Memory-like NK Cells Research Articles

Phenotypical changes in peripheral NK cells and their impact on the clinical outcomes of patients with severe pandemic influenza A(H1N1)

Abstract NK cells are crucial antiviral effectors. However, their role against emerging respiratory pathogens has not been extensively addressed in humans. Here, we characterized the phenotype of peripheral NK cells in patients with severe pandemic influenza A(H1N1) and age- and sex-matched healthy controls (HC) using an extended panel of flow cytometry antibodies against markers of activation, cytotoxicity, cytokine production, immune memory, and surface receptors. Enrolled patients were grouped according to their clinical outcome (survival vs. death). The study included 42 influenza patients (73% men) with a median age of 48 years, from which eight (26%) died during the follow-up period. All patients were admitted to the intensive care unit and required mechanical ventilation. Individuals with influenza differentiated from HC by reduced numbers of total, CD56bright, CD56dimCD16+, CD27+ memory-like, NKp46+, and perforin+ NK cell subpopulations, but increased CD69+ NK cells. Notably, lower percentages of CD27+ memory-like NK cells correlated with increased alkaline phosphatase levels, a readout of lung damage in patients with acute respiratory distress syndrome. Strikingly, a higher expression of the senescence marker CD57 in CD27+ memory-like NK cells and expansion of double-positive CD27+CD57+ NK cells was characteristic of deceased influenza patients, but not survivors. Finally, despite being reduced in the overall influenza group with respect to HC, increased percentages of IFN-γ+ NK cells distinguished death vs. survival outcomes. Collectively, our results demonstrate that alterations in the phenotype of NK cells influence with the progression and outcomes of patients with severe pandemic influenza A(H1N1) infection. Supported by grants from CONACyT (FORDECyT/10SE/2020/05/14-06, FORDECyT/10SE/2020/05/14-07) and SECTEI CDMX (SECTEI/050/2020) to JZ. JAR-N received a scholarship from CONACyT (CVU-1097402) for achieving her M.S.

Mass cytometry reveals single-cell kinetics of cytotoxic lymphocyte evolution in CMV-infected renal transplant patients

Cytomegalovirus (CMV) infection is associated with graft rejection in renal transplantation. Memory-likenatural killer (NK) cells expressing NKG2C and lacking FcεRIγ are established during CMV infection. Additionally, CD8+ T cells expressing NKG2C have been observed in some CMV-seropositive patients. However, invivo kinetics detailing the development and differentiation of these lymphocyte subsets during CMV infection remain limited. Here, we interrogated the invivo kinetics of lymphocytes in CMV-infected renal transplant patients using longitudinal samples compared with those of nonviremic (NV) patients. Recipient CMV-seropositive (R+) patients had preexisting memory-like NK cells (NKG2C+CD57+FcεRIγ-) at baseline, which decreased in the periphery immediately after transplantation in both viremic and NV patients. We identified a subset of prememory-like NK cells (NKG2C+CD57+FcεRIγlow-dim) that increased during viremia in R+ viremic patients. These cells showed a higher cytotoxic profile than preexisting memory-like NK cells with transient up-regulation of FcεRIγ and Ki67 expression at the acute phase, with the subsequent accumulation of new memory-like NK cells at later phases of viremia. Furthermore, cytotoxic NKG2C+CD8+ T cells and γδ T cells significantly increased in viremic patients but not in NV patients. These three different cytotoxic cells combinatorially responded to viremia, showing a relatively early response in R+ viremic patients compared with recipient CMV-seronegative viremic patients. All viremic patients, except one, overcame viremia and did not experience graft rejection. These data provide insights into the invivo dynamics and interplay of cytotoxic lymphocytes responding to CMV viremia, which are potentially linked with control of CMV viremia to prevent graft rejection.

A Fusion Protein Complex that Combines IL-12, IL-15, and IL-18 Signaling to Induce Memory-Like NK Cells for Cancer Immunotherapy.

Natural killer (NK) cells are a promising cellular therapy for cancer, with challenges in the field including persistence, functional activity, and tumor recognition. Briefly, priming blood NK cells with recombinant human (rh)IL-12, rhIL-15, and rhIL-18 (12/15/18) results in memory-like NK cell differentiation and enhanced responses against cancer. However, the lack of available, scalable Good Manufacturing Process (GMP)-grade reagents required to advance this approach beyond early-phase clinical trials is limiting. To address this challenge, we developed a novel platform centered upon an inert tissue factor scaffold for production of heteromeric fusion protein complexes (HFPC). The first use of this platform combined IL-12, IL-15, and IL-18 receptor engagement (HCW9201), and the second adds CD16 engagement (HCW9207). This unique HFPC expression platform was scalable with equivalent protein quality characteristics in small- and GMP-scale production. HCW9201 and HCW9207 stimulated activation and proliferation signals in NK cells, but HCW9207 had decreased IL-18 receptor signaling. RNA sequencing and multidimensional mass cytometry revealed parallels between HCW9201 and 12/15/18. HCW9201 stimulation improved NK cell metabolic fitness and resulted in the DNA methylation remodeling characteristic of memory-like differentiation. HCW9201 and 12/15/18 primed similar increases in short-term and memory-like NK cell cytotoxicity and IFNγ production against leukemia targets, as well as equivalent control of leukemia in NSG mice. Thus, HFPCs represent a protein engineering approach that solves many problems associated with multisignal receptor engagement on immune cells, and HCW9201-primed NK cells can be advanced as an ideal approach for clinical GMP-grade memory-like NK cell production for cancer therapy.

