Abstract Purpose To evaluate the impact of a patient support program (PSP) on the management of abemaciclib-related diarrhea in patients with hormone receptor-positive, human epidermal growth factor receptor 2–negative (HR+/HER2−) metastatic breast cancer (MBC) and its influence on adherence and patient-reported outcomes in routine clinical practice. Methods This is a multicenter, prospective, observational Spanish study in patients with locally advanced or MBC receiving abemaciclib and enrolled in the PSP, assessed over 6 months. The primary endpoint was the proportion of patients reducing or discontinuing abemaciclib due to diarrhea. The secondary endpoints included diarrhea-related temporary interruptions, diarrhea management, adherence, HRQoL, and satisfaction with the PSP. Descriptive statistics were applied and treatment modification endpoints were analyzed using Kaplan–Meier. Results The study included 39 patients (median age: 58 years), with a median time since diagnosis of MBC of 2 months. Diarrhea occurred in 89.7% of patients, with grade 3 events in 7.7% and no grade ≥ 4 events. Nine patients (23.1%) experienced treatment modifications due to diarrhea; however, no permanent treatment discontinuations were reported. Loperamide (over 75% of patients) and dietary modifications were the most used self-care strategies. At week 24, results from the ad hoc questionnaires showed that over 70% of the patients reported high satisfaction with all PSP aspects, and 80% were classified as treatment adherent. Conclusions Episodes of diarrhea were mostly graded 1–2 and no patients discontinued abemaciclib due to diarrhea. Patients reported high satisfaction with abemaciclib PSP, good adherence, and favorable quality of life, supporting the use of PSP in clinical practice.
Blancas et al. (2026) studied this question.