The 70-gene signature as a response predictor for neoadjuvant chemotherapy in breast cancer.

The 70-gene signature (MammaPrint) is a prognostic tool used to guide adjuvant treatment decisions. The aim of this study was to assess its value to predict chemosensitivity in the neoadjuvant setting. We obtained the 70-gene profile of stage II-III patients prior to neoadjuvant chemotherapy and classified the prognosis-signatures. Pathological complete remission (pCR) was used to measure chemosensitivity. Among 167 patients, 144 (86%) were having a poor and 23 (14%) a good prognosis-signature. None of the good prognosis-signature patients achieved a pCR (0/23), whereas 29/144 patients (20%) in the poor prognosis-signature group did (P = 0.015). All triple-negative tumors (n = 38) had a poor prognosis-signature. Within the non triple-negative subgroup, the response of the primary tumor remained associated with the classification of the prognosis-signature (P = 0.023). A pCR is unlikely to be achieved in tumors that have a good prognosis-signature. Tumors with a poor prognosis-signature are more sensitive to chemotherapy.