Abstract IA-04: Targeting the oncogenic state of RAS with tri-complex inhibitors

Abstract KRAS oncogenic driver mutations occur in approximately 30% of all human cancers, and in particular, in over 90% of patients with pancreatic ductal adenocarcinoma (PDAC). Small molecule inhibitors that selectively target the inactive, GDP-bound state of KRAS G12C mutant proteins have demonstrated clinical efficacy in non-small cell lung cancer (NSCLC) as monotherapies, and in the small subset of PDAC patients that harbor this mutation. However, there are no currently approved RAS-targeted therapy options for the majority of patients with non-G12C RAS mutant PDAC. We have designed a series of tri-complex inhibitors that specifically target the GTP-bound, active state of RAS (RAS (ON) ). These small molecule inhibitors bind non-covalently to an abundant intracellular protein, cyclophilin A (CypA). The resulting binary complex selectively engages RAS (ON), forming a tri-complex that sterically inhibits RAS interaction with downstream effectors. We have generated mutant-selective inhibitors that covalently engage RAS (ON) G12C (RMC-6291) or RAS (ON) G12D (RMC-9805). In addition, RMC-6236 is a RAS (ON) multi-selective inhibitor that non-covalently inhibits the active, GTP-bound state of mutant and wild-type variants of the canonical RAS isoforms (KRAS, NRAS, and HRAS). Here we will describe the mechanism of action of these investigational agents and the preclinical profiles that support their clinical evaluation in patients with PDAC as monotherapies and in combination therapy regimens with standard-of-care agents or as novel RAS (ON) inhibitor doublets. Citation Format: Mallika Singh. Targeting the oncogenic state of RAS with tri-complex inhibitors abstract. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84 (17 Suppl₂): Abstract nr IA-04.