Drug sensitivity profile of minor KRAS mutations in colorectal cancer using mix culture assay: The effect of AMG-510, a novel KRAS G12C selective inhibitor, on colon cancer cells is markedly enhanced by the combined inhibition of MEK and BCL-XL.

Colorectal cancer with a Kirsten rat sarcoma 2 viral oncogene homolog (KRAS) gene mutation is considered to be resistant to anti-EGFR agents. G12D is the most common KRAS mutation in colorectal cancer, followed by G12V and G13D. According to clinical and basic research data, patients with colorectal cancer exhibiting G12D and G12V KRAS mutations are resistant to anti-EGFR agents; however, this is not true of G13D and other minor mutations, which are still not well understood. The current study focused on minor KRAS mutations (G12A, G12C, G12S, Q61H and A146T) and evaluated whether these were resistant to anti-EGFR antibodies using a mix culture assay. The results demonstrated that all KRAS mutations, including minor mutations, were resistant to two anti-EGFR agents: Cetuximab and panitumumab. The combined effect of MEK and BCL-XL inhibition on colorectal cancer cells with KRAS minor mutations were subsequently evaluated. The combined effect of MEK and BCL-XL inhibitors was confirmed in all KRAS minor mutations. The sensitivity of AMG510, a novel KRAS G12C selective inhibitor, was also assessed. The mix culture assay revealed that AMG510 selectively exerted an antitumor effect on colon cancer cells with a G12C KRAS mutation. The combination of MEK and BCL-XL inhibition markedly enhanced the effect of AMG510 in colon cancer cells. The current study suggested that AMG510 may have potential clinical use in combination with MEK and BCL-XL inhibitors in the treatment of patients with colorectal cancer exhibiting the G12C KRAS mutation.