ONCOLOGY IN CLINICAL PRACTICE, 2025 (ESCI, Scopus)
Introduction. In hormone receptor-positive metastatic breast cancer without human epidermal growth factor receptor 2 overexpression (HR+/HER2-), a significant progression-free survival benefit has been obtained with cyclin-dependent kinase 4/6 (CDK 4/6) inhibitors in the first-line treatment. We mainly aimed to investigate whether the toxicities of CDK 4/6 inhibitors predict treatment response. Material and methods. This study was designed retrospectively. Atotal of 191 patients diagnosed with metastatic HR+/HER2- breast cancer were treated with CDK 4/6 inhibitors in four centers in T & uuml;rkiye included in our study. Results. One hundred and six patients received ribociclib, and 85 patients received palbociclib. The most common adverse event in both groups was neutropenia. In this study, we found that toxicities did not predict response rates. Additionally, the response rates (RR) in patients with albumin levels above 4.1 g/dl were better than that in patients with albumin levels of 4.1 g/dl and below in multivariate analysis when all patients were considered (OR = 4.76; 95% CI 1.30-17.46; p = 0.018). Conclusions. Toxicities of CDK4/6-inhibitors did not predict RRs. However, pretreatment albumin level may predict response to ribociclib.