Abstract 2329: Disulfiram metabolite modulates NK and T cell cytotoxicity against metastatic colorectal cancer through tumor derived NKG2D ligands
Authors: Dumut Daciana Catalina , Frydrych Ivo , Popper Miroslav , Garic Dusan , Paun Radu Alexandru , Centorame Amanda , Canavan Olivia , Shah Juhi , Mistrik Martin , Dzubak Petr , Bartek Jiri , Hajduch Marian , DeSanctis Juan Bautista , Radzioch Danuta 
Published: April 2023

Abstract
Introduction: Colorectal cancer (CRC) is the second leading cause of cancer-related death worldwide, contributing to one million deaths yearly. While survival is expected in early-stage disease, the 5-year survival rate is only 15% in metastatic CRC (mCRC). Frequently patients develop resistance to their chemotherapy regimens resulting in CRC metastatic lesions to appear in the lungs, liver, and brain. In recent years, the development of immunotherapy has become a promising avenue for the treatment of cold-tumor environments such as CRC. Indeed, dense infiltration of lymphocytes in CRC correlates with longer patient survival. Thus, patients suffering from mCRC would benefit from the combination of classical chemotherapy/radiotherapy with small immunomodulatory molecules capable of overcoming cancer cell resistance to therapy through chemo- and radio-sensitization. Recently, Antabuse’s metabolite dithiocarb-copper complex (CuET) was found to have anti-cancer activity. Here, we report for the first time on the immunomodulatory properties of CuET in the context of T/NK cell antitumor response in mCRC.
Methods: To assess CuET anticancer activity in vitro, we performed survival curve, colony-formation, and migration-invasion assays in the murine colorectal cancer cell lines MC-38 and CT-26, and in the human KRAS mutant HCT116 cell line. We assessed in vivo efficacy of CuET in ectopic and metastatic MC-38 and CT-26 models in respective C57BL/6 and BALB/c mice. We characterized tumor growth, mice survival, and tumor immunohistochemistry. We evaluated CuET’s immunomodulatory properties through immunophenotyping of mouse and human T/NK cell receptors as well as corresponding tumor cell ligands after CuET treatment. We assessed CuET’s effect on the functional anticancer cytotoxicity of human PBMC-derived T/NK cells.
Results: In vitro, CuET significantly inhibits viability, clonogenicity, and migration of tumor cells MC-38, CT-26, and HCT116 with IC50 values in the nanomolar range. In vivo, systemic treatment with CuET significantly reduces tumor growth in mice and prolongs survival (p=0.0041) when compared to controls. CuET significantly inhibits MC-38 liver metastasis growth in C57BL/6 mice. CuET recruits macrophages and T lymphocytes inside tumor cores and induces apoptosis. CuET induces the expression of NKG2D activating receptors in NK and T lymphocytes, as well as the expression of the corresponding ligands MICA/B and ULBP1/2 on tumor cells, enhancing the T/NK cell cytotoxic response anticancer.
Conclusion: CuET enhances the functional antitumor cytotoxic activity of NK and T lymphocytes in mice and in human PBMC. In summary, our findings demonstrate that Antabuse-derived copper-diethyldithiocarbamate, CuET, is a potent immunomodulator which could benefit patients with mCRC.
Citation Format: Daciana Catalina Dumut, Ivo Frydrych, Miroslav Popper, Dusan Garic, Radu Alexandru Paun, Amanda Centorame, Olivia Canavan, Juhi Shah, Martin Mistrik, Petr Dzubak, Jiri Bartek, Marian Hajduch, Juan Bautista DeSanctis, Danuta Radzioch. Disulfiram metabolite modulates NK and T cell cytotoxicity against metastatic colorectal cancer through tumor derived NKG2D ligands [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 2329.