ESR1 and breast cancer: In addition, TCGA data analysis showed that HDAC5 expression level was not significantly correlated with the prognosis of overall BC and ER-positive or HER2-positive subtypes, while in TNBC patients, patients with low HDAC5 expression had longer OS and better prognosis (Fig. 8D-G), suggesting that HDAC5 may be a potential therapeutic target for TNBC.