Targeting CDK4/6 pathways and beyond in breast cancer

Area of Science:

• Oncology
• Pharmacology
• Molecular Biology

Background:

• Metastatic or advanced breast cancer (mBC/ABC), particularly the hormone receptor-positive (HR+) subtype, remains a significant clinical challenge.
• Endocrine resistance is a key factor limiting treatment efficacy in HR+ breast cancer.
• The cyclin-dependent kinase (CDK) signaling pathway plays a crucial role in cell cycle regulation and cancer progression.

Purpose of the Study:

• To review the biological basis and clinical efficacy of CDK4/6 inhibitors in HR+/HER-2 negative advanced breast cancer.
• To analyze the safety profiles and impact on quality of life of CDK4/6 inhibitors.
• To discuss the current and future applications of CDK4/6 inhibitors in breast cancer treatment guidelines and research.

Main Methods:

• Review of preclinical and clinical data for selective CDK4/6 inhibitors (palbociclib, ribociclib, abemaciclib).
• Analysis of progression-free survival (PFS), overall survival (OS), and toxicity data from clinical trials.
• Examination of current international treatment guidelines and future research directions.

Main Results:

• All three CDK4/6 inhibitors significantly improve PFS when combined with endocrine therapy in first- and second-line settings for HR+/HER-2 negative ABC.
• The primary toxicities are hematological (neutropenia), diarrhea, and fatigue, with generally favorable safety profiles.
• Quality of life is maintained or improved, although overall survival benefits are still under investigation in some trials.

Conclusions:

• CDK4/6 inhibitors represent a major advancement in the treatment of HR+/HER-2 negative advanced breast cancer.
• These agents are increasingly incorporated into clinical guidelines due to demonstrated efficacy and manageable toxicity.
• Further research is warranted to explore their use in other breast cancer subtypes and early-stage disease.