Expansion Of Natural Killer Cells Research Articles

Optimizing glutamine concentration enhances ex vivo expansion of natural killer cells through improved redox status.

Amino acids are vital components of the serum-free medium that influence the expansion and function of NK cells. This study aimed to clarify the relationship between amino acid metabolism and expansion and cytotoxicity of NK cells. Based on analyzing the mino acid metabolism of NK-92 cells and Design of Experiments (DOE), we optimized the combinations and concentrations of amino acids in NK-92 cells culture medium. The results demonstrated that NK-92 cells showed a pronounced demand for glutamine, serine, leucine, and arginine, in which glutamine played a central role. Significantly, at a glutamine concentration of 13 mM, NK-92 cells expansion reached 161.9 folds, which was significantly higher than 55.5 folds at 2.5 mM. Additionally, under higher glutamine concentrations, NK-92 cells expressed elevated levels of cytotoxic molecules, the level of cytotoxic molecules expressed by NK-92 cells was increased and the cytotoxic rate was 68.42%, significantly higher than that of 58.08% under low concentration. In view of the close relationship between glutamine metabolism and intracellular redox state, we investigated the redox status within the cells. This study demonstrated that intracellular ROS levels in higher glutamine concentrations were significantly lower than those under lower concentration cultures with decreased intracellular GSH/GSSG ratio, NADPH/NADP+ ratio, and apoptosis rate. These findings indicate that NK-92 cells exhibit improved redox status when cultured at higher glutamine concentrations. Overall, our research provides valuable insights into the development of serum-free culture medium for ex vivo expansion of NK-92 cells.

Evaluating a combination treatment of NK cells and reovirus against bladder cancer cells using an in vitro assay to simulate intravesical therapy

Intravesical treatment using either reovirus or natural killer (NK) cells serves as an efficient strategy for the treatment of bladder cancer cells (BCCs); however, corresponding monotherapies have often shown modest cytotoxicity. The potential of a locoregional combination using high-dose reovirus and NK cell therapy in an intravesical approach has not yet been studied. In this study, we evaluated the effectiveness of reoviruses and expanded NK cells (eNK) as potential strategies for the treatment of bladder cancer. The anti-tumor effects of mono-treatment with reovirus type 3 Dearing strain (RC402 and RP116) and in combination with interleukin (IL)-18/-21-pretreated eNK cells were investigated on BCC lines (5637, HT-1376, and 253J-BV) using intravesical therapy to simulate in vitro model. RP116 and IL-18/-21-pretreated eNK cells exhibited effective cytotoxicity against grade 1 carcinoma (5637 cells) when used alone, but not against HT-1376 (grade 2 carcinoma) and 253J-BV cells (derived from a metastatic site). Notably, combining RP116 with IL-18/-21-pretreated eNK cells displayed effective cytotoxicity against both HT-1376 and 253J-BV cells. Our findings underscore the potential of a combination therapy using reoviruses and NK cells as a promising strategy for treating bladder cancer.

Abstract 1241: Enhancing NK cell therapy for head and neck cancer within the solid tumor microenvironment using a B7H3-targeting tri-specific killer engager (TriKE)

Abstract With an annual incidence rate exceeding 660,000 cases, and a death toll surpassing 325,000 per year, head and neck cancer (HNC) ranks as the seventh most common cancer in the world. Surgery, radiation and chemotherapy are used to treat HNC patients with modest and variable clinical success. However, these treatments prove less effective for human papillomavirus negative (HPV-) HNC patients, a subset of HNC patients with markedly worse prognosis. While significant advancements have been made in cancer immunotherapy over the past decade, its success also remains elusive for HNC due to factors such as the hypoxic solid tumor microenvironment (TME). To address the critical need for an improved therapeutic intervention, we leveraged the ability of natural killer (NK) cells in killing cancer cells without prior sensitization by developing a novel tri-specific killer engager (TriKE) that can direct NK cell killing of tumor within the hypoxic solid TME. The TriKE is composed of three domains: a humanized nanobody arm binding the activating receptor CD16 on NK cells, an interleukin (IL)-15 moiety that can drive expansion of NK cells, and a nanobody arm binding B7H3, a protein which high expression can be negatively correlated with overall survival of HPV- HNC patients. B7H3 is a prime target candidate because it is highly expressed on HPV- HNC cells, but minimally expressed on healthy tissues. In vitro testing using HPV- HNC patient blood samples revealed that B7H3 TriKE enhances activation (measured by NK cell degranulation and interferon-gamma production) and expansion of NK cells from these patients at levels equivalent to those observed in healthy controls. Furthermore, B7H3 TriKE is efficacious in its ability to drive high NK cell cytotoxicity in both acute (<48-hours) and prolonged (7-days) hypoxic (1% oxygen) models of HNC. Under acute hypoxia, B7H3 TriKE induces significantly more killing of targets by NK cells compared to IL-15 treatment, where NK cell cytotoxicity is impaired. In addition, B7H3 TriKE can boost the killing efficacy of NK cells exposed to prolonged hypoxia, surpassing limitations seen with IL-15 treatment. These findings strongly suggest that the B7H3 TriKE can bypass hypoxic suppression of NK effector functions in the solid TME. In vivo studies using immunocompromised mice engrafted with HPV- HNC cells revealed that B7H3 TriKE treatment significantly extends the survival of mice, compared to IL-15 treatment. Moreover, NK cells persisted in the blood of B7H3 TriKE-treated mice 28 days post-NK cell injection, highlighting the promising clinical translation of this immunotherapy. More in-depth characterization of NK cells from HPV- HNC patients are underway but altogether, these robust pre-clinical data present a novel avenue for the management of HNC for these patients. We plan to translate results from these studies to clinical trials in fall 2024. Citation Format: Melissa Khaw, Nicholas A. Zorko, Carly Selleck, Laura Bendzick, Zachary Davis, Peter Hinderlie, Madison Shackelford, Ann Lu, James Lim, Naomi Fujioka, Margaret MacMillan, John Wagner, Martin Felices, Jeffrey S. Miller. Enhancing NK cell therapy for head and neck cancer within the solid tumor microenvironment using a B7H3-targeting tri-specific killer engager (TriKE) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1241.

