Natural Killer Cell Trafficking Research Articles

P-135 - In vivo PET imaging of 89Zr-labelled Natural Killer cell trafficking to solid tumour under the influence of a therapeutic antibody

P-135 - In vivo PET imaging of 89Zr-labelled Natural Killer cell trafficking to solid tumour under the influence of a therapeutic antibody

C–C chemokine receptor 5 is essential for conventional NK cell trafficking and liver injury in a murine hepatitis virus-induced fulminant hepatic failure model

BackgroundPrevious studies have demonstrated that natural killer (NK) cells migrated into the liver from peripheral organs and exerted cytotoxic effects on hepatocytes in virus-induced liver failure.AimThis study aimed to investigate the potential therapeutic role of chemokine receptors in the migration of NK cells in a murine hepatitis virus strain 3 (MHV-3)-induced fulminant hepatic failure (MHV-3-FHF) model and its mechanism.ResultsBy gene array analysis, chemokine (C–C motif) receptor 5 (CCR5) was found to have remarkably elevated expression levels in hepatic NK cells after MHV-3 infection. The number of hepatic CCR5+ conventional NK (cNK) cells increased and peaked at 48 h after MHV-3 infection, while the number of hepatic resident NK (rNK) cells steadily declined. Moreover, the expression of CCR5-related chemokines, including macrophage inflammatory protein (MIP)-1α, MIP-1β and regulated on activation, normal T-cell expressed and secreted (RANTES) was significantly upregulated in MHV-3-infected hepatocytes. In an in vitro Transwell migration assay, CCR5-blocked splenic cNK cells showed decreased migration towards MHV-3-infected hepatocytes, and inhibition of MIP-1β or RANTES but not MIP-1α decreased cNK cell migration. Moreover, CCR5 knockout (KO) mice displayed reduced infiltration of hepatic cNK cells after MHV-3 infection, accompanied by attenuated liver injury and improved mouse survival time. Adoptive transfer of cNK cells from wild-type mice into CCR5 KO mice resulted in the abundant accumulation of hepatic cNK cells and aggravated liver injury. Moreover, pharmacological inhibition of CCR5 by maraviroc reduced cNK cell infiltration in the liver and liver injury in the MHV-3-FHF model.ConclusionThe CCR5-MIP-1β/RANTES axis played a critical role in the recruitment of cNK cells to the liver during MHV-3-induced liver injury. Targeted inhibition of CCR5 provides a therapeutic approach to ameliorate liver damage during virus-induced acute liver injury.

Innate Cell Engager (ICE®) AFM13 Combined with Preactivated and Expanded (P+E) Cord Blood (CB)-Derived Natural Killer (NK) Cells for Patients with Refractory CD30-Positive Lymphomas: Final Results

CONCLUSIONS Pts with refractory Hodgkin (HL) and other CD30+ lymphomas have few effective therapies available and targeted NK cell immunotherapy is an active area of research. Transfer of non-targeted NK cells has shown limited clinical benefit as target recognition of cancer cells by NK cells constitutes a barrier. The innate cell engager AFM13 is a first-in-class CD30/CD16A bispecific antibody construct that induces selective killing of CD30+ tumor cells by engaging and activating NK cells. As a single agent, AFM13 has limited clinical activity against HL, likely due to the reduced effector function of autologous NK cells in these pts, which provides the rationale for combining AFM13 with allogeneic NK cells. Our prior preclinical work identified a promising combination of CB-derived NK cells that were first IL-12/IL-15/IL-18-preactivated followed by ex vivo expansion (P+E) with engineered K562 feeder cells expressing membrane-bound IL-21, 4-1BBL and CD48 and exogenous IL-2, and subsequently complexed with AFM13 just before infusion; these cytokine-induced memory-like NK cells presented chimeric antigen receptor (CAR)-NK-like features and increased in vitro and in vivo antitumor activity compared to either non-AFM13-precomplexed P+E NK cells or to AFM13 alone (Kerbauy et al, Clin Cancer Res 2021). Building on this work we wished to study this CB NK-cell therapy in pts with refractory CD30+ lymphomas. This investigator-initiated single-center phase I-II trial (NCT04074746) evaluated the safety and activity of P+E AFM13-precomplexed CB NK cells followed by systemic AFM13. Pts ages 15-75 with CD30+ lymphomas refractory to brentuximab vedotin were enrolled. The goals were to identify the recommended phase 2 dose (RP2D) of NK cells, estimate the overall (ORR) and complete response (CR), event-free (EFS) and overall survival (OS) rates, and study NK cell activation and persistence. Each treatment cycle consisted of fludarabine/cyclophosphamide (days −5 to −3) followed by infusion (day 0) of the AFM13-precomplexed CB NK cells, cultured for 14 days as described above, and three weekly IV infusions of AFM13 (200 mg, days 7, 14 and 21). Two cycles were planned for pts 1-19 and up to 4 cycles from patient 20 on. Response was evaluated on day 28 of each cycle. Enrollment proceeded at 3 dose levels (DL) of 10 6, 10 7 and 10 8 NK/Kg, respectively. Each patient received the same NK dose in all cycles. Between 09/20-12/22 we enrolled 42 pts (37 HL, 5 NHL), pretreated with a median 7 lines, at DL1 (N=3), DL2 (N=3) and DL3 (N=36), with 1 (N=2), 2 (N=21), 3 (N=3) or 4 cycles (N=16). All had active progressive disease at enrollment and no bridging therapy was given. The cords used for each of the 117 cycles were selected without consideration for HLA match, which was 0/6 (N=53), 1/6 (N=46), 2/6 (N=14), 3/6 (N=3) and 4/6 (N=1). The product infused consisted of >94% NK cells (expanded >2,700 fold), with only 0.02% T cells. The NK cells were 96% viable, 91% bound to AFM13, and 97.6% CD16+. The products were infused fresh. There was 1 grade 2 infusion-related reaction (IRR) in 115 infusions of AFM13-NK (0.8%) and 27 IRR infusion related reactions in 350 infusions of AFM13 (7.7%) (1 G3, 26 G2). We saw no cases of CRS, ICANS or GVHD of any grade. DL3 (10 8 NK/Kg) was established as the RP2D. The ORR and CR were 92.8% and 66.7%, respectively (94.4% and 72.2%, respectively, in 36 pts treated at the RP2D). Nine pts had a response consolidated with SCT (5 allo, 4 auto). At median follow-up of 14 (6-34) months, the EFS/OS rates are 31%/76%; median EFS/OS are 8 months/not reached. No relapses were associated with antigen loss. In the subset of pts planned for 4 cycles at RP2D, 15 of 23 pts remained event free at 6 mo (4 pts with and 11 without SCT consolidation), for 6-month EFS/OS rates of 65%/83%. Overall, 8 of the 9 pts (89%) receiving a consolidation SCT are event free at 10 to 34 months. AFM-bound CB NK cells were detected in blood from day 1 post infusion for up to 3 weeks. Donor NK levels followed similar patterns after each cycle, which argues against a sensitization after the first NK infusion. CyTOF studies showed increased expression of AFM13 and activation markers in donor NK cells. We confirmed trafficking of AFM13-bound donor NK cells to tumor sites shortly after infusion. CB-derived cytokine-induced memory-like NK cells precomplexed with AFM13 have excellent tolerability and activity for pts with heavily pretreated and refractory CD30+ lymphoma.

