Discovery of Potent and Selective CDK9 Degraders for Targeting Transcription Regulation in Triple-Negative Breast Cancer.

Triple-negative breast cancer (TNBC) is highly aggressive with very limited treatment options due to the lack of efficient targeted therapies and thus still remains clinically challenging. Targeting transcription-associated cyclin-dependent kinases to remodel transcriptional regulation shows great promise in cancer therapy. Herein, we report the synthesis, optimization, and evaluation of new series of heterobifunctional molecules as highly selective and efficacious CDK9 degraders, enabling potent inhibition of TNBC cell growth and rapidly targeted degradation of CDK9. Moreover, the most potent CDK9 degrader (compound ) induces cell apoptosis and inhibits tumor growth in the MDA-MB-231 TNBC model. Furthermore, the RNA-seq, immunohistochemistry assays demonstrate that the CDK9 degrader downregulates the downstream targets, such as , at the transcriptional level, resulting apoptosis in TNBC cells. Our work establishes that is a highly potent and efficacious CDK9 degrader for targeting transcription regulation, which represents an effective strategy and great potential as a new targeted therapy for TNBC.