen Receptor Immunotherapy for Glioblastoma.

Chimeric antigen receptor (CAR) cell-based therapies have demonstrated limited success in solid tumors, including glioblastoma (GBM). GBMs exhibit high heterogeneity and create an immunosuppressive tumor microenvironment (TME). In addition, other challenges exist for CAR therapy, including trafficking and infiltration into the tumor site, proliferation, persistence of CARs once in the tumor, and reduced functionality, such as suboptimal cytokine production. Cytokine modification is of interest, as one can enhance therapy efficacy and minimize off-target toxicity by directly combining CAR therapy with cytokines, antibodies, or oncolytic viruses that alter cytokine response pathways. Alternatively, one can genetically modify CAR T-cells or CAR NK-cells to secrete cytokines or express cytokines or cytokine receptors. Finally, CARs can be genetically altered to augment or suppress intracellular cytokine signaling pathways for a more direct approach. Codelivery of cytokines with CARs is the most straightforward method, but it has associated toxicity. Alternatively, combining CAR therapy with antibodies (e.g., anti-IL-6, anti-PD1, and anti-VEGF) or oncolytic viruses has enhanced CAR cell infiltration into GBM tumors and provided proinflammatory signals to the TME. CAR T- or NK-cells secreting cytokines (e.g., IL-12, IL-15, and IL-18) have shown improved efficacy within multiple GBM subtypes. Likewise, expressing cytokine-modulating receptors in CAR cells that promote or inhibit cytokine signaling has enhanced their activity. Finally, gene editing approaches are actively being pursued to directly influence immune signaling pathways in CAR cells. In this review, we summarize these cytokine modification methods and highlight any existing gaps in the hope of catalyzing an improved generation of CAR-based therapies for glioblastoma.

NKX101, an Allogeneic Off-the-Shelf CAR NK Therapy Targeting NKG2D-Ls, Has Potent In Vitro Cytotoxicity Against Patient-Derived AML Leukemic Stem Cell (LSC) and Non-Leukemic Stem Cell (Non-LSC) Blasts

Introduction Acute myeloid leukemia (AML) is a malignancy of immature myeloid cells characterized by rapid proliferation of abnormal myeloblasts. Treatment options for patients with AML are limited, especially for relapsed/refractory (r/r) disease. Leukemic cells with stem cell features, known as leukemic stem cells (LSCs), have been implicated as the origin of relapse in minimal residual disease positive (MRD +) AML (Khaldoyanidi et al. 2022, Kamel et al. 2022). Additionally, absence of NKG2D-ligand (NKG2D-L) expression has been reported to be associated with stemness and the LSC population in AML (Paczulla et. al, 2019). NKX101 is an allogeneic, off-the-shelf, healthy donor-derived chimeric antigen receptor (CAR) NK cell therapy candidate engineered to express an NKG2D-L targeting CAR as well membrane bound IL-15. In a clinical trial, NKX101 has shown promise for the treatment of r/r AML, including generating complete responses (CR) with MRD negativity (MRD -). In this study, we utilize a flow cytometry-based approach to (i) evaluate NKG2D-L cell surface expression on normal hematopoietic cells vs. primary AML blasts, (ii) assess the expression pattern of NKG2D-Ls on AML blast subsets, and (iii) determine the potency of NKX101 cytotoxic killing of both LSC and non-LSC AML blasts. Methods NKX101 cells were generated from peripheral blood leukopaks from healthy donors. Cryopreserved bone marrow mononuclear cells (BMMCs) were obtained from AML patients in accordance with approved IRB protocols (n=20). BMMCs from healthy donors were used as controls (n=10). AML somatic mutation status was determined using an Illumina TruSight® Myeloid targeted sequencing panel. NKX101 cytotoxicity against patient derived AML blasts was assessed using a flow cytometry-based assay that simultaneously measured specific cytotoxicity AML blast/LSC markers. NKG2D-L protein expression on LSC and non-LSC subsets was determined using flow cytometry with fluorescently labeled monoclonal antibodies specific to MICA, MICB, and ULBP1-6. Results Utilizing patient-derived primary samples, we demonstrate that NKG2D-Ls are expressed on AML blast cells and expressed at higher levels on AML blast cells compared to healthy normal hematopoietic cells (p = 0.002). Furthermore, we show that NKG2D-Ls are expressed at similar levels on both LSC and non-LSC AML blast populations. Target cell specific flow cytometry-based cytotoxicity assays revealed that NKX101 cells potently kill patient-derived AML blasts in a dose-dependent manner. Moreover, NKX101 cells had similar cytotoxic potency on both LSC and non-LSC AML blasts subsets. Conclusions In summary, we show that NKG2D-Ls are expressed on the surface of AML blasts at levels above those observed in normal hematopoietic cells. NKG2D-Ls are expressed on both non-LSC AML blasts and on the LSC population implicated as the origin of relapse in AML. Additionally, the ability of NKX101 to potently kill AML LSC blasts suggests that NKG2D-L targeting may be a viable mechanism for eliminating LSC in the blood and bone marrow of patients with r/r AML. Taken together, these data support NKG2D-Ls as promising therapeutic targets for AML and support further investigation of NKX101 CAR NK cell therapy for the treatment of r/r AML.

