RAS-ON inhibition overcomes clinical resistance to KRAS G12C-OFF covalent blockade

Abstract

Selective KRASG12C inhibitors have been developed to covalently lock the oncogene in the inactive GDP-bound state. Two of these molecules, sotorasib and adagrasib, are approved for the treatment of adult patients with KRASG12C-mutated previously treated advanced non-small cell lung cancer. Drug treatment imposes selective pressures leading to the outgrowth of drug-resistant variants. Mass sequencing from patients’ biopsies identified a number of acquired KRAS mutations -both in cis and in trans- in resistant tumors. We demonstrate here that disease progression in vivo can also occur due to adaptive mechanisms and increased KRAS-GTP loading. Using the preclinical tool tri-complex KRASG12C-selective covalent inhibitor, RMC-4998 (also known as RM-029), that targets the active GTP-bound (ON) state of the oncogene, we provide a proof-of-concept that the clinical stage KRASG12C(ON) inhibitor RMC-6291 alone or in combination with KRASG12C(OFF) drugs can be an alternative potential therapeutic strategy to circumvent resistance due to increased KRAS-GTP loading. KRAS G12C mutant selective inhibitors targeting inactive state have been approved for use in non-small cell lung cancer (NSCLC). Here, using models derived from a patient with NSCLC who progressed on sotorasib (KRAS G12C inhibitor), the authors identify increased KRAS GTP loading as an adaptive resistance mechanism which could be targeted with KRAS G12C inhibitors selective to the GTP active state.