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FDA Clears Dako’s FISH-Based Assay For High-Risk Breast Cancer Patients

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The US Food and Drug Administration this week cleared Dako’s topoisomerase 2 alpha fluorescent in situ hybridization-based assay kit, designed to assess the risk of tumor recurrence and long-term survival in high-risk breast cancer patients.
 
The FDA said the first-in-class kit, which is expected to be available in the US in April or May, is indicated for premenopausal women with breast cancer or those who have a tumor size or lymph node status suggesting cancer recurrence or decreased survival. The kit detects changes in the TOP2A gene and “may help health care providers decide best follow-up options,” the agency said in a statement.
 
“When used with other clinical information and laboratory tests, this test can provide healthcare professionals with additional insight on the likely clinical course for breast cancer patients,” Daniel Schultz, director of FDA’s Center for Devices and Radiological Health, said in a statement. “It can also provide valuable information to assist healthcare providers and patients in better understanding the biology of breast cancer disease.”
 
The test is the first FDA-approved device to test for the topoisomerase 2 alpha, or TOP2A, gene. Changes in the gene signal that a patient’s cancer might recur or that long-term survival will decrease.
 
Dako submitted the test, called TOP2A FISH pharmDx, for FDA approval two years ago. The diagnostic received CE marking in Europe last summer. 
 
The FDA approved the test based on data Dako submitted using tumor samples and clinical data from 767 patients with high-risk tumors, across 21 centers in Denmark. Samples were taken from chemotherapy-experienced Danish patients following tumor resection.
 
The study results showed that the test predicted time-to-local or -distant recurrence and overall survival in women receiving anthracycline-based chemotherapy regimens. According to a Dako spokesperson, 23 percent of these samples showed changes in TOP2A genes.  
 
In a separate study, presented during the 2006 annual meeting of the Association of Clinical Oncology, researchers from the Danish Breast Cancer Cooperative Group reported from a large adjuvant study of 962 pre- and postmenopausal high-risk breast cancer patients randomized to receive chemotherapeutic regimens comprising either cyclophosphamide,epirubicin and 5-fluorouracil, or cyclophosphamide, methotrexate,and 5-fluorouracil.
 
The researchers reported that Dako’s test successfully identified TOP2A gene status in 96 percent of the 806patients who gave genetic material. For the primary study endpoint — recurrence-free survival — “a significant predictive value of TOP2A gene amplifications was found.” The researchers noted a similar trend with TOP2A deletions.
 

According to an FDA spokesperson, the FISH-based test “is relatively straight forward” and the technology is “robust.”

“TOP2A gene aberrations were significantly associated with several established prognostic factors and had independent prognostic value associated with a significantly worse prognosis both for RFS and overall survival,” the researchers reported. “Additionally, patients with TOP2A-amplified tumors had a significantly betterrecurrence-free survival with anthracycline-based chemotherapy than patients witha normal status.”
 
An FDA spokesperson told Pharmacogenomics Reporter this week that Dako’s test “is relatively straightforward,” and characterized the technology as “robust.” The agency reviewed the safety and effectiveness of the test, “but the platform was not a factor in the agency’s decision” to approve the test, the FDA spokesperson said.
 
Dako also makes the FDA-approved HercepTest, an immunohistochemistry-based assay that measures HER2 overexpression in breast cancer tissue. In this market, Dako competes with Vysis’ FDA-approved FISH test PathVysion. The National Comprehensive Cancer Network updated its treatment guidelines in May 2003, stating that FISH may be more accurate than IHC.
 
According to Dako, in order to detect changes in the TOP2A genes, it chose to develop a FISH-based test since it is “the only technology that counts the number of gene copies” in cancer cells.
 
Although Dako currently has the only FDA-approved in vitro diagnostic for TOP2A testing in high-risk breast cancer patients, it is not alone in this market. Two non-FDA approved assays exist for this indication, according to the Dako spokesperson: One is a FISH-probe and the other product uses FISH and chromogen. It is not immediately clear which companies market these tests.
 
Dako plans to target breast cancer oncologists and pathologists with its own sales force, at scientific seminars, through advertising, through publication in scientific journals, as well as online and face-to-face educational programs.
 
Dako did not reveal what the test would cost.

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