Press Release

A PDF of the release can be found here

Houston, TX, February 10, 2026 – Delphi Diagnostics today announced that clinical evidence presented at the 2025 San Antonio Breast Cancer Symposium (SABCS) continues to reinforce that the Endocrine Activity Index (EAI) provides meaningful insight into long-term outcomes and therapy response in patients with hormone receptor-positive, HER2-negative (HR+/HER2-) breast cancer across multiple independent cohorts and treatment settings.

Across three studies spanning Latin American, North American, and European patient populations, EAI consistently stratified prognosis and helped explain benefit from therapies, reinforcing its potential role in optimizing individualized treatment strategies.

Predicting Chemotherapy Regimen Effectiveness
Evidence from the PACS-01 trial, presented by Penault-Llorca et al., showed a significant predictive interaction between EAI and type of chemotherapy (6FEC vs 3FEC+3D) on distant recurrence-free interval (DRFI) in node-positive HR+ breast cancer patients. Tumors with high endocrine activity (score ≥1.5) derived no benefit from FEC plus Docetaxel vs FEC alone, and the 3FEC+3D regimen was less effective than 6FEC in this patient group.¹ Overall, these results provide further evidence on the ability of EAI to predict which patients benefit from taxanes in the HR+ population.

Prognostic Value in the Latin American Breast Cancer Cohort Study
In a multi-country Latin American cohort study led by Dr. Mazo Canola et al.², EAI Recurrence Risk (EAI_RR) was confirmed to be a strong predictor of disease-free survival (DFS) in HR+/HER2- breast cancer patients receiving adjuvant therapy. Patients with high EAI_RR demonstrated significantly longer DFS, independent of treatment type, tumor subtype, or traditional clinicopathologic factors. These findings confirm that EAI_RR’s prognostic information is valid in diverse patient populations.

Clarifying Treatment Benefit Beyond Prognosis
In an exploratory analysis from the PALLAS trial, Metzger et al. showed that intermediate levels of endocrine activity, as measured by EAI, were associated with improved invasive disease-free survival (iDFS) when palbociclib was added to endocrine therapy in patients who received prior adjuvant therapy containing paclitaxel compared to endocrine therapy alone.³
This is the first report of a biomarker-identified population that showed benefit from palbociclib in the PALLAS trial and highlights the potential for EAI to provide information that may allow for a more patient-specific approach to treatment decisions.

 “The data presented at SABCS 2025 further establishes the Endocrine Activity Index (EAI) as a diagnostic tool to inform treatment decisions in HR+/HER- breast cancer patients,” said Chief Medical Officer at Delphi Diagnostics, Federico A. Monzon, MD. “Across three independent datasets and multiple treatment contexts, EAI consistently identified biologic differences that translate into meaningful information for both patients and healthcare providers.”