A Pan-Cancer Single-Cell Transcriptomic Atlas of Natural Killer (NK) Cells Reveals Intrinsic and Extrinsic Mediators of NK Cell Anti-Tumor Functions

Background: Natural killer (NK) cells are critical mediators of anti-tumor immunity, engaging in direct cytotoxic responses and promoting pro-inflammatory immune microenvironments. The molecular mechanisms underlying these functions, however, have yet to be fully elucidated. This is due in part to a lack of understanding of the phenotypic and functional diversity of NK cells across cancer types. Here, we present a single-cell transcriptomic atlas of >250,000 NK cells spanning 340 patients across 17 cancer types to advance our understanding of tumor-infiltrating NK cells. Methods: We re-analyzed publicly available single-cell RNA-sequencing (scRNA-seq) datasets of primary, therapy-naïve tumors, as well as matching peripheral blood samples and healthy donor blood samples. We employed systematic computational analyses to deconvolute the phenotypic and functional diversity of tumor-infiltrating NK cells and define key regulators of NK cell functions in both a cancer type-specific and pan-cancer manner. Feature expression module scoring was used to infer phenotypic and functional characteristics of NK cell clusters in each cancer type. Transcription factor regulon and cell-cell communication prediction algorithms were applied to understand the mechanistic drivers of NK cell populations within tumors. Results: Tumor-infiltrating NK cells display distinct patterns of phenotypic and functional features across cancer types. Nonetheless, we identify consensus NK cell populations across cancers that demonstrate the utility and performance of our gene module-based phenotypic and functional annotations. Interestingly, we observe the enrichment of adaptive-like and CD56 bright NK cell populations in tumors that exhibit features of tissue residency, including the upregulation of ITGA1, ITGAE, and CD69 alongside the downregulation of FCG3RA. Notably, these tissue-resident populations display enhanced chemokine and cytokine activity compared to their recruited counterparts, suggesting the significance of tissue-resident NK cell populations in immune recruitment to tumors. We find the phenotypic composition of intra-tumoral NK cells is vastly different than that of circulating NK cells which harbor predominantly CD56 dim populations, as well as a significant proportion of adaptive-like NK cells in several cancer types. Leveraging the paired nature of several tumor and peripheral blood samples, we performed temporal comparative analyses that revealed the robust expression of KLF2 and S1PR5 in circulation which is then lost in paired tumor tissues. While KLF2 and S1PR5 have been previously implicated in the homing and migration of immune cells, their roles in the trafficking of NK cells to tumors have yet to be defined. In modeling transitions from canonical to stressed NK cell states, we not only identify well-established NK cell checkpoints ( TIM-3, LAG3, and CISH) but also identify novel putative checkpoints yet to be investigated in NK cells, such as the AP-1 family of transcription factors. Additionally, we examine extrinsic factors contributing to intra-tumoral NK cell phenotypes, detecting significant crosstalk between NK cells and immunomodulatory macrophages and CD4+ T cells mediated by galectin-9 and TGFβ interactions. Conclusions: We define the phenotypic and functional pan-cancer landscape of NK cells and uncover both intrinsic and extrinsic factors influencing their anti-tumor functions. We envision our NK cell atlas will facilitate the development of strategies to enhance NK cell-based immunotherapies against cancer.

