Abstract 903: Engineered iPSC-derived NK cells as next-generation immunotherapies for cancer
Authors: Swanson Lee , Goodman Spencer , Lyon Kenyon , Bernareggi Davide , Gonsalves Caryn , Schabla Max , Zhang Guoxin , Li Qin , Mitchell Leah , Kaufman Dan S. , Zhu Huang , Hollingsworth Robert 
Published: April 2023

Abstract
Engineered immune cells as immunotherapies has provided a new approach to treating cancer. Allogenic natural killer (NK) cell therapies have also been shown to mount potent responses against hematologic malignancies but are less likely to cause high-grade toxicities and can be mass produced for off-the-shelf usage. We have developed an iPSC-derived NK (iNK) platform amenable to engineering multiple features for improving efficacy against both solid and liquid tumors.Our previous studies showed that knocking out the CISH gene, which encodes a key regulator of activation, in iNK cells (CISH KO iNK cells) significantly improves their anti-cancer activity, in vivo persistence, metabolic fitness, polyfunctional cytokine production, and resistance to cell exhaustion. In this study we have expanded upon this work to show that CISH KO iNK cells increase anti-tumor activity against a broad range of both hematologic and solid tumor cell types in several types of in vitro assays, making CISH KO iNK cells an attractive cell therapy platform for additional development. CAR enabled NK cells using CARs developed for T-cells have shown clinical efficacy. However, recent studies using signaling modules of NK cell activating receptors (i.e., NKG2D and 2B4) for recombinant CAR signaling domains have demonstrated increased activity. In this study we screened a library of CAR constructs (targeting CD19) containing signaling modules from diverse immune cell signaling receptors including NK cell activating receptors, cytokine receptors, and integrins. Our screen identified several CAR signaling domains that performed better than both T cell CARs and previously reported NK cell CARs. To demonstrate the broad applicability of our top CAR construct, SLNK12, we generated SLNK12-CARs paired with antigen binding domains for various tumor antigens. We confirmed that SLNK12-CARs potently kill target cancer cell lines regardless of the antigen being targeted in monolayer, 3D spheroid, and serial killing assays in vitro. We also describe the development of iNK cells with enhanced ADCC activity. NK cells normally bind antibodies via their CD16A receptor, which has low affinity for the antibody Fc domain and thus limits therapeutic response. We have constructed a recombinant Fc-receptor that combines a high-affinity Fc-binding domain (to improve antibody binding) with our NK-optimized CAR signaling domains to enhance ADCC-mediated killing. These “enhanced ADCC” engineered CISH KO iNK cells possess potent anti-cancer activity in combination with several different therapeutic antibodies. Taken together, our results show that engineering CISH KO iNK cells with either NK-optimized CARs or enhanced ADCC receptors improves anti-tumor activity against a variety of solid tumor target lines in vitro.
Citation Format: Lee Swanson, Spencer Goodman, Kenyon Lyon, Davide Bernareggi, Caryn Gonsalves, Max Schabla, Guoxin Zhang, Qin Li, Leah Mitchell, Dan S. Kaufman, Huang Zhu, Robert Hollingsworth. Engineered iPSC-derived NK cells as next-generation immunotherapies for cancer [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 903.