The Real-world Experiences of Abemaciclib for Estrogen Receptor-positive Human Epidermal Growth Factor Receptor-negative-2 Metastatic Breast Cancer – Sharing from a Single Institute in Southern Taiwan

Abstract

Abstract Background: CDK 4/6 inhibitor (CDK4/6i) is the first-line therapeutic drug to treat ER-positive (ER+) HER2-negative (HER2 -) metastatic breast cancer (MBC) now. We have three CDK4/6i: Palbociclib, Ribociclib, and Abemaciclib. In the long-term follow-up study, there are some different results among the three CDK4/6i. Some real-world reports demonstrated some patients would have clinical benefits from Abemaciclib in the ER+ HER2- metastatic BC patients who had priorly received the other CDK 4/6 inhibitor (Palbociclib). In Taiwan, Abemaciclib is the third available CDK 4/6 inhibitor behind the other two CDK4/6i. However, Abemaciclib was not reimbursed in ER+ HER2- MBC by Taiwan Health Insurance until now. Most doctors in Taiwan have the less therapeutic experiences for Abemaciclib. In this article, we would share the clinical experiences for the first thirteen patients who were prescribed with Abemaciclib to treat ER+ HER2- MBC. Materials and Methods: This chart review study was conducted from January 1, 2020, to May 31, 2023. We reviewed the medical charts at National Cheng Kung University Hospital (NCKUH) and identified 13 patients who had received abemaciclib treatment for ER+ HER2− MBC. The study was approved by the Institutional Review Board at NCKUH (approval number: B-ER-112-220). All of the 13 patients were treated with abemaciclib (150 mg twice daily initially), in combination with other anti-cancer medications. We recorded the clinical parameters, including sex, age, treatments in neoadjuvant/adjuvant setting, metastatic sites, other prior CDK4/6i therapy, treatment lines of abemaciclib in the metastatic setting, survival period before abemaciclib treatment, time to treatment failure for abemaciclib, causes of abemaciclib discontinuation, dose reduction, and adverse effects (AEs) related to abemaciclib. Results: Up to the cut-off date (May 31, 2023), four (4/13) patients were still receiving therapy and nine patients (9/13) had discontinued abemaciclib therapy. Five (5/9) patients discontinued abemaciclib due to disease progression (PD), and two (2/9) patients interrupted abemaciclib treatment due to personal reasons. Two (2/9) patients stopped abemaciclib early because of AEs, and one patient died due to PD. The time to treatment failure for abemaciclib ranged from 1 to 41 months (average: 19.2 months, median: 14 months). AEs were noted in 12 patients (no recording in one patient), of which diarrhea (10/12), anemia (4/12), and neutropenia (3/12) were the most common. Conclusion: According to our real-world data, Abemaciclib is effective and safe for the ER+ HER2- metastatic BC cancer patients who they were heavily treated.