No abstract

Colorectal cancer is a common disease, both in Chile and worldwide. The most widely used chemotherapy schemes are based on 5-fluorouracil (5FU) as the foundational drug. Genetic polymorphisms have emerged as potential predictive biomarkers of response to chemotherapy, but conclusive evidence is lacking. Additionally, the interplay between hereditary variations and acquired mutations in the EGFR pathway remains unknown. This study aimed to investigate the role of genetic variants associated with 5FU-based chemotherapy on therapeutic effectiveness, considering their interaction with the EGFR pathway mutations. In a retrospective cohort of 63 patients diagnosed with metastatic colorectal cancer, a multivariate analysis revealed that liver metastases, DPYD, ABCB1 and MTHFR polymorphisms are independent indicators of a poor prognostic, irrespective of EGFR pathway mutations. BRAF V600E wild-type status and high-risk drug-metabolism polymorphisms correlated with a poor prognosis in this Chilean cohort. Additionally, findings from the genomics of drug sensitivity (GDSC) project demonstrated that cell lines with wild-type BRAF have higher IC50 values for 5-FU compared to BRAF-mutated cell lines. In conclusion, the genetic polymorphisms DPYD rs1801265, ABCB1 rs1045642 and MTHFR rs180113 may serve as useful biomarkers for predicting a poor prognosis in patients undergoing 5-fluorouracil chemotherapy, regardless of EGFR pathway mutations.