Abstract A55: Natural killer cells genetically modified to overexpress DNAM-1 exert enhanced antitumor responses against CD112/CD155+ sarcomas and other malignancies
Authors: Sayitoglu Ece C. , Chrobok Michael , Georgoudaki Anna-Maria , Josey Benjamin J. , Hartman Michelle , Vallabhaneni Esha , Herekar Rajeev , Bergeron Savannah , Krueger Robin , Sutlu Tolga , Alici Evren , Temple Harry T. , Duru Adil D. 
Published: June 2021

Abstract
Sarcomas are a broad category of cancers arising from cells of mesenchymal origin that occur in bone and soft tissues. They affect humans of all ages, and standard treatment options remain ineffective at increasing overall survival. Targeted immunotherapy is a rapidly developing field that offers extremely promising therapeutic prospects for many cancers. However, sarcomas are vastly understudied in this field. Natural killer (NK) cells are immune cells with inherent tumor-killing abilities that are a promising option for cancer immunotherapy. However, tumors can dysregulate the expression of NK cells ligands to escape immune detection, and the details of these escape mechanisms are not well known in sarcomas. Thus, a better understanding of NK cell-sarcoma interactions is necessary for the development of novel immunotherapies. In order to address this, we generated 20 cell lines from primary sarcoma tumors and characterized a group of known cancer-related NK cell receptor ligands. Our results show that all primary sarcoma cell lines express the inhibitory NKp44 ligand, PCNA, as well as CD112 and/or CD155, both of which are ligands for the NK cell activating receptor DNAM-1. However, NK cell cytotoxicity against sarcoma cells is still relatively low. Therefore, we generated a cell-based screening platform in which genetically modified (GM) NK cells that overexpress one activating receptor at a time are tested for degranulation against different sarcoma cell lines (n=12). Our results indicated patient-specific involvement of multiple NK cell receptors. In line with the conserved expression of CD112 and CD155 on sarcoma cells, we observed that DNAM-1+ GM-NK cells display significantly enhanced antitumor responses against all 12 cell lines when compared to wild-type (WT)-NK cells. We further confirmed that this enhanced NK cell response was indeed DNAM-1-dependent by interfering with the CD155/DNAM-1 interaction using blocking antibodies targeting either the receptor or its ligand. Additionally, the response of DNAM-1+ versus WT-NK cells was tested against various cancer cell lines, including those derived from a metastatic prostate carcinoma (LNCaP), primary pancreatic ductal adenocarcinoma (Capan-2), primary colorectal adenocarcinoma (Caco-2), primary lung alveolar basal epithelial adenocarcinoma (A549), metastatic neuroblastoma (SH-Sy5y), metastatic nerve sheath tumor (SNF02.2), two melanomas (A375 and DM6), and two leukemias (K562 and THP-1). In conclusion, DNAM-1 overexpression elicited a dynamic increase in NK cell degranulation against all cancer cell lines tested, including those that failed to induce a notable response in WT-NK cells, supporting the broad potential applicability of the DNAM-1+ GM-NK cells for the treatment of several malignancies. Furthermore, tumors expressing CD112 and/or CD155 can be targeted by DNAM-1+ GM-NK cells, and our GM NK cell screening platform can be used for rapid screening against not only sarcomas but also several cancers.
Citation Format: Ece C. Sayitoglu, Michael Chrobok, Anna-Maria Georgoudaki, Benjamin J. Josey, Michelle Hartman, Esha Vallabhaneni, Rajeev Herekar, Savannah Bergeron, Robin Krueger, Tolga Sutlu, Evren Alici, Harry T. Temple, Adil D. Duru. Natural killer cells genetically modified to overexpress DNAM-1 exert enhanced antitumor responses against CD112/CD155+ sarcomas and other malignancies [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr A55.