Luminal B-type tumors in the highest risk category (H2)—as assessed by MammaPrint testing that were treated with taxane and cyclophosphamide—had a significantly worse recurrence-free interval (RFI) rate compared to luminal B-type tumors classified in a lower high-risk (H1) in patients with HR-positive HER2-negative early-stage breast cancer, according to recent research from the 2024 ASCO Annual Meeting. 

Patients with high-risk tumors as categorized by MammaPrint who had anthracycline added to taxane and cyclophosphamide treatment had comparable 3-year RFI rates to the H1 high-risk group that received taxane and cyclophosphamide. There were no significant between-group differences in 3-year RFI rates regardless of H1 or H2 risk status. 

The study authors suggested this research continued to demonstrate the significant benefits of anthracycline-based chemotherapy for treating H2 luminal B-type tumors,” Joyce O’Shaughnessy, MD, of Baylor University Medical Center in Dallas, and colleagues wrote in their study abstract. “Conversely, [MammaPrint] H1 tumors do not appear to benefit from the addition of anthracycline to [chemotherapy] regimen.” 

In the prospective, observational FLEX study, researchers analyzed 614 patients with HR+ HER2- stage I-III breast cancer and BluePrint molecular subtyping data for luminal B-type tumors who received chemotherapy and had follow-up data at 3 years. They used the patient’s MammaPrint score to group high-risk tumors into H1 and H2 categories, with H2 being a higher risk category that includes more estrogen-receptor positive and basal subtype tumors.  

The researchers found similar baseline characteristics among patients with H1 and H2 tumors regarding age, race, lymph node status, and menopausal status; however, patients with H2 tumors were more likely to have grade 3 tumors than patients in the H1 group. Overall, H1 tumors comprised 86% of the group (n = 530), while H2 tumors were 14% of the group (n = 84). 

Among patients who received added anthracycline to their chemotherapy, there were no significant differences in 3-year RFI rates between patients who had H1 tumors and H2 tumors. However, among patients who received taxane and cyclophosphamide without anthracycline, those with H2 tumors had significantly worse 3-year RFI rates compared with patients who had H1 tumors. 

“These FLEX data add to the growing evidence identifying MammaPrint as a comprehensive genomic signature regarding both prognosis as well as selection of systemic therapy for HR+ HER2- EBC patients.”  

- Joyce O’Shaughnessy, MD, co-chair of breast cancer research and chair of breast cancer prevention research at Baylor University Medical Center, Dallas. 

-- 

References: 

https://meetings.asco.org/abstracts-presentations/233538 

https://clinicaltrials.gov/study/NCT03053193 

https://agendia.com/agendia-research-shows-highest-risk-mammaprint-category-predicts-strongest-chemosensitivity-in-women-with-early-stage-hrher2-breast-cancer/ 

Disclosures: Authors declared financial ties to drugmakers. See full study for details. FLEX is being supported by Agendia. 

Disclaimer: Narration was created using Elevenlabs AI text-to-voice tools and reviewed by MD /alert editorial staff. 

Photo Credit: Getty Images. 

By Jeff Craven, MD /alert Contributor