Overview of Oncotype DX^® Data at the 2009 San Antonio Breast Cancer Symposium

At the recent SABCS, Genomic Health and our collaborators were pleased to present the results from five new studies on the Oncotype DX^® breast cancer test, demonstrating that the test continues to play an important role in treatment decision-making and that it benefits an expanding population of patients with early stage, hormone receptor-positive breast cancer.

Highlights from the five studies presented at the conference include:

1. Oncotype DX Predicts Anthracycline-Based Chemotherapy Benefit in Women with ER+, N+ Breast Cancer (Abstract 112)
   
   An analysis, presented as a late-breaking poster during a discussion on multigene assays, reinforced the conclusion that chemotherapy does not appear to benefit patients with either 1-3 or 4 or more positive nodes for disease-free survival over 10 years, if their tumors have a low Recurrence Score result. Researchers from Southwest Oncology Group (SWOG), a National Cancer Institute-supported clinical trials cooperative group, observed no breast cancer specific survival (BCSS) benefit from chemotherapy in either the low (log-rank p=0.56) or intermediate (log-rank p=0.89) Recurrence Score categories; however, chemotherapy resulted in superior BCSS in the high Recurrence Score category (log-rank p=0.033).
2. Oncotype DX Leads to Fewer Recommendations of Chemotherapy for Women with Node-Positive Breast Cancer (Abstract 2031)
   
   A multi-institutional clinical survey involving over 150 physicians who currently use Oncotype DX in node-positive breast cancer patients found that treatment recommendations frequently changed based on Recurrence Score results, with an overall reduction in chemotherapy treatment recommendations. In the 138 patients with node-positive, hormone receptor-positive breast cancer where the physician had a specific treatment recommendation before obtaining the Oncotype DX Recurrence Score, recommended treatment changed from hormonal therapy plus chemotherapy to hormonal therapy alone in 46 patients (33%), and from hormonal therapy alone to hormonal therapy plus chemotherapy in 13 patients (9%) after obtaining the Recurrence Score.
3. Oncotype DX Can Be Successfully Performed on Breast Cancer Core Biopsy Samples, Suggesting Potential Role in Neoadjuvant Treatment Planning (Abstract 6021 )
   
   Researchers presented results from a study examining pathology review and quantitative RT-PCR analysis by Oncotype DX on more than 11,000 core biopsy samples processed at the Genomic Health laboratory between July 15, 2005 and May 31, 2009. Physicians use core needle biopsies to obtain breast cancer tumor tissue without surgery for the purposes of diagnosis. Surgery, adjuvant, and neoadjuvant treatment decisions are based on the analysis of core needle biopsy tissue. The overall Oncotype DX success rate in overall biopsy samples was greater than 97 percent, demonstrating that RT-PCR analysis by Oncotype DX can successfully be performed on core biopsies that have been fixed and paraffin-embedded.
   
   Previous studies have shown the Recurrence Score result to be associated with the likelihood of response to neoadjuvant therapy^(i)(ii)(iii). Patients with a higher Recurrence Score result had a greater chance of experiencing a response from neoadjuvant chemotherapy while patients with a lower Recurrence Score appeared to be more likely to achieve a response from endocrine therapy. Genomic Health plans to further assess the role of Oncotype DX in the neoadjuvant setting through a number of ongoing clinical trials.
4. Exploratory Analysis of Gene Expression Identifies New Potential Therapeutic Targets, Biomarkers Associated with Recurrence (Abstract 5165)
   
   In another study, researchers analyzed 371 genes and compared expression levels between hormone receptor-positive breast cancer cases and hormone receptor-negative cases. A number of the genes tested exhibited significantly higher expression in hormone receptor-positive breast cancer and pathway analysis showed substantial interconnectivity among these genes. The analysis further revealed several pathways that exhibit higher expression in hormone receptor-positive disease – some of which were also associated with a higher risk of recurrence after chemohormonal therapy -- suggesting that they may be potential therapeutic targets and providing a rationale for evaluating both currently available and investigational agents that target these pathways.
5. Oncotype DX and FISH Testing Both Detect Amplified HER2 Expression with Extra Copies of Chromosome 17 (Abstract 6004)
   
   Genomic Health^® researchers presented results of a large retrospective case-control study assessing the diagnosis of HER2 status, by both fluorescent in situ hybridization (FISH) testing and quantitative RT-PCR by Oncotype DX, to explore the association between polysomy 17 (extra copies of chromosome 17, a condition found in breast cancer patients that can complicate the interpretation of HER2 testing results), HER2 status, and breast cancer death. Polysomy 17 was found in HER2-amplified tumors in approximately one-third of the cases. While differences were not statistically significant, HER2-positive patients with polysomy 17 tended to have a worse prognosis than other breast cancer patients. HER2 status assessed by quantitative RT-PCR using Oncotype DX is highly concordant with HER2 status assessed by FISH, and therefore is an alternative to FISH.

• (i) Chang JC, Makris A, Gutierrez MC, et al. Gene expression patterns in formalin-fixed, paraffin-embedded core biopsies predict docetaxel chemosensitivity in breast cancer patients. Breast Cancer Res Treat. 2008;108(2):233-240.
• (ii) Gianni L, Zambetti M, Clark K, et al. Gene expression profiles in paraffin-embedded core biopsy tissue predict response to chemotherapy in women with locally advanced breast cancer. J Clin Oncol. 2005;23(29):7265-7277. Epub 2005 Sep 6.
• (iii) Akashi-Tanaka S, Shimizu C, Masashi A, et al. 21-gene expression profile assay on core needle biopsies predicts responses to neoadjuvant endocrine therapy in breast cancer patients. The Breast 2009;18(3):171-174.