188 Development of WU-NK-101, a feeder cell-free expanded allogeneic memory NK cell product with potent anti-tumor activity

BackgroundAllogeneic Natural Killer (NK) cells are emerging as a safe and effective modality for the treatment of cancer, overcoming several limitations associated with adoptive T cell therapies. Cytokine induced memory-NK cells offer several advantages over conventional NK cells, including enhanced functional persistence, efficacy, and metabolic fitness. Additionally, unlike iPSC and cord blood derived NK cells, they do not require engineering to enable functionality. Here we describe the use of WU-PRIME, a GMP-grade fusion protein complex to generate memory NK cells, and WU-EXPAND, a feeder cell free expansion system to expand memory-NK cells and create WU-NK-101. Further cryopreservation enables the large-scale, off-the-shelf manufacture of memory NK for cancer immunotherapy, with high anti-tumor activity.MethodsNK cells derived from healthy donor leukopheresate were either activated with WU-PRIME and then expanded with WU-EXPAND to form WU-NK-101 or immediately expanded with WU- EXPAND as controls and then cryopreserved. We compared NK cell expansion as well as post- thaw NK cell functionality as assessed by cytokine secretion and short-term and long-term anti- tumor functionality, long-term persistence in NSG mice, as well as anti-tumor activity in vivo.ResultsNK cells activated with WU-PRIME followed by WU-EXPAND (WU-NK-101), expand robustly in large-scale reactions, over 250-fold in 14 days. The cells maintain durable expression of CD25 after expansion, as well as several other hallmarks of the memory-NK phenotype as assessed by mass cytometry. As compared to cells expanded with WU-EXPAND only, WU-NK-101 cells have improved in vitro activity against K562 cells, as well as AML cell lines (TF-1, THP-1, and HL-60). Notably, this functionality is maintained long-term upon repeated challenge. In vivo, WU-NK-101 cells, compared to expanded NK cells have improved in vivo persistence (figure 1; 50,290 v. 9,623, p<0.0001). In vivo anti-tumor activity was also assessed in leukemia models, where Memory NK cells demonstrate superior anti-tumor activity compared to expanded NK cells.Abstract 188 Figure 1NK cell persistence in tumor-bearing mice. 10e6 cryopreserved NK cells were injected into K562 tumor-bearing mice, and supported with 50,000IU human IL-2 every other day. After 9 days, blood was harvested by cheek bleed and assessed for NK cells (hCD45+, CD56+, CD3) in the blood by flow cytometry.ConclusionsThe data demonstrate that WU-NK-101 generated using a feeder cell-free expansion system has a memory phenotype and improved in vitro and in vivo anti-tumor activity compared to conventional NK cells. This activation and expansion platform will enable the development and clinical translation of multiple allogeneic NK cell therapies.

Phenotypic and functional characteristics of a novel influenza hemagglutinin-specific memory NK cell

Immune memory represents the most efficient defense against invasion and transmission of infectious pathogens. In contrast to memory T and B cells, the roles of innate immunity in recall responses remain inconclusive. In this study, we identified a novel mouse spleen NK cell subset expressing NKp46 and NKG2A induced by intranasal influenza virus infection. These memory NK cells specifically recognize N-linked glycosylation sites on influenza hemagglutinin (HA) protein. Different from memory-like NK cells reported previously, these NKp46+NKG2A+ memory NK cells exhibited HA-specific silence of cytotoxicity but increase of IFN-γ response against influenza virus-infected cells, which could be reversed by Pifithrin-μ, a p53-HSP70 signaling inhibitor. During recall responses, splenic NKp46+NKG2A+ NK cells were recruited to infected lung and modulated viral clearance of virus and CD8+ T cell distribution, resulting in improved clinical outcomes. This long-lived NK memory bridges innate and adaptive immune memory response and promotes the homeostasis of local environment during recall response. Importance In this study, we demonstrate a novel HA-specific NKp46+NKG2A+ NK cell subset induced by influenza A virus infection. These memory NK cells show virus-specific decreased cytotoxicity and increased IFN-γ on re-encountering the same influenza virus antigen. In addition, they modulate host recall responses and CD8 T cell distribution, thus bridging the innate immune and adaptive immune responses during influenza virus infection.