Umbilical cord blood derived cellular therapy: advances in clinical development.

While cord blood (CB) is primarily utilized in allogeneic hematopoietic cell transplantation (HCT), the development of novel cell therapy products from CB is a growing and developing field. Compared to adult blood, CB is characterized by a higher percentage of hematopoietic stem cells (HSCs) and progenitor cells, less mature immune cells that retain a high capacity of proliferation, and stronger immune tolerance that requires less stringent HLA-matching when used in the allogenic setting. Given that CB is an FDA regulated product and along with its unique cellular composition, CB lends itself as a readily available and safe starting material for the development of off-the-shelf cell therapies. Moreover, non-hematologic cells such as mesenchymal stem cell (MSCs) residing in CB or CB tissue also have potential in regenerative medicine and inflammatory and autoimmune conditions. In this review, we will focus on recent clinical development on CB-derived cellular therapies in the field of oncology, including T-cell therapies such as chimeric antigen receptor (CAR) T-cells, regulatory T-cells, and virus-specific T-cells; NK-cell therapies, such as NK cell engagers and CAR NK-cells; CB-HCT and various modifications; as well as applications of MSCs in HCT.

Abstract 890: ADAM17 knockout NK or CAR NK cells augment antibody dependent cellular cytotoxicity (ADCC) and anti-tumor activity

Abstract Natural killer (NK) cells are a critical component of the innate immune system and do not elicit graft-versus-host disease, making them an attractive source of ‘off-the-shelf’ allogeneic cell therapy. NK cells are also amenable to CRISPR and chimeric antigen receptor (CAR) genomic engineering for enhanced functions. Another important anti-tumor role of NK cells is via antibody-dependent cell mediated cytotoxicity (ADCC). The process is mediated by CD16a of NK cells, which binds the Fc portion of antibodies. After NK cell activation, the CD16a ectodomain is rapidly cleaved from the NK cell surface by a disintegrin, Metalloprotease-17 (ADAM17), that is produced by both tumor cells and activated NK cells. This dampens NK cell activity by preventing NK cell attachment to antibody-coated target cells and diminishes CD16a signaling. Inhibiting ADAM17-mediated CD16a cleavage leads to augmented ADCC activity and increased cytokine production by human NK cells. Other NK cell activating receptors are known to be regulated by a similar mechanism1. In this study, we have utilized CRISPR-Cas9 ribonucleoproteins (RNPs) to disrupt the ADAM17 gene in isolated peripheral blood NK cells from healthy donors. FACS and Amplicon NGS Sequencing data confirmed successful disruption of the gene. Edited NK cells were expanded using IL-2 and stimulation with NKSTIM, a modified K562 stimulatory cell line expressing a membrane-bound form of IL-15 (mbIL-15) and 4-1BBL. IL-12 and IL-18 were added during expansion to drive memory-like NK cell differentiation. Furthermore, we transduced ADAM17 edited NK cells to express a CD70 CAR2 or CD19 CAR3 construct and mbIL-15. CAR expression was assessed by FACS. In vitro cytotoxicity was measured by IncuCyte. Using an artificial activation system (phorbol 12-myristate 13-acetate [PMA]), we showed that ADAM17 KO NK cells maintain dramatically higher surface expression of CD16a and CD62L than control NK cells. In IncuCyte cytotoxicity assays against Raji tumor cells in the presence of rituximab (anti-CD20), ADAM17 KO NK cells and ADAM17 KO CD19 CAR NK cells demonstrated higher cytotoxicity compared to control NK cells. Similarly, ADAM17 KO NK cells and ADAM17 KO CD70 CAR NK cells also showed enhanced cytotoxicity against 786-O tumor cells in the presence of anti-EGFR antibody, cetuximab. Furthermore, ADAM17/CISH/CBLB triple KO CD70 CAR NK cells exhibited enhanced antitumor efficacy in vivo in a 786-O RCC tumor and a HL60 AML xenograft model. Taken together, we show ADAM17 KO NK or ADAM17 KO CAR NK cells demonstrate improved ADCC and ADAM17 KO can enhance in vivo anti-tumor activity of CISH/CBLB KO CD70 CAR NK cells against relevant tumor models. These data support the further exploration of ADAM17 gene knockout NK cells for clinical application and to improve efficacy of therapeutic antibodies in combination with adoptive transfer of engineered NK cells. Citation Format: Chao Guo, Yanying Fan, Alexander Aronov, Nikki Kimura, Damie Juat, Jessica Sood, Ivan H. Chan, James B. Trager. ADAM17 knockout NK or CAR NK cells augment antibody dependent cellular cytotoxicity (ADCC) and anti-tumor activity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 890.

