Evolution of the CDK4/6 inhibitor abemaciclib: from palliative to adjuvant therapy. Clinical experience with abemaciclib in patients with hormone-receptor-positive, HER2-negative breast cancer

Abstract

Introduction. Cyclin-dependent kinase 4/6 inhibitors are indicated in endocrine therapy for the treatment of hormone receptorpositive, HER2-negative, advanced, or metastatic breast cancer. In the recent past, abemaciclib made its debut as a combinatorial partner for adjuvant therapy in hormone-dependent breast cancer. This article demonstrates the analysis of our own experience of introducing abemaciclib into clinical practice.Aim. The aim of the study was to evaluate the preliminary results of treatment of patients with hormone receptor-positive HER2-negative metastatic breast cancer using abemaciclib outside the framework of clinical trials, in the real clinical practice of an oncological dispensary.Materials and methods. A retrospective analysis of the results of treatment was carried out in 27 patients who were prescribed abe-maciclib in various regimens and lines from April 2021 to January 2022 in the conditions of routine practice in the Krasnodar region.Results and discussion. Analysis of the total population of 27 patients at a median follow-up of 8 months showed that the median PFS was not reached. The one-year PFS was 68.8%. Treatment outcomes were independent of prescribing abemaciclib to treat baseline metastatic disease or breast cancer progression after previous radical treatment (p = 0.60). The PFS did not depend on the expression of progesterone receptors in the tumor tissue (p = 0.326) and the proliferative activity index Ki-67 (p = 0.618). Patients who received no more than 2 lines of previous drug treatment for a history of metastatic breast cancer had the greatest benefit from abemaciclib therapy (p = 0.001).Conclusions. Despite a relatively difficult group of patients (96% of patients with visceral metastases), abemaciclib has demonstrated efficacy and safety. The effectiveness did not depend on the analyzed factors: Ki-67, the level of expression of progesterone receptors, the type of metastatic disease (de novo metastatic or progressive breast cancer). In view of the best results, it is advisable to prescribe abemaciclib in the early lines of therapy.