MAMMAPRINT TEST

What is it?

MammaPrint is a 70-gene microarray test, which is used to assess the risk of metastases at an early stage of breast cancer with greater accuracy than is possible using conventional methods. MammaPrint reveals the activity (expression) of 70 specific genes in the tumor sample and compares the resulting gene expression profile to reference expression profiles of ‘Low Risk’ or ‘High Risk’ profiles. The risk of tumor recurrence is determined according to the degree of similarity between the tumor’s gene expression profile and reference profiles.

The test is typically performed on a tumor biopsy removed during surgery, which is placed in a special solution to preserve the RNA to be used in the laboratory analysis (see instruction video at bottom of this page). To prevent destruction of tumor RNA by RNases from the hands, it is important to wear gloves when handling tumor tissue. Undamaged tumor RNA is essential for a successful analysis. To ensure sufficient RNA for the analysis, the sample should be taken from a region clear of necrotic and stromal tissue as this reduces the number of tumor cells in the sample. The best area to perform the biopsy is at the periphery of the tumor; the centre of a tumor is often necrotic, while the edges of the tumor often contain many stromal cells. The tumor biopsy must be taken within one hour of surgery.

Sample collection kits with clear instructions on the procedure used are provided to participating clinicians. It is then shipped overnight to Agendia’s  ISO 17025 certified laboratory in The Netherlands where the test is performed under an export permit obtained from the South African Department of Health. The sample must arrive at Agendia within 7 days of sampling. In general, results will be available for the physician and pathologist within 10 working days after receiving a tumor biopsy.

When do I recommend it?

To be eligible for a MammaPrint test, a breast cancer patient should fulfill the following international criteria:

• Tumor size < 5.0 cm
• Up to 3 positive lymph nodes
• Stage 1 and Stage 2 invasive breast cancer
• ER+ or ER-
• Tamoxifen independent

Based on local experience, the selection criteria for testing has been redefined for breast cancer patients in South Africa. This has been incorporated into the Gknowmix Logic Engine in order to identify patients not eligible for testing at referral. This innovation represents a unique development in the application of pathology supported genetic testing aimed at the exclusion of inappropriate genetic testing and instant transformation of information pooled from different sources, into an informative report for surgeons and oncologists.

The TargetPrint test which determines Her2/neu, ER and PR  status, is offered free of charge together with the MammaPrint test.

Local experience of the MammaPrint service  in routine clinical practice led to the following quotes from opinion leaders in breast cancer:

“Genomics is now an established and frequently used tool in medical research, and particularly in the oncology field.  In breast cancer, genomics has led to a better understanding of the biology and to a molecular reclassification of the disease.” – Dr Rika Pienaar, GVI Oncology, Panorama Hospital, Cape Town, South Africa.

”With the help of MammaPrint one-in-three patients can be saved from chemotherapy. This is a major relief to patients with good prognosis as chemotherapy is the most dreaded part of breast cancer therapy.” – Prof  J Apffelstaedt, Faculty of Health Sciences, University of Stellenbosch, Tygerberg, South Africa.

What are its benefits?

MammaPrint adds a new quality of data to existing prognostic tools as it gives better insight into the biology of the patient’s breast cancer tumor. As the test allows a better distinction to be drawn between high and low-risk patients, it is possible to reduce the number of breast cancer patients who are treated with chemotherapy. This means an improvement in the quality of life of breast cancer patients and substantial cost saving. It helps clinicians to make the best-informed decisions based on a clear risk assessment for the recurrence of distant metastases in breast cancer patients.

European research has revealed that approximately fifty percent of chemotherapy treatments among breast cancer patients are later discovered to have been unnecessary. MammaPrint is available for all lymph node-negative (and 1-3 node) breast cancer patients and there is no treatment restriction. If there is a low risk of the patient’s cancer recurring, adjuvant therapy and the toxicity and other side-effects often associated with such treatment may be avoided. MammaPrint is used for prognostication and can not be used as a stand-alone predictive test in order to determine response to chemotherapy, patient treatment or to predict the outcome of disease.

FDA clearance in February 2007 has acted as a positive catalyst for reimbursement not only in the US, but also in Europe, Oceania, South Africa and Latin America.

Scientific rationale

There has been an extensive effort over the past three decades to develop effective cancer therapies. However, according to recent statistics the overall incidence and mortality of cancer are not decreasing. The high incidence of breast cancer, which kills about 400 000 women worldwide each year, is of special concern in South Africa where more than 4000 women are diagnosed with breast cancer every year. About 40% of them are predicted to die from the disease. Breast cancer is currently curable in about 70% of patients, but only if it is diagnosed at an early stage and treated adequately.

MammaPrint uses advanced molecular technology (microarray analysis) to predict whether a patient’s breast cancer will metastasize (spread to other parts of a patient's body). A low risk classification implies that the patient has a 95% chance of being metastasis-free within the following 5 years (90% within the following 10 years). Patients classified as “high risk” has a 78% chance of being metastasis-free within the following 5 years (71% within the following 10 years).

