ERBB2 and breast cancer: At the same time, thetreatment of localized ER+/HER2-negative (HER2−) BC, which ischaracterized by poorer chemosensitivity compared to other clinical BCsubtypes, can be challenging [1].Pathological complete response (pCR) rates in HER2-negative (HER2−) BCare low, while the presence of residual disease does not have the sameprognostic value as in other clinical subtypes [2].