FDA has approved on Tuesday a new genetic test called MammaPrint®, “that determines the likelihood of breast cancer returning within five to 10 years after a woman’s initial cancer.” According to the FDA, the test, a product of Agendia (Amsterdam, the Netherlands), is the first cleared product that profiles genetic activity.
The company explains how its technology looks at gene expression signature of breast CA genes, and calculates the prognosis for development of distant mets in lymph nodes of negative patients:
MammaPrint® is a DNA micro array-based in vitro diagnostic laboratory service that measures the activity of 70 genes, providing information about the likelihood of tumour recurrence. The MammaPrint® test measures the level of expression of each of these genes in a sample of a woman’s surgically-removed breast cancer tumour and then uses a specific formula or 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…
Central to the MammaPrint® technology is the use of DNA microarrays. A DNA microarray is a collection of tens of thousands of genes, printed onto a glass slide. Each spot on the slide contains a unique DNA fragment with a known sequence.
To assess the global gene expression pattern of a tumor sample, messenger RNA (mRNA) is extracted from the sample and labeled with a fluorescent dye, as shown on left. The labeled mRNA, together with the labeled mRNA from a reference sample, is hybridized to the DNA microarray.
After Agendia receives the fresh tumor sample:
Isolation of RNA from frozen tumor tissue DNAse treatment of isolated RNA Transcription into cDNA and then into cRNA Fluorescent-labeling of tumor and reference cRNA cRNA purification; hybridization of the cRNAs of tumor and reference sample to the MammaPrint® microarrayScanning the MammaPrint® microarray and data acquisition Calculation and determination of the risk of recurrence in breast cancer patients
Agendia uses customized microarrays, manufactured by Agilent. Each microarray contains three identical sets of the 70 genes to be analyzed. This enables three independent measurements of the 70-gene profile, increasing confidence in the test result.
In addition, the customized arrays contain several hundred carefully selected normalization genes. Finally, negative control genes are present on each microarray; these are DNA sequences to which no human mRNA can bind and are used to monitor various technical aspects of the microarray process.