Cyclin-dependent Kinase 4/6 Inhibitor Treatment Use in Women Treated for Advanced Breast Cancer: Integrating ASCO/NCODA Patient-centered Standards in a Community Pharmacy

Background: Outpatients treated with oral anti-cancer drugs, including selective cyclin-dependent kinase 4/6 inhibitors (CDK4/6i), may benefit from a pharmacy practice setting adapted to support proper oral anti-cancer drug monitoring. This real-world study aimed to characterize patient-centered pharmacy practice aligned with American Society of Clinical Oncology (ASCO)/National Community Oncology Dispensing Association (NCODA) standards and to describe its impact on CDK4/6i treatment use.

Methods: This retrospective study included women with confirmed hormone receptor-positive/human epidermal growth factor 2 negative locally advanced or metastatic breast cancer treated with either palbociclib, abemaciclib or ribociclib combined with letrozole or fulvestrant. Pharmacists collected patient characteristics, clinical activities, and treatment patterns using data from the pharmacy chart. CDK4/6i treatment adherence rates were estimated based on medication claims data. Time-to-treatment discontinuation, a proxy for time-to-event, was assessed using the Kaplan-Meier estimate.

Results: Of the 195 patients assessed for eligibility, 65 were included in this study. The median observation duration was 13.6 months. An average of seven pharmaceutical care activities (range 2.8-21.7) per patient was documented for each treatment cycle. The mean proportion of days covered was 89.6%. The median time-to-treatment discontinuation was estimated at 44.2 months in patients treated with CDK4/6i + letrozole and 17.0 months in patients treated with CDK4/6i + fulvestrant. The average relative dose intensity was 85%, and the benefits of treatment were maintained regardless of the relative dose intensity levels.

Conclusion: A structured patient-centered pharmacy practice model integrating the ASCO/NCODA patient-centered standards and ongoing communication with patients and healthcare providers ensure timely refills, close monitoring, and allows patients to achieve high adherence and persistence rates comparable to those reported in clinical trials.