Abstract 2905: SENTI-301A, an off-the-shelf multi-armed preclinical CAR-NK cell therapy, for the treatment of GPC3 expressing tumors

Abstract Purpose: SENTI-301A is a novel off-the-shelf CAR-NK product candidate that uses gene circuits to enhance NK cell persistence and targeted cytotoxicity to address unmet needs in GPC3 expressing solid tumors such as hepatocellular carcinomas (HCC). Experimental procedures: SENTI-301A is a Multi-Armed, targeted chimeric antigen receptor (CAR) NK cell preclinical product candidate with a GPC3 CAR and calibrated-release interleukin-15 (crIL-15) engineered onto allogeneic healthy adult peripheral blood NK cells. The activating CAR is designed to target GPC3, an antigen overexpressed in several cancers, such as HCC. crIL-15 is a unique technology attaching wild type IL-15 to the membrane via a linker that can be cleaved by a ubiquitous protease. This results in membrane-bound and secreted IL-15 to provide both autocrine support to the CAR NK cells, and paracrine stimulation to other surrounding immune cells in the tumor microenvironment for enhanced antitumor response. Results: SENTI-301A exhibited increased crIL-15-driven survival and expansion (>30 days) without exogenous cytokine support compared to unengineered NK cells (~6 days). SENTI-301A also showed significantly higher in vitro cytotoxic activity (~20%) against GPC3 expressing cell lines compared to isogenic cells lacking the antigen, indicating CAR-mediated activation and antigen specificity. SENTI-301A also showed significant tumor killing function, IFNg, and Granzyme-B production, when co-cultured with HCC and other GPC3 expressing tumor cell lines at different effector:target ratios. SENTI-301A maintained the antitumor function in the presence of full-length soluble GPC3, reducing the risk of competition from shedding GPC3 with surface GPC3 for CAR-NK cell binding. In HCC mouse xenograft models, SENTI-301A showed NK cells tumor infiltration, and displayed enhanced persistence, antitumor function and increased median survival (p< 0.01), in comparison to unengineered NK cells. As next steps, the potential positive impact of immune checkpoint inhibitors (CPIs) in combination with SENTI-301A to enhance anticancer function is being assessed. Conclusions: SENTI-301A is a novel off-the-shelf preclinical CAR-NK cell therapy candidate that targets GPC3-expressing tumors in an antigen-specific manner and exhibits increased persistence via crIL-15. We are exploring the potential synergy between SENTI-301A and CPIs to enhance the existing antitumor functions of SENTI-301A. SENTI-301A is planned for clinical development with an investigational new drug application (IND) expected in 2023. Citation Format: Marcela Guzman Ayala, Deepika Kaveri, Enping Hong, Elizabeth Leitner, Priscilla Wong, Ronni Ponek, Lawrence Naitmazi, Pearley Chinta, Wesley Gorman, Mengxi Tian, Niran Almudhfar, Kelly Lee, Nicholas Frankel, Alba Gonzalez Junca, Russell Gordley, Philip Lee, Timothy Lu, Kanya Rajangam. SENTI-301A, an off-the-shelf multi-armed preclinical CAR-NK cell therapy, for the treatment of GPC3 expressing tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2905.