Abstract SY30-02: NK cells remember: Engineering NK cell memory-like responses for cancer immunotherapy

Abstract Natural killer (NK) cells are innate lymphoid cells that protect against infection and mediate anti-tumor immune responses. NK cell immunotherapy is a promising cellular therapy approach for leukemia, lymphoma, and other cancers. Multiple laboratories have advanced our understanding of innate NK cell memory and memory-like responses over the past decade, with a unifying definition of enhanced response to re-stimulation after an initial activation event. We identified that human cytokine-induced memory-like (memory) NK cells differentiate after a brief activation with IL-12, IL-15, and IL-18 and mediate enhanced responses against leukemia and other cancer targets. Pre-clinical studies have demonstrated their enhanced anti-tumor potential in vitro, and in vivo in syngeneic murine models and human xenografts. We translated this concept into a first-in-human clinical trial that demonstrated safe adoptive transfer of donor memory NK cells for patients with relapsed or refractory acute myeloid leukemia (AML) resulting in complete remissions. Correlative mass cytometry from this phase 1 study revealed the memory NK cell multidimensional phenotype and identified NKG2A as a major checkpoint for memory NK cell response to AML. Additional clinical trials of donor memory NK cells the HCT setting have demonstrated safety and anti-leukemia activity the immune compatible setting and has provided insights into persistence. Memory NK cells functionally persist for more than 60 days with a unique multidimensional phenotype in two clinical trials in leukemia patients. Further, CITE-seq single cell profiling reveals a unique memory NK cell transcriptomic signature. We have also developed approaches to gene edit and engineer memory-like NK cells with chimeric antigen receptors, expanding the spectrum of cancers for memory-like NK cellular therapy. CAR memory NK cells exhibit enhanced responses, compared with CAR conventional NK cells. Further, pairing with tumor targeting monoclonal antibodies can result in CAR-like responses via CD16/FcγRIIIa, providing additional activating signals that direct memory NK cell response. These studies identify a promising memory NK cell platform for cancer immunotherapy and highlight the importance of correlative studies during clinical trials to advance our understanding of human immunology. Citation Format: Todd A. Fehniger. NK cells remember: Engineering NK cell memory-like responses for cancer immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr SY30-02.

Memory-like Differentiation Enhances NK Cell Responses to Melanoma.

Treatment of advanced melanoma is a clinical challenge. Natural killer (NK) cells are a promising cellular therapy for T cell-refractory cancers, but are frequently deficient or dysfunctional in patients with melanoma. Thus, new strategies are needed to enhance NK-cell antitumor responses. Cytokine-induced memory-like (ML) differentiation overcomes many barriers in the NK-cell therapeutics field, resulting in potent cytotoxicity and enhanced cytokine production against blood cancer targets. However, the preclinical activity of ML NK against solid tumors remains largely undefined. Phenotypic and functional alterations of blood and advanced melanoma infiltrating NK cells were evaluated using mass cytometry. ML NK cells from healthy donors (HD) and patients with advanced melanoma were evaluated for their ability to produce IFNγ and kill melanoma targets in vitro and in vivo using a xenograft model. NK cells in advanced melanoma exhibited a decreased cytotoxic potential compared with blood NK cells. ML NK cells differentiated from HD and patients with advanced melanoma displayed enhanced IFNγ production and cytotoxicity against melanoma targets. This included ML differentiation enhancing melanoma patients' NK-cell responses against autologous targets. The ML NK-cell response against melanoma was partially dependent on the NKG2D- and NKp46-activating receptors. Furthermore, in xenograft NSG mouse models, human ML NK cells demonstrated superior control of melanoma, compared with conventional NK cells. Blood NK cells from allogeneic HD or patients with advanced melanoma can be differentiated into ML NK cells for use as a novel immunotherapeutic treatment for advanced melanoma, which warrants testing in early-phase clinical trials.

Multidimensional Analyses of Donor Memory-Like NK Cells Reveal New Associations with Response after Adoptive Immunotherapy for Leukemia.