Abstract 5236: Adoptive natural killer therapy is effective for synovial sarcoma cell lines

Abstract Despite the development of multimodal therapy consisting of surgery, radiotherapy, and chemotherapy, the prognosis of patients with metastatic or relapsed synovial sarcoma (SS) remains poor. A novel treatment option including immunotherapy is urgently required. Natural killer (NK) cells are innate immune cells that can recognize and kill tumor cells. The cytolytic activity of NK cells is determined by the balance of signals from both inhibitory and activating receptors expressed on cell surface. Activating receptors include NKp30, NKp44, NKp46, NKG2D, and DNAM-1. Furthermore, tumor cells with low HLA class I expression are potentially even more sensitive to NK-mediated cytotoxic killing due to a lack of inhibitory signals. We previously reported that HLA class I expression was down regulated in one third of patients with synovial sarcoma, suggesting that NK cell therapy may be effective for patients with SS. However, the efficacy of NK cells treatment in SS was not well established. In this study, we evaluated surface ligands for NK cell activation on SS cell lines and demonstrated the effectiveness of activated allogenic NK cells for SS cell lines in vitro.The surface expression of ligands for NK cell-activating receptors including NKp30, NKp44, NKp46, NKG2D, and DNAM-1 in three SS cell lines (SYO-I, HS-SY-II, and Yamato-SS) was evaluated using flow cytometry. Peripheral blood from two healthy donors were ficoll-separated to collect peripheral blood mononuclear cells (PBMCs). Then, PBMCs were stimulated with irradiated K562 cells expressing the NK-stimulatory molecules 4-1BB ligand and membrane-bound Interleukin 15 in the presence of human Interleukin-2 in RPMI1640 with 10% FBS. The cells were expanded for 14 days, and the expanded NK cells are CD3-CD56+ NK cells. These expanded cells are reproducible in their function, and we have utilized these cells for in vitro cytotoxicity assays. 2x10E4 of SS cell lines (SYO-I, HS-SY-II, and Yamato-SS) were seeded in a 96 well plates and cultured overnight. Then, allogenic NK cells or activated T cells as a control at various tumor effector ratio. The cells were co-cultured with activated T cells or NK cells in the presence of low dose interleukin2. Forty-eight hours later, cell viabilities were measured using WST-8 assay.Ligands for NKp44, NKp30, NK2GD, were expressed in all three SS cell lines. It suggested that SS cells upregulate activating receptor ligands for NK cells. In addition, cytotoxicity of allogenic NK cells for SS cell lines was significantly higher than that of activated T cells. To determine whether cytotoxic activity was effect of allogenic NK cells, CD107a mobilization assay using flowcytometry was performed. CD107a mobilization assay demonstrated degranulation of NK cells, leading us that NK cells had an antitumoral effect on SS cell lines in vitro. Based on these initial findings, we were able to demonstrate that allogenic NK cells may be a promising immune therapy for SS. Citation Format: Naoki Oike, Tomohiro Miyazaki, Yudai Murayama, Takashi Ariizumi, Akira Ogose, Minori Baba, Hiroyuki Kawashima, Chihaya Imai. Adoptive natural killer therapy is effective for synovial sarcoma cell lines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5236.

Abstract 1240: Enhancing NK cell function in the ‘cold’ tumor microenvironment of prostate cancer with a novel tri-specific killer engager