Abstract 2907: Development of a CAR-NK cellular platform for cancer immunotherapy

Abstract Although Chimeric Antigen Receptor (CAR)-T cell therapy has proven to be successful in treating multiple hematological malignancies, their use is limited due to the potential life-threatening adverse events, including cytokine release syndrome (CRS), neurotoxicity and graft-versus-host disease (GVHD). CAR natural killer (CAR-NK) cells are rapidly emerging as a promising alternative cellular therapeutic with improved efficacy and reduced adverse effects. Moreover, due to the intrinsic characteristics of NK cells, whereby they lack antigen-specific cell surface receptors, CAR-NK cells offer the additional advantage of being an “off-the-shelf” product, thus satisfying the requirement for large-scale production for cancer immunotherapy, giving it the potential to reach more patients at a reduced cost. Here we outline the method to generate, expand and enrich human primary CD19 CAR-NK cells, and demonstrate their efficacy in-vitro against CD19-expressing target cancer cells. Human primary NK cells were isolated from healthy donors and transduced with a clinically tested CD19-targeting CAR lentiviral vector (LV) or GFP expressing LV, as an empty vector transduced control. Transduction efficiency greater than 10% or 20% was achieved following transduction and expansion over a 7-day period in response to CD19 CAR LV or GFP LV respectively. Following sufficient expansion, cytotoxicity of the CD19 CAR-NK cells was tested in-vitro in a Tumor Killing Assay (TKA) against CD19+ (Raji) or CD19- (SKOV-3) target cells. As expected, CD19 CAR-NK cells displayed increased cytotoxicity towards CD19+ target cells when compared to non-transduced or GFP transduced controls. This effect was not observed with CD19 negative cancer cells, strongly suggesting specific CD19 CAR mediated killing. Moreover, CD19 CAR-NK cells showed increased degranulation and IFNꝩ secretion when compared to both non-transduced and GFP-transduced controls, suggesting increased NK cell activation and cytotoxicity. Additionally, when degranulation of CD19 CAR positive and CD19 CAR negative NK populations was directly compared, the level of NK cell degranulation was analogous between the two populations, suggesting that CD19 CAR NK cells can enhance the cytotoxic activity of neighboring non-transduced cells, resulting in enhanced killing of CD19+ target cells by the total NK population present. Taken together these data demonstrate the generation, expansion and enrichment of CD19 CAR-NK cells with enhanced cytotoxic activity towards CD19+ target cells. This culture system provides the scientific community a platform to screen novel CAR-constructs and to test novel immunomodulators which could enhance NK cell expansion or functional potential to further develop new, more widely available cellular therapeutics to treat cancer. Citation Format: Karina Di Gregoli, Ravindra Mode, Kaitlin Mitchell, David Cobeta-Lopez, Sabrina de Munnik, Rene McLaughlin, Gemma Moiset, Louise Brackenbury, Lauren Schewitz-Bowers, Robert Nunan. Development of a CAR-NK cellular platform for cancer immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2907.

Limitations and Overcomes of CAR-NK for Cancer Immunotherapy

Adoptive cell treatment utilising chimeric antigen receptor (CAR) immunotherapy is gaining remarkable breakthroughs. In solid tumours, CAR immunotherapy lags far behind. CAR T cell production, does not have tumor-specific antigens, and is not effective in CAR T cell infiltration and trafficking into tumour sites, therapy-associated toxicity, immunosuppressive TME, and antigen escape are among the primary obstacles for CAR immunotherapy in solid tumours. Compared to CAR T cells, CAR NK cells have a number of benefits, including the ability to be processed from preexisting cell lines with mismatched MHC, the ability to kill bad cells via CAR-independent and CAR-dependent pathway with less toxicity. One clinical study demonstrated the effectiveness and safety of CAR NK cell treatment. However, CAR NK cell therapy also has its drawbacks, including, low persistence, lack of transporting pathway, immunosuppressive tumour microenvironment, and low lentivirus transduction efficiency. Solving these issues are significantly important for this technology to be accepted in future use.

Developing CAR T and CAR NK cells for HIV-1 eradication

Since HIV-1 was first discovered in the early 1980s, this virus has killed nearly 400,000 people around the world. However, up to now, there is no known cure for HIV-1 infection, because the removal of the HIV-1 repository is unreachable. In recent years, scientists began to apply the chimeric antigen receptor (CAR), an immunotherapy that has made great progress in hematological malignancies treatment, to the remedy of people infected with HIV-1, hoping to "kill" the virus completely after "shock" treatment. This review discussed the latest research progress of different types of CAR T cells, including CD4-based, scFv-based, and bi-/tri-specific CAR T cells, in HIV-1 therapy, and their advantages and limitations in detail. Additionally, it also briefly reviewed the function of NK cells in fighting HIV-1 infection and summarized the research results of CAR NK cells in AIDS treatment.

