The pathological response acquired an impactful role as prognostic biomarker due to the evidence offered by the CTNeoBC pooled analysis of neoadjuvant breast cancer clinical trials, suggesting that patients achieving a pathologic complete response (pCR) had a significantly better prognosis than those who had residual disease, and this association was strongest in patients with triple-negative and HER2–positive disease [7,8]. This evidence concerns the gene ERBB2 and breast cancer.