Natural killer (NK) cells are an emerging cancer cellular therapy and potent mediators of antitumor immunity. Cytokine-induced memory-like (ML) NK cellular therapy is safe and induces remissions in patients with acute myeloid leukemia (AML). However, the dynamic changes in phenotype that occur after NK-cell transfer that affect patient outcomes remain unclear. Here, we report comprehensive multidimensional correlates from ML NK cell-treated patients with AML using mass cytometry. These data identify a unique in vivo differentiated ML NK-cell phenotype distinct from conventional NK cells. Moreover, the inhibitory receptor NKG2A is a dominant, transcriptionally induced checkpoint important for ML, but not conventional NK-cell responses to cancer. The frequency of CD8α+ donor NK cells is negatively associated with AML patient outcomes after ML NK therapy. Thus, elucidating the multidimensional dynamics of donor ML NK cells in vivo revealed critical factors important for clinical response, and new avenues to enhance NK-cell therapeutics. SIGNIFICANCE: Mass cytometry reveals an in vivo memory-like NK-cell phenotype, where NKG2A is a dominant checkpoint, and CD8α is associated with treatment failure after ML NK-cell therapy. These findings identify multiple avenues for optimizing ML NK-cell immunotherapy for cancer and define mechanisms important for ML NK-cell function.This article is highlighted in the In This Issue feature, p. 1775.

CAR-modified memory-like NK cells exhibit potent responses to NK-resistant lymphomas

AbstractNatural killer (NK) cells are a promising cellular immunotherapy for cancer. Cytokine-induced memory-like (ML) NK cells differentiate after activation with interleukin-12 (IL-12), IL-15, and IL-18, exhibit potent antitumor responses, and safely induce complete remissions in patients with leukemia. However, many cancers are not fully recognized via NK cell receptors. Chimeric antigen receptors (CARs) have been used to enhance tumor-specific recognition by effector lymphocytes. We hypothesized that ML differentiation and CAR engineering would result in complementary improvements in NK cell responses against NK-resistant cancers. To test this idea, peripheral blood ML NK cells were modified to express an anti-CD19 CAR (19-CAR-ML), which displayed significantly increased interferon γ production, degranulation, and specific killing against NK-resistant lymphoma lines and primary targets compared with nonspecific control CAR-ML NK cells or conventional CAR NK cells. The 19-CAR and ML responses were synergistic and CAR specific and required immunoreceptor tyrosine-based activation motif signaling. Furthermore, 19-CAR-ML NK cells generated from lymphoma patients exhibited improved responses against their autologous lymphomas. 19-CAR-ML NK cells controlled lymphoma burden in vivo and improved survival in human xenograft models. Thus, CAR engineering of ML NK cells enhanced responses against resistant cancers and warrants further investigation, with the potential to broaden ML NK cell recognition against a variety of NK cell–resistant tumors.

Cytokine-Induced Memory-like NK Cells Exhibit Massive Expansion and Long-Term Persistence after Infusion Post-Haploidentical Stem Cell Transplantation: A Report of the First Three Cases in a Phase I Trial

Cytokine-Induced Memory-like NK Cells Exhibit Massive Expansion and Long-Term Persistence after Infusion Post-Haploidentical Stem Cell Transplantation: A Report of the First Three Cases in a Phase I Trial

CD56dim CD57- NKG2C+ NK cells retaining proliferative potential are possible precursors of CD57+ NKG2C+ memory-like NK cells.

Formation of the adaptive-like NK cell subset in response to HCMV infection is associated with epigenetic rearrangements, accompanied by multiple changes in the protein expression. This includes a decrease in the expression level of the adapter chain FcεRIγ, NKp30, and NKG2A receptors and an increase in the expression of NKG2C receptor, some KIR family receptors, and co-stimulating molecule CD2. Besides, adaptive-like NK cells are characterized by surface expression of CD57, a marker of highly differentiated cells. Here, it is shown that CD57-negative CD56dim NKG2C+ NK cells may undergo the same changes, as established by the similarity of the phenotypic expression pattern with that of the adaptive-like CD57+ NKG2C+ NK cells. Regardless of their differentiation stage, NKG2C-positive NK cells had increased HLA-DR expression indicating an activated state, both ex vivo and after cultivation in stimulating conditions. Additionally, CD57- NKG2C+ NK cells exhibited better proliferative activity compared to CD57+ NKG2C+ and NKG2C- NK cells, while retaining high level of natural cytotoxicity. Thus, CD57- NKG2C+ NK cells may represent a less differentiated, but readily expanding stage of the adaptive-like CD57+ NKG2C+ NK cells. Moreover, it is shown that NK cells have certain phenotypic plasticity and may both lose NKG2C expression and acquire it de novo during proliferation, induced by IL-2 and K562-mbIL21 feeder cells.

