Real-world Studies of CDK4/6 Inhibitors

This study aims to collect clinical data and case information from real-world clinical practice of patients with HR+/HER2- advanced breast cancer treated with CDK4/6 inhibitors combined with endocrine therapy.

The main research objectives include: 1. To evaluate the differences in efficacy among different CDK4/6 inhibitors combination regimens in advanced patients; 2. To investigate the subsequent treatment options chosen by patients in the real world after progression on CDK4/6 inhibitors, with the aim of constructing a predictive model for the response to subsequent treatments, thereby providing support for clinical decision-making for both doctors and patients in such situations.

The secondary objectives include: 1. To truly reflect the differences in adverse reactions of different CDK4/6 inhibitors in the Chinese population through the collection of laboratory and imaging results; 2. To collect tumor samples or peripheral blood samples from some patients for genomic and transcriptomic analyses, in preparation for translational research on the mechanism of CDK4/6 inhibitors resistance.

Inclusion criteria

• Age ≥ 18 years old;
• Patients diagnosed with HR+/HER2- (as defined by the ASCO/CAP guidelines) advanced breast cancer who were treated in our hospital from March 2022 to March 2025;
• Received CDK4/6 inhibitors (including but not limited to the four currently marketed ones: palbociclib, abemaciclib, ribociclib, and dalpiciclib) as advanced-stage treatment for at least one cycle;
• Have complete medical history records, including demographic information, pathological reports, treatment records, laboratory test results, and imaging examination reports, etc.

Exclusion criteria

• Incomplete medical history data.
• Only received CDK4/6 inhibitors monotherapy.
• Received CDK4/6 inhibitors as neoadjuvant/postoperative adjuvant intensification therapy.