Data from the FLEX Study demonstrate that MammaPrint High Risk 2, BluePrint Luminal B, is predictive of benefit from AC-T therapy, with a significantly higher 3-year IDFS rate than with TC therapy, alone.
• Higher 3-year IDFS for High Risk 2 patients treated with ACT-T than for TC-treated patients (100% vs 94.8%)
– At 4-years, IDFS for patients with High Risk 2 tumors was 99.2% with AC-T and 92.6% with TC alone
– High Risk 2 patients may benefit from the addition of doxorubicin to taxane/cyclophosphamide therapy
• No difference in 3-year IDFS rates for High Risk 1 patients treated with AC-T or TC (95.9% vs 95.9%)
– Potential opportunity to avoid added toxicities of anthracycline in High Risk 1, Luminal B patients
• Clinical and pathologic variables did not predict anthracycline benefit. A significant treatment-by-MammaPrint interaction demonstrated that AC-T benefit increased with higher genomic risk (adjusted HR 0.09; 95% CI 0.01 – 0.85, p=0.036)
O’Shaughnessy et al., JCO Precis Oncol. 2026
*Referenced with permission from the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) for Breast Cancer V.5.2026. © National Comprehensive Cancer Network, Inc. 2026. All rights reserved. Accessed August 17, 2026. To view the most recent and complete version of the guidelines, go online to NCCN.org. NCCN makes no warranties of a whatsoever regarding their content, use or application and disclaims any responsibility for their application or use in any way. ^This information is presented for HCPs to use their clinical judgment.
