On August 12, 2025 Agendia, Inc., a leader in innovative genomic testing for breast cancer, reported the publication of new findings in JNCI Cancer Spectrum validating the predictive utility of the MammaPrint 70-gene assay for chemotherapy benefit in patients with hormone receptor-positive, HER2-negative (HR+HER2-) early-stage breast cancer (Press release, Agendia, AUG 12, 2025, View Source;Early-Breast-Cancer-Using-Real-World-Evidence-from-the-FLEX-Study [SID1234655152]). The peer-reviewed article, titled "MammaPrint Predicts Chemotherapy Benefit in HR+HER2- Early Breast Cancer: FLEX Registry Real-World Data," highlights how the MammaPrint Index predicts benefit from chemotherapy using a real-world, prospective, observational dataset.

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The findings are based on data from the ongoing FLEX Study (NCT03053193), a real-world data (RWD) study designed to collect whole transcriptome genomic data annotated with clinical data and outcomes from patients undergoing standard of care MammaPrint testing. This analysis included a propensity-score matched cohort of 1,002 patients with HR+HER2- breast cancer who received either chemotherapy with endocrine therapy or endocrine therapy only, with 5-year median follow-up. The results demonstrate that the MammaPrint Index is a strong continuous predictor of distant recurrence-free interval (DRFI) and chemotherapy benefit.

"This propensity-score matched population offers statistically robust evidence supporting the benefit of chemotherapy for patients with MammaPrint High Risk cancers. At the same time, it supports foundational results from MINDACT (NCT00433589) that showed no significant benefit of chemotherapy for patients with MammaPrint Low Risk breast cancer," said Adam Brufsky, MD, PhD, Professor of Medicine at UPMC and first author of the study. "These findings strengthen the evidence that MammaPrint is a chemopredictive comprehensive genomic test for guiding treatment decisions in early-stage breast cancer."

Key Findings:

The study showed that the MammaPrint Index was significantly predictive of 5-year DRFI for both endocrine therapy only (R²=0.99, p<0.001) and endocrine therapy + chemotherapy (R²=0.90, p<0.001).
Chemotherapy provided the greatest absolute benefit of up to 14.2% (average: 10.9%) to patients with MammaPrint High Risk 2 (H2) breast cancer, with an average 5.5% benefit for High Risk 1 (H1), and minimal benefit in Low or UltraLow Risk categories.
A multivariate Cox model confirmed a significant interaction between the MammaPrint Index and chemotherapy benefit (HR=0.15, p=0.047), independent of age, tumor stage, nodal status, or grade.
"This study marks a milestone in the large body of data supporting the predictive value of MammaPrint in breast cancer, and underscores Agendia’s commitment to providing robust, clinically actionable genomic insights that personalize care and improve outcomes for individuals diagnosed with breast cancer," said William Audeh, MD, MS, Chief Medical Officer at Agendia. "It also highlights the growing impact of the FLEX Study, which has now enrolled more than 20,000 breast cancer patients and continues to make meaningful contributions to the field of breast cancer research." The publication is available online in JNCI Cancer Spectrum.