Navigation Links
Mayo Clinic research on tamoxifen leads to recommendation for CYP2D6 gene test
Date:12/13/2008

SAN ANTONIO - Findings from a new study have prompted Mayo Clinic researchers to recommend CYP2D6 gene testing for postmenopausal women about to begin tamoxifen therapy. This data confirms that women with an inherited deficiency in the CYP2D6 gene, which is important for the metabolism of tamoxifen, have a nearly fourfold higher risk of early breast cancer recurrence compared to women who have not inherited the deficiency. The research findings, announced jointly by investigators from Mayo Clinic and the Austrian Breast and Colorectal Cancer Study Group (ABCSG) confirmed results from a previous study conducted by Mayo Clinic.

VIDEO ALERT: Additional audio and video resources, including excerpts from an interview with Dr. Goetz describing the research, are available on the Mayo Clinic News Blog http://newsblog.mayoclinic.org/2008/12/11/gene-testing-may-be-key-for-treating-some-women-with-breast-cancer/, with password: sabcs08g.

The latest findings will be presented today at the Cancer Therapy & Research Center-American Association for Cancer Research (CTRC-AACR) 31st annual San Antonio Breast Cancer Symposium.

Tamoxifen, approved by the Food and Drug Administration (FDA) to both prevent development of estrogen-receptor-positive (ER+) breast cancer and as a therapy to stop ER+ breast cancer from coming back, is a "pro-drug"; it must be metabolized in the liver to become active. Mayo researchers had previously discovered that the drug is less effective in postmenopausal breast cancer patients who had a deficiency in the CYP2D6 gene, which is key for activating tamoxifen and many other drugs. However, until now, testing for the gene has not been done routinely at most medical centers.

"These new results validate our earlier findings," says the study's lead investigator, Matthew Goetz, M.D., an assistant professor of oncology and pharmacology at Mayo Clinic, "and strongly suggest that going forward, postmenopausal patients being considered for tamoxifen therapy should be tested for CYP2D6 before beginning therapy."

The research teams examined DNA from a subset of postmenopausal women treated in the ABCSG-8 study, which previously randomized nearly 3,900 women whose ER+ breast cancer had been surgically treated. One group was randomized to five years of tamoxifen therapy, and the other randomized to tamoxifen for two years followed by three years of anastrozole, an aromatase inhibitor. The initial results of ABCSG-8, reported in 2005, concluded that women who switched to anastrozole had a 40 percent reduced risk of breast cancer recurrence compared to staying on tamoxifen.

The aim of the new study was to determine whether CYP2D6 genetic variation would identify a subgroup of patients at higher risk of recurrence within the context of the ABCSG-8 trial. "Among the patients randomized to tamoxifen, poor metabolizers had a 3.8-fold increase in risk of developing breast cancer recurrence than extensive metabolizers across the five-year span," said Michael Gnant, M.D., professor of Surgery at the Medical University of Vienna, Austria, and president of ABCSG. "That is the key message coming out of this great collaboration between the Mayo Clinic team and the Austrian Breast and Colorectal Cancer Study Group."

However, the researchers also demonstrated that among patients who switched to anastrozole, there was no increased risk of breast cancer recurrence for CYP2D6 poor metabolizers in years three to five. The benefit of switching to anastrozole, says Dr. Goetz, may be most pronounced in the group of patients with deficient CYP2D6 metabolism. "Poor metabolizers who were fortunate to not develop breast cancer recurrence in the first two years of tamoxifen appear to be rescued by anastrozole," he says.

The findings reported by Mayo and ABCSG highlight the emerging science of pharmacogenomics. Researchers in this field are studying whether genetic differences in how patients metabolize or process drugs can be used to individualize therapy.

Additionally, in collaboration with bioTheranostics (a molecular diagnostics testing firm), the researchers examined whether a tumor-based test, HOXB13: IL17BR gene expression ratio, and a 5-gene molecular grade index were prognostic markers of distant breast cancer recurrence. Dr. Goetz and his colleagues confirmed that high expression of both HOXB13:IL17BR and molecular grade index, found in 25 percent of the tumors, led to a nearly threefold higher risk of recurrence elsewhere in the body compared to patients whose tumors were considered to be low risk according to these gene markers.

These findings suggest that the combined index will identify patients with early stage breast cancer who haveith a higher risk of distant metastases when treated only with hormonal therapy, the researchers say.


'/>"/>

Contact: Karl Oestreich
newsbureau@mayo.edu
507-284-5005
Mayo Clinic
Source:Eurekalert

Related biology news :

1. New book helps medical students master clinical skills
2. Biochemistry of human physiology in health and disease is focus of updated clinical text
3. Self-assembling nano-fiber gel delivers high concentrations of clinically approved drugs
4. A new journal where molecular biology meets clinical research
5. Prosthetic vein valve designed to direct blood flow shows promising pre-clinical results
6. Clinical trial for new tuberculosis vaccine
7. JDRF-funded clinical trial demonstrates continuous glucose monitoring improves blood sugar control
8. Building bridges between the clinic and the laboratory
9. New study spotlights National Institutes of Health grant outcomes for clinical research
10. NCI grant launches clinical trials for colon cancer screening
11. Florida researchers receive JDRF Excellence in Clinical Research Award
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:5/16/2017)... 16, 2017  Veratad Technologies, LLC ( www.veratad.com ), ... and identity verification solutions, announced today they will participate ... May 15 thru May 17, 2017, in ... Trade Center. Identity impacts the lives ... today,s quickly evolving digital world, defining identity is critical ...
(Date:4/18/2017)... April 18, 2017  Socionext Inc., a global expert in SoC-based ... edge server, the M820, which features the company,s hybrid codec technology. ... by Tera Probe, Inc., will be showcased during the upcoming Medtec ... show at the Las Vegas Convention Center ... Click here ...
(Date:4/11/2017)... DUBLIN , Apr. 11, 2017 Research ... Tracking Market 2017-2021" report to their offering. ... The global eye tracking market to grow at ... The report, Global Eye Tracking Market 2017-2021, has been prepared based ... report covers the market landscape and its growth prospects over the ...
Breaking Biology News(10 mins):
(Date:10/10/2017)... ... 10, 2017 , ... For the second time in three ... Mentoring Award. Representatives of the FirstHand program travelled to Washington, D.C. Tuesday, October ... US2020’s mission is to change the trajectory of STEM education in America by ...
(Date:10/10/2017)... ... October 10, 2017 , ... USDM Life Sciences ... the life sciences and healthcare industries, announces a presentation by Subbu Viswanathan and ... presentation, “Automating GxP Validation for Agile Cloud Platforms,” will present a revolutionary approach ...
(Date:10/9/2017)... Charlotte, N.C. (PRWEB) , ... October 09, 2017 , ... ... Purple announced Dr. Christopher Stubbs, a professor in Harvard University’s Departments of Physics and ... Dr. Stubbs was a member of the winning team for the 2015 Breakthrough Prize ...
(Date:10/7/2017)... ... October 06, 2017 , ... ... Hi-C metagenome deconvolution product, featuring the first commercially available Hi-C kit. Researchers ... perform Hi-C metagenome deconvolution using their own facilities, supplementing the company’s full-service ...
Breaking Biology Technology: