KRAS inhibitor-18 (compound 3-10) is a potent KRAS G12C inhibitor with an IC 50 of 4.74 µM. KRAS inhibitor-18 shows p-ERK inhibition activities with IC 50 s of 66.4, 11.1 µM in MIA PaCA-2, A549 cells, respectively. KRAS inhibitor-18 has the potential for the research of pancreatic, colorectal, and lung cancers.