Abstract 1947: Studies on pMEK inhibitors for the treatment of RAS-mutant cancers as a single agent or combinations

Abstract RAS mutations are the most common oncogene in human cancers and KRAS has the highest frequency in non-small cell lung cancer (NSCLC) and pancreatic cancer (PDAC). KRAS G12C inhibitors have been approved to treat NSCLC patients. However, drug-resistance is eventually developed for these treatments. Preclinical studies suggested MAPK pathway reactivation is one possible mechanism. Among many MEK inhibitors in clinical development, CH5126766 binds to MEK1 inactive conformation and blocks its phosphorylation and activation. We believe this compound should prevent MAPK “paradoxical activation” commonly observed in most RAF and MEK inhibitors such as vemurafenib and cobimetinib. We studied this compound in various in vitro assays and found its potential in combating the paradoxical activation, which might be the cause of drug-resistance for MAPK signal pathway inhibitors, including RAS-, RAF- MEK- and ERK-inhibitors, as a single agent or in combination with above-mentioned inhibitors. In addition, we are developing a series of compounds based on CH5126766, by improving the inhibition of MEK1/2 kinase activity in addition to its activation. In summary, studies on the pMEK inhibitor demonstrated that this class of compounds might mitigate the MAPK pathway reactivation and prolong drug efficacies in clinical. Detailed research results will be discussed. Citation Format: Xiaobing Lv, Min Xu, Yong Hu, Lanjiao Zhao, Xiuquan Chen, Youqin Chen, Chen Yang, Jizhi Li, Chen Chen. Studies on pMEK inhibitors for the treatment of RAS-mutant cancers as a single agent or combinations 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 1947.