Characterization of Rhesus Macaque Liver-Resident CD49a+ NK Cells During Retrovirus Infections.

CD49a+ tissue resident NK cells have been implicated in memory-like NK cell responses, but while this population is well-characterized in mice and in humans, they are poorly described in non-human primates (NHP) which are particularly critical for modeling human viral infections. Others and we have shown that memory-like NK cells are enriched in the liver and because of the importance of NHP in modeling HIV infection, understanding the immunobiology of CD49a+ NK cells in SIV-infected rhesus macaques is critical to explore the role of this cell type in retroviral infections. In this study mononuclear cells isolated from livers, spleens, and peripheral whole blood were analyzed in acutely and chronically lentivirus-infected and experimentally-naïve Indian rhesus macaques (RM). NK cells were then identified as CD45+CD14−CD20−CD3−NKG2A/C+ cells and characterized using multiparametric flow-cytometry. Our data show that in RM, CD49a+ NK cells increase in the liver following retroviral infections [median = 5.2% (naïve) vs. median = 9.48% (SIV+) or median = 16.8% (SHIV+)]. In contrast, there is little change in CD49a+ NK frequencies in whole blood or spleens of matched animals. In agreement with human and murine data we also observed that CD49a+ NK cells were predominantly Eomeslow T-betlow, though these frequencies are elevated in infected animal cohorts. Functionally, our data suggests that infection alters TNF-α, IFN-γ, and CD107a expression in stimulated CD49a+ NK cells. Specifically, our analyses found a decrease in CD49a+ CD107a+ TNFα+ IFNγ− NK cells, with a simultaneous increase in CD49a+ CD107a+ TNFα− IFNγ+ NK cells and the non-responsive CD49a+ CD107a− TNFα− IFNγ− NK cell population following infection, suggesting both pathogenic and inflammatory changes in the NK cell functional profile. Our data also identified significant global differences in polyfunctionality between CD49a+ NK cells in the naïve and chronic (SHIV+) cohorts. Our work provides the first characterization of CD49a+ NK cells in tissues from RM. The significant similarities between CD49a+ NK cells from RM and what is reported from human samples justifies the importance of studying CD49a+ NK cells in this species to support preclinical animal model research.

A first-in-class ex vivo combination between cytokine-induced memory like (CIML) NK cells and a CD38 targeting antibody recruiting molecule (ARM) as a novel approach to target NK cells without cellular engineering for the treatment of multiple myeloma.

8523 Background: Cytokine-induced memory-like (CIML) NK cells differentiate after a brief preactivation with interleukin-12 (IL-12), IL-15, and IL-18 and exhibit enhanced responses to cytokine or activating receptor restimulation for several weeks to months. Antibody Recruiting Molecules (ARM) are bifunctional molecules that simultaneously bind a given tumor marker and engage endogenous IgG antibodies, therefore binding and activating NK cells via their FcR and targeting them to kill tumors cells. A first in class therapy that has the potential to improve the activity of CIML NK cells by combining them with KP1237, a CD38-ARM is presented for the treatment of newly diagnosed multiple myeloma (MM) patients who are minimal residual disease positive (MRD+) and eligible for autologous stem cell transplant (ASCT). Methods: Specific killing of CD38 expressing MOLP-8 cells by CIML NK cells alone or in combination with KP1237 was measured. Additionally, NK and CIML NK cells from healthy volunteers and MM patients at various stages of the disease were tested for activity against autologous and allogeneic tumor cell targets. In these experiments, surface phenotype and activation status of NK cells were determined. Results: A statistically significant increase in specific killing was observed when KP1237 was used in combination with CIML NK cells in an ADCC assay against CD38 expressing MOLP-8 (p = 0.0105, mean 61.8 ± SD 9.1 and mean 83.7 ± SD 13.58 for CIML NK alone and CIML NK+KP1237, respectively). This effect was accompanied by an increase in plasma membrane retention of CD107a. Surface phenotype of NK and CIML NK cells from healthy volunteers and MM patients was compared since the functional activity of NK cells from such patients is debated. We report surface expression of CD56, CD16, CD57, NKG2D, Nkp44, Nkp46, CD107a, KIR2DL2/3/DS2, and CD69 as well as frequencies of CD57hi CD56+ mature versus CD57lo CD56+ immature NK cell subsets. Further, autologous CIML NK cells + KP1237 exhibit cytotoxicity towards patient plasma cells. Conclusions: The activity of CIML NK cells towards CD38 expressing MM target cells is improved by the addition of KP1237 avoiding the need for cellular engineering with chimeric antigen receptors. This led to the development of the combination drug product consisting of patient autologous CIML NK cells, KP1237 and IVIG. Clinical development is under way for (MRD+) MM patients eligible for ASCT.

