Discovery of Novel Fedratinib-Based HDAC/JAK/BRD4 Triple Inhibitors with Remarkable Antitumor Activity against Triple Negative Breast Cancer

Multitarget HDAC inhibitors capable of simultaneously
blocking
the BRD4-LIFR-JAK1-STAT3 signaling pathway hold great potential for
the treatment of TNBC and other solid tumors. Herein, novel Fedratinib-based
multitarget HDAC inhibitors were rationally designed, synthesized,
and biologically evaluated, among which compound 25ap stood out as a potent HDAC/JAK/BRD4 triple
inhibitor. Satisfyingly, compound 25ap led to concurrent inhibition of HDACs and the BRD4-LIFR-JAK1-STAT3
signaling pathway, which was validated by hyper-acetylation of histone
and α-tubulin, hypo-phosphorylation of STAT3, downregulation
of LIFR, MCL-1, and c-Myc in MDA-MB-231 cells. The multitarget effects
of 25ap contributed to
its robust antitumor response, including potent antiproliferative
activity, remarkable apoptosis-inducing activity, and inhibition of
colony formation. Notably, 25ap possessed an acceptable therapeutic window between normal and cancerous
cells, desirable in vitro metabolic stability in mouse microsome,
and sufficient in vivo exposure via intraperitoneal administration.
Additionally, the in vivo antitumor potency of 25ap was demonstrated in an MDA-MB-231 xenograft
model.