Pharmacological perturbation of CDK9 using selective CDK9 inhibition or degradation

Area of Science:

• Molecular Biology
• Pharmacology
• Cancer Therapeutics

Background:

• Cyclin-dependent kinase 9 (CDK9) regulates transcriptional elongation and is a key target in cancers with transcriptional dysregulation.
• Existing therapies often involve CDK9 inhibition, but novel strategies are needed for enhanced efficacy.

Purpose of the Study:

• To characterize THAL-SNS-032, a selective CDK9 degrader, and compare its effects to a CDK9 inhibitor (NVP-2) and the parent compound (SNS-032).
• To investigate the potential of thalidomide conjugation for creating selective degraders from multi-targeted inhibitors.

Main Methods:

• Characterization of NVP-2 (selective ATP-competitive CDK9 inhibitor).
• Development and characterization of THAL-SNS-032 (CDK9 degrader via Cereblon E3 ligase binding).
• Assessment of CDK9 levels, transcriptional changes, and apoptosis induction following compound treatment and washout.

Main Results:

• THAL-SNS-032 rapidly degraded CDK9 selectively, without affecting other SNS-032 targets.
• Transcriptional changes induced by THAL-SNS-032 more closely resembled those of NVP-2 than SNS-032.
• CDK9 degradation by THAL-SNS-032 resulted in prolonged cytotoxic effects compared to CDK9 inhibition, with sustained apoptosis post-washout.

Conclusions:

• Thalidomide conjugation is a viable strategy to convert multi-targeted inhibitors into selective degraders.
• Kinase degradation can elicit distinct and potentially more prolonged pharmacological effects than kinase inhibition.
• Selective CDK9 degradation offers a promising therapeutic avenue for cancers driven by transcriptional dysregulation.