Abstract 1072: Combination of 5-Fluorouracil or ONC212 plus KRAS G12D inhibitor MRTX1133 against colorectal and pancreatic cancer cells results in immune-stimulatory cytokine patterns and unexpected synergies independent of G12D mutation
Authors: Tajiknia Vida , El-Deiry Wafik , Schwermann Maximilian Pinho , Zhou Lanlan , Huntington Kelsey 
Published: June 2023

Abstract
BACKGROUND: Advanced metastatic colorectal cancer (mCRC) has a 14% 5-year survival rate with little progress made for microsatellite stable tumors. KRAS mutations occur in about 40-50% of mCRC and are associated with more aggressive drug resistance and lack of response to anti-EGFR therapies. Recent advances have led to small molecules targeting KRAS G12C that have been undergoing clinical testing in lung, mCRC, and other tumor types. ONC212 is a fluorinated imipridone with strong anti-cancer activity in nM range and preclinical efficacy against pancreatic and other malignancies. Through extensive structure-based drug design, MRTX1133 was identified as a noncovalent, potent, and selective inhibitor of KRASG12D. MRTX1133 suppresses KRASG12D signaling in cells and in vivo, MRTX1133 binds to the switch II pocket and inhibits the protein-protein interactions necessary for activation of the KRAS pathway.
MATERIALS & METHODS: We investigated cell viability and drug synergies of 5-FU or ONC212 plus KRAS G12D inhibitor MRTX1133 in 6 human CRC and 4 human pancreatic cancer cell lines at 72 hours. Experiments evaluated drug effects on pERK using western blot at 6 and 24 hours. We evaluated changes at 48 hours in cytokine profiles in treated cells using a custom panel of 62 cytokines, chemokines, and growth factors associated with tumor growth, immune stimulation or immune suppression.
RESULTS: Colorectal and pancreatic cancer cell lines had IC50 sensitivities ranging from 7 to 12 microM for 5-FU 0.2-0.8 microM for ONC212, &gt;100 nM to &gt;5,000 nM for MRTX1133 (G12D N=4: LS513 &gt;100, HPAF-II &gt;1,000, SNUC2B &gt;5,000, PANC-1 &gt;5,000). For non-G12D, the range of IC50 for MRTX1133 was &gt;1,000 to &gt;5,000 nM for CRC lines with G12V, G13D, or WT KRAS (N=7). Synergies between MRTX1133 and either 5-FU or ONC212 were observed across cell lines regardless of the presence of KRAS G12D mutation with combination indices of &lt;0.5 indicating strong synergy. The observed synergy was greater with the combination of MRTX1133 and ONC212 compared to the synergy with 5-FU. Among the cytokine alterations, IL8/CXCL8, MICA, Angiopoietin 2, VEGF and TNF-alpha were reduced while IL-18/IL-1F4 increased with all treatments.
CONCLUSIONS: Our ongoing studies reveal the potential activity of MRTX1133 against mCRC and pancreatic cancer cells regardless of KRAS G12D mutation and synergies were observed with 5-FU and ONC212 regardless of KRAS G12D mutation. Immune stimulatory cytokine profiles were observed with 5-FU, MRTX1133 and combination. The results suggest that KRAS G12D, KRAS G13D and WT KRAS should not be excluded from clinical trials especially with combination therapies involving MRTX1133 and standard-of-care 5-FU.
Citation Format: Vida Tajiknia, Wafik El-Deiry, Maximilian Pinho Schwermann, Lanlan Zhou, Kelsey Huntington. Combination of 5-Fluorouracil or ONC212 plus KRAS G12D inhibitor MRTX1133 against colorectal and pancreatic cancer cells results in immune-stimulatory cytokine patterns and unexpected synergies independent of G12D mutation [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 1072.