First prospective outcome data for the second-generation multigene test Endopredict in ER-positive/HER2-negative breast cancer.

PURPOSE: Prospectively collected outcome data of patients (pts) whose adjuvant systemic therapy recommendation was based on the clinico-molecular test EndoPredict® (EP) are presented. METHODS: Pts with ER-positive, HER2-negative early breast cancer with 0-3 positive lymph nodes were enrolled. The EP was carried out on all tumor samples. Pts were evaluated for treatment compliance, local recurrence, distant metastases and overall survival. Censored time-to-event outcomes were analysed by Cox proportional hazards models. Additional estimates of the event-free-survival were calculated by the Kaplan-Meier method. Hypothesis testing was conducted on two-sided exploratory 5% significance levels. RESULTS: 373 consecutive pts were enrolled. EP classified 238 pts (63.8%) as low risk and 135 pts (36.2%) as high risk. Median follow-up was 41.6 months. Risk for disease recurrence or death in EPclin high-risk patients was twofold higher in comparison with EPclin low-risk patients (hazard ratio (HR) 2.05 (95% CI 0.85-4.96; p = 0.110). Patients with EPclin high risk were at significant higher risk of distant metastases than patients with EPclin low risk (HR 5.18; 95% CI 1.04-25.74; p = 0.0443). EPclin high-risk patients who actually underwent adjuvant CTX had a 3-year-DFS of 96.3% (95% CI 92.2-100) in contrast to EPclin high-risk patients without CTX (3-year-DFS: 91.5% (95% CI 82.7-100%); HR 0.32; 95% CI 0.10-1.05; p = 0.061). CONCLUSION: These first prospective outcome results show that EP, in clinical routine, is a valid clinico-molecular test, to predict DFS and to guide decision of adjuvant CTX use in ER-positive, HER2-negative early breast cancer pts with 0-3 positive lymph nodes. Adjuvant CTX seems to be beneficial for EPclin high-risk patients.