Abstract Introduction: Natural killer (NK) cells are associated with good prognosis in patients with metastatic castration-resistant prostate cancer (mCRPC). However, NK cell function is hindered in the immunosuppressive and hypoxic tumor microenvironment (TME) of mCRPC. To improve NK cell-mediated responses against mCRPC, we designed a novel Tri-specific Killer Engager (TriKE®) that engages with NK cell activating receptor CD16, binds to prostate-specific membrane antigen (PSMA) that is highly and specifically expressed on mCRPC, and has an interleukin (IL)-15 moiety that is essential for NK cell survival, proliferation, and priming. Methods: PSMA TriKE was produced using the mammalian expression system and tested using healthy donor and prostate cancer patient-derived NK cells. Flow cytometry-based functional and dye dilution proliferation assays were used to compare activation and proliferation of NK cells treated with PSMA TriKE or IL-15. NK cell cytolytic capacity against C4-2 cells, a PSMA-expressing prostate cancer line, was measured using IncuCyte live cell imaging. In various assays, hypoxic (1% oxygen) culture condition and cytokine-induced myeloid-derived suppressor cells (MDSC) were incorporated to better examine PSMA TriKE function in the physiological setting of mCRPC. In vivo testing of the PSMA TriKE was performed using C4-2 xenograft model and expanded NK cells in NSG mice. Results: PSMA TriKE significantly enhanced expansion of peripheral blood NK cells derived from healthy donors up to 8-fold. Additionally, PSMA TriKE induced significantly higher NK cell degranulation and intracellular IFNγ and TNFα buildup, when compared to IL-15 treatment, after incubation with C4-2 cells. Responses of NK cells derived from prostate cancer patients were equivalent to healthy controls. Although NK cell activation was not observed against PSMA knockout (KO) C4-2, indicating specificity of PSMA TriKE treatment, bystander killing of PSMA-KO C4-2 was achieved with PSMA TriKE treatment when wildtype C4-2 cells were cocultured. This suggests potential PSMA TriKE benefit in controlling tumor antigen escape, through natural cytotoxicity once primed. In settings that mimic the TME of mCRPC, NK cells treated with PSMA TriKE in prolonged exposure to hypoxia showed retention of cytotoxicity against C4-2 while IL-15 treated NK cells showed greatly impaired cytotoxicity. Similarly, MDSC suppressed NK cell cytotoxicity in the presence of IL-15, but PSMA TriKE treatment abrogated MDSC-induced suppression. Finally, PSMA TriKE enhanced tumor control and improved survival of mice as compared to IL-15 and no treatment groups in vivo. Conclusion: PSMA TriKE demonstrates potential in overcoming suppression of NK cells in the TME of mCRPC and is a promising candidate for advanced prostate cancer therapy. Citation Format: Shee Kwan Phung, Yvette Soignier, Nicholas Zorko, Rhett L. Waller, Josh Walker, Trygve Nelson, Carly Selleck, Laura Bendzick, Philippa Kennedy, Jeffrey S. Miller, Martin Felices. Enhancing NK cell function in the ‘cold’ tumor microenvironment of prostate cancer with a novel tri-specific killer engager [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1240.

Abstract 3615: Targeting high-risk neuroblastoma by TGFβ imprinted natural killer cells

Abstract Background: Neuroblastoma (NB) is a common malignant extracranial solid tumor in children, responsible for 11% of cancer deaths in pediatric patients under 15 (Smith et al, Cancer, 2014). High-risk neuroblastoma is a metastatic disease in children aged 18 months or older with L2, M, or MS disease with amplification of the MYCN oncogene (Chuang Pediatr Blood Cancer 2021). Recent analyses by COG show that HR Neuroblastoma still has a 5-year event free survival of 51% despite an extensive treatment regimen (Steven et al, ASCO, 2022). To address improved tumor targeting and overcome antigen escape, chimeric antigen receptor (CAR) technology to Natural Killer (NK) cell therapy has been adapted (Chu/Cairo, et al, Frontiers in Oncology, 2019). TGFβ is a potent mechanism of the NK cell anti-tumor resistance and is present at elevated levels in the NB tumor microenvironment (TME) (Foltz, Cancers, 2018). Studies demonstrated that blockade of TGF-β signaling in NK cells caused the accumulation of NK cells that produce IFN-γ and neutralization of TGF-β prevented NKG2D downregulation and also restored NK cell anti-tumor reactivity (Nayyar/Chu/Cairo, et al Frontierls in Oncology, 2018). ROR1, a transmembrane protein is highly expressed on the majority of NB (Rebagay/Yan Front Oncol, 2012). Our group has successfully expanded functional and active peripheral blood NK cells (exPBNK) with irradiated feeder cells and electroporated CAR mRNA to exPBNK (Chu/Cairo, et al Cancer Immunol Res, 2015). Objective: To determine in vitro cytotoxicity against neuroblastoma cells by ex vivo expanded TGFβ imprinting (TGFβi) NK cells. Methods: TGFβi NK cells are generated by culturing expanded NK cells with irradiated K562-41BBL-mbIL21 in 50 IU/mL IL-2 plus 10 ng/mL TGFβ every 2-3 days for two weeks. NK and TGFβi NK cells specific in-vitro cytotoxicity were compared via luciferase reporter assay against ROR1+ NB cell lines as we previously described (Chu/Cairo, et al, JITC, 2022). Cytokine/chemokine levels secreted by NK and TGFβi NK cells were compared using ELISA assays (Chu/Cairo, et al, JITC, 2022). Results: We have successfully expanded TGFβi NK cells. These TGFβi NK cells showed significantly enhanced in vitro cytotoxicity against NB cells compared to NK cells under TGFβ environment (20+2.4% vs 0%; p<0.001) at E:T=3:1 and consistently, TGFβ-imprinting NK secreted significantly high level of TNF-alpha (393.7pg/ml+16.77pg/ml) against NB cells (p<0.001) compared to NK cells (79.7pg/ml+14.7pg/ml) under TGFβ environment. Conclusion: Our data indicate TGFβi NK cells may be a promising novel therapy to overcome the immunosuppression of TGFβ in the tumor microenvironment for pediatric NB tumors. We will further engineer these TGFβi NK cells to express anti-ROR1 CAR to enhance the targeting specificity against NB tumors and investigate the anti-tumor effects of anti-ROR1 CAR TGFβi NK cells against NB tumors in-vitro and in-vivo (Funded by U54 CA232561). Citation Format: Jessica A. Ayala-Cuesta, Yaya Chu, Keira Foley, Meijuan Tian, Kayleigh Klose, Alyssa S. Mendelowitz, Timothy P. Cripe, Dean A. Lee, Mitchell S. Cairo. Targeting high-risk neuroblastoma by TGFβ imprinted natural killer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3615.

