Case/UHC/EXACT sciences researchers show positive impact of gene marker on DNA stool test

Researchers at Case Western Reserve University School of Medicine and the Ireland Cancer Center of University Hospitals of Cleveland report identifying a new DNA gene marker, vimentin, that was shown in a recent study to be three times more effective in detecting colon cancer than the standard doctor’s office test that detects blood in the stool. The study, appearing in the August 3, 2005 issue of the Journal of the National Cancer Institute, was conducted by a team also comprised of researchers with the Howard Hughes Medical Institute and from the Massachusetts biotechnology company, EXACT Sciences Corporation.

Through use of this single vimentin marker, the researchers were able to detect colon cancer in 46 percent of patients studied, compared with 15 percent for the standard fecal occult blood test. The vimentin marker was also very effective in detecting colon cancer in the early stages of development, when the disease is most curable.

The researchers targeted a gene called vimentin that usually does not play a role in normal colon cells, but serves as a marker for the development of colorectal cancer. The analysis, which was performed using vimentin alone and no other markers in the panel, relied on DNA extracted from stool samples of the participating patients. The analysis detected cancers in 43 of 94 patients (46 percent), and detected early stages of cancer in 26 out of 60 cases, or 43 percent of the time.

Although the analysis with vimentin picked up less than half of the colon cancers studied, the news is highly encouraging, according to Sanford Markowitz, M.D., Ph.D., the paper’s senior author, who said vimentin appears to be a powerful marker that could be used in combination with other DNA markers to dramatically increase the rate of detection. “We are now working with our collaborators at EXACT Sciences to combine vimentin with other DNA markers to see if we can develop a panel of tests that will ultimately detect 100 percent of colon cancers,” he said. Case recently licensed the vimentin marker to EXACT Sciences for exclusive use in future versions of EXACT’s technology that will focus on both adenoma and colorectal cancer detection.

Markowitz added that the current gold standard for colon cancer screening is the colonoscopy, where a scope with a camera allows a doctor to examine the interior of the colon. “But it is an invasive test that has not had universal public acceptance,” he said. “Molecular tests are non-invasive and could represent an alternative approach that could help facilitate mass screening for the 80 million Americans over age 50 who are at risk for colon cancer.”

He emphasizes that death from colon cancer is preventable by early detection. “Everyone should talk to their doctor about screening for colon cancer,” he said. “We hope that vimentin will be included in the near future as a powerful marker in a molecular panel for stool-based colon cancer screening and that it will further encourage mass screening. Nonetheless, please don’t wait until then to get screened.”