Preclinical and clinical studies of CAR-NK-cell therapies for malignancies.

The development of chimeric antigen receptor T (CAR-T) cell therapy, a specific type of immunotherapy, in recent decades was a fantastic breakthrough for the treatment of hematological malignancies. However, difficulties in collecting normal T cells from patients and the time cost of manufacturing CAR-T cells have limited the application of CAR-T-cell therapy. In addition, the termination of related clinical trials on universal CAR-T cell therapy has made further research more difficult. Natural killer (NK) cells have drawn great attention in recent years. Chimeric antigen receptor-NK (CAR-NK) cell therapy is a promising strategy in the treatment of malignant tumors because of its lack of potential for causing graft-versus-host disease (GVHD). In this review, we will address the advances in and achievements of CAR-NK cell therapy.

CAR-NK Cells for Cancer Therapy: Molecular Redesign of the Innate Antineoplastic Response.

The Chimeric Antigen Receptor (CAR) has arisen as a powerful synthetic biology-based technology with demonstrated versatility for implementation in T and NK cells. Despite CAR T cell successes in clinical trials, several challenges remain to be addressed regarding adverse events and long-term efficacy. NK cells present an attractive alternative with intrinsic advantages over T cells for treating solid and liquid tumors. Early preclinical and clinical trials suggest at least two major advantages: improved safety and an off-the-shelf application in patients due to its HLA independence. Due to the early stages of CAR NK translation to clinical trials, limited data is currently available. By analyzing these results, it seems that CAR NK cells could offer a reduced probability of Cytokine Release Syndrome (CRS) or Graft versus Host Disease (GvHD) in cancer patients, reducing safety concerns. Furthermore, NK cell therapy approaches may be boosted by combining it with immunological checkpoint inhibitors and by implementing genetic circuits to direct CAR-bearing cell behavior. This review provides a description of the CAR technology for modifying NK cells and the translation from preclinical studies to early clinical trials in this new field of immunotherapy.

Natural killer cells and acute myeloid leukemia: promises and challenges.

Acute myeloid leukemia (AML) is considered as one of the most malignant conditions of the bone marrow. Over the past few decades, despite substantial progresses in the management of AML, relapse remission remains a major problem. Natural killer cells (NK cells) are known as a unique component of the innate immune system. Due to swift tumor detection, distinct cytotoxic action, and extensive immune interaction, NK cells have been used in various cancer settings for decades. It has been a growing knowledge of therapeutic magnitudes ranging from adoptive NK cell transfer to chimeric antigen receptor NK cells, aiming to achieve better therapeutic responses in patients with AML. In this article, the potentials of NK cells for treatment of AML are highlighted, and challenges for such therapeutic methods are discussed. In addition, the clinical application of NK cells, mainly in patients with AML, is pictured according to the existing evidence.

Progress and prospects for use of cellular immunotherapy in pancreatic cancer.

Pancreatic cancer (PC) is a highly malignant tumor with an increasing incidence rate in recent years. Because pancreatic cancer has an insidious onset, unknown pathophysiology, and poor prognosis, the overall survival rate of pancreatic cancer patients has not improved considerably even with extensive treatment methods such as surgery, radiation, biotherapy, and targeted therapy. Therefore, finding and developing more effective and safe treatments for pancreatic cancer is critical. Cellular immunotherapy has achieved considerable advances in the field of oncology in recent years. Technology is continuously advancing, with new breakthroughs virtually every month, and pancreatic cancer eradication is expected to improve considerably. This article examines the advance of chimeric antigen receptor NK cell immunotherapy (CAR-NK) cell immunotherapy for pancreatic cancer research, as well as research ideas for pancreatic cancer treatment.

Importance of T, NK, CAR T and CAR NK Cell Metabolic Fitness for Effective Anti-Cancer Therapy: A Continuous Learning Process Allowing the Optimization of T, NK and CAR-Based Anti-Cancer Therapies.

