Genomic Breast Cancer Study Adds Real-World Evidence Across Diverse Patient Populations

Early-stage breast cancer treatment planning requires balancing recurrence risk, tumor biology, and the potential benefit of systemic therapy. These decisions can be challenging when certain patient groups are underrepresented in clinical research. Long-term real-world data from broader patient populations can help fill these evidence gaps by clarifying how genomic findings influence treatment selection and outcomes.

Agendia (Irvine, CA, USA) has now expanded its FLEX Study to more than 25,000 enrolled patients to generate additional evidence in this setting. The prospective, observational study links whole transcriptome profiling with complete clinical data in early-stage breast cancer. Its primary goal is to collect genomic and clinical data from at least 30,000 patients and follow them for up to 10 years.

FLEX incorporates MammaPrint and BluePrint testing into its data platform to connect genomic tumor characteristics with treatment patterns and long-term outcomes. MammaPrint is an FDA-cleared 70-gene expression profiling test that stratifies distant metastasis risk into UltraLow Risk, Low Risk, High Risk 1, and High Risk 2 categories. BluePrint is an 80-gene molecular subtyping assay that classifies tumors as Luminal-type, HER2-type, or Basal-type based on tumor biology beyond traditional immunohistochemistry.

As of July 2025, 12,354 FLEX participants, representing 54% of the cohort, had reached three years of follow-up, while 6,206 participants, or 27%, had reached five years. The study population includes 2,235 self-reported Black or African American patients, 2,125 Latin American or Hispanic patients, and 602 Asian American or Pacific Islander patients with early-stage breast cancer. FLEX also includes substantial representation of less common tumor histologies, including 2,981 invasive lobular carcinoma tumors and 853 tumors with mixed invasive lobular and ductal histology.

The expanding dataset has contributed to eight peer-reviewed publications and more than 66 international congress abstracts. In JNCI Cancer Spectrum on September 1, 2025, FLEX real-world data showed that MammaPrint risk categories predicted chemotherapy benefit in hormone receptor-positive, HER2-negative early-stage breast cancer, with High Risk 1 and High Risk 2 tumors associated with 5.5% and 10.9% greater benefit, respectively. 

Additional FLEX analyses published in JCO Precision Oncology in 2026 and npj Breast Cancer in 2026 examined anthracycline benefit and racial disparities across MammaPrint and BluePrint subtypes, further extending the study’s evaluation of how genomic classification relates to treatment response and outcomes across diverse patient groups.

“Reaching more than 25,000 patients is a meaningful milestone for FLEX and, most importantly, represents thousands of individual breast cancer journeys that are helping expand our understanding of the disease. By bringing together patients across a broad range of ages, ethnicities, genders and health statuses and connecting their tumor biology with treatment decisions and long-term outcomes, FLEX is helping generate the real-world evidence needed to make personalized breast cancer care a reality,” said Mark Straley, Chief Executive Officer.

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