Real-world treatment outcomes of abemaciclib in older patients with HR+, HER2- metastatic breast cancer in Japan

To understand the real-world use of abemaciclib in older patients (≥65 years) with HR+, HER2− metastatic breast cancer (MBC) in Japan. This study retrospectively analyzed a Japanese administrative claims database for patients with HR+, HER2− MBC who received abemaciclib as the first CDK4/6 inhibitor (CDK4/6i) from November 2018 to May 2023. Patient characteristics and treatment patterns were summarized. Median time to discontinuation (mTTD) and chemotherapy-free survival (CSF) was estimated using Kaplan – Meier method. Among 3,699 abemaciclib-treated patients with HR+, HER2− MBC, 1,681 (45.4%) were ≥65 years old. Among these, abemaciclib + fulvestrant (55.0%) was the most common regimen. The mTTD (95% CI) of first abemaciclib therapy was 12.8 months (11.4–13.6). The overall mTTD (95% CI) with all the BC drugs after starting abemaciclib was 40.2 months (37.0–44.0). The median (95% CI) CFS after starting abemaciclib was 34.8 months (30.2–39.5). Among 1,149 older patients who discontinued the abemaciclib therapy, 897 (78.1%) patients received subsequent treatment. The most common first subsequent therapy was the endocrine therapy + CDK4/6i regimen (34.9%). This study indicated that abemaciclib regimens were feasible for older patients with HR+, HER2− MBC in Japan. Abemaciclib is prescribed for the treatment of early or metastatic breast cancer in Japan. We used a big database from Japan that has anonymized information for about 46.3 million patients from 500 hospitals. We described the patient characteristics and drug treatments among older patients (≥65 years old) with hormone receptor-positive (HR+), human epidermal growth factor receptor 2 negative (HER2−) metastatic breast cancer who were treated with abemaciclib in Japan. We included 3,699 patients with HR+, HER2− metastatic breast cancer who were treated with abemaciclib. Among these, 45.4% were older patients with a median age of 72 years. Abemaciclib + fulvestrant (55.0%) was the most commonly prescribed regimen in older patients. The median time to discontinuation for first abemaciclib treatment was 12.8 months in older patients. Among 1,149 older patients who discontinued the abemaciclib therapy, 78.1% of patients received subsequent treatment. The most common subsequent therapy was endocrine therapy + CDK4/6 inhibitors (34.9%). Our study indicated that abemaciclib regimens were feasible for older patients with HR+, HER2− metastatic breast cancer in Japan.

本研究旨在明确日本地区激素受体阳性（hormone receptor-positive, HR+）、人表皮生长因子受体2阴性（human epidermal growth factor receptor 2 negative, HER2−）转移性乳腺癌（metastatic breast cancer, MBC）老年患者（≥65岁）中阿贝西利（abemaciclib）的真实世界应用情况。本研究回顾性分析了日本行政理赔数据库中2018年11月至2023年5月期间，将阿贝西利作为首款细胞周期蛋白依赖性激酶4/6抑制剂（cyclin-dependent kinase 4/6 inhibitor, CDK4/6i）治疗的HR+、HER2− MBC患者数据，对患者基线特征与治疗模式进行总结，并采用卡普兰-迈耶法（Kaplan–Meier method）估算停药中位时间（median time to discontinuation, mTTD）与无化疗生存期（chemotherapy-free survival, CSF）。
本次研究共纳入3699例接受阿贝西利治疗的HR+、HER2− MBC患者，其中1681例（45.4%）为≥65岁的老年患者，该群体中位年龄为72岁。阿贝西利联合氟维司群（fulvestrant）是该老年群体最常见的治疗方案（55.0%）。老年患者首程阿贝西利治疗的停药中位时间（95%置信区间）为12.8个月（11.4~13.6）；启动阿贝西利治疗后，所有乳腺癌相关药物治疗的整体停药中位时间（95%置信区间）为40.2个月（37.0~44.0）；启动阿贝西利治疗后的无化疗生存期中位值（95%置信区间）为34.8个月（30.2~39.5）。在1149例停用阿贝西利治疗的老年患者中，897例（78.1%）接受了后续治疗，其中最常见的首项后续治疗方案为内分泌治疗联合CDK4/6抑制剂（34.9%）。
本研究使用的大型数据库涵盖日本500家医院约4630万例患者的匿名化健康信息。研究结果表明，阿贝西利治疗方案在日本HR+、HER2− MBC老年患者中具备临床可行性，目前阿贝西利在日本被批准用于早期或转移性乳腺癌的治疗。