Low FOXA1 expression predicts good response to neo-adjuvant chemotherapy resulting in good outcomes for luminal HER2-negative breast cancer cases

FOXA1 expression is a good prognostic marker for endocrine therapy in hormone-positive breast cancer. We retrospectively examined breast cancer patients with luminal human epidermal growth factor receptor 2 (HER2)-negative tumours, as defined by immunohistochemistry, who received neo-adjuvant chemotherapy (NAC) and investigated the relationship between treatment effects and FOXA1 expression. Biopsy specimens from 103 luminal HER2-negative tumours were immunohistochemically examined. FOXA1 effects on chemo-sensitivity were also investigated employing in vitro experiments. FOXA1 and Ki67 expressions independently predicted a pathological complete response (pCR). Knockdown of FOXA1 by siRNA boosted the chemo-effect in oestrogen receptor-positive cells. The Cox hazards model revealed a pCR to be the strongest factor predicting a good patient outcome. Our present study showed low FOXA1 expression to be associated with a good response to NAC in luminal HER2-negative breast cancer. Improved outcomes of these patients suggest that NAC should be recommended to patients with low FOXA1 tumours.