title: Genetic determinants of cancer drug efficacy and toxicity: practical considerations and perspectives.
abstract: Drug-metabolizing enzymes are responsible for the activation or detoxification of cytotoxic drugs. Allelic variants are present with a variable frequency in different populations around the world and have an important role in the therapeutic index of such drugs. It is known that polymorphisms in thiopurine methyltransferase and dihydropyrimidine dehydrogenase have been associated with altered drug metabolism and increased risk of severe toxicity from 6-mercaptopurine and 5-fluorouracil, respectively. Additionally, a variant number of dinucleotide-repeat sequences in the promotor for uridine 5'-diphosphate glucuronosyltransferase 1A1 influences the glucuronidation of SN-38, the active metabolite of irinotecan, which is associated with severe toxicity, including diarrhea and neutropenia. In the same way, polymorphisms in thymidylate synthase have been associated with pyrimidine-associated toxicity and also with response to chemotherapy. The examples shown in this review demonstrate the usefulness of pre-screening patients for well-characterized polymorphism to identify the best-tolerated and most-effective treatment.
authors.affiliation: Division of Clinical Research, Instituto Nacional de Cancerología, UNAM, Tlalpan, Mexico. myrnac@prodigy.net.mx
authors.forename: Myrna
authors.initials: M
authors.lastname: Candelaria
authors.forename: Lucia
authors.initials: L
authors.lastname: Taja-Chayeb
authors.forename: Claudia
authors.initials: C
authors.lastname: Arce-Salinas
authors.forename: Silvia
authors.initials: S
authors.lastname: Vidal-Millan
authors.forename: Alberto
authors.initials: A
authors.lastname: Serrano-Olvera
authors.forename: Alfonso
authors.initials: A
authors.lastname: Dueñas-Gonzalez
mesh_terms: D000970:Antineoplastic Agents / Q000009:adverse effects / Q000378:metabolism / Q000627:therapeutic use*; D003564:Cytidine Deaminase / Q000235:genetics / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D042943:Dihydrouracil Dehydrogenase (NADP) / Q000235:genetics / Q000378:metabolism; D004720:Endonucleases / Q000235:genetics / Q000378:metabolism; D014453:Glucuronosyltransferase / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008754:Methylenetetrahydrofolate Dehydrogenase (NADP) / Q000235:genetics; D008780:Methyltransferases / Q000235:genetics / Q000378:metabolism; D009369:Neoplasms / Q000188:drug therapy* / Q000235:genetics; D010597:Pharmacogenetics; D011110:Polymorphism, Genetic / Q000235:genetics; D020641:Polymorphism, Single Nucleotide / Q000235:genetics / Q000502:physiology; D013940:Thymidylate Synthase / Q000235:genetics / Q000378:metabolism; D016896:Treatment Outcome; D000099148:UGT1A1 Enzyme
chemical_list: D000970:Antineoplastic Agents; D003564:Cytidine Deaminase; D003577:Cytochrome P-450 Enzyme System; D004268:DNA-Binding Proteins; D042943:Dihydrouracil Dehydrogenase (NADP); D004720:Endonucleases; D014453:Glucuronosyltransferase; D008754:Methylenetetrahydrofolate Dehydrogenase (NADP); D008780:Methyltransferases; D013940:Thymidylate Synthase; D000099148:UGT1A1 Enzyme; C022745:thiopurine methyltransferase; C071447:ERCC1 protein, human