Real-world data on patients with HR+, HER2- early breast cancer prescribed with abemaciclib adjuvant therapy for 2 years in Japan

BACKGROUND: This study aimed to investigate patient characteristics and treatment patterns and completion rates over a 2-year follow-up period among Japanese patients with early breast cancer (EBC) who received adjuvant therapy with abemaciclib in real-world clinical practice. METHODS: This retrospective observational study used a Japanese administrative claims database to examine patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative EBC who received abemaciclib adjuvant therapy from December 2021-November 2024. Results were summarized descriptively. RESULTS: Of the 2042 eligible patients, 439 (median age [min-max] of 55 [26-84] years, with 99.3% being females) had a ≥2-year follow-up (median duration of follow-up: 890 days). Among these, 70.6% completed 2 years of abemaciclib+ endocrine therapy [ET], 21.9% discontinued abemaciclib but continued ET, and 7.5% discontinued both within 2 years. A dose of 300 mg/day was initiated in 92.3% of patients and dose reduction occurred in 58.3% of patients in 2-year follow-up group. Anti-diarrheal agents and probiotics were frequently prescribed initially, with rates declining over time. CONCLUSIONS: This study demonstrates that adjuvant abemaciclib+ET is being used at the labeled dosage in most Japanese patients. Furthermore, 2-year completion rates in patients with 2-year follow-up were comparable to the clinical trial data from monarchE (69%).