Pharmacogenetics of colorectal cancer in a third-level hospital in Valencia.

Objectives: Genetic variants with associated pharmacokinetic and pharmacodynamic effects have an impact on the development of adverse drug reactions and survival of patients with colorectal cancer.

Methods: A selection of genetic variants was performed according to the established chemotherapy and the pharmacogenetic databases. Genotyping was performed using MassArray technology (Agena Bioscience). Variant-toxicity and survival-genotype correlations were assessed using logistic regression (SPSS v.28.0.1.1).

Results: Genotyping of 25 SNPs was performed in 96 patients. In relation to the DPYD gene, 3.5 % had the rs75017182 mutation; 4.7 % the rs1801158 mutation and 7.1 % the rs1801160 mutation. Genotypic frequencies in the UGT1A1 gene were 39.4 % (*1/*1); 37.9 % (*1/*28); 19.7 % (*28/*28); and 3 % (*1/*36). The genotypes CT of the rs1801160 variant, AT of the rs67376798 variant (DPYD) and *1/*36 (UGT1A1) were associated with low survival (p-value: 0.006, <0.001, and 0.052, respectively). The most frequent adverse reactions were gastrointestinal disorders, followed by neurotoxicity. The CC genotype (rs1801160, DPYD) was associated with a lower risk for developing severe gastrointestinal events, whereas CC (rs1801158, DPYD) was associated with a lower risk of developing severe general hematologic toxicity.

Conclusions: The population frequencies obtained in our study for rs1801160 and rs75017182 (DPYD); and for *1/*28, *28/*, and *1/*36 (UGT1A1) were inconsistent with the frequencies reported for the Spanish population in the literature. The genotypes CT of rs1801160, AT of rs67376798 (DPYD), and 1/*36 (UGT1A1) were associated with lower survival rates.