Drug therapy is necessary to treat metastatic and recurrent breast cancer. In Japan, two types of cyclin-dependent kinases (i.e., CDK4/6 inhibitors) are covered under the national healthinsurance system: palbociclib (since December 2017) and abemaciclib (since November 2018). Although there are many reports on the use and side effects of palbociclib in clinical practice, there are few such reports on abemaciclib. Therefore, we investigated the rate of neutropenia and associated background factors in patients taking abemaciclib. Of the 39 patients taking abemaciclib recruited for the study, 22 satisfied the inclusion criteria. Of these, 7 developed Grade 3 or higher neutropenia and had a significantly lower body weight and body mass index (BMI). Furthermore, the white blood cell and neutrophil counts before administration were significantly lower in the expression group compared with the non-expressing group. To predict the development of Grade 3 or higher neutropenia, the receiver operating characteristic (ROC) curve was used to calculate a BMI cut-off value of 23.9 (specificity 85.7%, sensitivity 73.3%, area under the ROC curve 0.80). Based on this cut-off value, BMI was divided into two groups (<23.9 and ≥23.9) and Fisher's exact test was performed. Patients with a low body mass index were more likely to develop Grade 3 or higher neutropenia as a result of increased dosage per kilogram body weight, while among patients with BMI < 25, those with BMI < 23.9 were at high risk of developing Grade 3 or higher neutropenia. Accordingly, caution is required in the treatment of such patients.

In order for pharmacists to be collaboratively involved with patients in pharmacotherapy, there is a need to improve patients’ understanding of pharmacists’ involvement in extended pharmacotherapy, i.e., their interpersonal work. This study explores the factors that affect patients’ perceptions of pharmacists’ interpersonal work. A survey on patients’ perceptions of pharmacists’ interpersonal work was conducted among 450 patients aged 20 years or older who visited a pharmacy. Logistic regression analysis was performed with low and high patient perceptions of pharmacists’ interpersonal work as the objective variables. Valid responses were obtained from 350 participants. More than half of the respondents did not understand the nature of the interpersonal work of pharmacists. Patients who were unaware of pharmacists checking for side effects were more prevalent than those who were unaware of other interpersonal work. Explanations from the family pharmacist (OR＝2.25, P＝0.033) and trust in the pharmacist (OR＝1.11, P＝0.001) had a positive influence on patients’ perceptions of the pharmacist’s interpersonal tasks. As pharmacy pharmacists are increasingly becoming more involved with patients’ drug treatment and to ensure safe drug treatment practices for patients, it is considered important for pharmacists to actively explain their involvement in drug treatment to patients. This will be conducive to building trusting relationships, and for pharmacists to fulfil their function as family pharmacists.