This analysis independently validated previous findings and further helps to establish EAI as the first genomic assay shown to predict benefit from a contemporary taxane-based chemotherapy regimen in HR+/HER2− breast cancer.

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HOUSTON, June 22, 2026 /PRNewswire/ — Delphi Diagnostics today announced the publication of findings from the GEICAM/9906 clinical trial demonstrating that the company’s Endocrine Activity Index (EAI) can identify patients with hormone receptor-positive, HER2-negative (HR+/HER2−) breast cancer who derive meaningful benefit from adjuvant chemotherapy containing weekly paclitaxel.

The study, published in Clinical Cancer Research, is titled “Sensitivity to endocrine therapy index predicts benefit from weekly adjuvant paclitaxel for hormone receptor-positive breast cancer in the GEICAM/9906 trial,” and was conducted by investigators from the GEICAM Spanish Breast Cancer Group and The University of Texas MD Anderson Cancer Center.

This prospective-retrospective analysis independently validated previous findings and further helps to establish EAI as the first genomic assay shown to predict benefit from a contemporary taxane-based chemotherapy regimen in HR+/HER2− breast cancer.

The study evaluated tumor samples and outcomes from patients enrolled in the landmark GEICAM/9906 randomized phase III trial. Investigators found that patients with very low endocrine activity, score of <0.75 as measured by EAI, experienced significantly improved distant recurrence-free outcomes when weekly paclitaxel was added to anthracycline-based chemotherapy. In contrast, patients with higher endocrine activity did not demonstrate additional benefit from paclitaxel treatment.

“This study represents an important milestone for precision oncology and provides independent confirmation that endocrine activity within an HR+/HER2- breast tumor can predict sensitivity to specific chemotherapy approaches,” said Federico A. Monzon, MD, Chief Medical Officer at Delphi Diagnostics. “These findings support the potential for EAI to help clinicians personalize treatment decisions and select chemotherapy regimens more likely to benefit individual patients.”

The results build upon previous clinical evidence and demonstrate reproducibility across two independent randomized clinical trials. Together, these studies suggest that EAI may provide oncologists with actionable information beyond traditional prognostic tests by helping determine not only whether chemotherapy should be considered, but which chemotherapy strategy is most likely to provide clinical benefit.

“Current genomic assays primarily estimate recurrence risk, but they generally do not predict which specific chemotherapy regimen will be most effective,” said Winz Casagrande, Chief Executive Officer, Delphi Diagnostics. “EAI represents a new generation of predictive biomarkers designed to guide treatment selection and help deliver more individualized care for patients with breast cancer.”

The GEICAM/9906 analysis showed that approximately 16% of HR+/HER2− tumors exhibited low endocrine activity and were associated with improved outcomes from weekly paclitaxel-containing therapy. The findings support the growing role of biologically informed treatment selection and may help reduce unnecessary exposure to treatments unlikely to provide benefit.

1. Martín M, Rodriguez-Lescure A, et. al. Sensitivity to endocrine therapy index predicts benefit from weekly adjuvant paclitaxel for hormone receptor-positive breast cancer in the GEICAM/9906 trial. Clin Cancer Res. 2026 May 26. doi: 10.1158/1078-0432.CCR-26-0177. Epub ahead of print. PMID: 42189890.

About EAI
Delphi Diagnostics’ Endocrine Activity Index® (EAI™) test can provide actionable information for prognosis and prediction of dose-intense taxane-based chemotherapy benefit in stage II-III, HR+ HER2- breast cancer. The EAI measures endocrine activity in a breast tumor, and for prognostic use, the Index Score is adjusted for baseline prognosis using molecular subtype genes (RNA4) and clinical factors such as tumor size and regional lymph node involvement. The EAI test has been shown in various studies to be a consistent prognostic indicator for long-term outcomes in stage II-III breast cancer patients, to be independent of other prognostic tests, as well as to be predictive for response to dose-intense chemotherapy.

About Delphi Diagnostics
Delphi Diagnostics Inc. is a Texas-based company focused on advancing clinically valid tests for the prognosis and prediction of breast cancer treatment. Delphi Diagnostics, Inc. holds an exclusive license from The University of Texas MD Anderson Cancer Center in Houston, TX to commercialize the Endocrine Activity Index, a technology that was developed by the laboratory of Dr. W. Fraser Symmans**. The Endocrine Activity Index (EAI) test measures endocrine activity in stage II-III, HR+HER2- breast cancer. Delphi’s vision is to make the EAI test available to breast cancer patients and open new pathways for personalized breast cancer treatment. To learn more, visit www.delphi-diagnostics.com.

**Dr. Symmans has a personal financial relationship with Delphi that has been identified as a conflict of interest with this research and is managed by MD Anderson’s Conflict of Interest Committee.

Media Contact:
Emily Granger
Delphi Diagnostics Inc.
egranger@delphi-diagnostics.com
508.341.9331

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SOURCE Delphi Diagnostics Inc