ESR1 and breast cancer: MammaTyper® showed substantial agreement with IHC for ESR1/ER and ERBB2/HER2, and moderate agreement for PGR/PR and MKI67/Ki67.<h4>Conclusion</h4>Overall, MammaTyper® pCR score may serve as a standardized tool for predicting NACT response in HR+/HER2-negative BC, potentially guiding treatment strategies.