First French Pilot Quality Assessment of the EndoPredict Test for Early Luminal Breast Carcinoma

Genomic signatures are needed for the determination of prognosis in patients with early stage, estrogen receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-negative breast cancers. EndoPredict test is a RNA-based multigene assay that assesses the risk of 10-year relapse in this context. Quality assessment is a mandatory requirement for a laboratory to address the analytical quality of these molecular analyses. The aim of the study was to demonstrate the robustness of this prognostic test, its usefulness for the patient's treatment strategy, at the national level.

This study presents a pilot quality assessment (QA) of the EndoPredict test using composite design, including the follow-up of internal control values (qREF) of the 12 genes of the assay for 151 independent tests and one formalin-fixed paraffin embedded (FFPE) breast cancer sample. The evaluation of the test was performed by comparing the results of six independent medical laboratories.

All measures were highly reproducible and quantification of the qREF showed a standard deviation of less than 0.50 and a coefficient of variation always of <2%. All laboratories found concordant results for the breast cancer samples. The mean EndoPredict (EP) score for the breast cancer sample was 4.97±0.24. The mean of EPclin score was 3.07±0.05.

This first French independent reported QA assessed the robustness and reproducibility of the EndoPredict test. Such a simple composite design could represent an adapted QA for an expensive diagnostic test.