Abstract 1062: Antiproliferative activity of EC359, an inhibitor of leukemia inhibitory factor receptor (LIF-R), singly and in combination with chemotherapy drugs against pancreatic cancer cell lines

Abstract

Abstract Although combination chemotherapy treatments such as FOLFIRINOX (5-fluorouracil, oxaliplatin, irinotecan), gem-abraxane (gemcitabine and nab-paclitaxel) and GTX (gemcitabine, docetaxel and capecitabine) have improved survival of pancreatic cancer patients incrementally, 5-year-survival for this disease remains dismal. New and more effective treatments are needed. Pancreatic stellate cells (PSCs), a form of fibroblasts that comprise much of the pancreatic tumor microenvironment, interact with the cancer cells via the cytokine leukemia inhibitory factor (LIF) and its receptor, LIF-R. This interaction contributes to tumor progression, survival, and resistance to various therapies, and is an important target for novel therapy. A small molecule inhibitor of LIF-R, EC359, inhibits growth of breast cancer cell line tumor explants in mice (Mol Cancer Ther 18: 1341-1354, 2019) and potentially modulates the activity of gemcitabine against such explants (Genes Cancer 10: 1-10, 2019). Given the involvement of the LIF axis in pancreatic cancer, EC359 was tested for its ability to inhibit proliferation of the human pancreatic cancer cell lines PANC-1, Capan-1, and Capan-2, and its possible influence on activity of chemotherapy drugs against these cell lines. Five-day drug exposures were conducted in 96-well plates. Relative cell density determined using vital stains (alamarBlue©, neutral red) was reported as a percent of the fluorescence/absorbance of control cultures. The 3 cell lines exhibited different sensitivities to EC359, with IC50 values ranging from 5 nM (Capan-1) to 150 nM (Capan-2). When combined with anti-pancreatic cancer standard-of-care drugs, EC359 yielded synergistic interactions in a concentration-dependent manner. Depending on the cell line, EC359 decreased the IC50 value for oxaliplatin by as much as 83%. Such enhancements of cytotoxicity for other drugs were up to 84% for docetaxel, 67% for paclitaxel, and 50% for irinotecan. EC359 was also synergistic with IBR120 (a novel small molecule inhibitor of RAD51) against PANC-1 cells. EC359 additively inhibited proliferation in combination with irinotecan or 5-FUdR. The nanomolar activity of EC359 against pancreatic cancer cell lines makes it a good candidate for potential treatment of this generally refractory disease. The synergistic interaction of EC359 with standard-of-care drugs provides an opportunity for increasing the therapeutic index for these agents, and ultimately improving clinical outcomes for pancreatic cancer and other cancers against which EC359 is currently in clinical trial. Citation Format: Peter J. Ferguson, Hareesh Nair, Mark D. Vincent, James Koropatnick. Antiproliferative activity of EC359, an inhibitor of leukemia inhibitory factor receptor (LIF-R), singly and in combination with chemotherapy drugs against pancreatic cancer cell lines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1062.