How selective are clinical CDK4/6 inhibitors?

Area of Science:

• Oncology
• Molecular Biology
• Pharmacology

Background:

• Cyclin-dependent kinase 4/6 (CDK4/6) inhibitors are effective in breast cancer and expanding to other malignancies.
• Initial understanding of CDK4/6 inhibitors focused on G1 cell cycle arrest.
• Emerging evidence reveals more complex cellular responses to CDK4/6 inhibition.

Purpose of the Study:

• To review the multifaceted cellular responses to FDA-approved CDK4/6 inhibitors.
• To summarize the mechanisms of action beyond G1 arrest.
• To explore the off-target landscape of CDK4/6 inhibitors in clinical trials.

Main Methods:

• Literature review of cellular responses to palbociclib, ribociclib, and abemaciclib.
• Analysis of emerging mechanisms including quiescence, senescence, autophagy, metabolism, and immunogenicity.
• Compilation of data on off-target effects of drugs in clinical trials.

Main Results:

• CDK4/6 inhibitors induce complex cellular responses, including modulation of quiescence, senescence, autophagy, metabolism, and tumor immunogenicity.
• These effects can be driven by interactions with unexpected targets.
• Off-target profiles of investigational CDK4/6 inhibitors are being characterized.

Conclusions:

• The cellular response to CDK4/6 inhibitors is more complex than previously thought.
• Comprehensive characterization of drug selectivity is vital for optimizing clinical efficacy and safety.
• Understanding off-target effects can facilitate drug repurposing for other diseases.