Biomarkers of primary and secondary resistance to cyclin dependent kinases 4 and 6 inhibitors in metastatic estrogen receptor-positive/human epidermal growth factor receptor 2-negative breast cancer: a narrative review

Key Points

• Resistance mechanisms impede the efficacy of CDK4/6 inhibitors in treating breast cancer, specifically in hormone receptor-positive cases.
• Key resistance factors have been identified but are not yet incorporated into clinical practice to guide treatment.
• The analysis highlights the diverse mechanisms of resistance on a case-by-case basis, demanding tailored treatment approaches.
• Individualized strategies to re-sensitize cancer cells may improve the effectiveness of cell cycle inhibition therapies.

Abstract