Genomic Health Identifies Genes Associated With Colon Cancer Recurrence

Genomic Health announced results of studies that have identified genes that could help predict the likelihood of recurrence and chemotherapy benefit for early-stage (stage II and III) colon cancer. The company is conducting detailed analyses of these studies to select a final gene set for a clinical assay to quantify the risk of recurrence and likelihood of chemotherapy benefit, which will be evaluated in an independent validation study.

Results of the studies were presented January 26, 2008 at ASCO GI, the American Society of Clinical Oncology's Gastrointestinal Cancers Symposium, in Orlando, Florida.

"These results allow us to conclude that quantitative gene expression using methods developed by Genomic Health can identify genes that may predict the likelihood of colon cancer recurrence and chemotherapy benefit," said Steven Shak, M.D., chief medical officer of Genomic Health. "This marks an important step in our effort to develop a test to personalize treatment decisions for early-stage colon cancer patients using the same rigorous clinical development and validation process as we did with Oncotype DX for breast cancer."

Both study reports used Genomic Health's quantitative RT-PCR to analyze RNA expression for 375 cancer-related and reference genes from colon tumors of patients who were treated with surgery alone or with surgery and adjuvant 5-fluorouracil/leucovorin (5-FU/LV) chemotherapy.

The first report evaluated colon cancers from patients treated with surgery alone, including 270 patients from the National Surgical Adjuvant Breast & Bowel Project (NSABP) C-01/C-02 study and 765 patients who were treated at the Cleveland Clinic. Researchers identified 65 genes significantly associated with colon cancer recurrence across both patient populations. The range of individual gene expression was associated with an up to 11-fold difference in risk of disease recurrence.

The second report analyzed colon cancers from an additional 508 patients who were treated with surgery plus 5-FU/LV chemotherapy in NSABP study C-06. Of the 375 genes, the researchers identified 56 that were significantly associated with disease prognosis for stage II and III colon cancer in this study as well as in patients treated with surgery alone in NSABP C-01/C-02 and at the Cleveland Clinic. Furthermore, the collaborators used 15 of the 56 genes as a preliminary model to stratify patients into recurrence risk categories.

Genomic Health has completed four independent studies involving 1,851 colon cancer patients to evaluate a total of 761 genes. These data will support the selection of the final gene set, which will undergo clinical validation of its utility in guiding treatment decisions with adjuvant 5-FU/LV chemotherapy.