Discovery of novel mutations in the dihydropyrimidine dehydrogenase gene associated with toxicity of fluoropyrimidines and viewpoint on preemptive pharmacogenetic screening in patients.
BACKGROUND
Dihydropyrimidine dehydrogenase (DPD) is the initial and rate-limiting enzyme of the metabolic pathway of 5-fluorouracil (5-FU) and other fluoropyrimidines to inactive compounds. For this reason, severe, life-threatening toxicities may occur in patients with deficient DPD activity when administered standard doses of 5-FU and its prodrugs.


METHODS
We selected three patients with colorectal adenocarcinoma who displayed unexpected severe adverse reactions after treatment with 5-FU and capecitabine. To investigate the possible involvement of deficient variants of the DPD gene (DPYD), a denaturing HPLC (dHPLC) approach followed by target exon sequencing of DPYD was performed on DNA extracted from peripheral blood.


RESULTS
Three novel non-synonymous mutations of DPYD, c.2509-2510insC, c.1801G>C, and c.680G>A, were detected in these subjects. Due to the absence of other deficient variants of DPYD and the compatibility of adverse reactions with fluoropyrimidine treatment, the novel variants were associated with a poor-metabolizer phenotype.


CONCLUSIONS
Stratification of patients on the basis of their genotype may help prevent toxicity, and the large body of evidence about the pathogenesis of fluoropyrimidine-induced adverse reactions strongly encourages the adoption of best practice recommendations to appropriately address this important clinical issue. This approach is of utmost importance within a preventive, prognostic, and personalized approach to patient care in the oncology setting.
Division of Pharmacology, Department of Clinical and Experimental Medicine, University of Pisa, 55, Via Roma, 56126 Pisa, Italy.
Marzia
M
Del Re
Cytogenetics and Molecular Genetics Unit, University Hospital, Pisa, Italy.
Angela
A
Michelucci
Medical Oncology Unit, ASL4, Prato, Italy.
Angelo
A
Di Leo
Medical Oncology Unit, Azienda Ospedaliera Carlo Poma, Mantova, Italy.
Maurizio
M
Cantore
Medical Oncology Unit, Azienda Ospedaliera Garibaldi, Catania, Italy.
Roberto
R
Bordonaro
Cytogenetics and Molecular Genetics Unit, University Hospital, Pisa, Italy.
Paolo
P
Simi
Division of Pharmacology, Department of Clinical and Experimental Medicine, University of Pisa, 55, Via Roma, 56126 Pisa, Italy.
Romano
R
Danesi
Colorectal cancer; DPD; Fluoropyrimidines; Prediction, Personalization, Medicine; Toxicity