Simple SummaryCancer treatments are evolving at a very rapid pace. Some of the most novel anti-cancer medicines under development rely on the modification of immune cells in order to transform them into potent tumor-killing cells. However, the tumor microenvironment (TME) is competing for nutrients with these harnessed immune cells and therefore paralyzes their metabolic effective and active anti-cancer activities. Here we describe strategies to overcome these hurdles imposed on immune cell activity, which lead to therapeutic approaches to enhance metabolic fitness of the patient’s immune system with the objective to improve their anti-cancer capacity.Chimeric antigen receptor (CAR) T and CAR NK cell therapies opened new avenues for cancer treatment. Although original successes of CAR T and CAR NK cells for the treatment of hematological malignancies were extraordinary, several obstacles have since been revealed, in particular their use for the treatment of solid cancers. The tumor microenvironment (TME) is competing for nutrients with T and NK cells and their CAR-expressing counterparts, paralyzing their metabolic effective and active states. Consequently, this can lead to alterations in their anti-tumoral capacity and persistence in vivo. High glucose uptake and the depletion of key amino acids by the TME can deprive T and NK cells of energy and building blocks, which turns them into a state of anergy, where they are unable to exert cytotoxic activity against cancer cells. This is especially true in the context of an immune-suppressive TME. In order to re-invigorate the T, NK, CAR T and CAR NK cell-mediated antitumor response, the field is now attempting to understand how metabolic pathways might change T and NK responses and functions, as well as those from their CAR-expressing partners. This revealed ways to metabolically rewire these cells by using metabolic enhancers or optimizing pre-infusion in vitro cultures of these cells. Importantly, next-generation CAR T and CAR NK products might include in the future the necessary metabolic requirements by improving their design, manufacturing process and other parameters. This will allow the overcoming of current limitations due to their interaction with the suppressive TME. In a clinical setting, this might improve their anti-cancer effector activity in synergy with immunotherapies. In this review, we discuss how the tumor cells and TME interfere with T and NK cell metabolic requirements. This may potentially lead to therapeutic approaches that enhance the metabolic fitness of CAR T and CAR NK cells, with the objective to improve their anti-cancer capacity.

Combinatorial Natural Killer Cell-based Immunotherapy Approaches Selectively Target Chordoma Cancer Stem Cells.

Chordoma is a rare tumor derived from notochord remnants that has a propensity to recur and metastasize despite conventional multimodal treatment. Cancer stem cells (CSC) are implicated in chordoma's resistant and recurrent behavior; thus strategies that target CSCs are of particular interest. Using in vitro cytotoxicity models, we demonstrated that anti-programmed death-ligand 1 (N-601) and anti-epidermal growth factor receptor (cetuximab) antibodies enhanced lysis of chordoma cells by healthy donor and chordoma patient NK cells through antibody-dependent cellular cytotoxicity (ADCC). Treatment of NK cells with an IL-15 superagonist complex (N-803) increased their cytotoxicity against chordoma cells, which was further enhanced by treatment with N-601 and/or cetuximab. PD-L1-targeted chimeric antigen receptor NK cells (PD-L1 t-haNKs) were also effective against chordoma cells. CSCs were preferentially vulnerable to NK cell killing in the presence of N-601 and N-803. Flow cytometric analysis of a chordoma CSC population showed that CSCs expressed significantly more NK activating ligand B7-H6 and PD-L1 than non-CSCs, thus explaining a potential mechanism of selective targeting. These data suggest that chordoma may be effectively targeted by combinatorial NK cell-mediated immunotherapeutic approaches and that the efficacy of these approaches in chordoma and other CSC-driven tumor types should be investigated further in clinical studies.

