5-fluorouracil toxicity in the treatment of colon cancer associated with the genetic polymorphism 2846 A>G (rs67376798).

Colorectal cancer is the second most common cancer in Europe. Most antineoplastic regimens in first-line treatment involve 5-fluorouracil or oral prodrug capecitabine, combined with other antineoplastic agents such as oxaliplatin or irinotecan. It is well known that 5-fluorouracil and capecitabine are agents that can be toxic in cases of decreased dihydropyrimidine dehydrogenase activity because this enzyme is the main limiting factor in the metabolism of both agents. In this paper, we describe the case of a patient who developed severe toxicity to 5-fluouracil and who had a mutation in the gene encoding the enzyme dihydropyrimidine dehydrogenase.

Validation of a fast and low-cost alkaline lysis method for gDNA extraction in a pharmacogenetic context.

PURPOSE: Translation of pharmacogenetic findings from the research laboratory to the clinical practice demands simple and efficient procedures. In this sense, we evaluated the suitability of a modified protocol for genomic DNA extraction based on alkaline lysis of cells. METHODS: Dried blood samples were obtained from 48 patients diagnosed with colorectal cancer. A total of 11 mutations in the dihydropyrimidine dehydrogenase gene and related to 5-fluorouracil toxicity were searched by amplicon sequencing and real-time PCR with fluorescent probes. RESULTS: Genomic DNA extracted with the alkaline lysis method, both from dried blood samples and buccal swabs, fulfilled the quality requirements of the two genotyping methods assayed, which yielded 100 % concordant results for 11 genetic variants with relevance to cancer chemotherapy. CONCLUSIONS: The assessed protocol has shown to be a very fast and economical approach to perform genetic analyses in the clinical laboratory for pharmacological purposes.