Translating Research into Practice: the Prosigna® (PAM50) Gene Signature Assay

Gene expression analyses using DNA microarrays found that breast cancer tumors can be classified into 4 main subtypes: Luminal A, Luminal B, human epidermal growth factor receptor 2 (HER2)-enriched, and basal-like. These intrinsic subtypes differ in their relapse patterns. For example, Luminal A breast cancer is associated with a low risk of relapse, but the time frame for relapse can extend beyond 10 years. In basal-type disease, relapses typically occur within the first 5 years. The prediction analysis of microarray PAM50 gene set is the standard test used for identifying the gene expression–based intrinsic subtypes in breast cancer. Studies suggest that the PAM50 gene set assay can be used to help predict prognosis in metastatic breast cancer, risk of recurrence in estrogen receptor–positive patients, and benefit of chemotherapy. Multiple laboratory techniques can be used to quantify gene expression, including the nCounter system, which can be used to evaluate expression of multiple genes simultaneously and does not require signal amplification for detection. In the future, gene signatures may allow selection of specific chemotherapy agents for certain patients.