A saturation mutagenesis screen uncovers resistant and sensitizing secondary KRAS mutations to clinical KRAS G12C inhibitors

Abstract

Significance KRAS G12C inhibitors have demonstrated promising efficacy in non–small-cell lung cancer patients harboring the KRAS G12C mutation. However, the mechanism of resistance remains to be fully understood. To understand the consequences of single amino acid changes within KRAS G12C , we conducted a saturation mutagenesis screen of the KRAS G12C protein and assessed the mutational impact on drug sensitivity. Not only did our screen reveal resistant hits that were identified from patients’ samples (V8L, C12F, R68S, H95D, H95R, and Y96C), but we also discovered variants that sensitize the inhibition. Furthermore, we examined the human genetics databases and identified germline or somatic KRAS mutations that appear among the strong resistance hits. Our study positions future drug discovery targeting KRAS G12C toward focusing on inhibitors preserving potency against resistance mutations at key residues.