ERBB2 and breast cancer: In that sense, the DEFINITIVE phase III trial, funded by the European Union with Horizon Europe 2023–2024 work program, will investigate the clinical value of HER2DX by randomizing patients with stage II-IIIA HER2+ breast cancer to be based on HER2DX results or by physician ́s choice, and will began enrolling patients in June 2024.