Abstract 4604: Imipridones ONC201 and ONC212 exhibit anti-tumor activity in biliary tract cancers and synergy when combined with trametinib and olaparib in vitro

Abstract Background: Biliary tract cancers (BTCs) are an aggressive group of malignancies affecting 220, 000 new individuals globally each year. Despite advances in immunotherapy and targeted therapies, 5-year survival remains at 2% for those with metastatic disease. Thus, new therapies are desperately needed. The novel imipridone class of antineoplastic agents show promising activity in preclinical pancreatic ductal adenocarcinoma models; however, have not been investigated in BTC. Dordaviprone (ONC201) is a dopamine receptor D2 and mitochondrial protease ClpP modulator that induces apoptosis in cancer cells through both upregulation of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and the integrated stress response. ONC212 is a second-generation imipridone that targets orphan GPCR 132 and ClpP, leading to reduced oxidative phosphorylation from ClpX suppression. We hypothesized that the ONC201 and ONC212 would demonstrate antitumor effects in BTCs, both alone, and in combination with MEK and PARP inhibition. Methods: Two established BTC cell lines, RBE and HuCCT1, were used for these experiments. Sensitivity of RBE and HuCCT1 cells to ONC201, ONC212, MEK inhibition (trametinib), and PARP inhibition (olaparib) was assessed using CellTiter-Glo® luminescent cell viability assay. Each cell line was plated on 96-well plates and treated with ONC201 concentrations ranging from 0uM to 40uM for RBE and 0uM to 32uM for HuCCT1; ONC212 ranging from 0nM to 752nM for RBE and 0nM to 640nM for HuCCT1; trametinib ranging from 0nM to 24nM for RBE and 0nM to 16nM for HuCCT1; and olaparib ranging from 0uM to 256uM for RBE and 0uM to 124uM for HuCCT1. Results were analyzed after 72 hours of incubation. Synergy studies were conducted in both cell lines, combining each imipridone with either trametinib or olaparib, and SynergyFinder® was used to evaluate synergy. Western blotting was performed on lysates generated from treated cell lines. Results: Both ONC201 and ONC212 demonstrated antineoplastic effects in two BTC cell lines. Half maximal inhibitory concentrations (IC50) of ONC201 in RBE and HuCCT1 cell lines were 2. 5uM and 2. 0uM, respectively. The IC50 of ONC212 in RBE and HuCCT1 was 47nM and 39nM, respectively, which was similar to IC50s demonstrated with cytotoxic chemotherapy (gemcitabine IC50 = 7. 57nM (RBE) and 9. 84nM (HuCCT1) ). Both lines also demonstrated sensitivity to trametinib (IC50 = 5. 9nM (RBE) and 3. 7nM (HCCT1) ), and to a lesser extent olaparib (IC50 = 64uM (RBE) and 31uM (HuCCT1) ). Although synergy was noted with several combinations, this was most striking with the combination of ONC212 and either trametinib or olaparib. Further analysis of key signal transduction pathways, including MAPK and PI3K, as well as analysis of mechanisms of cell-death through apoptosis, autophagy, ferroptosis, and necroptosis is underway Citation Format: Grace Sun, Alexis J. Lannigan, Jasper Chan, Maximilian Schwermann, Varun V. Prabhu, Lanlan Zhou, Wafik S. El-Deiry, Alexander Grenander Raufi. Imipridones ONC201 and ONC212 exhibit anti-tumor activity in biliary tract cancers and synergy when combined with trametinib and olaparib in vitro abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 4604.