The use of MammaPrint as a prognostic indicator has been validated in three independent studies and is a much more accurate prognostic tool than traditional indicators such as NIH, St. Gallen and Adjuvant! Online, which show considerable discordance. Currently approximately 85% of breast cancer patients, identified with traditional prognostic algorithms as being high risk, receive chemotherapy.  MammaPrint  identifies only about 60% as high risk. Of the 15% patients with a good prognosis (and not needing chemotherapy) according to traditional prognostic algorithms, metastases developed in 24% of patients. In comparison, metastases only developed in 13% of the 40% good prognosis patients identified with MammaPrint with 96% overall survival rate (Van de Vijver et al. 2002). Prognostication with Mammaprint would therefore, by more accurately defining those who need adjuvant chemotherapy, save approximately 30% of patients with early breast cancer unnecessary chemotherapy.  

Age when first detected, type of cancer (ER-positive tumors are the most common), nodal status, hormonal treatment with tamoxifen alone or in combination with polychemotherapy and whether or not the ovaries are removed, are all factors which may play a significant role in cancer recurrence and survival. A MammaPrint validation study performed by the TransBIG group showed that each classical feature such as estrogen receptor (ER) status and tumor size loose their significance when compared with the gene profile. There is 30% discordance in ER reading between laboratories worldwide, hence resulting in contradicting outcomes with similar protocols and wrong conclusions. Analytical laboratory test validation for MammaPrint demonstrated greater than 99.9% agreement.

In February 2007 the U.S. Food and Drug Administration approved MammaPrint for clinical use to determine the likelihood of breast cancer recurring within 10 years after a woman's initial diagnosis.  "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.

The costs of unnecessary therapy and dealing with frequent side effects are serious economic considerations. For example, it has been estimated that approximately 60-80% of patients with node-negative breast cancer will be alive 10 years after initial treatment without adjuvant therapy. Even so, up to 58% of patients with node-negative breast cancer may develop recurrent disease and reduction of cancer recurrence in patients has been documented as a result of adjuvant chemotherapy or tamoxifen. In this situation, it becomes crucial to identify patients with node-negative breast cancer at highest risk for recurrence so that they may receive appropriate adjuvant therapy, while patients at lower risk can be spared the toxic effects and unnecessary expenditure can be avoided.

Research and collaboration with Agendia: Gknowmix is the exclusive distributor of MammaPrint® in Southern Africa and signed a collaborative agreement with the University of Stellenbosch, South Africa, to promote genome research innovation. A research protocol has been submitted for ethics approval to study the clinical utility of transcriptional profiling in the South African population in comparision with the use of conventional prognostic markers.

Agendia B.V., headquartered in Amsterdam in The Netherlands, provides innovative diagnostic testing for the treatment of cancer patients which is based on gene expression analysis. Agendia was established by researchers from the Netherlands Cancer Institute. MammaPrint® forms a new category of molecular diagnostic test (the In Vitro Diagnostic Multivariate Index Assays (IVDMIA)), and was the first to be approved by the US Food and Drug Administration (FDA) for use in the diagnosis and prognosis of breast cancer. Time Magazine proclaimed MammaPrint® to be one of the best discoveries of 2007 in the area of healthcare.


References
Buyse M, Loi S, van’t Veer L, et al. Validation and Clinical Utility of a 70-Gene Prognostic Signature for Women With Node-Negative Breast Cancer. Journal of the National Cancer Institute, 17, 1183-1192, 2006.

Cleator S and Ashworth A, Molecular profiling of breast cancer: clinical implications. Br J Cancer 90:1120-1124, 2004.

Early Breast Cancer Trialists’ Collaborative Group (EBCTCG). Effects of chemotherapy and hormonal therapy for early breast cancer on recurrence and 15-year survival: an overview of the randomised trials. Lancet 2005; 365: 1687–1717.

Kotze MJ, Malan J, Pienaar R, Apffelstaedt J. The role of molecular genetic testing in modern breast health management. SA Fam Pract 2005; 47 (9): 38-40.

Van de Vijver MJ, He YD, van’t Veer LJ, et al. A gene-expression signature as a predictor of survival in breast cancer. N Engl J Med 347:1999-2009, 2002.

Van ’t Veer LJ, Dai H, van de Vijver MJ, et al. Gene expression profiling predicts clinical outcome of breast cancer. Nature 415:530-6, 2002.

INSTRUCTIONS FOR TUMOUR BIOPSY COLLECTION

The video below illustrates how to take the sample for analysis using the MammaPrint Service. Please press the button on the left hand side to start the video. If you prefer to download the video directly to your computer, right-click on this link with your mouse and select Save Target As or Save Link As from the popup menu.