An updated ASCO clinical practice guideline recommends the MammaPrint assay as an optional biomarker tool to help guide treatment for certain women with early-stage breast cancer.
MammaPrint (Agendia) — a 70-gene signature genomic test — may be used to guide decisions on whether to withhold adjuvant systemic chemotherapy among women with ER–positive or PR–positive, HER-2–negative, node-negative breast cancer who are at a high clinical risk for recurrence. The assay can identify women within this population who have a good prognosis and may not benefit from chemotherapy.
“Some women with breast cancer are more likely to have a recurrence of cancer and need to receive chemotherapy to lower this risk,” Vered Stearns, MD, co-director of the Breast and Ovarian Cancer Program at Sidney Kimmel Comprehensive Cancer Center, and co-chair of the expert panel that developed the guideline update, said in a press release. “The MammaPrint test can now be added to the list of tests that help clinicians identify women who need chemotherapy and those who do not.”
The expert panel reviewed the results of the phase 3 MINDACT study — the first prospective randomized controlled trial of a breast cancer recurrence genomic assay with level 1A clinical evidence — along with other published literature on the assay to determine its clinical usefulness.
The MINDACT trial compared MammaPrint with traditional clinical assessments in 6,693 women. Results showed the test accurately predicted which patients with early-stage breast cancer derived the most benefit from adjuvant chemotherapy, and its use appeared associated with a 14% reduction in chemotherapy prescription.
Other key recommendations of the update include:
MammaPrint may be used among women with ER– or PR–positive, HER-2–negative breast cancer with one to three positive lymph nodes who are at a high clinical risk for recurrence. However, patients should be informed that a benefit from chemotherapy cannot be excluded, especially among patients with more than one involved lymph node;
MammaPrint is not recommended for use in women who have a low clinical risk for recurrence; and
MammaPrint is not recommended for use among women with HER-2–positive tumors or triple-negative breast tumors.
Women in the two groups for whom the guidelines recommend MammaPrint as an option may receive hormone therapy alone if they have a low score.
“Certain women with a low-risk score on MammaPrint may not need chemotherapy and may be spared its side effects,” Ian Krop, MD, PhD, instructor in medicine at Dana-Farber Cancer Institute and assistant professor at Harvard Medical School, as well as co-chair of the expert panel, said in the release.
Due to the availability of several assays with clinical utility, more data are needed to assist clinicians in choosing exactly which assay is best for their patients, the panel noted.
“At this time, head-to-head comparisons of the different assays are limited,” the panel wrote. “Clinicians should choose a test that they are most comfortable with to guide treatment decisions.” – by Melinda Stevens
Disclosure: Krop reports employment or leadership role with and stock/other ownership in AMAG Pharmaceuticals; a consultant/advisory role with and research funding from Genentech; and other relationship with Novartis. Stearns reports research funding from AbbVie, Celgene Merck, MedImmune, Novartis, Pfizer and Puma Biotechnology. Please see the full guideline for a list of all other authors’ relevant financial disclosures.