CAR-NK Cells Targeting Sars-Cov-2 Glycosites As COVID-19 Treatment

Introduction: Banana Lectin (BanLec) is a glycoprotein-binding lectin derived from banana fruit that has antiviral activity. BanLec binds high mannose glycans expressed on the viral envelopes of HIV, Ebola, influenza, and coronaviruses. BanLec mitogenicity can be divorced from antiviral activity via a single amino acid change (H84T). The SARS-CoV-2 spike (S) protein is decorated with high mannose N-glycosites that are in close proximity to the viral receptor binding domain (RBD). Our goal was to use the H84T-BanLec as the extracellular targeting domain of a chimeric antigen receptor (CAR). We hypothesized that engineering NK cells to express an H84T-BanLec CAR would specifically direct antiviral cytotoxicity against SARS-CoV-2.Methods: H84T-BanLec was synthesized and added to a 4-1BB.ζ CAR by subcloning into an existing retroviral vector. To modify primary human NK cells, CD3-depleted peripheral blood mononuclear cells were first activated with lethally irradiated feeder cells (K562.mbIL15.4-1BBL), then transduced with transiently produced replication incompetent γ-retrovirus carrying the H84T-BanLec.4-1BB.ζ CAR construct. Vector Copy Number (VCN) per cell was measured and CAR protein expression detected with Western blotting. 293T cells were engineered to express human ACE2 (hACE2.293T), the binding receptor for SARS-CoV-2. CAR expression on NK cells and SARS-CoV-2 S-protein binding to hACE2.293T were measured using FACS. S-protein pseudotyped lentivirus carrying a firefly Luciferase (ffLuc) reporter was produced. Viral infectivity was measured using bioluminescence (BL) detection in virally transduced cells. H84T-BanLec CAR NK cells were added to our S-protein pseudotyped lentiviral infectivity assay and degree of inhibited transduction was measured. NK cell activation was assessed with detection of IFNγ and TNFα secretion using ELISA.Results: A median of 4.5 integrated H84T-BanLec CAR copies per cell was measured (range 3.5-7.45, n=4). The CAR was detected by Western blot in NK cell lysates using antibodies to TCRζ and H84T-BanLec. Surface expression of the CAR on primary NK cells was recorded on day 4 after transduction (median [range], 67.5% CAR-positive [64.7-75%], n=6; Fig. 1). CAR expression was maintained on NK cells in culture for 14 days (58.9% CAR-positive [43.6-66.7%], n=6; Fig. 1). ACE2 expression and binding of recombinant S-proteins to hACE2 on hACE2.293T but not parental 293Ts was verified. S-protein pseudotyped lentiviral transduction of hACE2.293T was confirmed with increase in BL from baseline across diminishing viral titer (n=3; Fig. 2). Control 293T cells without hACE2 expression were not transduced, confirming specificity of viral binding and entry dependent on hACE2 (n=3; Fig. 2). S-protein pseudoviral infectivity of hACE2.293T cells was inhibited by both H84T-BanLec CAR-NK and unmodified NK cells, with enhanced inhibition observed in the CAR-NK condition (mean % pseudovirus infectivity +/- SEM of hACE2.293T in co-cultures with unmodified NK vs. H84T-BanLec CAR-NK; 65 +/-11% vs 35%+/- 6% for 1:1 effector-to-target ratio, p=0.05; 78 +/-3% vs 68%+/- 3% for 1:2.5 effector-to-target ratio, p=0.03; n=6; Fig.3). Both unmodified and H84T-BanLec CAR-NK cells were stimulated to secrete inflammatory mediators when co-cultured with pseudoviral particles and virally infected cells. CAR-NK cells showed overall higher cytokine secretion both at baseline and with viral stimulation.Conclusions: A glycoprotein binding H84T-BanLec CAR was stably expressed on the surface of NK cells. CAR-NK cells are activated by SARS-CoV-2 S-pseudovirus and virally infected cells. Viral entry into hACE2 expressing cells was inhibited by H84T-BanLec CAR-NK cells. Translation of H84T-BanLec CAR-NK cells to the clinic may have promise as an effective cellular therapy for SARS-CoV-2 infection. [Display omitted] DisclosuresMarkovitz: University of Michigan: Patents & Royalties: H84T BanLec and of the H84T-driven CAR construct. Bonifant: Merck, Sharpe, Dohme: Research Funding; BMS: Research Funding; Kiadis Pharma: Research Funding.

