Abstract 1932: Overcoming acquired resistance to KRAS(G12D) inhibition using a KRAS-HSP90 hetero-bifunctional small molecule therapeutic agent

Abstract KRAS mutations are highly prevalent across many different cancer types. Recent advancements in KRAS-targeted drugs, such as the FDA-approved KRAS(G12C) inhibitors sotorasib and adagrasib for NSCLC patients, have shown great promise in the clinic. Nonetheless, these new agents fail to address other mutations, such as KRAS(G12D), which overall is the most common KRAS mutation in cancers, being found in 37% of pancreatic ductal adenocarcinomas, 12.5% of colorectal cancers and 4.9% of lung adenocarcinomas. Recently, MRTX1133 has been described as a selective, non-covalent inhibitor of KRAS(G12D) that shows promising preclinical efficacy and is undergoing clinical testing. However, based on prior clinical experience with sotorasib and adagrasib, acquired resistance to MRTX1133 may reasonably be anticipated. In fact, we find that KRAS(G12D)-mutated cell lines and a patient-derived organoid model exhibit varying degrees of inherent resistance to MRTX1133. To examine the consequences of blocking KRAS signaling, we employed a KRAS(G12D)-specific PROTAC, which simulated the effects of KRAS deletion. This demonstrated that receptor tyrosine kinase (RTK) activation could compensate for loss of KRAS signaling and was a key de novo resistance mechanism. This suggests that combination therapies may need to be individually tailored to treat patients resistant to KRAS(G12D)-targeted therapies. Additionally, we developed MRTX1133 resistant cells by culturing sensitive AsPC-1 pancreatic cancer cells in gradually increasing concentrations of the inhibitor. The resulting resistant cells displayed a complex RTK activation profile compared to parental cells. To counteract this, we employed KRAS(G12D)-CHAMP RNK08179, a hetero-bifunctional small molecule agent that simultaneously targets both KRAS(G12D) and HSP90, an RTK-regulating chaperone protein. RNK08179 effectively suppressed both KRAS signaling and RTK activation in MRTX1133-resistant cancer models, overcoming the compensatory resistance mechanisms observed with MRTX1133 alone. These findings highlight the potential of KRAS-CHAMPs as a novel, effective treatment strategy for KRAS-driven cancers, particularly those resistant to KRAS(G12D) inhibitors. Citation Format: Ines Pulido Endrino, Laura gunder, Qiyue Luan, Chenghao Ying, Zimo Yang, Jinhua Li, Yaya Wang, Yuetong Sun, Chuhe Liu, Yan Dai, Haoxin Zhou, Malek Massad, Ian Papautsky, Thomas L. Prince, Guoqiang Wang, Kevin P. Foley, Weiwen Ying. Overcoming acquired resistance to KRAS(G12D) inhibition using a KRAS-HSP90 hetero-bifunctional small molecule therapeutic agent [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(6_Suppl):Abstract nr 1932.