Abstract 319: Imipridone ONC212 and trametinib combination therapy demonstrates anti-neoplastic effects through immune-mediated mechanisms in pancreatic ductal adenocarcinoma cell lines
Authors: Raufi Alexander G. , Cruz Arielle De La , Carlsen Lindsey , Huntington Kelsey , Zhou Lanlan , Prabhu Varun , Allen Joshua , El-Deiry Wafik S. 
Published: June 2022

Abstract
Pancreatic ductal adenocarcinoma (PDAC) is characterized by limited therapeutic options and an extremely high mortality-to-incidence ratio. Chemotherapy remains the primary treatment for metastatic disease and results in only modest improvements in median overall survival, typically with significant toxicity. We previously reported a novel treatment approach with the combination of the imipridone ONC212 and the MEK inhibitor trametinib. This combination demonstrated synergy in multiple KRAS-mutated and KRAS wild-type pancreatic cancer cell lines (BxPC3, PANC1, HPAF-II, AsPC-1). Using Western Blot, we assessed markers of autophagy, including Beclin-1 and LC3B, as well as key second messenger pathway activation/suppression with p-AKT/AKT and p-ERK/ERK. The mechanism of this synergy appears to be heterogeneous, working through autophagy inhibition, MAPK/PI3K pathway perturbation, activation of the integrated stress response and increased cell surface expression of death receptor 5. Further investigation has revealed that ONC212 also appears to synergize with various autophagy inhibitors including hydroxychloroquine and chloroquine. We hypothesized that combining trametinib and ONC212 may also induce cell death in-part through immune cell-mediated mechanisms. To explore this, we performed immune cell co-culture experiments using HPAF-II PDAC cells and natural killer (NK-92) cells at a 1:1 effector-to-target cell ratio with or without ONC212, trametinib, or the combination of the two at different concentrations. We assessed the levels of NK cell mediated-tumor cell death 4, 8, and 24-hours after simultaneous treatment and initiation of co-culture using fluorescent microscopy. Compared to trametinib, ONC212 only treated co-culture showed greater NK cell-mediated tumor cell death. At 24-hours, we also observed an increase in NK cell-mediated killing of PDAC cells with dual treatment as compared to single agent alone or vehicle controls. Importantly, this combination did not appear to have any effect on NK or tumor cell viability. Thus, this combination may represent a potential therapeutic modality for PDAC and may hold promise if combined with immunotherapy. Further in vitro experiments will be conducted to evaluate the effect of ONC212, trametinib, and other autophagy inhibitors on the PDAC tumor microenvironment using a T cell co-culture system. Similarly, in vivo murine studies will also be performed to assess the translational potential of this combination.
Citation Format: Alexander G. Raufi, Arielle De La Cruz, Lindsey Carlsen, Kelsey Huntington, Lanlan Zhou, Varun Prabhu, Joshua Allen, Wafik S. El-Deiry. Imipridone ONC212 and trametinib combination therapy demonstrates anti-neoplastic effects through immune-mediated mechanisms in pancreatic ductal adenocarcinoma 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 319.