Charting a killer course to the solid tumor: strategies to recruit and activate NK cells in the tumor microenvironment.

The ability to expand and activate natural Killer (NK) cells ex vivo has dramatically changed the landscape in the development of novel adoptive cell therapies for treating cancer over the last decade. NK cells have become a key player for cancer immunotherapy due to their innate ability to kill malignant cells while not harming healthy cells, allowing their potential use as an "off-the-shelf" product. Furthermore, recent advancements in NK cell genetic engineering methods have enabled the efficient generation of chimeric antigen receptor (CAR)-expressing NK cells that can exert both CAR-dependent and antigen-independent killing. Clinically, CAR-NK cells have shown promising efficacy and safety for treating CD19-expressing hematologic malignancies. While the number of pre-clinical studies using CAR-NK cells continues to expand, it is evident that solid tumors pose a unique challenge to NK cell-based adoptive cell therapies. Major barriers for efficacy include low NK cell trafficking and infiltration into solid tumor sites, low persistence, and immunosuppression by the harsh solid tumor microenvironment (TME). In this review we discuss the barriers posed by the solid tumor that prevent immune cell trafficking and NK cell effector functions. We then discuss promising strategies to enhance NK cell infiltration into solid tumor sites and activation within the TME. This includes NK cell-intrinsic and -extrinsic mechanisms such as NK cell engineering to resist TME-mediated inhibition and use of tumor-targeted agents such as oncolytic viruses expressing chemoattracting and activating payloads. We then discuss opportunities and challenges for using combination therapies to extend NK cell therapies for the treatment of solid tumors.

Tracking adoptive natural killer cells via ultrasound imaging assisted with nanobubbles.

The recent years has witnessed an exponential growth in the field of natural killer (NK) cell-based immunotherapy for cancer treatment. As a prerequisite to precise evaluations and on-demand interventions, the noninvasive tracking of adoptive NK cells plays a crucial role not only in post-treatment monitoring, but also in offering opportunities for preclinical studies on therapy optimizations. Here, we describe an NK cell tracking strategy for cancer immunotherapy based on ultrasound imaging modality. Nanosized ultrasound contrast agents, gas vesicles (GVs), were surface-functionalized to label NK cells. Unlike traditional microbubble contrast agents, nanosized GVs with their unique thermodynamical stability enable the detection of labeled NK cells under nonlinear contrast-enhanced ultrasound (nCEUS), without a noticeable impact on cellular viability or migration. By such labeling, we were able to monitor the trafficking of systematically infused NK cells to a subcutaneous tumor model. Upon co-treatment with interleukin (IL)-2, we observed a rapid enhancement in NK cell trafficking at the tumor site as early as 3h post-infusion. Altogether, we show that the proposed ultrasound-based tracking strategy is able to capture the dynamical changes of cell trafficking in NK cell-based immunotherapy, providing referencing information for early-phase monotherapy evaluation, as well as understanding the effects of modulatory co-treatment. STATEMENT OF SIGNIFICANCE: In cellular immunotherapies, the post-infusion monitoring of the living therapeutics has been challenging. Several popular imaging modalities have been explored the monitoring of the adoptive immune cells, evaluating their trafficking and accumulation in the tumor. Here we demonstrated, for the first time, the ultrasound imaging-based immune cell tracking strategy. We showed that the acoustic labeling of adoptive immune cells was feasible with nanosized ultrasound contrast agents, overcoming the size and stability limitations of traditional microbubbles, enabling dynamical tracking of adoptive natural killer cells in both monotherapy and synergic treatment with cytokines. This article introduced the cost-effective and ubiquitous ultrasound imaging modality into the field of cellular immunotherapies, with broad prospectives in early assessment and on-demand image-guided interventions.

Mapping the chemotactic landscape in NK cells reveals subset-specific synergistic migratory responses to dual chemokine receptor ligation

Natural killer (NK) cells have a unique capability of spontaneous cytotoxicity against malignant cells and hold promise for off-the-shelf cell therapy against cancer. One of the key challenges in the field is to improve NK cell homing to solid tumors. To gain a deeper understanding of the cellular mechanisms regulating trafficking of NK cells into the tumor, we used high-dimensional flow cytometry, mass cytometry, and single-cell RNA-sequencing combined with functional assays, creating a comprehensive map of human NK cell migration phenotypes. We found that the chemokine receptor repertoire of peripheral blood NK cells changes in a coordinated manner becoming progressively more diversified during NK cell differentiation and correlating tightly with the migratory response of the distinct NK cell subsets. Simultaneous ligation of CXCR1/2 and CX3CR1, synergistically potentiated the migratory response of NK cells. Analysis of 9471 solid cancers from publicly available TCGA/TARGET repositories revealed dominant chemokine patterns that varied across tumor types but with no tumor group expressing ligands for more than one chemokine receptor present on mature NK cells. The finding that chemokine stimulation can elicit a synergistic migratory response in NK cells combined with the identified lack of naturally occurring pairs of chemokines-chemokine receptors in human cancers may explain the systematic exclusion of NK cells from the tumor microenvironment and provides a basis for engineering next-generation NK cell therapies against malignancies. The Polish Ministry of Science and Higher Education, the National Science Centre, Poland, The Norwegian Cancer Society, the Norwegian Research Council, the South-Eastern Norway Regional Health Authority, The Swedish Cancer Society, the Swedish Children's Cancer Foundation, The Swedish Research Council, The Center of Excellence: Precision Immunotherapy Alliance, Knut and Alice Wallenberg Foundation and National Cancer Institute.

