Press Release

• The project will combine data from two key clinical trials to assess the value of the SET_2,3 assay in HR+/HER2− breast cancer patients with lymph node involvement.
• The aim of this collaboration is to advance the personalization of adjuvant treatment and improve therapeutic decision-making.
• The initiative brings together international experts and strengthens translational research in breast cancer.

A PDF of the release can be found here

Madrid, 23 June 2026.- GEICAM Spanish Breast Cancer Group, UNICANCER and the biotechnology company Delphi Diagnostics have announced a new international scientific collaboration to carry out a pooled analysis project of the sensitivity to endocrine therapy assay (SET_2,3), a molecular biomarker of growing relevance in breast cancer. SET_2,3 is known commercially as the Endocrine Activity Index Recurrence Risk (EAI_RR) and as SET_2,3for research purposes.

The study will integrate data from two landmark adjuvant clinical trials (GEICAM/9906 and UNICANCER’s PACS 01) to assess the clinical value of the SET_2,3 (EAI_RR) assay in patients with early breast cancer with hormone receptor-positive (HR+) and HER2-negative disease with lymph node involvement.

Advancing personalization of adjuvant treatment

The main objective of this pooled analysis is to determine whether the SET_2,3 (EAI_RR) assay, a gene-expression–based test, can help predict which patients derive greater benefit from different taxane-based chemotherapy strategies (paclitaxel versus docetaxel) in the adjuvant setting after surgery.

By integrating clinical and molecular data from both studies, the research aims to further clarify the prognostic and predictive value of this biomarker, as well as its potential to support more personalized therapeutic decisions in patients with early-stage breast cancer.

The SET_2,3 (EAI_RR) assay: a biomarker with clinical potential

The SET_2,3 (EAI_2,3) assay is a genomic index designed to measure endocrine-related transcriptional activity that analyzes the expression of multiple tumor-related genes. Its clinical utility is twofold: on the one hand, it helps estimate disease prognosis and, on the other, it provides information on which treatments may be more effective for each patient.

This biomarker was developed by Dr. W. Fraser Symmans of UT MD Anderson Cancer Center and has already shown promising results in previous analyses, including those conducted in the GEICAM/9906 and PACS 01 trials.

The added value of the pooled analysis

To date, the SET_2,3 (EAI_RR) assay has been evaluated independently in each of these breast cancer clinical trials: in PACS 01, in patients treated with docetaxel, and in GEICAM/9906, in patients treated with paclitaxel, along with other relevant trials such as SWOG S8814 or CALGB 9741.

GEICAM/9906 and PACS-01 studies have a very similar design, differing mainly in the taxane used in the experimental treatment arm. Pooling their data will enable analysis of a larger patient cohort, strengthen the robustness of the scientific evidence, and explore in greater depth the ability of the SET_2,3 (EAI_RR) assay to identify which treatment offers the greatest benefit in each case.

An international and multidisciplinary collaboration to advance precision oncology

The project brings together experts from leading international institutions, including Dr. Miguel Martín and Dr. Federico Rojo from GEICAM; Dr. Frédérique Penault-Llorca representing UNICANCER; and Dr. W. Fraser Symmans as scientific expert.

Funded by Delphi Diagnostics, this study leverages combined clinical and molecular insights from the participating cooperative groups. By unifying these datasets, the project seeks to amplify the collective impact of both trials, driving the scientific publications led by the newly formed consortium.

Scientific and clinical relevance

This initiative represents a significant step forward in translational research in breast cancer. In the future, its results could help improve prognostic precision in HR+ breast cancer, enable greater personalization of adjuvant chemotherapy, and identify which patients are most likely to benefit from specific taxane-based treatments.

About Unicancer

Unicancer is the only French hospital network entirely dedicated to the fight against cancer and the sole national hospital federation specialising in oncology. It brings together France’s 18 comprehensive cancer centres (CCCs) – private, non-profit institutions – as well as two affiliated members. A major player in research, Unicancer is the leading academic sponsor of clinical trials in oncology in Europe, with over 140 active trials, including 60 international studies, sponsored by Unicancer R&D. In addition, over 700 trials are sponsored by the CCCs. A pioneer in the use of health data, Unicancer has launched five real-world data programmes since 2014 through its Data and Partnerships Department, including ESME (109,000 patients), CANTO (over 13,000 patients) and OncoDataHub (ODH, over 60,000 patients). Every year, more than 600,000 patients benefit from the latest scientific, therapeutic and organisational advances in oncology, driven by an agile model combining excellence, humanism, solidarity and innovation. www.unicancer.fr

GEICAM Spanish Breast Cancer Research Group

Founded in 1995, GEICAM is a non-profit organization that leads academic breast cancer research in Spain. Over the past 30 years, it has conducted 187 studies involving more than 70,000 women and men. GEICAM brings together nearly 1,000 investigators from 231 Spanish and international hospitals and collaborates with 52 research centers worldwide. Its mission is to promote independent clinical, epidemiological, and translational research in oncology, using a multidisciplinary approach and quality standards, to improve health outcomes, as well as prevention, medical education, and the dissemination of knowledge about this disease to patients and society.

Visit our website at www.geicam.org

GEICAM Media Contact: Carolina Manrique Patrón
Communications, External Relations & Events Director
M: +34 699 066 206
cmanrique@geicam.org