A novel, non-feeder-cell approach to generate large numbers of Cytokine-Induced Memory-Like NK cells for adoptive cells therapies

Abstract We have constructed two heterodimeric multi-cytokine fusions, HCW9201 and HCW9206, to support a “Kick and Expand” approach to activate and induce proliferation of purified NK cells for adoptive cell therapy (ACT). HCW9201 is a heterodimeric fusion protein complex comprising human IL-15 (complexed with an IL-15Rα-sushi domain), IL-18 and IL-12. HCW9206 is heterodimeric fusion protein comprising human IL-15 (complexed with an IL-15Rα-sushi domain), IL-7, and IL-21. When purified human NK cells from peripheral blood were activated with HCW9201 for three hours and then incubated with HCW9206 in combination with a capture antibody, the HCW9201-activated NK cells expanded approximately 100–300 folds within 14 days. The expanded NK cells exhibit a cytokine-induced memory-like (CIML) phenotype with a high metabolic rate and respiratory capacity, remarkable anti-tumor activity, and persistence when they were adoptively transferred into NSG mice. They also retained their heightened responsiveness when re-stimulated with tumor targets. Cytokine dependent epigenetic demethylation imprints of the Ifng promoter region were also observed for at least 10 days after the NK cells were adoptively transferred to NSG mice. In conclusion, a simple, scalable, non-feeder-cell-based “Kick and Expand” process was developed to support the generation of large numbers of CIML NK cells for multiple rounds of ACT using peripheral blood NK cell. We also provide data to show that these CIML NK cells are an excellent source for generation of CAR-NK cells.

Memory and Memory-Like NK Cell Responses to Microbial Pathogens.

NK cells are cytotoxic lymphocytes that provide systemic defense against pathogens and malignancy. Although historically considered cells of the innate immune system, NK cells are now known to be capable of memory or memory-like immune responses in certain settings. Memory NK responses were initially reported over a decade ago in studies involving mouse models of cytomegalovirus infection and delayed-type hypersensitivity reactions to chemical haptens and viral antigens. Since then, a growing body of literature suggests that memory or memory-like NK cell responses may occur in a broader range of immunological settings, including in response to various viral and bacterial infections, and some immunization protocols. Memory-like NK cell responses have also now been reported in humans and non-human primates. Here, we summarize recent studies demonstrating memory or memory-like responses by NK cells in settings of infection and immunization against infectious agents.

Phenotypic and Functional Analysis of Human NK Cell Subpopulations According to the Expression of FcεRIγ and NKG2C.

Human memory-like NK cells are commonly defined by either a lack of FcεRIγ or gain of NKG2C expression. Here, we investigated the heterogeneity of human CD56dim NK cell subpopulations according to the expression of FcεRIγ and NKG2C in a large cohort (n = 127). Although the frequency of FcεRIγ− and NKG2C+ NK cells positively correlated, the FcεRIγ− and NKG2C+ NK cell populations did not exactly overlap. The FcεRIγ+NKG2C+, FcεRIγ−NKG2C+, and FcεRIγ−NKG2C− NK cell populations were only evident after HCMV infection, but each had distinct characteristics. Among the subpopulations, FcεRIγ−NKG2C+ NK cells exhibited the most restricted killer immunoglobulin-like receptor repertoire, suggesting clonal expansion. Moreover, FcεRIγ−NKG2C+ NK cells exhibited the lowest Ki-67 and highest Bcl-2 expression, indicating the long-lived quiescent memory-like property. Functionally, FcεRIγ−NKG2C+ NK cells had weak natural effector function against K562 but strong effector functions by CD16 engagement, whereas FcεRIγ+NKG2C+ NK cells had strong effector functions in both settings. Anatomically, the FcεRIγ+NKG2C+, FcεRIγ−NKG2C+, and FcεRIγ−NKG2C− NK cell populations were present in multiple human peripheral organs. In conclusion, we demonstrate the heterogeneity of memory-like NK cells stratified by FcεRIγ and NKG2C and suggest both markers be utilized to better define these cells.

