e12539 Background: This study assessed a staged dose-escalation protocol for adjuvant abemaciclib in routine Russian clinical practice. Methods: We analyzed the outcomes of adjuvant abemaciclib administered at 150 mg once daily during the first month, followed by 150 mg twice daily from month 2 until completion of 2 years of therapy, in 64 women with HR+/HER2- breast cancer between 2022 and 2025. The age range was 28–80 years (median 49), and 48% of patients were premenopausal. All patients had high-risk recurrence criteria consistent with the monarchE trial: 65.6% had N2–3 disease, while 34.4% had N1 disease with additional high-risk features. Grade 3 histology was present in 43.7% of cases, and Ki-67 > 20% was observed in 64.1%. All patients underwent radical surgery (± radiotherapy). Neoadjuvant and adjuvant chemotherapy were administered in 62.5% and 32.9% of patients, respectively. In 4.6% of patients (≥75 years old), abemaciclib was initiated after neoadjuvant endocrine therapy and surgery. All patients received adjuvant endocrine therapy with aromatase inhibitors (with ovarian suppression for premenopausal women) as well as zoledronic acid or denosumab (100% of cases). Results: Adverse events during abemaciclib therapy were reported in 89% of patients, with diarrhea being the most common (all grades: 80%; grade 3: 7.8%). Dose reduction was required in 20% of patients, while permanent discontinuation occurred in only 2.9% (due to grade 3 diarrhea). No thromboembolic complications were observed. In one case (1.6%), interstitial lung disease of grade 1 was detected on baseline CT scan at the start of abemaciclib treatment; its manifestations resolved completely after completion of the 2-year therapy. A total of 28% of patients completed the full 2-year course of abemaciclib, while the remainder continue treatment at the time of analysis. No cases of disease progression or death were reported. All patients maintained a high quality of life and remained socially active. Conclusions: Staged escalation of adjuvant abemaciclib therapy is effective and safe, preserves a high quality of life, and reduces the incidence of severe diarrhea and treatment discontinuation in routine clinical practice.
Kolyadina et al. (Thu,) studied this question.