Targeting CD70 using CAR NK cells to enhance NK cells cytolytic effect against osteosarcoma

Abstract Background: Cure rates for osteosarcoma (OS) have not improved in >30 years and no new effectivetherapies have been identified for metastatic disease. Natural killer (NK) cells have become an attractive tool for cancer immunotherapy. Efficay is improved by direct tumor targeting introducing a specific chimeric antigen receptor (CAR). Emerging knowledge suggests CD70 to be a viable candidate as expression is higher in lung metastases and it has been correlated with tumor escape from immune surveillance. Objective: To assess whether using CD70 CAR-NK cells we can enhance trafficking, homing and proliferation of NK cells and therefore therapeutic efficacy against OS. Methods: We analyzed the cBioportal database to verify CD70 expression in OS. Surface expression of CD70 on human OS cell lines and normal osteoblasts was determined by flow cytometry. CD70 CAR constructs were sequenced, verified and transduced into NK cells. CD70 CAR NK and control NK cells cytolytic activity against OS cells was evaluated by IncuCyte. In vitrocytokine release was measured upon CD70 CAR NK/NK cells exposure to OS cells (IsoPlexis). Results: Database analysis confirmed OS CD70 gene amplification. Flow cytometry showed variable expression of CD70 on OS cells and no expression on human osteoblasts. There was an increase in CD70 CAR NK percent lysis against OS cells at the highest effector:target ratios compared to control NK cells. We found a predominant release in the chemoattractive/stimulatory cytokines upon OS cells exposure to CD70 CAR NK cells. Conclusion: CD70 has immunotherapy potential against OS. CD70 CAR NK cells have increased cytolytic activity against OS cells in vitro. Cytolytic activity may be influenced by the release of specific cytokines.

Abstract 4077: Dual-targeted CAR-NK cell therapy: optimized CAR design to prevent antigen escape and elicit a deep and durable response in multiple myeloma

Abstract Introduction: Multiple myeloma (MM) is an incurable hematologic malignancy and new strategies that offer a chance of obtaining long-term progression free survival are urgently needed. MM is associated with profound immune alterations and dysfunction of natural killer (NK) cells have been demonstrated to be crucial factors in MM progression. Myeloma cells are susceptible to killing by natural killer (NK) cells but acquire the ability to elude NK cell surveillance by avoiding recognition and suppressing NK cell function. Given the role of NK cells in the pathogenesis of MM, interest in harnessing NK cells to treat the cancer has been energized by the remarkable success of other adoptive cell therapies such as chimeric antigen receptor (CAR)-T cells. However, relapses associated with residual low-to-negative BCMA-expressing MM cells have been reported, necessitating the identification of additional targets. GPRC5D, expressed on MM cells from primary marrow samples with a distribution independent of BCMA. Methods: To prevent BCMA-antigen escape and elicit a deeper and more durable response in MM, we developed a new multiplexed edited NK cell configuration to restore anti-myeloma NK cell immunity, consisting of anti-BCMA VHH and anti-GPRC5D VHH antibodies, NKG2D and 2B4 co-stimulation signaling domains, and IL-15. Results: Dual targeting BCMA/GPRC5D CAR-NK showed potent in vitro killing of both BCMA+ and GPRC5D+ myeloma cells. Utilizing a repeated rounds of cancer cell clearance assay, BCMA/GPRC5D CAR NK cells showed remarkable persistence and antigen-mediated expansion of CAR-NK cells after more than 4 rounds of tumor cell re-challenges. Moreover, in comparison with single targeted BCMA CAR-NK cells, Dual targeting BCMA/GPRC5D CAR-NK cells effectively lysed BCMA negative target cells. In addition, in BCMA-antigenic escape model, it achieved more sustained tumor control than single targeting BCMA CAR-NK cells. PD-1/PD-L1 axis inhibition has been reported to enhance NK cell activity against MM cells by augmenting NK cell trafficking, immune complex formation, and cytotoxicity against PD-L1-expressing MM cells. We also demonstrated that combination of BCMA/GPRC5D CAR-NK with anti-PDL1-IL15 also showed more persistent tumor control. Conclusions: Our studies demonstrate the development of dual targeting BCMA/GPRC5D CAR NK cells may represent a highly effective off-the-shelf therapeutic product as a monotherapy or in combinations with other immune-regulating agents. Citation Format: Cuiqing Yang, Yifang Wang, Tingting Liu, Chao Wang, Huanyu Wang, Qingyang Wang, Qin Wang, Gang Ye, Renhong Tang, Zhuoxiao Cao. Dual-targeted CAR-NK cell therapy: optimized CAR design to prevent antigen escape and elicit a deep and durable response in multiple myeloma. [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 4077.

Trial in progress: Natural killer (NK) cells with TGFβ receptor I inhibitor vactosertib and IL-2 in patients with metastatic colorectal cancer or hematologic malignancies.