Building a Better Defense: Expanding and Improving Natural Killer Cells for Adoptive Cell Therapy.

Natural killer (NK) cells have gained attention as a promising adoptive cell therapy platform for their potential to improve cancer treatments. NK cells offer distinct advantages over T-cells, including major histocompatibility complex class I (MHC-I)-independent tumor recognition and low risk of toxicity, even in an allogeneic setting. Despite this tremendous potential, challenges persist, such as limited in vivo persistence, reduced tumor infiltration, and low absolute NK cell numbers. This review outlines several strategies aiming to overcome these challenges. The developed strategies include optimizing NK cell expansion methods and improving NK cell antitumor responses by cytokine stimulation and genetic manipulations. Using K562 cells expressing membrane IL-15 or IL-21 with or without additional activating ligands like 4-1BBL allows "massive" NK cell expansion and makes multiple cell dosing and "off-the-shelf" efforts feasible. Further improvements in NK cell function can be reached by inducing memory-like NK cells, developing chimeric antigen receptor (CAR)-NK cells, or isolating NK-cell-based tumor-infiltrating lymphocytes (TILs). Memory-like NK cells demonstrate higher in vivo persistence and cytotoxicity, with early clinical trials demonstrating safety and promising efficacy. Recent trials using CAR-NK cells have also demonstrated a lack of any major toxicity, including cytokine release syndrome, and, yet, promising clinical activity. Recent data support that the presence of TIL-NK cells is associated with improved overall patient survival in different types of solid tumors such as head and neck, colorectal, breast, and gastric carcinomas, among the most significant. In conclusion, this review presents insights into the diverse strategies available for NK cell expansion, including the roles played by various cytokines, feeder cells, and culture material in influencing the activation phenotype, telomere length, and cytotoxic potential of expanded NK cells. Notably, genetically modified K562 cells have demonstrated significant efficacy in promoting NK cell expansion. Furthermore, culturing NK cells with IL-2 and IL-15 has been shown to improve expansion rates, while the presence of IL-12 and IL-21 has been linked to enhanced cytotoxic function. Overall, this review provides an overview of NK cell expansion methodologies, highlighting the current landscape of clinical trials and the key advancements to enhance NK-cell-based adoptive cell therapy.

Abstract A099: Preliminary pharmacodynamic characterization in patients with platinum-resistant ovarian cancer treated with nemvaleukin in combination with pembrolizumab

Abstract A099: Preliminary pharmacodynamic characterization in patients with platinum-resistant ovarian cancer treated with nemvaleukin in combination with pembrolizumab

Opposing diet, microbiome, and metabolite mechanisms regulate inflammatory bowel disease in a genetically susceptible host

Inflammatory bowel diseases (IBDs) are chronic conditions characterized by periods of spontaneous intestinal inflammation and are increasing in industrialized populations. Combined with host genetics, diet and gut bacteria are thought to contribute prominently to IBDs, but mechanisms are still emerging. In mice lacking the IBD-associated cytokine, interleukin-10, we show that a fiber-deprived gut microbiota promotes the deterioration of colonic mucus, leading to lethal colitis. Inflammation starts with the expansion of natural killer cells and altered immunoglobulin-A coating of some bacteria. Lethal colitis is then driven by Th1 immune responses to increased activities of mucin-degrading bacteria that cause inflammation first in regions with thinner mucus. A fiber-free exclusive enteral nutrition dietalso induces mucus erosion but inhibits inflammation by simultaneously increasing an anti-inflammatory bacterial metabolite, isobutyrate. Our findings underscore the importance of focusing on microbial functions-not taxa-contributing to IBDs and that some diet-mediated functions can oppose those that promote disease.

Elotuzumab Enhances CD16-Independent NK Cell-Mediated Cytotoxicity against Myeloma Cells by Upregulating Several NK Cell-Enhancing Genes.