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

CD38 is a multifunctional cell surface protein that is frequently overexpressed on malignant plasma cells as well as on immune suppressive cells within the tumor microenvironment and constitutes a validated immunotherapeutic target in the treatment of multiple myeloma (MM). At ONK Therapeutics we are developing a gene edited, cord blood-derived NK (CBNK) cell product targeting CD38 for treatment of patients with relapsed and/or refractory MM.The product will be generated using a workflow shown in Figure 1A. This involves starting with cord blood that is processed for NK expansion using a clinically validated, Epstein Barr Virus-transformed lymphoblastoid cell line (EBV-LCL) feeder layer. The NK cells would undergo genetic engineering that involves gene editing followed by a non-viral chimeric antigen receptor (CAR) introduction process mediated by the TcBuster (TcB) DNA transposon system (Biotechne). This is followed by a second round of expansion on the EBV-LCL feeder layer resulting in a characterized NK cell product that can then be cryopreserved.In order to develop protocols for optimizing the best transfection efficiencies using the Maxcyte ATx instrument, GFP mRNA (TriLink) was used for transfecting CBNK cells using different electroporation programs. High transfection efficiency was obtained using all programs (Figure 1B.), with the best from program NK4.Since the product employs an optimized affinity second generation anti CD38 CAR (Stikvoort et al., Hemasphere 2021) which could also target CD38 expressed on neighbouring activated NK cells, it is imperative to knock out (KO) the cell surface expression of CD38 on the CAR-NK cells. To achieve this we carried out CRISPR Cas9 based KO studies of CD38 (Figure 1C. left top), using guide RNAs targeting CD38 (Synthego) in the form of a ribonucleoprotein (RNP) complex with Cas9. CBNK cells were transfected using the Maxcyte ATx instrument and CD38 cell surface expression monitored. As shown in Figure 1C. (left top), complete CD38 KO was achieved 11 days post transfection.ONK Therapeutics is actively involved in targeting and downregulating the negative regulator of cytokine signalling, cytokine inducible SH2-containing protein (CIS), which is encoded by the CISH gene, as part of their CBNK products. It has been demonstrated that in addition to facilitating greater cytokine signalling, CISH KO also confers greater metabolic capacity to NK cells resulting in their increased persistence (Daher et al., Blood 2021). Therefore, ONK Therapeutics have evaluated CISH KO in CBNK cells (Figure 1C, top right) using the same scheme that was used for the CD38 KO. Guide RNAs in the form of a RNP complex with Cas9 (Synthego) were transfected into CBNK cells and intracellular CIS protein levels monitored over time. Almost complete KO was attained by 9 days post transfection. In order to dial in CISH KO as part of the product, we further carried out a simultaneous KO of CD38 and CISH, in addition to individual KO of CD38 or CISH (Fig 1C, bottom). Simultaneous multiplexing of the CD38 and CISH KOs resulted in efficient double KO (DKO) . The extent of knock down leading to KO in the DKO setting was very similar to that of individual gene KOs.We then introduced the anti CD38 CAR as part of a transposon that could be transposed by TcB transposase in CBNK cells. After DKO of CD38 and CISH in CBNK cells, the transposon DNA and mRNA for transposase were electroporated. CAR expression was detected 4-5 days post transposition (Figure 1D) with more than 50% of cells expressing the anti CD38 CAR. These CAR expressing CBNK cells were then tested for functionality in a co-culture kill assay against the CD38 positive MM cell line, RPMI8226, which was engineered to express firefly luciferase. In a 4 hour killing assay, robust killing of the RPMI8226 cells was achieved by the CAR-CBNK cells with an EC 50 ten times lower (more potent) than that of mock electroporation control CBNK cells.To our knowledge this is the first successful expression of an anti CD38 CAR in cord-derived NK cells, and with a double CD38/CISH KO, using non-viral CAR insertion approaches. Current work is focusing on designing and developing a manufacturing-ready workflow for this potential product and further examining the effects of CAR NK cell activity in a DKO setting where both KOs contribute to improved metabolism and potentially NK cell persistence, as well as exploring the added benefit of a DR5 TRAIL variant to enhance cytotoxicity. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Generation of an NFκB-Driven Alpharetroviral "All-in-One" Vector Construct as a Potent Tool for CAR NK Cell Therapy.

Immune cell therapeutics are increasingly applied in oncology. Especially chimeric antigen receptor (CAR) T cells are successfully used to treat several B cell malignancies. Efforts to engineer CAR T cells for improved activity against solid tumors include co-delivery of pro-inflammatory cytokines in addition to CARs, via either constitutive cytokine expression or inducible cytokine expression triggered by CAR recognition of its target antigen—so-called “T cells redirected for universal cytokine-mediated killing” (TRUCKs) or fourth-generation CARs. Here, we tested the hypothesis that TRUCK principles could be expanded to improve anticancer functions of NK cells. A comparison of the functionality of inducible promoters responsive to NFAT or NFκB in NK cells showed that, in contrast to T cells, the inclusion of NFκB-responsive elements within the inducible promoter construct was essential for CAR-inducible expression of the transgene. We demonstrated that GD2CAR-specific activation induced a tight NFκB-promoter-driven cytokine release in NK-92 and primary NK cells together with an enhanced cytotoxic capacity against GD2+ target cells, also shown by increased secretion of cytolytic cytokines. The data demonstrate biologically relevant differences between T and NK cells that are important when clinically translating the TRUCK concept to NK cells for the treatment of solid malignancies.