TPS273 Background: Natural killer (NK) cell therapy is emerging as a promising therapy for patients (pts) with solid tumors and hematologic malignancies with no reported toxicity associated with the cell therapy product itself. NK cell trials in solid tumors are limited by immune inhibitory tumor microenvironments that prevent trafficking and activity of donor NK cells, which is largely governed by TGFβ signaling. We recently developed a novel platform for ex vivo expansion of healthy donor NK cells. We previously showed these cells to be safe in a dose-escalation study when given without cytokine support, with early evidence of response in pts with metastatic colorectal cancer (CRC) and in pts with hematologic malignancies. IL-2 has been well-established as an important activating cytokine supporting NK cells in humans, but can also induce regulatory T cells, which further suppress NK cells by producing TGFβ. We seek to improve upon the early activity we previously observed with NK cells alone by administering concurrently with IL-2 and by limiting the inhibitory tumor microenvironment and regulatory T cells with TGFβ receptor 1 inhibitor vactosertib. Methods: This phase Ib open-label study evaluates the safety and persistence (primary objectives), and the clinical and biological activity and trafficking (secondary objectives) of our novel NK cell therapy in combination with IL-2 (aldesleukin) and TGFβ receptor 1 inhibitor vactosertib. Up to 12 pts with metastatic CRC or relapsed/refractory hematologic malignancies will be enrolled. Pts will undergo low-dose lymphodepletion with fludarabine and cyclophosphamide followed by 2 infusions of NK cells, administered 14 days apart. Concurrently, pts will receive aldesleukin subcutaneously 3 times weekly and vactosertib orally 5 consecutive days/week x4 weeks total. Pts will undergo pre- and post-treatment biopsies for quantification of NK cell trafficking and exploration of immune cell profiling changes in the tumor microenvironment. The trial is currently open to enrollment, with 1 pt accrued at time of submission. Clinical trial information: NCT05400122 .

756P Glypican-3 (GPC3) and NKp46 directed FLEX-NK engager antibody (CYT-303) recruits natural killer (NK) cells to tumors in a preclinical hepatocellular carcinoma (HCC) mouse model

GPC3 is an oncofetal antigen that is highly expressed in HCC while minimally expressed in adult normal tissues except placenta. CYT-303 is a multifunctional bispecific NK engager targeting NK cell activating receptor NKp46 and GPC3 expressed on tumor cells constructed with Cytovia’s Flex-NK scaffold with a fully functional Fc. Previously, we reported CYT-303 in vitro treatment of Hep3B tumor cells demonstrated cytolysis and cytokine production as well as in vivo tumor growth inhibition when combined with both PBNK and iNK cells. Here we further characterized the CYT-303 dose-response for tumor growth inhibition in vivo and its influence on NK cell distribution. CYT -303 pharmacokinetics was evaluated in tumor-bearing mice. Anti-tumor efficacy and dose response of CYT-303 in the presence of human PBNKs or iNKs was evaluated in NSG-IL15 mice bearing subcutaneous Hep3B tumors. Biodistribution of the NK cells were analyzed by flow cytometry. CYT-303 pharmacokinetics in tumor bearing mice was similar to normal mice suggesting no target mediated clearance. In the Hep3B tumor model in PBNK or iNK injected NSG-hIL-15 mice, CYT-303 showed dose dependent tumor growth inhibition compared to control hIgG1 treated mice. Consistent with CYT-303 tumor growth inhibition, increased NK cells were detected in the tumor compared to control animals. Blood NK cells in CYT-303 treated animals were significantly lower compared to IgG1 isotype control treated mice suggesting CYT-303 could facilitate NK cell trafficking from blood into the tumor. Blood AFP (alpha fetoprotein), a biomarker in HCC, decreased with CYT-303 tumor growth inhibition. Pharmacologically active CYT-303 doses were identified. CYT-303 can help recruit NK cells to the tumor site to achieve tumor growth inhibition.

A Pilot Phase I Trial of IL-21 Expanded Ideal-Donor Natural Killer (NK) Cells in Combination with Mogamulizumab in Patients with Cutaneous T-Cell Lymphomas (CTCL) or Adult T-Cell Leukemia/Lymphomas (ATLL)

A Pilot Phase I Trial of IL-21 Expanded Ideal-Donor Natural Killer (NK) Cells in Combination with Mogamulizumab in Patients with Cutaneous T-Cell Lymphomas (CTCL) or Adult T-Cell Leukemia/Lymphomas (ATLL)

Inclusion criteria: how NK cells gain access to T cells.

Natural killer (NK) cells play an important role in host defense against viral infections and malignancy, and their role for regulating other components of the antiviral response is being investigated. In this issue of the JCI, Ali et al. examine the mechanisms by which NK cells migrate into the white pulp and mediate suppression of virus-specific T cells. Herein, the authors show that an acute lymphocytic choriomeningitis virus (LCMV) infection induced a potent type I IFN (IFN-I) response that resulted in the expression of chemokine receptor CXCR3 ligands and permitted NK cell trafficking to T cell zones. Collectively, these findings have broad implications for vaccination strategies and warrant further investigation into the transcriptomic profiles of these regulatory NK cells.

RNA-Seq Analysis Reveals CCR5 as a Key Target for CRISPR Gene Editing to Regulate In Vivo NK Cell Trafficking.