Multiple myeloma (MM) is an intractable hematological malignancy caused by abnormalities in plasma cells. Combination therapy using antibodies and natural killer (NK) effectors, which are innate immune cells with safe and potent antitumor activity, is a promising approach for cancer immunotherapy and can enhance antitumor effects. Elotuzumab (Elo) is an immune-stimulatory antibody that targets the signaling lymphocytic activation molecule family 7 (SLAMF7) expressed on the surface of MM and NK cells. We confirmed that Elo strongly promoted NK cell-mediated antibody-dependent cellular cytotoxicity (ADCC) against SLAMF7-positive MM cells in a CD16-dependent NK cell line, and also activated expanded NK cells derived from peripheral blood mononuclear cells of healthy donors and patients with MM in the present study. However, the antitumor effects and genes involved in the direct promotion of NK cell-mediated activation using Elo in CD16-independent NK cells are not clearly known. In this study, we demonstrated that Elo pretreatment significantly enhanced CD16-independent NK cell-mediated cytotoxicity in both SLAMF7-positive MM.1S and SLAMF7-negative K562, U266, and RPMI 8226 tumor cells. Upon direct simulation of CD16-independent NK cells with Elo, increased levels of CD107a degranulation and IFN-γ secretion were observed along with the upregulation of granzyme B, TNF-α, and IL-1α gene expression. The enhanced NK cell function could also be attributed to the increased expression of the transcription factors T-BET and EOMES. Furthermore, the augmentation of the antitumor effects of CD16-independent NK cells upon pretreatment with Elo enhanced the expression of CRTAM, TNFRSF9, EAT-2, and FOXP3 genes and reduced the expression of HSPA6. Our results suggest that Elo directly promotes the cytotoxic function of CD16-independent NK cells against target cells, which is associated with the upregulation of the expression of several NK cell-enhancing genes.

Integrated Analysis of Single-Cell and Bulk RNA Sequencing Data Reveals Memory-like NK Cell Subset Associated with Mycobacterium tuberculosis Latency.

Natural killer (NK) cells are innate-like lymphocytes that belong to the family of type-1 innate lymphoid cells and rapidly respond to virus-infected and tumor cells. In this study, we have combined scRNA-seq data and bulk RNA-seq data to define the phenotypic and molecular characteristics of peripheral blood NK cells. While the role of NK cells in immune surveillance against virus infections and tumors has been well established, their contribution to protective responses to other intracellular microorganisms, such as Mycobacterium tuberculosis (Mtb), is still poorly understood. In this study, we have combined scRNA-seq data and bulk RNA-seq data to illuminate the molecular characteristics of circulating NK cells in patients with active tuberculosis (TB) disease and subjects with latent Mtb infection (LTBI) and compared these characteristics with those of healthy donors (HDs) and patients with non-TB other pulmonary infectious diseases (ODs). We show here that the NK cell cluster was significantly increased in LTBI subjects, as compared to patients with active TB or other non-TB pulmonary diseases and HD, and this was mostly attributable to the expansion of an NK cell population expressing KLRC2, CD52, CCL5 and HLA-DRB1, which most likely corresponds to memory-like NK2.1 cells. These data were validated by flow cytometry analysis in a small cohort of samples, showing that LTBI subjects have a significant expansion of NK cells characterized by the prevalence of memory-like CD52+ NKG2C+ NK cells. Altogether, our results provide some new information on the role of NK cells in protective immune responses to Mtb.

Abstract B040: Trispecific killer engagers against IGF1R and fetal form of insulin receptor induce human natural killer cell mediated killing of hormone receptor positive breast cancer in vitro and in vivo

Abstract Patients with hormone receptor-positive (HR+) breast cancers frequently recur with metastatic disease 5-20 years after the initial diagnosis and completion of chemotherapy and prolonged treatment with hormonal therapy. Thus, patients with metastatic HR+ breast cancer need new therapeutic options. A potential mechanism of therapeutic resistance in HR+ patients is the presence of slow-growing, well-differentiated cancer cells that result in clinically detectable metastases after a prolonged latency. One way to eliminate these cancer cells is with immunotherapy (IT). Unfortunately HR+ breast cancers have not responded to current T-cell based IT. The objective of this study is to target HR+ breast cancers using a natural killer (NK) cell based approach that targets cell surface receptors in HR+ breast cancer. The type I IGF receptor (IGF1R) is expressed on HR+ breast cancers and its expression is tightly related to ER function. Endocrine therapy resistance is associated with increased expression of the A-isoform or fetal form of IR (IR-A) and depend on IR signaling. We hypothesized that a drug that would target NK cells to IGF1R or IR-A expressing HR+ cells will be effective in killing them. We generated IGF1R or IR-A specific Tri specific Killer Engagers (TriKE) that leverage expression of IGF1R and IR-A on HR+ cells to cause NK directed death. The IGF1R TriKE consists of humanized single domain antibody (VHH) sequence of a CD16 nanobody to engage and activate NK cells, a humanized VHH of a nanobody against IGF1R to target HR+ breast cancer cells, and an IL-15 molecule between them to drive NK cell expansion and survival. The IGF1R TriKE did not bind embryonal fibroblasts from IGF1R knock out mice (R- cells) but bound R-/IGF1R cells (R- cells engineered to express human IGF1R) and to IGF1R+ MCF-7 and T47D breast cancer cells indicating specific binding to IGF1R on cells. It did not cause downregulation of IGF1R levels in multiple HR+ breast cancer cells and did not inhibit signaling via IGF1R. It specifically induced NK cell degranulation, measured by surface CD107a expression and intracellular IFNγ, against IGF1R+ target breast cancer cells (MCF-7, T-47D, ZR-75-1) in a functional assay compared to the anti-IGF1R nanobody. It did not induce degranulation of NK cells against IGF1R negative cells suggesting that the functionality was specific for IGF1R expressing targets. The IGF1R TriKE enhanced cell killing of HR+ breast cancer cells as measured by cytotoxicity assays. IGF1R TriKE combined with human NK cells inhibited tumor growth of MCF-7 tumors in NSG mice compared to control groups. Human NK cells persisted in peripheral blood three weeks after final NK infusion based on flow cytometry assessment. The IR-A TriKE incorporated a novel engineered non-immunoglobulin IR-A specific peptide binder. Our preliminary data show that the IR-A TriKE degranulated NK cells against breast cancer cells overexpressing IR-A. These data indicate that this strategy could be an effective treatment for HR+ metastatic breast cancer and make them responsive to IT. Citation Format: Courtney Baar, Emily Chiu, Yvette Soignier, Behiye Kodal, Jeffrey S Miller, Martin Felices, Deepali Sachdev. Trispecific killer engagers against IGF1R and fetal form of insulin receptor induce human natural killer cell mediated killing of hormone receptor positive breast cancer in vitro and in vivo [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Breast Cancer Research; 2023 Oct 19-22; San Diego, California. Philadelphia (PA): AACR; Cancer Res 2024;84(3 Suppl_1):Abstract nr B040.

