The relationship between the expression of FOXA1 and GATA3 and the efficacy of neoadjuvant endocrine therapy.

BACKGROUND: Estrogen receptor (ER)/GATA3/Forkhead box A1 (FOXA1) network is necessary for the ERα functional signature. High FOXA1 expression indicates a good prognosis in ER-positive breast cancer. However, little is known about the significance of FOXA1 and GATA3 expression in neoadjuvant endocrine therapy (NAE). The aim of this study is to investigate their predictive potential for NAE and their expression changes after NAE.

METHODS: FOXA1 and GATA3 expression was evaluated using immunohistochemistry in 66 patients with ER-positive/HER2-negative breast cancer who had been treated with NAE. The association between biological marker expressions and the efficacy of NAE and their expression changes after NAE were analyzed.

RESULTS: The median pre-treatment FOXA1 and GATA3 expressions were 94.6 and 90 %. Pre-treatment FOXA1 expression was positively correlated with GATA3 (P = 0.0003) and progesterone receptor (PgR) (P = 0.0138). There was no correlation between pre- or post-treatment FOXA1 and GATA3 expressions and the efficacy of NAE. Post-treatment Ki67 expression was significantly lower in tumors with partial response (PR) (P = 0.0007). In terms of the changes of the expression, PgR, Ki67, and FOXA1 expression significantly decreased after NAE (P < 0.0001, P < 0.0001, and P < 0.0001, respectively).

CONCLUSIONS: FOXA1 and GATA3 expression was not correlated with the efficacy of NAE, but FOXA1 expression was significantly reduced after NAE.