The use of ribociclib in real clinical practice: results of a single-center observational retrospective study

Abstract

Introduction. The standard initial treatment for patients with hormone receptor positive, HER2 negative, metastatic breast cancer (HR+/HER2– mBC) involves the use of CDK4/6 inhibitors (CDK4/6i) in combination with endocrine therapy. The combination therapy has proven effectiveness in numerous Phase II and III randomized controlled trials (RCTs). Nonetheless, RCTs may not fully represent real-world clinical situations due to their stringent inclusion criteria, resulting in a specific patient population.Aim. Analyze of ribociclib using for treating patients with HR+/HER2– advanced breast cancer (mBC) at the Republican Clinical Oncology Dispensary.Materials and methods. Patients diagnosed with HR+/HER2– mBC who were treated in clinical routine with ribociclib in combination with different endocrine agents between 2016 and 2020 were identified and enrolled in this retrospective study. Clinicopathological characteristics and clinical outcomes were recorded with particular emphasis on ribociclib therapy course (progression-free survival (PFS), toxicity, dose reduction).Results. Data from n = 101 patients were evaluated. The mean patient age was 61 years. The study included 67 (66.3%) patients with progression after radical treatment and 34 (33.7%) patients with primary disseminated breast cancer. Dose reduction due to adverse events was performed in n = 14 cases (13.9%). Presence of prior therapy lines and lower ECOG status were associated with shorter PFS, whereas estrogen positivity and the choice of fulvestrant over aromatase inhibitor were positively associated with PFS. Metastatic pattern, progesterone positivity and dose reduction due to toxicity did not significantly impact on PFS.Conclusion. Our real-world data analysis on ribociclib treatment in Russian regional hospital supports data from RCTs regarding both treatment efficacy and safety of CDK4/6i for treatment of patients with HR+/HER2– mBC. Currently, by expanding our experience with CDK4/6 inhibitors in different groups of patients with mBC, we will be able to provide patients with optimal treatment options.