High and selective cytotoxicity of ex vivo expanded allogeneic human natural killer cells from peripheral blood against bladder cancer: implications for natural killer cell instillation after transurethral resection of bladder tumor

BackgroundNon-muscle-invasive bladder cancer (NMIBC) is treated with transurethral resection of bladder tumor (TURBT) followed by intravesical instillation of chemotherapy or Bacillus Calmette–Guérin therapy. However, these treatments have a high recurrence rate and side effects, emphasizing the need for alternative instillations. Previously, we revealed that expanded allogeneic human natural killer (NK) cells from peripheral blood are a promising cellular therapy for prostate cancer. However, whether NK cells exhibit a similar killing effect in bladder cancer (BCa) remains unknown.MethodsExpansion, activation, and cryopreservation of allogeneic human NK cells obtained from peripheral blood were performed as we previously described. In vitro cytotoxicity was evaluated using the cell counting kit-8. The levels of perforin, granzyme B, interferon-γ, tumor necrosis factor-α, and chemokines (C-C-motif ligand [CCL]1, CCL2, CCL20, CCL3L1, and CCL4; C-X-C-motif ligand [CXCL]1, CXCL16, CXCL2, CXCL3, and CXCL8; and X-motif ligand 1 and 2) were determined using enzyme-linked immunosorbent assay. The expression of CD107a, major histocompatibility complex class I (MHC-I), MHC-I polypeptide-related sequences A and B (MICA/B), cytomegalovirus UL16-binding protein-2/5/6 (ULBP-2/5/6), B7-H6, CD56, CD69, CD25, killer cell Ig-like receptors (KIR)2DL1, KIRD3DL1, NKG2D, NKp30, NKp46, and CD16 of NK cells or BCa and normal urothelial cells were detected using flow cytometry. Cytotoxicity was evaluated using lactate dehydrogenase assay in patient-derived organoid models. BCa growth was monitored in vivo using calipers in male NOD-scid IL2rg−/− mice subcutaneously injected with 5637 and NK cells. Differential gene expressions were investigated using RNA sequence analysis. The chemotaxis of T cells was evaluated using transwell migration assays.ResultsWe revealed that the NK cells possess higher cytotoxicity against BCa lines with more production of cytokines than normal urothelial cells counterparts in vitro, demonstrated by upregulation of degranulation marker CD107a and increased interferon-γ secretion, by MICA/B/NKG2D and B7H6/NKp30-mediated activation. Furthermore, NK cells demonstrated antitumor effects against BCa in patient-derived organoids and BCa xenograft mouse models. NK cells secreted chemokines, including CCL1/2/20, to induce T-cell chemotaxis when encountering BCa cells.ConclusionsThe expanded NK cells exhibit potent cytotoxicity against BCa cells, with few toxic side effects on normal urothelial cells. In addition, NK cells recruit T cells by secreting a panel of chemokines, which supports the translational application of NK cell intravesical instillation after TURBT from bench to bedside for NMIBC treatment.

Development of Innate-Immune-Cell-Based Immunotherapy for Adult T-Cell Leukemia-Lymphoma.

