KRAS Secondary Mutations That Confer Acquired Resistance to KRAS G12C Inhibitors, Sotorasib and Adagrasib, and Overcoming Strategies: Insights From In Vitro Experiments

Abstract

Introduction: KRAS mutations have been recognized as undruggable for many years. Recently, novel KRAS G12C inhibitors, such as sotorasib and adagrasib, are being developed in clinical trials and have revealed promising results in metastatic NSCLC. Nevertheless, it is strongly anticipated that acquired resistance will limit their clinical use. In this study, we developed in vitro models of the KRAS G12C cancer, derived from resistant clones against sotorasib and adagrasib, and searched for secondary KRAS mutations as on-target resistance mechanisms to develop possible strategies to overcome such resistance.Methods: We chronically exposed Ba/F3 cells transduced with KRAS G12C to sotorasib or adagrasib in the presence of N-ethyl-N-nitrosourea and searched for secondary KRAS mutations. Strategies to overcome resistance were also investigated.Results: We generated 142 Ba/F3 clones resistant to either sotorasib or adagrasib, of which 124 (87%) harbored secondary KRAS mutations. There were 12 different secondary KRAS mutations. Y96D and Y96S were resistant to both inhibitors. A combination of novel SOS1 inhibitor, BI-3406, and trametinib had potent activity against this resistance. Although G13D, R68M, A59S and A59T, which were highly resistant to sotorasib, remained sensitive to adagrasib, Q99L was resistant to adagrasib but sensitive to sotorasib. Conclusions:We identified many secondary KRAS mutations causing resistance to sotorasib, adagrasib, or both, in vitro. The differential activities of these two inhibitors depending on the secondary mutations suggest sequential use in some cases. In addition, switching to BI-3406 plus trametinib might be a useful strategy to overcome acquired resistance owing to the secondary Y96D and Y96S mutations.

KRAS G12C Mutations in NSCLC: From Target to Resistance

“…An Important contribution to the understanding of resistance mechanisms was provided by Koga et al, [ 69 ] who generated 142 Ba/F3 clones resistant to either sotorasib or adagrasib. Thereof, 124 (87%) harboured secondary KRAS mutations, comprising 12 distinct KRAS mutations including Y96D/S, resistant to both inhibitors.…”

KRAS is vulnerable to reversible switch-II pocket engagement in cells

“…Furthermore, recent studies have identified secondary mutations in KRAS(G12C) cell lines responsible for acquired resistance to MRTX849 and AMG510 treatment in both clinic-derived tumor samples and in resistance mutagenesis experiments. 11,33,34 KRAS proteins with mutations at Y96 were found to be resistant to inhibition by both MRTX849 and AMG510, and proteins with mutations at H95 were found to be resistant to inhibition by MRTX849. These resistance studies further support interactions around H95 as critical to the binding of SII-P-targeted inhibitors.…”

Harnessing Carcinoma Cell Plasticity Mediated by TGF-β Signaling

“…KRAS mutation was found in over 30% of cancer patients and was thought to be “undruggable” until the KRAS G12C mutation was discovered with a new targeting pocket in the switch II domain of KRAS [ 123 , 124 ]. However, KRAS secondary mutations can also result in new resistance to KRAS G12C inhibitors that require further studies in this field [ 125 ].…”