CDK4/6 inhibitors in advanced HR+/HER2- breast cancer – a multicenter real word data analysis

Purpose CDK4/6 inhibitors (CDK4/6i) combined with endocrine therapy are considered standard-of-care for first-line therapy of patients with hormone receptor positive, HER2 negative advanced breast cancer (HR+/HER- ABC). Here, we analyzed real world data (RWD) on CDK4/6i treatment at four certified German Breast Cancer Centers.

Methods Patients with HR+/HER2- ABC who were treated with CDK4/6i in clinical routine between November 2016 and December 2020 at Saarland University Medical Center, Charité University Hospital Berlin, University Medical Center Bonn and University Medical Center Hospital Schleswig-Holstein, Campus Kiel, were identified and enrolled in this retrospective analysis. Clinicopathological characteristics were recorded with particular emphasis on CDK4/6i therapy (progression-free survival (PFS), toxicity, dose reduction, therapy discontinuation, prior and subsequent therapies).

Results Data from N=448 patients were evaluated. The mean patient age was 63 (± 12) years. 165 patients (36.8 %) had primary metastatic disease. 319 patients (71.3 %) received Palbociclib, 114 patients (25.4 %) Ribociclib, and 15 patients (3.3 %) Abemaciclib. Dose reduction was performed in 132 cases (29.5 %). 57 patients (12.7 %) discontinued the treatment with CDK4/6i due to side effects. 196 patients (43.8 %) experienced disease progression under CDK4/6i treatment. The median PFS was 17 months. Presence of hepatic metastases and advanced therapy lines was associated with shorter PFS, whereas estrogen receptor positivity was positively associated with median PFS.

Conclusion Our RWD analysis indicates treatment efficacy and safety of CDK4/6 inhibitors. In comparison to data from the approval relevant RCTs, median PFS was lower but within the expected range for RWD.

Publication History

Article published online:
21 June 2022