Identification of (S)-10-Hydroxycamptothecin as a potent BRD4 inhibitor for treating triple-negative breast cancer

•10-HCPT was identified to be a reversible inhibitor of BRD4.•10-HCPT can induce apoptosis and inhibit the growth of MDA-MB-231 cells.•10-HCPT showed an antitumor effect in triple-negative breast cancer.•10-HCPT showed no obvious systemic toxicity in vivo and in vitro.