Diasio, Robert B.

Dihydropyrimidine dehydrogenase (DPD) is one of the factors that determine the efficacy and toxicity of 5-fluorouracil. Variations in DPD activity may result from alterations at the transcriptional level of the DPYD gene. Heterogeneity in DPYD expression has been reported, but the molecular mechanisms responsible for this remain unclear. We investigated methylation of the DPYD promoter as a mechanism for transcriptional regulation of DPYD in the RKO colorectal cancer cell line. We demonstrate that the active transcription machinery for DPYD is present in RKO cells, but promoter binding of Sp1, a transactivator of DPYD, was inhibited, which on subsequent examination was shown to be associated with dense promoter methylation. Treatment with 5-aza-2′-deoxycytidine alone or the combination of 5-aza-2′-deoxycytidine and trichostatin A induced demethylation of the promoter and markedly increased the DPYD mRNA level in RKO cells but not in unmethylated WiDr cells. Furthermore, in vitro methylation of the DPYD promoter decreased promoter activity. These data suggest an important role for methylation in DPYD suppression. The transcriptional suppression of DPYD by methylation may be responsible for the increased 5-fluorouracil sensitivity observed in some patients. This may also provide insight into the mechanism underlying the downregulation of DPYD in some colorectal cancers.

Emerging technologies have greatly expanded our ability to detect, characterize, and treat colorectal cancer. The Coalition of Cancer Cooperative Groups convened a multidisciplinary panel, the Scientific Leadership Council in GI cancer, to discuss and advise on the priorities and opportunities to advance current and future approaches into the clinical arena to impact most rapidly the morbidity and mortality from this disease. The Council's recommendations for research priorities are the result of engagement of community and academic oncologists, patient advocacy groups, and other stakeholders including the pharmaceutical industry and governmental agencies. We detail some key prospects for investigation in the areas of colon cancer detection, prevention, and surgical and medical management. Many are in early or definitive clinical trials, and a focus on rapid accrual is urged. The implementation of biology-directed laboratory investigations, both in association with ongoing clinical trials and as a separate developmental strategy for targeted therapies, is supported as the route to individualized therapy.

Learning ObjectivesAfter completing this course, the reader should be able to: Discuss recent progress in the treatment of patients with advanced colorectal cancer.Define the continuum-of-care approach and how it may differ from our current approach to the treatment of patients with advanced colorectal cancer.Identify key factors in treatment selection for patients with advanced colorectal cancer.Explain the impact of each active drug in the treatment of advanced colorectal cancer and the impact of treatment with multiple agents over the course of the disease.CME Access and take the CME test online and receive 1 AMA PRA Category 1 Credit™ at CME.TheOncologist.com