Hologic, Inc. and its subsidiary, Biotheranostics, Inc., have released new study data showing that the Breast Cancer Index test identified which premenopausal patients with early-stage, hormone-receptor positive (HR+) breast cancer benefited from the addition of ovarian function suppression (OFS) to primary adjuvant endocrine therapy. The Breast Cancer Index test is the first biomarker to be evaluated in a cohort from the landmark Suppression of Ovarian Function Trial (SOFT), according to the company. The translational study results were featured in the official press program at the 2022 San Antonio Breast Cancer Symposium (SABCS).1
“There is a significant need for biomarkers to aid in treatment decisions for premenopausal women with breast cancer. Our study presented at SABCS is the first to examine a biomarker’s ability to determine benefit of ovarian function suppression in these women,” says Ruth O’Regan, MD, chair of Medicine and Charles A. Dewey Professor at the University of Rochester. “These data found that the Breast Cancer Index test identified women who received benefit from ovarian function suppression as well as those who did not, which is incredibly important given the potential impact of this more intensive treatment approach in young women. While these data are promising, we look forward to further investigating the test’s utility to help inform ovarian function suppression treatment decisions in the future.”
The SOFT trial was an international, three-arm, non-blinded, randomized clinical trial of 3,066 premenopausal women with HR+ breast cancer. The trial demonstrated that the addition of OFS to five years of primary adjuvant endocrine therapy (either tamoxifen or exemestane) reduced the risk of recurrence compared to adjuvant tamoxifen alone.2 OFS typically involves hormonal drug injections with a gonadotropin-releasing hormone (GnRH) agonist or surgical removal of the ovaries (bilateral oophorectomy).3 In an effort to evaluate the potential of a biomarker to assist in patient selection for this more intensive approach, the new study presented at SABCS evaluated the predictive and prognostic ability of the Breast Cancer Index test in a cohort of patient tumor samples (n=1,717) from the SOFT trial. Notably, the patient characteristics in this retrospective translational study were highly representative of the original SOFT trial.
The data found that the Breast Cancer Index genomic assay identified which premenopausal women with early-stage, HR+ breast cancer benefited from more intensive endocrine therapy (exemestane plus OFS) compared to tamoxifen alone. The Breast Cancer Index test identified 58% of women who benefited from the addition of OFS, experiencing an absolute benefit of 11.6%, compared with 42% who did not benefit (p<0.01 in adjusted analysis). The data also found that the Breast Cancer Index test’s predictive performance was generally consistent across subgroups, including nodal status, prior chemotherapy, age and HER2-negative patients. Compared to the benefit shown with exemestane plus OFS versus tamoxifen alone, the benefit for tamoxifen plus OFS versus tamoxifen alone was smaller, which is consistent with data reported from the SOFT trial itself. The study also confirmed the prognostic value of the Breast Cancer Index test, as women with higher Breast Cancer Index test risk scores were more likely to experience disease recurrence.
“Multiple clinical studies and national oncology guidelines affirm the predictive ability of the Breast Cancer Index test for extended endocrine therapy,” says Kevin Thornal, group president, Global Diagnostic Solutions at Hologic. “These new data further establish the Breast Cancer Index test as a significant endocrine response biomarker and reveal additional predictive capabilities of the test. As we explore its predictive power earlier in a patient’s journey, we aim to uncover broader potential clinical utility in more women with early-stage, HR+ breast cancer.”
1. https://www.sabcs.org/Program/Schedule-at-a-Glance. Accessed November 10, 2022.
2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4341825/. Accessed November 10, 2022.
3.https://www.hopkinsmedicine.org/kimmel_cancer_center/cancers_we_treat/breast_cancer_program/treatment_and_services/survivorship/endocrine_therapy/premenopausal_women.html. Accessed November 10, 2022.
4. Referenced with permission from the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) for Breast Cancer V.4.2022. © National Comprehensive Cancer Network, Inc. 2022. All rights reserved. Accessed November 10, 2022. To view the most recent and complete version of the guideline, go online to NCCN.org. NCCN makes no warranties of any kind whatsoever regarding their content, use or application and disclaims any responsibility for their application or use in any way.