Simple SummaryAdoptive immunotherapy utilizing ex vivo expanded natural killer (NK) cells is being explored in the clinical and preclinical settings to treat hematological tumors. Previous work has shown that a large fraction of ex vivo expanded NK cells traffic into the liver following i.v. infusion. In this manuscript, Levy et al. show that ex vivo expansion of NK cells alters the mRNA transcription and surface expression of several chemokine receptors. The observed shift in chemotactic receptor expression may compromise the homing of infused cells into sites where hematological tumors reside, such as bone marrow, lymph nodes, and peripheral blood, by promoting preferential trafficking into liver tissue. Here we demonstrate clustered regularly interspaced short palindromic repeats (CRISPR) gene abrogation of C-C chemokine receptor type 5 (CCR5) as a novel strategy that reduces the trafficking of adoptively transferred ex vivo expanded NK cells into liver tissue and increases NK cell presence in the circulation. A growing number of natural killer (NK) cell-based immunotherapy trials utilize ex vivo expansion to grow and activate allogenic and autologous NK cells prior to administration to patients with malignancies. Recent data in both murine and macaque models have shown that adoptively infused ex vivo expanded NK cells have extensive trafficking into liver tissue, with relatively low levels of homing to other sites where tumors often reside, such as the bone marrow or lymph nodes. Here, we evaluated gene and surface expression of molecules involved in cellular chemotaxis in freshly isolated human NK cells compared with NK cells expanded ex vivo using two different feeder cells lines: Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines (LCLs) or K562 cells with membrane-bound (mb) 4-1BB ligand and interleukin (IL)-21. Expanded NK cells had altered expression in a number of genes that encode chemotactic ligands and chemotactic receptors that impact chemoattraction and chemotaxis. Most notably, we observed drastic downregulation of C-X-C chemokine receptor type 4 (CXCR4) and upregulation of C-C chemokine receptor type 5 (CCR5) transcription and phenotypic expression. clustered regularly interspaced short palindromic repeats (CRISPR) gene editing of CCR5 in expanded NK cells reduced cell trafficking into liver tissue and increased NK cell presence in the circulation following infusion into immunodeficient mice. The findings reported here show that ex vivo expansion alters multiple factors that govern NK cell homing and define a novel approach using CRISPR gene editing that reduces sequestration of NK cells by the liver.

Cytokines Orchestrating the Natural Killer-Myeloid Cell Crosstalk in the Tumor Microenvironment: Implications for Natural Killer Cell-Based Cancer Immunotherapy.

Natural killer (NK) cells are endowed with germline-encoded receptors that enable them to detect and kill malignant cells without prior priming. Over the years, overwhelming evidence has identified an essential role for NK cells in tumor immune surveillance. More recently, clinical trials have also highlighted their potential in therapeutic settings. Yet, data show that NK cells can be dysregulated within the tumor microenvironment (TME), rendering them ineffective in eradicating the cancer cells. This has been attributed to immune suppressive factors, including the tumor cells per se, stromal cells, regulatory T cells, and soluble factors such as reactive oxygen species and cytokines. However, the TME also hosts myeloid cells such as dendritic cells, macrophages, neutrophils, and myeloid-derived suppressor cells that influence NK cell function. Although the NK-myeloid cell crosstalk can promote anti-tumor responses, myeloid cells in the TME often dysregulate NK cells via direct cell-to-cell interactions down-regulating key NK cell receptors, depletion of nutrients and growth factors required for NK cell growth, and secretion of metabolites, chemokines and cytokines that ultimately alter NK cell trafficking, survival, and cytotoxicity. Here, we review the complex functions of myeloid-derived cytokines in both supporting and suppressing NK cells in the TME and how NK cell-derived cytokines can influence myeloid subsets. We discuss challenges related to these interactions in unleashing the full potential of endogenous and adoptively infused NK cells. Finally, we present strategies aiming at improving NK cell-based cancer immunotherapies via pathways that are involved in the NK-myeloid cell crosstalk in the TME.

CRISPR Gene-Editing of Chemokine Receptors As a Novel Strategy to Redirect NK Cell Trafficking In Vivo

