Cetuximab Enhances the Efficacy of MRTX1133, a Novel KRAS Inhibitor, in Colorectal Cancer Treatment.

Background/aim: Kirsten Rat Sarcoma viral oncogene homolog (KRAS) has remained undruggable for decades. KRAS has predominantly been used to evaluate the applicability of anti-Epidermal Growth Factor Receptor (EGFR) antibody drugs. However, various KRAS inhibitors have recently emerged. Unfortunately, KRAS inhibitors have not been effective against colorectal cancer. Therefore, this study aimed to determine the effects of MRTX1133, a novel KRAS inhibitor, in combination with an anti-EGFR antibody, cetuximab, on signal transduction and cell proliferation.

Materials And Methods: The KRAS-mutated LS513 and KRAS wild-type CACO-2 human colon cancer cell lines were utilized. The KRAS mutation was stably transduced into the CACO-2 cells using a retrovirus. We evaluated the effects of the drugs using the CCK-8 assay and assessed the activity of proteins related to the MAPK pathway using western blotting.

Results: We demonstrated that the administration of MRTX1133, a novel KRAS inhibitor, to KRAS-mutated colorectal cancer cells led to feedback activation of the ERK pathway via EGFR activation, inducing drug resistance. Intriguingly, when MRTX1133 was used in combination with cetuximab, KRAS-mutant colorectal cancer growth was effectively inhibited, both in vitro and in vivo.

Conclusion: The combination of MRTX1133 and cetuximab serves as a potential and promising therapeutic approach for colorectal cancer with KRAS mutation. KRAS is a frequent genetic mutation not only in colorectal cancer, but also in pancreatic and lung cancer, and the results of this study open new avenues for potential treatment of many cancer patients.