LPM3770277, a Potent Novel CDK4/6 Degrader, Exerts Antitumor Effect Against Triple-Negative Breast Cancer

Area of Science:

• Oncology
• Molecular Biology
• Drug Discovery

Background:

• Triple-negative breast cancer (TNBC) presents a significant clinical challenge due to its high malignancy and limited effective treatments.
• Cyclin-dependent kinase 4 and 6 (CDK4/6) play a crucial role in cell cycle regulation, making them attractive therapeutic targets.
• Existing CDK4/6 inhibitors have shown success in certain cancers, but novel therapeutic strategies are needed for TNBC.

Purpose of the Study:

• To develop a novel CDK4/6 degrader targeting triple-negative breast cancer (TNBC) utilizing hydrophobic tagging technology.
• To synthesize and evaluate compounds based on the abemaciclib metabolite structure for their efficacy against TNBC.
• To investigate the mechanism of action and in vivo efficacy of the lead compound.

Main Methods:

• Synthesis of three novel compounds based on abemaciclib's major metabolite.
• In vitro cytotoxicity assays to evaluate compound efficacy.
• Binding assays and CDK4/6 protein degradation studies to confirm target engagement and degradation.
• Mechanistic studies involving proteasome and lysosome-promoted autophagy.
• In vivo evaluation using a TNBC xenograft mouse model.

Main Results:

• LPM3770277 emerged as the most potent compound, demonstrating significant binding to CDK4/6 and inducing time- and dose-dependent degradation of CDK4/6 proteins.
• The degradation mechanism involves both the proteasome and lysosome-promoted autophagy pathways.
• In vivo studies showed LPM3770277 exhibited superior anti-tumor efficacy and safety compared to abemaciclib in a TNBC xenograft model, despite similar cell cycle arrest effects.
• LPM3770277 effectively reduced tumor growth and showed a favorable safety profile.

Conclusions:

• This study successfully developed and characterized a novel CDK4/6 degrader, LPM3770277, for triple-negative breast cancer (TNBC).
• Hydrophobic tagging technology represents a viable strategy for developing new treatments targeting CDK4/6 in TNBC.
• LPM3770277 demonstrates significant potential as a therapeutic agent for TNBC, offering improved efficacy and safety over existing inhibitors.