γδ T cells and natural killer (NK) cells have attracted much attention as promising effector cell subsets for adoptive transfer for use in the treatment of malignant and infectious diseases, because they exhibit potent cytotoxic activity against a variety of malignant tumors, as well as virus-infected cells, in a major histocompatibility complex (MHC)-unrestricted manner. In addition, γδ T cells and NK cells express a high level of CD16, a receptor required for antibody-dependent cellular cytotoxicity. Adult T-cell leukemia-lymphoma (ATL) is caused by human T-lymphotropic virus type I (HTLV-1) and is characterized by the proliferation of malignant peripheral CD4+ T cells. Although several treatments, such as chemotherapy, monoclonal antibodies, and allogeneic hematopoietic stem cell transplantation, are currently available, their efficacy is limited. In order to develop alternative therapeutic modalities, we considered the possibility of infusion therapy harnessing γδ T cells and NK cells expanded using a novel nitrogen-containing bisphosphonate prodrug (PTA) and interleukin (IL)-2/IL-18, and we examined the efficacy of the cell-based therapy for ATL in vitro. Peripheral blood samples were collected from 55 patients with ATL and peripheral blood mononuclear cells (PBMCs) were stimulated with PTA and IL-2/IL-18 for 11 days to expand γδ T cells and NK cells. To expand NK cells alone, CD3+ T-cell-depleted PBMCs were cultured with IL-2/IL-18 for 10 days. Subsequently, the expanded cells were examined for cytotoxicity against ATL cell lines in vitro. The proportion of γδ T cells in PBMCs was markedly low in elderly ATL patients. The median expansion rate of the γδ T cells was 1998-fold, and it was 12-fold for the NK cells, indicating that γδ T cells derived from ATL patients were efficiently expanded ex vivo, irrespective of aging and HTLV-1 infection status. Anti-CCR4 antibodies enhanced the cytotoxic activity of the γδ T cells and NK cells against HTLV-1-infected CCR4-expressing CD4+ T cells in an antibody concentration-dependent manner. Taken together, the adoptive transfer of γδ T cells and NK cells expanded with PTA/IL-2/IL-18 is a promising alternative therapy for ATL.

CD8 cis-targeted IL-2 drives potent antiviral activity against hepatitis B virus.

CD8+ T cells are key antiviral effectors against hepatitis B virus (HBV), yet their number and function can be compromised in chronic infections. Preclinical HBV models displaying CD8+ T cell dysfunction showed that interleukin-2 (IL-2)-based treatment, unlike programmed cell death ligand 1 (PD-L1) checkpoint blockade, could reverse this defect, suggesting its therapeutic potential against HBV. However, IL-2's effectiveness is hindered by its pleiotropic nature, because its receptor is found on various immune cells, including regulatory T (Treg) cells and natural killer (NK) cells, which can counteract antiviral responses or contribute to toxicity, respectively. To address this, we developed a cis-targeted CD8-IL2 fusion protein, aiming to selectively stimulate dysfunctional CD8+ T cells in chronic HBV. In a mouse model, CD8-IL2 boosted the number of HBV-reactive CD8+ T cells in the liver without substantially altering Treg or NK cell counts. These expanded CD8+ T cells exhibited increased interferon-γ and granzyme B production, demonstrating enhanced functionality. CD8-IL2 treatment resulted in substantial antiviral effects, evidenced by marked reductions in viremia and antigenemia and HBV core antigen-positive hepatocytes. In contrast, an untargeted CTRL-IL2 led to predominant NK cell expansion, minimal CD8+ T cell expansion, negligible changes in effector molecules, and minimal antiviral activity. Human CD8-IL2 trials in cynomolgus monkeys mirrored these results, achieving a roughly 20-fold increase in peripheral blood CD8+ T cells without affecting NK or Treg cell numbers. These data support the development of CD8-IL2 as a therapy for chronic HBV infection.

Sufficiently activated mature natural killer cells derived from peripheral blood mononuclear cells substantially enhance antitumor activity.

Peripheral blood-derived natural killer (NK) cells spontaneously lyse tumor cells without prior sensitization. However, NK cells in peripheral blood (PBNK cells) are in a resting state and exhibit inhibitory phenotypes and impaired cytotoxicity. Thus, strengthening the cytotoxic effector function of PBNK cells and improving NK cell expansion in vitro for a convenient allogeneic therapy are essential. Pure cytokine activation and expansion of NK cells (super NK [SNK])from peripheral blood mononuclear cells were studied. Markers of activated and inhibited NK cells and cytokine secretion by NK cells were examined using flow cytometry. NK cell antitumor activity in vitro was assessed using lactate dehydrogenase (LDH) cytotoxicity assay and an Incucyte real-time imaging system. Additionally, the function of SNK cells against ascites caused by ovarian cancer in NOD-Prkdc(em26Cd52)il2rg(em26Cd22)/Nju (NCG)mice was determined. In a further investigation of the differences between PBNK and SNK, the mRNA of both cells was sequenced and analyzed. Human peripheral blood mononuclear cells showed selective NK cell expansion upon cytokine activation and culture. Both SNK and PBNK cells expressed activation markers, but at different levels, and SNK cells secreted more cytokines related to cytotoxicity than PBNK cells did. Accordingly, SNK cells exhibited strong antitumor activity ex vivo and improved NCG mice survival after intraperitoneal ovarian cancer transplantation. Mechanistically, SNK cells expressed more genes associated with nucleotide metabolism, fatty acid, and ATP metabolism than PBNK cells. SNK cells derived from peripheral blood mononuclear cells have sufficiently activated mature characteristics and high antitumor activity, rendering them a highly promising and essential therapeutic approach for cancer treatment.

Interleukin-2 is required for NKp30-dependent NK cell cytotoxicity by preferentially regulating NKp30 expression.