Allogeneic and autologous natural killer (NK) cell-based therapies have proven to be safe in patients with hematological malignancies across multiple clinical trials. However, at present, only a small percentage of patients who have received NK cell based therapy have achieved complete remissions. NK cells must first traffic into the tumor microenvironment in order to effectively lyse tumor targets in vivo. Many hematological malignancies reside in or metastasize through bone marrow (BM) compartments. Recent studies in both murine and macaque models evaluating NK cell distribution following intravenous (i.v.) infusion unexpectedly revealed preferential trafficking into liver tissue over BM niches, which for hematological malignancies is undesirable. Therefore, we evaluated surface expression and mRNA transcript abundance of critical chemotactic receptors and adhesion molecules in primary fresh and ex vivo expanded NK cells. NK cells from six healthy donor PBMC samples were expanded for 14 days ex vivo, using two different irradiated feeder cell lines (either EBV-infected LCL or K562 cells with membrane-bound IL-21 and 41BBL). mRNA from fresh and expanded NK cells was sequenced and analyzed for differential gene expression. We observed the transcriptome of NK cells expanded with the two different feeder cell lines were similar, with only 13 differentially expressed genes. However, we observed the transcriptional landscape between fresh and expanded NK cells to be vastly different (Figure 1A). As expected, amongst the thousands of differentially expressed genes, mitotic phase transitions and DNA replication were pathways that were strongly enriched in expanded compared to fresh NK cells. Further, expanded NK cells had a robust amplification in mRNA transcription of known surface cytotoxicity and activation receptors, as well as enhanced mRNA transcription of chemotactic ligands that are implicated in bridging the innate and adaptive immune responsesincluding XCL1, XCL2, CCL5, CXCL16, and CXCL8. Remarkably, we found expanded NK cells had upregulated mRNA transcription and surface expression of CCR1, CCR5, CXCR3, and CXCR6, coupled with a substantial decrease in mRNA transcription and surface expression of CXCR4 (Figure 1B). We postulate that this particular shift in molecular expression may have the net effect of routing adoptively transferred NK cells out of the circulation into liver and other inflammatory environments, ultimately impeding cellular trafficking into the bone marrow (BM). To test this hypothesis, we used CRISPR/Cas9 to disrupt the CCR5 gene which has upregulated expression in expanded NK cells. Five days following ex-vivo expansion, NK cells were electroporated with a mix of 3 sgRNAs targeting CCR5, complexed with Cas9. Electroporated cultures harvested on day 14 maintained their proliferative capacity and had a substantial reduction in CCR5 expression (22%) compared to non-electroporated control NK cells (88%; Figure 1C). Both expanded NK cell populations were then injected i.v. into NSG mice, with blood, BM, lungs, and livers being harvested 24 hours following infusion. Disrupting CCR5 in NK cells significantly reduced cellular trafficking into the liver compared to control NK cells (p<.01). Moreover, the percentage of infused CCR5 CRISPR/Cas9 disrupted NK cells in the circulation was increased compared to control NK cells (Figure 1D). In conclusion, these collective data reveal NK cells undergo profound transcriptional changes when cultivated ex vivo. Many chemotactic receptors that were previously unknown to be impacted by ex vivo expansion were discovered to have a shift in transcriptional regulation which would be predicted to compromise NK cell homing to the bone-marrow. Importantly, we show for the first time that CRISPR gene-editing of chemokine receptors can be used as a novel strategy to redirect NK cell trafficking in vivo, which could bolster the effectiveness of adoptive NK cell immunotherapy for hematological malignancies and other cancers. Figure 1 Disclosures No relevant conflicts of interest to declare.

PET Imaging of the Natural Killer Cell Activation Receptor NKp30.

Redirecting the immune system in cancer treatment has led to remarkable responses in a subset of patients. Natural killer (NK) cells are innate lymphoid cells being explored as they engage tumor cells in different mechanisms compared with T cells, which could be exploited for treatment of nonresponders to current immunotherapies. NK cell therapies are monitored through measuring peripheral NK cell concentrations or changes in tumor volume over time. The former does not detect NK cells at the tumor site, and the latter is inaccurate for immunotherapies because of pseudoprogression. Therefore, new imaging methods are required as companion diagnostics for optimizing immunotherapies. Methods: In this study, we developed and completed preclinical in vivo validation of 2 antibody-based PET probes specific for NKp30, an activation natural cytotoxicity receptor expressed by human NK cells. Quantitative, multicolor flow cytometry during a variety of NK cell activation conditions was completed on primary human NK cells and the NK92MI cell line. Human renal cell carcinoma (RCC) tumors were stained for the NK cell receptors CD56, NKp30, and NKp46 to determine expression on tumor-infiltrating NK cells. An NKp30 antibody was radiolabeled with 64Cu or 89Zr and evaluated in subcutaneous xenografts and adoptive cell transfer mouse models. Results: Quantitative flow cytometry showed consistent expression of the NKp30 receptor during different activation conditions. NKp30 and NKp46 costained in RCC samples, demonstrating the expression of these receptors on tumor-infiltrating NK cells in human tumors, whereas tumor cells in one RCC sample expressed the peripheral NK marker CD56. Both PET tracers showed high stability and specificity in vitro and in vivo. Notably, 89Zr-NKp30Ab had higher on-target contrast than 64Cu-NKp30Ab at their respective terminal time points. 64Cu-NKp30Ab delineated NK cell trafficking to the liver and spleen in an adoptive cell transfer model. Conclusion: The consistent expression of NKp30 on NK cells makes it an attractive target for quantitative imaging. Immunofluorescence staining on human RCC samples demonstrated the advantages of NKp30 targeting versus CD56 for detection of tumor infiltrating NK cells. This work advances PET imaging of NK cells and supports the translation of imaging agents for immunotherapy monitoring.

Improved Bone Marrow Homing of NK Cells through PM21 Particle Stimulated Enhancement of Fucosylation of E-Selectin Ligand

