[Pharmacogenetics in oncology: 5-fluorouracil and the dihydropyrimidine dehydrogenase]

Dtsch Med Wochenschr. 2008 Jul;133(28-29):1501-4. doi: 10.1055/s-2008-1081098.
[Article in German]

Abstract

5-fluorouracil (5-FU) forms the basis for the chemotherapy of advanced colorectal cancer and of other solid tumours. About 9% of patients suffer from serious, sometimes even life-threatening adverse effects of a 5-FU therapy, such as haemotoxicity, which cannot be reliably predicted by conventional clinical and pharmacokinetic criteria. The systemic exposure to 5-FU is fundamentally determined by the genetically polymorphic enzyme dihydropyrimidine dehydrogenase (DPD). This deficiency is closely related to 5-FU-induced toxicity and a variety of non-synonymous variants has been detected in affected patients. The exon14-skipping mutation is the gene defect most frequently associated with serious 5-FU-related adverse effects and it has been reported ten times more often in affected individuals than in the general population. The 2846A>T polymorphism, which leads to an amino acid substitution, appears to be of comparable importance. While the causative role of premature stop codons - presumably resulting from spontaneous mutations - is very likely, the pathophysiological relevance of various other amino acid changes is still unclear. Patients who harbour a high-risk genotype should not be treated with 5-FU if therapeutic alternatives are available. The present data indicate that complete genotyping of the encoding DPYD gene is desirable, in the interest of drug safety, before treatment is started, although only a small number of patients would actually benefit. A method for the quantification of the DPD activity in vivo would have the advantage of reflecting all genetic and non-genetic influences.' However, no such method is currently available for routine use. Prospective genotyping for the exon 14-skipping and the 2846A>T-polymorphisms may result in a reduction of serious, 5-FU-induced, toxic events of about 25%. Cost-effective screening methods should enable the future implementation of DPYD genotyping in clinical routine.

Publication types

  • English Abstract
  • Review

MeSH terms

  • Amino Acid Substitution / genetics
  • Antimetabolites, Antineoplastic / adverse effects
  • Antimetabolites, Antineoplastic / metabolism
  • Antimetabolites, Antineoplastic / therapeutic use*
  • Dihydropyrimidine Dehydrogenase Deficiency
  • Dihydrouracil Dehydrogenase (NADP) / genetics*
  • Dihydrouracil Dehydrogenase (NADP) / metabolism
  • Exons / genetics
  • Fluorouracil / adverse effects
  • Fluorouracil / metabolism
  • Fluorouracil / therapeutic use*
  • Genotype
  • Humans
  • Mutation
  • Neoplasms / drug therapy*
  • Neoplasms / genetics*
  • Polymorphism, Genetic

Substances

  • Antimetabolites, Antineoplastic
  • Dihydrouracil Dehydrogenase (NADP)
  • Fluorouracil