RMC-7977

RMC-7977 is a highly selective inhibitor of the active GTP-bound forms of KRAS, HRAS, and NRAS, with affinity for both mutant and wild type (WT) variants (RAS(ON) multi-selective)3...Analysis of relapsed tumors identified Myc copy number gain as a prevalent candidate resistance mechanism, which could be overcome by combinatorial TEAD inhibition in vitro. Together, these data establish a strong preclinical rationale for the use of broad-spectrum RAS-GTP inhibition in the setting of PDAC and identify a promising candidate combination therapeutic regimen to overcome monotherapy resistance.

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). 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).

RMC-7977 is a potent, oral small molecule inhibitor of both wild-type and mutant GTP-bound RAS oncoproteins (RASMULTI) and is a preclinical tool compound representative of the clinical candidate RMC-6236, currently in clinical evaluation (NCT05379985)...Gilteritinib and the gilteritinib/venetoclax combination selected for survival of cells harboring NRAS mutations, but RMC-7977 inhibited outgrowth of all cell populations...In vivo studies investigating the tolerability and activity of RMC-7977 and RMC-7977 combinations in RAS mutant/FLT3i-resistant patient-derived xenograft models are ongoing and will be presented. Collectively, our data provide preclinical evidence that combination therapies leveraging RASMULTI(ON) inhibition are effective in suppressing RAS-mutant AML clones, a common mechanism of resistance to currently approved targeted therapies in AML and a current area of high unmet clinical need.