Introduction Therapy of marrow borne disease such as leukemias or myelomas require the eradication of tumor cells that are resident in the bone marrow. Cell based therapies are increasingly a promising modality toward potential complete cures of such marrow malignancies. In particular, natural killer (NK) cell therapeutics are an attractive therapeutic modality due to their inherent ability to broadly detect and kill tumors. However, for NK cells to kill the marrow resident blasts, they must traffic to the bone marrow. Key for marrow homing is the proper fucosylation of extracellular proteins (such as e.g. P-selectin glycoprotein ligand-1, PSGL) on NK cells which is necessary for E-selectin binding. PM21 particles are plasma membrane particles prepared from CSTX002 cell line (K562 cells modified to express membrane bound IL-21 [mbIL21] and 4-1bbl, K562.mbIL21.41BBL) and can be used to potently stimulate expansion of NK cells that have high anti-tumor potency, similarly as to the expansion with CSTX002 feeder cells that have mbIL21 stimulation. Shown herein is that NK cells stimulated with PM21 particles have increased fucosylation of E-selectin binding ligands and have increased homing to the bone marrow in mice. Methods NK cells were expanded from PBMCs obtained from healthy donors by stimulating with PM21 particles (200 µg/mL) in SCGM media supplemented with 10% FBS and IL-2 (100 U/mL). PM21 particles were prepared from CSTX002 cell line as previously described. The fucosylation status of E-selectin ligands on expanded NK cells were analyzed by flow cytometry with the HECA452 mAb that only binds the fucosylated forms. ChIP-seq analysis was performed on NK cells expanded from feeder cell co-cultures with CSTX002 and by probing with anti-STAT3. For physiological trafficking studies, whole PBMCs were pre-activated in vitro for two days with PM21 particles (200 µg/mL) and then injected ip into NSG mice and treated or not with PM21-particles (2x/weekly). Organs were harvested 16 days later and analyzed by flow cytometry for the presence of human NK cells. Results NK cells expanded using PM21 or other stimulation methods were comparatively analyzed for fucosylation status by staining with HECA452. The NK cells stimulated with mbIL21, either through PM21 or CSTX002 feeder cells, were found to have highest HECA452 staining compared NK cells stimulated with IL-2, soluble IL-21, soluble 4-bbl, unmodified K562, or K562 modified with only mbIL21 (no 4-1bbl). To determine transcriptional changes responsible for the apparent increase in fucosylation, anti-STAT3 ChIP-seq analysis was performed on naïve NK cells or those expanded with CSTX002. STAT3 is a transcription factor that is activated upon IL-21 stimulation. The anti-STAT3 ChIP-seq analysis elucidated that CSTX002 stimulated NK cells have enhanced STAT3 binding to the FUT7 gene and that FUT7 expression increased. To determine if stimulation with PM21 particles can enhance homing of NK cells to bone marrow, NSG mice were injected ip with NK cells stimulated in vitro for 2 days with PM21, and then the mice were treated with or without PM21 particles (ip, 800 µg, 3x per week). Analysis of the bone marrow from sacrificed animals showed that a greater amount of human NK cell were present in the marrow in animals treated with ip doses of PM21 particles. Conclusions NK cells expanded with PM21 particles had increased fucosylation of likely E-selecting ligands. This higher degree of fucosylation is likely due to the enhanced expression of fucosyl transferase 7, shown bye ChIP-seq analysis of CSTX002 stimulated NK cells. In vivo studies show that stimulation with PM21 does allow for increased trafficking of NK cells to the bone marrow. Disclosures Oyer: Kiadis Pharma: Equity Ownership, Patents & Royalties. Igarashi:Kiadis Pharma: Employment, Equity Ownership, Patents & Royalties. Altamore:Kiadis Pharma: Equity Ownership, Patents & Royalties. Lee:Kiadis Pharma: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding. Copik:Kiadis Pharma: Equity Ownership, Patents & Royalties, Research Funding.

NK cells are activated and primed for skin-homing during acute dengue virus infection in humans

Despite animal models showing that natural killer (NK) cells are important players in the early defense against many viral infections, the NK cell response is poorly understood in humans. Here we analyze the phenotype, temporal dynamics, regulation and trafficking of NK cells in a patient cohort with acute dengue virus infection. NK cells are robustly activated and proliferate during the first week after symptom debut. Increased IL-18 levels in plasma and in induced skin blisters of DENV-infected patients, as well as concomitant signaling downstream of the IL-18R, suggests an IL-18-dependent mechanism in driving the proliferative NK cell response. Responding NK cells have a less mature phenotype and a distinct chemokine-receptor imprint indicative of skin-homing. A corresponding NK cell subset can be localized to skin early during acute infection. These data provide evidence of an IL-18-driven NK cell proliferation and priming for skin-homing during an acute viral infection in humans.

Overcoming Resistance to Natural Killer Cell Based Immunotherapies for Solid Tumors

Despite advances in the diagnostic and therapeutic modalities, the prognosis of several solid tumor malignancies remains poor. Different factors associated with solid tumors including a varied genetic signature, complex molecular signaling pathways, defective cross talk between the tumor cells and immune cells, hypoxic and immunosuppressive effects of tumor microenvironment result in a treatment resistant and metastatic phenotype. Over the past several years, immunotherapy has emerged as an attractive therapeutic option against multiple malignancies. The unique ability of natural killer (NK) cells to target cancer cells without antigen specificity makes them an ideal candidate for use against solid tumors. However, the outcomes of adoptive NK cell infusions into patients with solid tumors have been disappointing. Extensive studies have been done to investigate different strategies to improve the NK cell function, trafficking and tumor targeting. Use of cytokines and cytokine analogs has been well described and utilized to enhance the proliferation, stimulation and persistence of NK cells. Other techniques like blocking the human leukocyte antigen-killer cell receptors (KIR) interactions with anti-KIR monoclonal antibodies, preventing CD16 receptor shedding, increasing the expression of activating NK cell receptors like NKG2D, and use of immunocytokines and immune checkpoint inhibitors can enhance NK cell mediated cytotoxicity. Using genetically modified NK cells with chimeric antigen receptors and bispecific and trispecific NK cell engagers, NK cells can be effectively redirected to the tumor cells improving their cytotoxic potential. In this review, we have described these strategies and highlighted the need to further optimize these strategies to improve the clinical outcome of NK cell based immunotherapy against solid tumors.