Nilufar Montazer

Abstract RAS oncogenes (collectively NRAS , HRAS and especially KRAS ) are among the most frequently mutated genes in cancer, with common driver mutations occurring at codons 12, 13 and 61 1 . Small molecule inhibitors of the KRAS(G12C) oncoprotein have demonstrated clinical efficacy in patients with multiple cancer types and have led to regulatory approvals for the treatment of non-small cell lung cancer 2,3 . Nevertheless, KRAS G12C mutations account for only around 15% of KRAS -mutated cancers 4,5 , and there are no approved KRAS inhibitors for the majority of patients with tumours containing other common KRAS mutations. Here we describe RMC-7977, a reversible, tri-complex RAS inhibitor with broad-spectrum activity for the active state of both mutant and wild-type KRAS, NRAS and HRAS variants (a RAS(ON) multi-selective inhibitor). Preclinically, RMC-7977 demonstrated potent activity against RAS-addicted tumours carrying various RAS genotypes, particularly against cancer models with KRAS codon 12 mutations ( KRAS G12X ). Treatment with RMC-7977 led to tumour regression and was well tolerated in diverse RAS-addicted preclinical cancer models. Additionally, RMC-7977 inhibited the growth of KRAS G12C cancer models that are resistant to KRAS(G12C) inhibitors owing to restoration of RAS pathway signalling. Thus, RAS(ON) multi-selective inhibitors can target multiple oncogenic and wild-type RAS isoforms and have the potential to treat a wide range of RAS-addicted cancers with high unmet clinical need. A related RAS(ON) multi-selective inhibitor, RMC-6236, is currently under clinical evaluation in patients with KRAS -mutant solid tumours (ClinicalTrials.gov identifier: NCT05379985).

Abstract Patients with advanced cancers harboring activating mutations in RAS, particularly those with non-small cell lung cancer, often develop brain metastases leading to increased morbidity and mortality. KRASG12V is the second most frequent RAS mutation in RAS-addicted cancers, including pancreatic cancer (34 %), colorectal cancer (21 %), and non-small cell lung cancer (19%). RMC-5127 is an orally bioavailable, mutant-selective tri-complex inhibitor of the GTP-bound (ON) form of RASG12V. RMC-5127 non-covalently binds to an abundant intracellular chaperone protein cyclophilin A (CypA), resulting in a binary complex that engages RASG12V(ON) to form a high-affinity tri-complex that sterically inhibits RAS binding to effectors. RMC-5127 drove deep suppression of RAS pathway activity, inhibited cell proliferation, and induced apoptosis in a panel of KRASG12V mutant human cancer cells in vitro but only caused submaximal inhibition in the panel of K/N/HRAS wildtype cancer cells, indicative of selectivity for KRASG12V over K/N/HRAS wildtype. Repeated oral dosing of RMC-5127 resulted in profound and durable anti-tumor activity in subcutaneous CDX and PDX models of KRASG12V mutant NSCLC, PDAC, and CRC in vivo. Dose-dependent exposure of RMC-5127 was observed in the whole brain of naïve mice, indicating the compound is brain penetrant. An intracranial xenograft model of KRASG12V tumors was established in immunodeficient mice to assess the CNS anti-tumor activity of RMC-5127. The intracranial tumor exposure of RMC-5127 was comparable with that observed in the whole brains of naïve mice and was sufficient to drive robust pharmacodynamic responses in the brain tumor. Moreover, RMC-5127 exhibited profound and durable anti-tumor activity in the intracranial model, with tumor regressions at well-tolerated doses. The anti-tumor activity of RMC-5127 in intracranial tumors was consistent with that in subcutaneous tumors at equivalent tumor exposures. In conclusion, these preclinical data demonstrate that RMC-5127 is a CNS-penetrant RASG12V(ON) inhibitor and support further study to determine the potential to benefit patients with advanced RASG12V-mutated cancers, including those that have developed or are at risk of developing brain metastases. Citation Format: Zhe Chen, Andre Eriksson, Bianca Lee, Jay Dinglasan, Nilufar Montazer, Jim Cregg, Anne Edwards, Kate Sanders, Jacqueline A. Smith, David Wildes, Mallika Singh, Zhican Wang, Jingjing Jiang. RMC-5127, a first-in-class, orally bioavailable mutant-selective RASG12V(ON) inhibitor is central nervous system (CNS)-penetrant and demonstrates anti-tumor activity in a preclinical intracranial xenograft model [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 3340.

Abstract The KRASG12V mutation is the second most common oncogenic RAS mutation and is frequently observed in pancreatic, lung, and colorectal cancers. Developing a selective inhibitor of KRASG12V presents significant drug discovery challenges. The intrinsic GTP hydrolysis rate of KRASG12V is about 12-fold lower than that of KRASG12C, further biasing the cellular KRASG12V pool to the active, GTP-bound (“RAS(ON)”) state and emphasizing the importance of targeting the KRASG12V(ON) state for maximal suppression of this oncogenic driver. Additionally, achieving selectivity over wild-type RAS with small molecules is difficult because the valine residue introduced by KRASG12V is neither amenable to covalent inhibition nor to formation of polar, non-covalent interactions. We have previously applied our tri-complex inhibitor platform, which uses chemical re-remodeling of the cellular chaperone cyclophilin A (CypA) in order to bind to undruggable surfaces, to design mutant-selective inhibitors targeting KRASG12C, KRASG13C, KRASG12D, and KRASQ61H, in addition to the RASMULTI inhibitor RMC-6236. Here, we describe RM-048, a potent, selective, and oral tri-complex inhibitor of KRASG12V(ON). RM-048 binds to CypA with high affinity to form a binary complex. Binding to CypA creates a neomorphic interface that forms a selective, high-affinity, non-covalent interaction with KRASG12V(ON). The resulting tri-complex sterically blocks effector binding to KRASG12V(ON), thereby inhibiting downstream signaling. RM-048 potently suppressed ERK phosphorylation and proliferation in KRASG12V mutant cancer cells. In preclinical species, RM-048 showed good bioavailability, dose-proportional exposure, and low clearance, allowing for oral dosing. In human xenograft tumors harboring KRASG12V mutations, a single dose of RM-048 induced dose-dependent, deep, and durable suppression of RAS pathway signaling in vivo. Repeated daily oral administration of RM-048 was well tolerated and demonstrated profound anti-tumor activity, driving tumor regressions across a panel of KRASG12V xenograft models, including NSCLC, PDAC, and CRC models. RM-048 complements the mutant-selective tri-complex KRAS(ON) inhibitors RMC-6291 (KRASG12C) and RMC-9805 (KRASG12D) by potentially providing a mutant-selective inhibitor option for patients with tumors harboring one of the most frequent RAS mutations. Preclinical combination studies with RAS companion inhibitors, including the RASMULTI inhibitor RMC-6236, are ongoing. Citation Format: Bianca J Lee, Jim Cregg, Anne Edwards, Jerry Chen, Andre Eriksson, Emily Tonogai, Aidan Tomlinson, Kyle Seamon, Mariela Moreno Ayala, Nataliya Tovbis Shifrin, Nilufar Montazer, Kate Sanders, Jun Huang, Kang-Jye Chou, Benjamin Madej, Yang Liu, Zhican Wang, Zhengping Wang, John Knox, Elena Koltun, Jingjing Jiang, Adrian Gill, Jacqueline A.M. Smith. Selective inhibition of the active state of KRASG12V with the non-covalent, tri-complex inhibitor RM-048 [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr B137.