Chimeric Antigen Receptor Modified Memory-like (CAR-ML) NK Cells Exhibit Potent Responses to NK-Resistant Tumors

NK cells are cytotoxic innate lymphoid cells that mediate anti-tumor responses and traffic to most tissues. NK cells activated briefly with IL-12, IL-15, and IL-18 differentiate into memory-like (ML) NK cells with enhanced anti-tumor effects, which has been translated into clinical trials for patients with leukemia. Adoptive cellular therapy with donor ML NK cells were safe and induced CR/CRi in >50% of rel/ref AML patients in a first-in-human phase 1 clinical trial at Washington University (PMID27655849). In preliminary results, donor ML NK cells expand and can persist for months in an immune-compatible recipients during or after allogeneic hematopoietic cell transplantation (HCT), and maintain potent effector function. However, NK cell recognition of many cancer types is limited, since they depend on expression of stress-induced activating receptor ligands. We hypothesized that ML NK cells engineered with chimeric antigen receptors (CAR) would demonstrate improved anti-tumor responses against classically NK-resistant targets. To test this idea, ML NK cells were engineered to express an anti-CD19-CAR, and responses against NK-resistant B-cell malignancies evaluated in vitro and in vivo. CAR-modified primary human ML NK cells (CAR-ML) were transduced with an anti-CD19-CD8a-41BB-CD3z-GFP (CD19-CAR-ML) lentivirus. This differentiation and transfection approach resulted in approximately 15-25% of ML NK cells transduced with the CAR construct, as determined flow cytometry staining for soluble CD19 and GFP. As an additional control, αCD33-CD8a-41BB-CD3z-GFP CAR-transduced ML NK cells and GFP- internal control ML NK cells were used. Here, in vitro functional assays were used to determine if CD19-CAR enhances ML NK cells in an antigen (CD19)-specific manner. CD19-CAR-ML (GFP+) and control ML NK (GFP-) cells were evaluated for functional responses to CD19-positive or CD19-negative tumor targets in vitro. CD19-CAR-ML NK cells demonstrated significantly increased IFN-γ production (44±4% vs. 15±3%, p<0.001); mean ± SEM) and degranulation (31±4% vs. 5±1%, p<0.001) against NK-resistant CD19+ Raji targets, compared to control GFP- and CD33-CAR ML NK cells. To understand the contributions of ML differentiation on the enhanced functionality of CD19-CAR modified NK cells, we compared CD19-CAR-ML NK cells to control CD19-CAR NK cells that were treated with IL-15 only. CD19-CAR-ML NK cells also exhibited significantly increased effector responses compared to control CAR NK cells against CD19+ targets (p<0.01). CD19-CAR-ML NK cells responded similarly to GFP- ML NK cells against CD19-negative Kasumi leukemia targets. Finally, CD19-CAR-ML NK cells also exhibited significantly enhanced killing, degranulation, and IFN-γ production against primary CD19+ follicular lymphoma targets from patient lymph nodes (p<0.01). To establish the translational utility of this approach, autologous CD19-CAR-ML NK cells generated from lymphoma patients demonstrated significantly increased IFN-γ production (p<0.05) and degranulation (p<0.01) against their own CD19+ lymphoma targets, compared to control ML NK cells (GFP-). These data confirm contributions of both ML differentiation and CAR expression in the enhanced antigen-specific, anti-tumor responses observed in CAR-ML NK cells. To test the expansion and persistence of ML NK cells transduced with CD19 or CD33-CAR were transferred into CD19+ Raji-bearing NSG mice and supported in vivo with IL-15. After three weeks, mice were sacrificed and NK (CD56) cell persistence and tumor (CD19) burden assessed by flow cytometry. CD19-CAR ML recipient mice had reduced tumor burden in the BM, spleen, and blood compared to CD33-CAR ML treated mice. Notably, CD19-CAR-ML (GFP+) were increased to >70% of human NK cells from 20% in the CD33-CAR-ML recipient mice, suggesting antigen-specific CAR-expressing NK cells expand or survive better in vivo than non-transduced ML or non-specific CAR-ML NK cells in vivo. Thus, combining CAR with ML differentiation results in NK cells with enhanced responses to NK resistant tumors. These studies warrant continued CAR-ML development and provide the pre-clinical rationale for translating this combination NK cell therapy approach to the clinic. Figure Disclosures Fehniger: Cyto-Sen Therapeutics: Consultancy; Horizon Pharma PLC: Other: Consultancy (Spouse).

Influenza Vaccination Primes Human Myeloid Cell Cytokine Secretion and NK Cell Function.

Cytokine-induced memory-like (CIML) NK cells generated in response to proinflammatory cytokines in vitro and in vivo can also be generated by vaccination, exhibiting heightened responses to cytokine stimulation months after their initial induction. Our previous study demonstrated that in vitro human NK cell responses to inactivated influenza virus were also indirectly augmented by very low doses of IL-15, which increased induction of myeloid cell-derived cytokine secretion. These findings led us to hypothesize that IL-15 stimulation could reveal a similar effect for active influenza vaccination and influence CIML NK cell effector functions. In this study, 51 healthy adults were vaccinated with seasonal influenza vaccine, and PBMC were collected before and up to 30 d after vaccination. Myeloid and lymphoid cell cytokine secretion was measured after in vitro PBMC restimulation with low-dose IL-15, alone or in combination with inactivated H3N2 virus; the associated NK cell response was assessed by flow cytometry. PBMC collected 30 d postvaccination showed heightened cytokine production in response to IL-15 compared with PBMC collected at baseline; these responses were further enhanced when IL-15 was combined with H3N2. NK cell activation in response to IL-15 alone (CD25) and H3N2 plus IL-15 (CD25 and IFN-γ) was enhanced postvaccination. We also observed proliferation of less-differentiated NK cells with downregulation of cytokine receptors as early as 3 d after vaccination, suggesting cytokine stimulation in vivo. We conclude that vaccination-induced "training" of accessory cells combines with the generation of CIML NK cells to enhance the overall NK cell response postvaccination.

