SAN ANTONIO, Dec. 17 /PRNewswire-FirstCall/ -- Genomic Health, Inc. today announced the results of several studies looking at the roles and relationships of genes measured by the company's Oncotype DX breast cancer assay, including an analysis of more than 10,000 node-negative tumors indicating that all 21 genes impact the assessment of an individual woman's tumor. This research was presented at the 29th Annual San Antonio Breast Cancer Symposium.
Oncotype DX measures the expression of 16 cancer-related genes plus 5 reference genes of an individual tumor to generate a "Recurrence Score" to quantify risk of recurrence and likelihood of response to chemotherapy. To assess the degree to which components of this multi-gene assay influence the Recurrence Score, researchers measured expression of the 16 individual cancer genes relative to reference genes in 10,618 tumor specimens on a scale of 0 to 15, where a one-unit increment is associated with a twofold change in expression. Results suggest that every cancer gene used in the Oncotype DX 21-gene panel impacts the Recurrence Score due to the potentially large variation in quantitative expression for each gene in different patients. The study found this result even though expression of certain genes and gene families; including ER, HER2 and a group of five genes linked to proliferation, have the largest coefficients used in calculating the Recurrence Score.
"Our ongoing clinical work is generating an abundance of useful and important data, as evidenced by the collective findings presented in San Antonio," said Steven Shak, M.D., chief medical officer of Genomic Health. "With standardized quantitative measurements now analyzed in 20,000-plus tumor samples, Genomic Health has the unique opportunity to generate and share knowledge about the biology of breast cancer, which may lead to the development of more effective individualized treatment for breast cancer patients."
Study of 20,000 Samples Finds Heterogeneity in Three Breast Cancer Subtypes
A second study, conducted in the same cohort of 10,618 tumor samples plus an additional 9,432 samples analyzed recently for a total of 20,050 samples, used RT-PCR analysis as measured by Oncotype DX to identify the breast cancer subtypes revealed by a standardized quantitative expression assay. Three major subtypes of breast cancer were identified: patients with ER-positive and HER2-negative disease; those with HER2-positive disease; and those negative for ER, HER2 and the progesterone receptor (PR), or triple negative breast cancer. These three subtypes have been proposed previously, but the standardized quantitative Oncotype DX test revealed that there is significant heterogeneity within each subtype that is likely to be important for individualizing treatment. These results may help explain why patients with each subtype respond so differently to treatment, and underscore the importance of standardized measurement of gene expression as a clinical tool.
Study of 20,000 Samples Shows Proliferation Genes and Hormone Genes Provide Independent Assessment
In a third study using the same 20,050 tumor samples, Genomic Health investigators examined whether genes linked to proliferation were associated with hormone and growth factor receptors. The hormone receptor genes, ER and PR, as well as the HER2 growth factor receptor gene, are well-known markers for disease risk and treatment success; however, the analysis found that the expression of the proliferation genes was largely independent of the hormone and growth factor receptor genes. These results may explain why distinct contributions of multiple genes are required to characterize the biology and treatment of individual breast cancers.
Kaiser, NSABP Study Finds ER Predictive, PR Prognostic
Separately, Genomic Health, the Pittsburgh-based National Surgical Adjuvant Breast and Bowel Project (NSABP) and Kaiser Permanente presented findings from a study that assessed whether PR expression and ER expression were associated with disease prognosis or were predictive of response to adjuvant therapy with tamoxifen.
Researchers used Oncotype DX to measure the association between PR and ER expression and outcomes in more than 1,000 patients from two previously conducted Kaiser and NSABP studies. In both studies, expression of ER was associated with how a patient benefits from treatment with tamoxifen, but was not significantly associated with prognosis in untreated patients, indicating that it is a predictive factor. In contrast, these findings showed PR to be a characteristic of disease progression, or prognostic factor, but not predictive of benefit from tamoxifen. These results indicate that not all women with estrogen receptor-positive breast cancer benefit equally from tamoxifen.
"Over the years there have been conflicting reports about the relative roles of ER and PR as prognostic and/or predictive factors in breast cancer," said Norman Wolmark, M.D., chairman of the National Surgical Adjuvant Breast and Bowel Project (NSABP), and the Department of Human Oncology at Allegheny General Hospital in Pittsburgh, Pennsylvania. "Thanks to these findings, which suggest very distinct roles, we believe we can better chart how a woman's disease will progress and whether she's likely to respond to hormone therapy based on her individual quantitative PR and ER measurements."
About Oncotype DX
Oncotype DX represents the first diagnostic multi-gene expression test service commercially available that has clinical evidence validating its ability to predict the likelihood of breast cancer recurrence, the likelihood of patient survival within 10 years of diagnosis and the likelihood of chemotherapy benefit. Oncotype DX has been extensively evaluated in multiple independent studies involving more than 2,600 breast cancer patients, including a large validation study published in The New England Journal of Medicine and a chemotherapy benefit study published in the Journal of Clinical Oncology. For more information about Oncotype DX, please visit http://www.oncotypedx.com/ .
About Genomic Health
Genomic Health, Inc. is a life science company focused on the development and commercialization of genomic-based clinical laboratory services for cancer that allow physicians and patients to make individualized treatment decisions. In 2004, Genomic Health launched its first test service, Oncotype DX(TM), which has been shown to predict the likelihood of breast cancer recurrence and the likelihood of chemotherapy benefit in early-stage breast cancer patients. The company was founded in 2000 and is located in
Redwood City, California. For more information, please visit http://www.genomichealth.com/ .
Forward Looking Statements
This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, including statements relating to the conclusions suggested by research results, the continued usefulness and importance of data generated by ongoing clinical work, the potential for Genomic Health to develop more effective individualized treatments for breast cancer patients, the significance of various clinical outcomes and possible future uses for Oncotype DX, Genomic Health's expectations regarding additional studies and expansion of the clinical utility of Oncotype DX, its potential effect on clinical practice and treatment decisions for patients, and the applicability of clinical study results to actual outcomes. Forward-looking statements are subject to risks and uncertainties that could cause actual results to differ materially. These risks and uncertainties include the risks set forth in our Quarterly Report on Form 10-Q for the quarter ended September 30, 2006, which is on file with the Securities and Exchange Commission and is available on the SEC's website at http://www.sec.gov/. These forward-looking statements speak only as of the date hereof. We disclaim any obligation to update these forward-looking statements.
