Mayo researchers will present these findings at the 2005 American Society of Clinical Oncology (ASCO) Annual Meeting in Orlando, Fla. The three drugs involved in their investigation are irinotecan, oxaliplatin and capecitabine, and each is individually approved by the Food and Drug Administration (FDA) for the treatment of cancer.
"By using the genetic test prior to the start of chemotherapy, we demonstrated that you can put these drugs together safely," says Mayo Clinic medical oncologist Matthew Goetz, M.D., the study's lead investigator. Co-investigator and oncology researcher Matthew Ames, Ph.D., adds, "We defined different patient populations based on a specific genetic variant to provide a better understanding of how this three-drug regimen will affect individual patients."
Significance of the Mayo Clinic Research
Of the three drugs, irinotecan can be particularly toxic for some patients. Despite the antitumor benefit of each drug, researchers have had difficulty putting the drugs together because the toxicity can be lethal.
The genetic test detects a change in the DNA of a gene that encodes for a protein involved in the metabolism of irinotecan. The test gives scientists advance knowledge of the individual risk for toxicity from irinotecan. As a result, scientists are able to tailor this chemotherapy regimen to the individual, thus reducing toxicity. This kind of customized dosing approach based on a person's genetic makeup is known as "pharmacogenomics" and is the newest frontier of 21st century medicine.
"In the past, a physician knew that the genetic test could predict a higher risk for irinotecan-related toxicity," says Dr. Goet