LAUSR

Metastatic (m) colorectal cancer (CRC) is an incurable, frequently lethal disease present in approximately 25% of newly diagnosed CRC patients, and almost 50% of the patients with CRC will develop metastatic disease. For mCRC, while systemic therapies (cytotoxic therapy, targeted therapy, immunotherapy or their combinations) have extended patient’s life expectancy, not all patients are candidates for these treatments. Immunotherapy has achieved significant curative effects in patients with solid tumors; however, a considerable proportion of mCRC patients (~90%) are not responsive to immune checkpoint blockade (ICB) leaving a gap in the CRC immunotherapy options. Natural killer (NK) cells are cytotoxic innate lymphoid cells that display potent effector responses against a wide variety of tumor cells; however, they are frequently dysfunctional in cancer patients. NK cells from CRC patients exhibit decreased expression of activating receptors and reduced cytokine production after stimulation with CRC cells with a more accentuated phenotype in advanced stages of the disease. Memory-like (ML) NK cells differentiated after IL-12, IL-15, and IL-18 activation have been shown to overcome limitations associated with deficient tumor recognition and poor anti-tumor activity. In clinical trials, ML NK cells were safe and active against acute myeloid leukemia (Romee R et al, Sci Transl Med, 2016). Preclinically, ML NK cells exhibited improved responses against melanoma (Marin ND et al, Clin Cancer Res, 2021) and ovarian cancers, compared to conventional NK cells. Here, we hypothesized that memory-like differentiation will enhance multiple aspects of the NK cell response against CRC cells. Allogeneic ML NK cells displayed enhanced IFN-γ production against four CRC cell lines DLD-1 (p=0.015), SW480 (p=0.0005), HT-29 (p=0.0005) and HCT116 (p=0.001), as well as primary patient derived CRC tumoroids (p=0.0156), compared to conventional (c) NK cells. ML NK cells also exhibited superior and sustained killing of CRC cell lines over time compared to cNK cells, as measured by Incucyte assays and using CRC tumoroids. Furthermore, IFN-γ production was significantly reduced after blockade of NKG2D, DNAM-1 and NKp46 (p<0.01) revealing mechanistic insights into how ML NK cells recognize CRC targets. Finally, using a xenograft model of CRC in NSG mice, we demonstrated that ML NK cells exhibited superior control of Luciferase expressing HCT116 cells compared to cNK cells (p=0.01) as measured by bioluminescent imaging (BLI). Collectively, these findings demonstrate that ML NK cells exhibit enhanced responses against CRC cells, and thus warrants further investigation in clinical trials for CRC patients, especially those who are not candidates for standard of care therapy or failed ICB. Citation Format: Nancy D. Marin, Michelle Becker-Hapak, Quazim A. Alayo, Melissa Berrien-Elliot, Lynne Marsala, Naomi Sonnek, Miriam T. Jacobs, Jennifer A. Foltz, Alice Zhou, Jennifer Tran, Pamela Wong, Celia Cubit, Kimberly Hwang, Timothy Schappe, Ryan C. Fields, Matthew A. Ciorba, Todd A. Fehniger. Memory like differentiation enhances in vitro and in vivo NK cell responses against colorectal 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 893.