Structure-Based Discovery of HS34: A Highly Selective and Orally Bioavailable CDK9 Inhibitor for Triple-Negative...

Area of Science:

• Oncology
• Molecular Biology
• Drug Discovery

Background:

• Triple-negative breast cancer (TNBC) is an aggressive subtype lacking targeted therapies.
• TNBC is highly dependent on Cyclin-Dependent Kinase 9 (CDK9) for transcription.

Purpose of the Study:

• To discover novel, potent, and selective CDK9 inhibitors for TNBC treatment.
• To explore a structure-based drug design strategy targeting CDK9-specific conformations.

Main Methods:

• Structure-based drug design was employed to identify inhibitors.
• HS34, a coumarin-based compound, was synthesized and characterized.
• Cellular assays, mechanistic studies, and xenograft models were used to evaluate HS34 efficacy.

Main Results:

• HS34 demonstrated low-nanomolar potency and high selectivity for CDK9.
• HS34 exhibited potent antiproliferative activity against TNBC cells, surpassing KB-0742.
• HS34 suppressed RNAP II phosphorylation, downregulated Mcl-1 and c-Myc, induced apoptosis, and blocked invasion.
• HS34 showed favorable DMPK properties and significant antitumor efficacy in vivo.

Conclusions:

• HS34 is a potent and selective CDK9 inhibitor with therapeutic potential for TNBC.
• Exploiting target-specific conformational features is an effective strategy for kinase inhibitor design.