March 2007
The U.S. Food and Drug Administration (FDA) cleared for marketing a test that determines the likelihood of breast cancer returning within five to 10 years after a woman’s initial cancer. It is the first cleared molecular test that profiles genetic activity.
The MammaPrint test uses the latest in molecular technology to predict whether existing cancer will metastasize (spread to other parts of a patient’s body). The test relies on microarray analysis, a powerful tool for simultaneously studying the patterns of behavior of large numbers of genes in biological specimens.
The recurrence of cancer is partly dependent on the activation and suppression of certain genes located in the tumor. Prognostic tests like the MammaPrint can measure the activity of these genes, and thus help physicians understand their patients’ odds of the cancer spreading.
“Clearance of the MammaPrint test marks a step forward in the initiative to bring molecular-based medicine into current practice,” said Andrew C. von Eschenbach, M.D., Commissioner of Food and Drugs. “MammaPrint results will provide patients and physicians with more information about the prospects for the outcome of the disease. This information will support treatment decisions.”
Agendia compared the genetic profiles of a large number of women suffering from breast cancer and identified a set of 70 genes whose activity confers information about the likelihood of tumor recurrence. The MammaPrint test measures the level of activity of each of these genes in a sample of a woman’s surgically removed breast cancer tumor, then uses a specific formula, known as an algorithm, to produce a score that determines whether the patient is deemed low risk or high risk for spread of the cancer to another site. The result may help a doctor in planning appropriate follow-up for a patient when used with other clinical information and laboratory tests.
The MammaPrint is the first cleared in vitro diagnostic multivariate index assay (IVDMIA) device. Several months ago, FDA issued a draft guidance document concerning the need for these complex molecular tests to meet pre-market review and post-market device requirements even when the tests are developed and used by a single laboratory. Although FDA regulates diagnostic tests sold to laboratories, hospitals and physicians, it uses discretion when regulating tests developed and performed by single laboratories.
Prior to clearance, FDA requested evidence that the MammaPrint had been properly validated for its intended use. Agendia submitted data from a study using tumor samples and clinical data from 302 patients at five European centers. These studies confirmed that the test was useful in predicting time to distant metastasis in women who are under age 61 and in the two earliest stages of the disease (Stage I and Stage II) and who have tumor size equal to or less than five centimeters and no evidence that the cancer has spread to nearby lymph nodes (lymph node negative). FDA plans to publish a special controls guidance document describing types of data that should support claims for genetic profiling for breast cancer prognosis.
PHYSICIAN’S VIEWPOINT
Following are the comments of Jayanthi Srinivasiah, MD (Dr. Jay)
The current testing that has been approved, MammaPrint, looks at 70 different regulator genes for breast cancer, which can predict chances of recurrence in a distant site in women who have stage one and two breast cancers that are node negative and resected. Similar profiling assays like the Oncotype DX assay (21 gene profile assay) is currently available in the United States and is being evaluated in an an ongoing Taylor RX adjuvant clinical trial for Breast Cancers that are node negative and ER positive. [Jayanthi Srinivasiah] Both these tests and other similar gene profiling assays will hopefully avoid toxic therapies in the low risk subset of patients and help provide more aggressive and directed therapies for high risk patients. The mammaprint and oncotype DX are some of the prototypes of more sophisticated assays to come in the future. Evaluation of these and similar tests in clinical trial settings in conjunction with newer therapies would be exciting.
Dr. Jay is a physician with Georgia Cancer Specialists. She is board certified in Oncology and Hematology, has received several “Top Docs” awards nationally and locally, and was a cover story feature in M.D. NEWS’ December 2003 issue.
