Abstract
Objective: This study explored the predictors of dropping out from abemaciclib therapy, a cyclin-dependent kinase 4 and 6 inhibitor, in patients with breast cancer.
Material and Methods: Between November 2018 and March 2023, 147 patients with breast cancer treated with abemaciclib at Osaka Medical and Pharmaceutical University Hospital and Kindai University Nara Hospital were included. The exclusion criteria were as follows: lack of blood testing within 2 weeks prior to starting abemaciclib therapy, transfer to another facility after the commencement of abemaciclib therapy, and discontinuation of abemaciclib therapy due to the diagnosis of another cancer. The duration from the initiation of abemaciclib to dropout for any reason and to temporary suspension or dose reduction due to adverse events were analyzed as outcome variables using multivariate Cox regression analysis.
Results: Baseline weight <54 kg, bone metastases, and hemoglobin level ≤12.4 g/dL were independent predictors of dropout for any reason. The main adverse events leading to dropout were liver enzyme elevation and gastrointestinal symptoms. Additionally, focusing on the adverse event of abemaciclib, a baseline weight <54 kg was an independent predictor of temporary suspension or dose reduction due to adverse events. The most common adverse events leading to temporary suspension or dose reduction were neutropenia and diarrhea.
Conclusion: Patients with lower body weight are more susceptible to the adverse events of abemaciclib, increasing their risk of treatment dropout. In such patients, strict monitoring of adverse events and consideration of more frequent medical visits are necessary from the start of abemaciclib therapy.