Natural killer (NK) cells are key effectors in cancer immunosurveillance, eliminating a broad spectrum of cancer cells without major histocompatibility complex (MHC) specificity and graft-versus-host diseases (GvHD) risk. The use of allogeneic NK cell therapies from healthy donors has demonstrated favorable clinical efficacies in treating diverse cancers, particularly hematologic malignancies, but it requires cytokines such as IL-2 to primarily support NK cell persistence and expansion. However, the role of IL-2 in the regulation of activating receptors and the function of NK cells expanded for clinical trials is poorly understood and needs clarification for the full engagement of NK cells in cancer immunotherapy. Here, we demonstrated that IL-2 deprivation significantly impaired the cytotoxicity of primary expanded NK cells by preferentially downregulating NKp30 but not NKp46 despite their common adaptor requirement for expression and function. Using NK92 and IL-2-producing NK92MI cells, we observed that NKp30-mediated cytotoxicity against myeloid leukemia cells such as K562 and THP-1 cells expressing B7-H6, a ligand for NKp30, was severely impaired by IL-2 deprivation. Furthermore, IL-2 deficiency-mediated NK cell dysfunction was overcome by the ectopic overexpression of an immunostimulatory NKp30 isoform such as NKp30a or NKp30b. In particular, NKp30a overexpression in NK92 cells improved the clearance of THP-1 cells in vivo without IL-2 supplementation. Collectively, our results highlight the distinct role of IL-2 in the regulation of NKp30 compared to that of NKp46 and suggest NKp30 upregulation, as shown here by ectopic overexpression, as a viable modality to harness NK cells in cancer immunotherapy, possibly in combination with IL-2 immunocytokines.

NK cell-activating receptor NKp46 does not participate in the development of obesity-induced inflammation and insulin resistance

Recent evidence establishes a pivotal role for obesity-induced inflammation in precipitating insulin resistance and type-2 diabetes. Central to this process is the proinflammatory M1 adipose-tissue macrophages (ATMs) in epididymal white adipose tissue (eWAT). Notably, natural killer (NK) cells are a crucial regulator of ATMs since their cytokines induce ATM recruitment and M1 polarization. The importance of NK cells is shown by the strong increase in NK-cell numbers in eWAT, and by studies showing that removing and expanding NK cells respectively improve and worsen obesity-induced insulin resistance. It has been suggested that NK cells are activated by unknown ligands on obesity-stressed adipocytes that bind to NKp46 (encoded by Ncr1), which is an activating NK-cell receptor. This was supported by a study showing that NKp46-knockout mice have improved obesity-induced inflammation/insulin resistance. We therefore planned to use the NKp46-knockout mice to further elucidate the molecular mechanism by which NKp46 mediates eWAT NK-cell activation in obesity. We confirmed that obesity increased eWAT NKp46+ NK-cell numbers and NKp46 expression in wild-type mice and that NKp46-knockout ablated these responses. Unexpectedly, however, NKp46-knockout mice demonstrated insulin resistance similar to wild-type mice, as shown by fasting blood glucose/insulin levels and glucose/insulin tolerance tests.Obesity-induced increases in eWAT ATM numbers and proinflammatory gene expression were also similar. Thus, contrary to previously published results, NKp46 does not regulate obesity-induced insulin resistance. It is therefore unclear whether NKp46 participates in the development of obesity-induced inflammation and insulin resistance. This should be considered when elucidating the obesity-mediated molecular mechanisms that activate NK cells.

Optimizing the cryopreservation and post-thaw recovery of natural killer cells is critical for the success of off-the-shelf platforms.

Natural killer (NK) cells are a promising allogeneic, off-the-shelf, cellular immunotherapy product. These cells can be manipulated ex vivo, genetically edited to enhance tumor targeting and expanded to produce large cell banks for multiple patient infusions. Therapeutic efficacy of these products depends on the recovery of viable and functional cells post-thaw. Post-thaw loss of viability and cytolytic activity results in large, and often variable, discrepancies between the intended cell dose (based on counts at cryopreservation) and the actual dose administered. Compared to their highly activated state in fresh culture, post-thaw NK cells demonstrate critical changes in cytokine production, cytotoxic activity, in vivo proliferation and migration. When these NK cells are introduced into the highly immunosuppressive tumor microenvironment, the functional changes induced by cryopreservation further limits the clinical potential of these products. This report will review the impact of cryopreservation on ex vivo expanded NK cells and outlines strategies described in published studies to recover post-thaw function.

Suppression of NK Cell Activation by JAK3 Inhibition: Implication in the Treatment of Autoimmune Diseases.

Natural killer (NK) cell is an essential cytotoxic lymphocyte in our innate immunity. Activation of NK cells is of paramount importance in defending against pathogens, suppressing autoantibody production and regulating other immune cells. Common gamma chain (γc) cytokines, including IL-2, IL-15, and IL-21, are defined as essential regulators for NK cell homeostasis and development. However, it is inconclusive whether γc cytokine-driven NK cell activation plays a protective or pathogenic role in the development of autoimmunity. In this study, we investigate and correlate the differential effects of γc cytokines in NK cell expansion and activation. IL-2 and IL-15 are mainly responsible for NK cell activation, while IL-21 preferentially stimulates NK cell proliferation. Blockade of Janus tyrosine kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway by either JAK inhibitors or antibodies targeting γc receptor subunits reverses the γc cytokine-induced NK cell activation, leading to suppression of its autoimmunity-like phenotype in vitro. These results underline the mechanisms of how γc cytokines trigger autoimmune phenotype in NK cells as a potential target to autoimmune diseases.