Abstract 1546: The CD30/CD16A bispecific innate immune cell engager AFM13 elicits heterogeneous single-cell NK cell responses and effectively triggers memory-like (ML) NK cells

Abstract Natural killer (NK) cells are crucial effector cells of the innate immune system capable of rapidly recognizing and eliminating infected, stressed and malignant cells. NK cells discriminate tumor targets from healthy cells via integration of activating and inhibitory receptor signals. One barrier to the broad application of NK cells across many cancer types is inconsistent cancer cell recognition, which may be overcome by immune cell engagers. AFM13 is a tetravalent bispecific antibody based on the ROCK platform characterized by bivalent binding to CD30 and CD16A with clinical efficacy in CD30+ malignancies. However, our understanding of NK cell functional responses triggered via AFM13 remain incomplete. Moreover, adoptively transferred memory-like (ML) NK cells have demonstrated enhanced anti-tumor activity (Romee R et al, Sci Transl Med, 2016) that may be receptive to AFM13-based targeting to enhance target cell recognition. To address these questions, we analyzed single-cell conventional (cNK) and ML (IL-12/15/18-induced) NK cell functional responses to NK-resistant CD30+ lymphoma cells +/- AFM13. Primary cNK cells co-incubated with AFM13-treated Hut-78 cells demonstrated increased IFN-γ, TNF, and degranulation, compared to Hut-78 cells or Raji (CD30-) targets + AFM13 as a negative control (p<0.05). To define the single-cell specificity of NK cell responses to AFM13, similar assays were performed using mass cytometry analysis of 39 lineage, maturation, activating and inhibitory receptors, and function-relevant NK cell markers. tSNE-based multidimensional analyses revealed marked distinctions between Hut-78 and AFM13-Hut-78 stimulated cNK cells, due in part to IFN-γ, MIP-1α, CD107a, and CD16. To define the impact of specific NK receptors, SPADE was used to define highly activated IFN-γ+ NK cell sub-populations. In a KIR3DL1+ donor, activation was primarily within the KIR3DL1+ subset, consistent with the lack of its inhibitory ligand (HLA-Bw4). In KIR3DL1 negative donors, responding NK cells were enriched in mature KIR2DL2/L3+CD57+ NK cells that lacked NKG2A. Additional experiments revealed that both control and ML NK cells exhibited increased IFN-γ, degranulation, and cytotoxicity with AFM13 (P<0.01), and AFM13-stimulated ML NK cells exhibited the highest IFN-γ response and killing. Collectively, these data indicate that target cell recognition of NK cells can be significantly enhanced by AFM13, yet influenced by inhibitory receptor expression, maturation state, and memory-like differentiation. Thus, these data suggest that the status and repertoire of NK cells in a patient may offer diagnostic potential for therapeutic response, and the combination of ML NK cells with AFM13 appears to be a promising therapeutic approach. Citation Format: Nancy Marin, Michelle Becker-Hapak, Joachim Koch, Melissa M. Berrien-Elliott, Mark Foster, Carly Neal, Ethan McClain, Sweta Desai, Julia A. Wagner, Timothy Schappe, Lynne Marsala, Pamela Wong, Martin Treder, Todd A. Fehniger. The CD30/CD16A bispecific innate immune cell engager AFM13 elicits heterogeneous single-cell NK cell responses and effectively triggers memory-like (ML) NK cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1546.

Semaphorin 7A modulates cytokine-induced memory-like responses by human natural killer cells.