Human antigen-specific memory natural killer cell responses develop against HIV-1 and influenza virus and are dependent on MHC-E restriction

ABSTRACTFor over a decade, multiple studies have disputed the notion of natural killer (NK) cells as purely innate lymphocytes by demonstrating that they are capable of putative antigen-specific immunological memory against multiple infectious agents including two critical global health priorities – HIV and influenza. However, the mechanisms underlying antigen specificity remain unknown. Herein, we demonstrate that antigen-specific human NK cell memory develops upon exposure to both HIV and influenza, unified by a conserved and epitope-specific targetable mechanism firmly dependent on the activating CD94/NKG2C receptor and its ligand HLA-E, and confirm these findings by three rigorous and novel assays. We validated the permanent acquisition of antigen-specificity by individual memory NK cells by single-cell cloning. We identified biomarkers of antigen-specific NK cell memory through RNA-Seq transcriptomic fingerprints and complex immunophenotyping by 30-parameter flow cytometry showing elevated expression of KLRG1, α4β7 and NKG2C. Finally, we show individual HLA-E-restricted peptides that may constitute the dominant response in HIV-1- and influenza-infected persons in vivo. Our findings clarify the mechanisms behind formation of antigen-specific memory NK cells, and suggest they could be targeted for future vaccines, cure strategies, or other therapeutic interventions.

HIV-1-induced cytokines deplete homeostatic ILCs and expand TCF7-dependent memory NK cells: Supplemental Figures and Tables

HIV-1-infected people who take medications that suppress viremia, preserve CD4+ T cells, and prevent AIDS, have chronic inflammation with increased cardiovascular mortality. To investigate the etiology of this inflammation, the effect of HIV-1 on innate lymphoid cells (ILCs) and NK cells was examined. Homeostatic ILCs in blood and intestine were depleted permanently. NK cells were skewed towards a memory subset. Cytokines that are elevated during HIV-1 infection reproduced both abnormalities ex vivo. Pseudotime analysis of single NK cell transcriptomes revealed a developmental trajectory towards a subset with expression profile, chromatin state, and biological function like memory T lymphocytes. Expression of TCF7, a WNT transcription factor, increased over the course of the trajectory. TCF7 disruption, or WNT inhibition, prevented memory NK cell induction by inflammatory cytokines. These results demonstrate that inflammatory cytokines associated with HIV-1 infection irreversibly disrupt homeostatic ILCs and cause developmental shift towards TCF7+ memory NK cells.

Tracking the fate of antigen-specific versus cytokine-activated natural killer cells after cytomegalovirus infection

Natural killer (NK) cells provide important host defense and can generate long-lived memory NK cells. Here, by using novel transgenic mice carrying inducible Cre expressed under the control of Ncr1 gene, we demonstrated that two distinct long-lived NK cell subsets differentiate in a mouse model of cytomegalovirus (MCMV) infection. NK cells expressing the MCMV-specific Ly49H receptor differentiated into memory NK cells by an activating signaling through Ly49H and Ly49H− NK cells differentiated into cytokine-activated NK cells by exposure to inflammatory cytokines during infection. Interleukin-12 is indispensable for optimal generation of both antigen-specific memory NK cells and cytokine-activated NK cells. MCMV-specific memory NK cells show enhanced effector function and augmented antitumor activity in vivo as compared with cytokine-activated NK cells, whereas cytokine-activated NK cells exhibited a more robust response to IL-15 and persisted better in an MCMV-free environment. These findings reveal that NK cells are capable of differentiation into distinct long-lived subsets with different functional properties.