In the current study, our data indicated that the low expression of FBW7 contributes to the drug resistance of BC cells upon JQ1 treatment....The combination of JQ1 with a Mcl-1 inhibitor (S63845) resensitized the FBW7 knockdown tumours to JQ1 treatment in vivo. Our study paves the way for a novel therapeutic potential of BETis with Mcl-1 inhibitors for BC patients with a low FBW7 expression.