Cytokine-induced memory-like (CIML) NK cells are endowed with the capacity to mediate enhanced effector functions upon cytokine or activating receptor restimulation for several weeks following short-term preactivation with IL-12, IL-15, and IL-18. Promising results from a first-in-human clinical trial highlighted the clinical potential of CIML NK cells as adoptive immunotherapy for patients with hematologic malignancies. However, the mechanisms underlying CIML NK cell differentiation and increased functionality remain incompletely understood. Semaphorin 7A (SEMA7A) is a potent immunomodulator expressed in activated lymphocytes and myeloid cells. In this study, we show that SEMA7A is substantially upregulated on NK cells stimulated with cytokines, and specifically marks activated NK cells with a strong potential to release IFN-γ. In particular, preactivation of NK cells with IL-12+IL-15+IL-18 resulted in greater than tenfold upregulation of SEMA7A and enhanced expression of the ligand for SEMA7A, integrin-β1, on CIML NK cells. Strikingly, preactivation in the presence of antibodies targeting SEMA7A lead to significantly decreased IFN-γ production following restimulation. These results imply a novel mechanism by which cytokine-enhanced SEMA7A/integrin-β1 interaction promotes CIML NK cell differentiation and maintenance of increased functionality. Our data suggest that targeting SEMA7A/integrin-β1 signaling might provide a novel immunotherapeutic approach to potentiate antitumor activity of CIML NK cells.

Cytokine-induced memory-like natural killer cells have enhanced function, proliferation, and in vivo expansion against ovarian cancer cells

ObjectiveNatural killer (NK) cells are lymphocytes well suited for adoptive immunotherapy. Attempts with adoptive NK cell immunotherapy against ovarian cancer have proven unsuccessful, with the main limitations including failure to expand and diminished effector function. We investigated if incubation of NK cells with interleukin (IL)-12, IL-15, and IL-18 for 16h could produce cytokine-induced memory-like (CIML) NK cells capable of enhanced function against ovarian cancer. MethodsNK cells were preactivated briefly with IL-12, IL-15, and IL-18, rested, then placed against ovarian cancer targets to assess phenotype and function via flow cytometry. Real-time NK-cell-mediated tumor-killing was evaluated. Using ascites cells and cell-free ascites fluid, NK cell proliferation and function within the immunosuppressive microenvironment was evaluated in vitro. Finally, CIML NK cells were injected intraperitoneal (IP) into an in vivo xenogeneic mouse model of ovarian cancer. ResultsCIML NK cells demonstrate enhanced cytokine (IFN-γ) production and NK-cell-mediated killing of ovarian cancer. NK cells treated overnight with cytokines led to robust activation characterized by temporal shedding of CD16, induction of CD25, and enhanced proliferation. CIML NK cells proliferate more with enhanced effector function compared to controls in an immunosuppressive microenvironment. Finally, human CIML NK cells exhibited potent antitumor effects within a xenogeneic mouse model of ovarian cancer. ConclusionsCIML NK cells have enhanced functionality and persistence against ovarian cancer in vitro and in vivo, even when exposed to ascites fluid. These findings provide a strategy for NK cell-based immunotherapy to circumvent the immunosuppressive nature of ovarian cancer.

NK-cell responses are biased towards CD16-mediated effector functions in chronic hepatitis B virus infection

Phenotypic and functional natural killer (NK)-cell alterations are well described in chronic hepatitis B virus (cHBV) infection. However, it is largely unknown whether these alterations result from general effects on the overall NK-cell population or the emergence of distinct NK-cell subsets. Human cytomegalovirus (HCMV) is common in cHBV and is associated with the emergence of memory-like NK cells. We aimed to assess the impact of these cells on cHBV infection. To assess the impact of memory-like NK cells on phenotypic and functional alterations in cHBV infection, we performed in-depth analyses of circulating NK cells in 52 patients with cHBV, 45 with chronic hepatitis C virus infection and 50 healthy donors, with respect to their HCMV serostatus. In patients with cHBV/HCMV+, FcεRIγ- memory-like NK cells were present in higher frequencies and with higher prevalence than in healthy donors with HCMV+. This pronounced HCMV-associated memory-like NK-cell expansion could be identified as key determinant of the NK-cell response in cHBV infection. Furthermore, we observed that memory-like NK cells consist of epigenetically distinct subsets and exhibit key metabolic characteristics of long-living cells. Despite ongoing chronic infection, the phenotype of memory-like NK cells was conserved in patients with cHBV/HCMV+. Functional characteristics of memory-like NK cells also remained largely unaffected by cHBV infection with the exception of an increased degranulation capacity in response to CD16 stimulation that was, however, detectable in both memory-like and conventional NK cells. The emergence of HCMV-associated memory-like NK cells shapes the overall NK-cell response in cHBV infection and contributes to a general shift towards CD16-mediated effector functions. Therefore, HCMV coinfection needs to be considered in the design of immunotherapeutic approaches that target NK cells in cHBV. In chronic hepatitis B virus infection, natural killer (NK)-cell phenotype and function is altered. In this study, we demonstrate that these changes are linked to the emergence of a distinct NK-cell subset, namely memory-like NK cells. The emergence of these memory-like NK cells is associated with coinfection of human cytomegalovirus that affects the majority of patients with chronic hepatitis B.