NanoString's Prosigna Breast Cancer Assay can help identify node-positive early-stage breast cancer

NanoString Technologies, Inc., a privately held provider of life science tools for translational research and molecular diagnostic products, today announced new results from the combined data analysis of the Austrian Breast & Colorectal Cancer Study Group 8 (ABCSG-8) and Arimidex, Tamoxifen, Alone or in Combination (ATAC) studies. The results indicated that NanoString's Prosigna Breast Cancer Assay can be used to help identify node-positive early-stage breast cancer patients who are at low risk of recurrence. These data were presented during the Breast Cancer Oral Abstract Session at the 2013 Annual American Society of Clinical Oncology (ASCO) meeting on Sunday, June 2.

According to current treatment guidelines by the National Comprehensive Cancer Network (NCCN), postmenopausal women with node-positive hormone receptor positive (HR+) early-stage breast cancer should be considered high risk and should receive adjuvant chemotherapy in addition to five years of endocrine therapy. The results of both randomized clinical studies and meta-analyses suggest that a substantial portion of women with node-positive disease may be adequately treated with adjuvant endocrine therapy alone. However, identifying these low risk node-positive patients has been challenging due to the heterogeneity of the node-positive patient population, which includes patients with different numbers of positive lymph nodes and diverse tumor genomics.

The objective of the new study was to determine whether the risk score assessed by the Prosigna Assay provides additional prognostic information for risk of metastasis over and above standard clinical variables in patients with either one positive lymph node, or two to three positive lymph nodes. The authors of this new study concluded that the Prosigna Assay, which is based on the PAM50 gene signature, helped identify a subset of postmenopausal women with node-positive HR+ early-stage breast cancer, including patients with one positive node, as well as some with two positive nodes that had a low risk of recurrence. The authors concluded that identifying this subset of patients may help physicians assess treatment options, including whether the patients might be adequately treated with adjuvant endocrine therapy alone.

Dr. Michael Gnant of the Medical University of Vienna and the Austrian Breast & Colorectal Cancer Study Group presented the results. "Our results show that the Prosigna Assay, in addition to clinicopathological variables, can further segment women with node-positive breast cancer and help identify those with a low risk of metastasis. The Prosigna Assay may help their physicians consider the appropriate treatment regimen for those patients, including the possibility of treating them with adjuvant endocrine therapy alone."

These new findings were derived from the analysis of the combined data set and long term follow-up from 2,485 patients in the ABCSG-8 and ATAC studies. Patients in the combined data set were grouped into one of three categories based on the number of positive nodes.

Results of the analysis also indicated that the outputs of the Prosigna Assay, which include a risk score, a risk group based on the risk score, and an intrinsic subtype, add statistically significant prognostic information to that provided by the clinical and pathological variables in all groups. For node-positive patients, the risk score added prognostic information related to metastasis risk over and above the Clinical Treatment Score.

Of all the patients in the study with one positive node, 40 percent were categorized as low-risk based on their risk score and experienced an absolute 10-year risk of distant recurrence rate of 6.6 percent, while 71 percent were categorized as Luminal A subtype and experienced an absolute 10-year risk of distant recurrence of 8.4 percent. Separately, the analysis also demonstrated that patients with the Luminal A subtype have statistically significant different risk of metastasis than Luminal B.

"This study adds to the body of evidence supporting the value of our PAM50-based Prosigna Assay, by indicating that it may provide each breast cancer patient an assessment of her individual risk by taking into account both the specific number of her positive lymph nodes and the genomics of her tumor. This approach can help identify a substantial number of node-positive patients who have reduced risk and provide additional information to physicians about patient management strategies," said Brad Gray, President and CEO of NanoString Technologies.