Real-World Clinical Experience of First-Line Ribociclib Combined with an Aromatase Inhibitor in Metastatic Breast...

Area of Science:

• Oncology
• Medical Research
• Clinical Trials

Background:

• Hormone receptor-positive, HER2-negative (HR+/HER2-) breast cancer often develops endocrine resistance.
• Dysregulation of the cyclin D-CDK4/6-Rb pathway is a key mechanism in endocrine resistance.
• Cyclin-dependent kinase 4 and 6 inhibitors (CDK4/6i) combined with endocrine therapy (ET) improve progression-free survival (PFS) in HR+/HER2- breast cancer.

Purpose of the Study:

• To evaluate the clinical effectiveness and safety of first-line ribociclib (a CDK4/6i) combined with an aromatase inhibitor (AI) in patients with HR+/HER2- advanced or metastatic breast cancer.
• To assess progression-free survival (PFS) and adverse events (AEs) in this patient population.

Main Methods:

• Retrospective and prospective analysis of 132 patients with metastatic HR+/HER2- breast cancer treated with ribociclib and AI as first-line therapy.
• Data collected between June 2022 and January 2025, with follow-up until October 2025.

Main Results:

• Median PFS was 30 months; 12-, 24-, and 36-month PFS rates were 82.15%, 72.24%, and 28.75%, respectively.
• Overall response rate (ORR) was 41.7%, and clinical benefit rate (CBR) was 89.3%.
• Neutropenia was the most common AE (89.4%), with 47.7% being grade 3-4. Hepatotoxicity and QTc prolongation were less frequent.

Conclusions:

• The combination of ribociclib and AI demonstrated significant efficacy and a manageable safety profile in first-line treatment for HR+/HER2- metastatic breast cancer.
• Results are consistent with pivotal studies, supporting ribociclib's role as a gold standard therapy in this setting.
• Efficacy was observed across various patient subgroups, including those with different tumor grades, Ki 67 levels, and menopausal statuses.