Résumé : ADRB2 mediates trastuzumab resistance in preclinical models of HER2+ breast cancer. We evaluated ADRB2 gene expression as a prognostic and predictive biomarker in HER2+ early breast cancer patients. Opposing our initial hypothesis, a high ADRB2 expression may exert antiproliferative, antiangiogenic, and immunogenic effects, and thus be associated with a favorable prognosis in patients with HER2+ early breast cancer.