In this study we use a novel, covalent tri-complex KRASG12C(ON) inhibitor, RM-029, which targets KRASG12C in the active state in combination with the SHP2 inhibitor RMC-4550 (both preclinical tool compounds), and studied their in vivo anti-tumor activity on transplantable KRAS-mutant lung cancer mouse models...In vitro, RM-029 exhibited higher potency for inhibition of cell viability than the KRASG12C(OFF) inhibitor MRTX849 in both human and murine NSCLC cell lines.