Positive Results from Two Studies of the PAM50-Based In Vitro Diagnostic Assay will be Presented at the Annual IMPAKT Breast Cancer Conference

NanoString Technologies, Inc., a privately held provider of life science tools for translational research and molecular diagnostic products, today announced results from two studies that are featured in oral presentations this week at IMPAKT Breast Cancer Conference. The studies demonstrated that the Prosigna™ Breast Cancer Prognostic Gene Signature Assay can estimate risk of recurrence (ROR) between five and 10 years after diagnosis in postmenopausal women with hormone receptor-positive HR+, node-positive and node-negative early-stage breast cancer.

Despite recent improvements in breast cancer treatment, some women with HR+ early-stage breast cancer remain at risk of disease recurrence after remaining disease-free for the first five years following diagnosis. Identifying newly diagnosed women with HR+ breast cancer who are at highest risk of having their cancer recur between five and 10 years after diagnosis is a priority for oncologists seeking to help breast cancer patients make more informed treatment decisions. These patients may benefit by extending the duration of their adjuvant endocrine therapy. The presentations later this week are follow-on analyses of data from two large-scale clinical trials, and evidence that the Prosigna Breast Cancer Assay provides valuable information that assists with treatment decisions by identifying patients at highest risk of this late recurrence.

"The Prosigna ROR score can successfully assess the risk for late recurrence in patients with HR+ early-stage breast cancer, and may be used in the future to enable a more informed treatment decision related to the continued use of systemic endocrine therapy," said Dr. Michael Gnant, Professor at the Medical University of Vienna and President of the Austrian Breast & Colorectal Cancer Study Group.

"We are pleased with the positive results of these studies, as oncologists and women with early-stage breast cancer need an advanced diagnostic tool that better informs their treatment decisions," said Brad Gray, President and Chief Executive Officer of NanoString Technologies. "The study results that will be presented at the IMPAKT Breast Cancer Conference add to the mounting evidence supporting the Prosigna Breast Cancer Assay and its ability to inform treatment decisions for women with early-stage breast cancer."

Key Study Results Presented at IMPAKT Breast Cancer Conference:

Presentations: Best Abstract Session, Friday May 3rd at 10:45 AM in Gold Hall

In the study described in the abstract, "Predicting risk for late metastasis: The PAM50 risk of recurrence (ROR) score after 5 years of endocrine therapy in postmenopausal women with HR+ early-stage breast cancer: A study on 1,478 patients from the ABCSG8 trial," Dr. Michael Gnant and colleagues describe their finding that the ROR score provided by NanoString's Prosigna Breast Cancer Assay added prognostic information about the risk of late recurrence of breast cancer to the standard pathological variables in a study population including 1,478 postmenopausal women with estrogen receptor positive, node-positive and node-negative early-stage breast cancer (p<0.0001).  Patients categorized as low risk based on the Prosigna ROR score had Distant Recurrence Free Survival (DRFS) after year five of 98.7%, while patients with high ROR scores had DRFS after year five of 91.5%.

In the study described in the abstract, "Comparison of five different scores for the prediction of late recurrence for estrogen receptor positive breast cancer," Dr. Ivana Sestak and colleagues assessed and compared the value of five different prognostic scores for predicting distant recurrence in the first five years after diagnosis, and between five and 10 years after diagnosis, for all patients in the Arimidex, Tamoxifen, Alone or in Combination (ATAC) trial. In a multivariate analysis, the ROR score was one of only two genomic prognostic scores that provided additional prognostic information regarding risk of distant recurrence between five and 10 years.

About the Prosigna™ Breast Cancer Prognostic Gene Signature Assay

Prosigna assesses risk of recurrence (ROR) in postmenopausal women with early-stage hormone receptor positive (HR+) breast cancer. The Prosigna Assay has received a CE mark and is available for use by healthcare professionals in the European Union and Israel; it is not available in North America.

Based on the PAM50 gene signature initially discovered by Charles Perou, Ph.D. and colleagues, the Prosigna Assay provides a subtype classification based on the fundamental biology of an individual's breast tumor (referred to as intrinsic subtyping), and a prognostic score (referred to as the ROR score). The ROR score estimates the probability of cancer recurrence within 10 years in postmenopausal women with HR+ early-stage breast cancer who have been treated with endocrine therapy alone. The Prosigna Assay was validated in two clinical studies with more than 2,400 patient samples and results were presented at the 2011 and 2012 San Antonio Breast Cancer Symposiums.

The Prosigna Assay requires minimal hands-on time and can be offered in Europe and Israel through qualified pathology laboratories, empowering oncologists and pathologists to manage the diagnostic evaluation of breast cancer patients locally and using the laboratory infrastructure already in place. The Prosigna Assay runs on NanoString's proprietary nCounter Analysis system, which offers a simple, reproducible and cost-effective way to profile many genes simultaneously with high sensitivity and precision. The nCounter Analysis System is currently available for "Research Use Only" in North America.