WU-NK-101 (W-NK), a Memory-like (ML) NK Cell, Intrinsically Overcomes Factors Restricting Adoptive Cell Therapy (ACT) in Acute Myeloid Leukemia (AML)

ML-NK cells are generated from conventional (c) NK cells activated with cytokines IL-12/15/18 which results in enhanced fitness, in vivo persistence, and function against tumor targets. While effective in early phase clinical trials, a 1 donor to 1 recipient cell product hinders commercial development as a cellular therapeutic. Here, W-NK is a cytokine-reprogrammed, expanded, cryopreserved ML-NK product derived from healthy human peripheral blood (PBMC) cNK cells, with scalable manufacturability. W-NKs harness the benefits of ML-NKs, and further overcome challenges previously reported for adoptive cell therapy (ACT) in AML: antigen escape, limited tumor trafficking/infiltration, and restricted function in tumor microenvironment (TME).

W-NK characterization was performed by scRNA-seq (10X Genomics) and multidimensional flow and mass cytometry.Functionality was evaluated by in vitro cytotoxicity assays against AML cell lines (THP-1, and HL-60) and bioenergetics assays (Seahorse XF), under different conditions: conventional (N) media (pH 7, glucose 11 mM), or two models for TME (TME-aligned media - pH 5.9, glucose 6 mM, immune suppressive agents, e.g., PGE2, TGFb1, and malignant ascites), and in hypoxia (0.1% O₂; AVATAR). In vivo efficacy was evaluated in NSG mice bearing THP-1 AML tumors. Proteomic data was acquired by tandem-mass spectrometry (Sciex Zeno TOF 7600). Cell trafficking was measured by fluorescent-labeled W-NK in NSG mice.

W-NK cells are transcriptionally distinct from cNKs. Sc-RNA-seq analysis revealed important transcriptional and compositional differences compared to cNK cells, including novel NK clusters expressing metabolic (GLUL), proliferation-associated (Ki67) and IL-15-inducible genes (TXNIP) known to enhance NK responses. Additionally, W-NKs express higher levels of activating receptors (i.e., 2B4, DNAM-1, NKG2D, NKp30, etc.), cytotoxic effector proteins (i.e., granzyme B), and lower levels of inhibitory receptors leading to increased potency in vitro against HL-60 cells (mEC50 1.7 and 5.2; p= 0.032; W-NK vs. cNK respectively) and demonstrated a dose dependent reduction of tumor burden in THP-1 xenografts (p=0.015). W-NK also express high levels of CXCR4 (81.6% positive, MFI 5552), contributing to improved bone marrow (BM) homing (16.5 ± 2.4%) compared to data previously reported for IL-2-expanded NK cells (3%; Sato et al. CCR. 2020). Once in the TME, unlike cNK and T-cells, W-NK cytotoxic function is preserved (TME-media vs. N-media-; W-NK: 96.5% vs. 88.2%, p=0.45; cNK: 44.1% vs.13.5%, p=0.009; T-cell: 53.2 % vs. 25.2%, p=0.041, respectively). This is potentially due to W-NK resistance to hypoxia, and improved metabolic fitness/flexibility. W-NK cytotoxic activity was also preserved in hypoxic conditions (90% vs. 89.5%, p=0.2) compared to cNK (24% vs. 6.9%, p=0.02; normoxia vs. hypoxia). Metabolically, W-NK express higher levels of cell surface nutrient transporters, implying better adaptation to adverse TMEs (i.e., upregulation of amino acids, lactate, and pyruvate). This might enable utilization of diverse macronutrients, activation of metabolic pathways, and optimal ATP manufacturing, and is supported by upregulation of REACTOME pathways capturing amino-acid and lipid metabolism, as well as mitochondrial function. Lastly, W-NK did not attack cells from healthy human tissues including PBMCs, indicating that W-NK are not indiscriminate killers. This observation would predict low myelosuppression and a favorable safety profile.

In summary, W-NK are effective against AML cells, robustly home to the BM, overcome hypoxia, immunosuppression, and nutritional scarcity to survive/function within the leukemia TME. Moreover, they are not restricted to a single antigen target thereby mitigating antigen escape. These features, which overcome challenges for ACT, herald the promise of NK cell therapy and augur positively for patients being treated with W-NK in a Phase 1 study in R/R AML (NCT# 05470140).