October 2021: The Food and Drug Administration has approved abemaciclib (Verzenio, Eli Lilly and Company) in combination with endocrine therapy (tamoxifen or an aromatase inhibitor) for adjuvant treatment of adult patients with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative, node-positive, early breast cancer at high risk of recurrence and a Ki-67 score of less than 20%, as determined by an FDA- This is the first CDK 4/6 inhibitor to be approved for breast cancer adjuvant treatment.
Agilent, Inc. submitted the Ki-67 IHC MIB-1 pharmDx (Dako Omnis) assay, which was authorised by the FDA as a companion diagnostic for this indication.
Adult women and men with HR-positive, HER2-negative, node-positive, resected, early breast cancer with clinical and pathological characteristics consistent with a high risk of disease recurrence were involved in monarchE (NCT03155997), a randomised (1:1), open-label, two-cohort multicenter trial. Patients were given either 2 years of abemaciclib plus their doctor’s choice of standard endocrine medication or normal endocrine therapy alone.
Invasive disease-free survival was the primary effectiveness outcome measure (IDFS). The trial found a statistically significant improvement in IDFS (HR 0.626; 95 percent CI: 0.488, 0.803; p=0.0042) in patients with a high risk of recurrence and a Ki-67 Score of less than 20% (N=2003). Patients receiving abemaciclib with tamoxifen or an aromatase inhibitor had an IDFS of 86.1 percent (95 percent CI: 82.8, 88.8) at 36 months, while those receiving tamoxifen or an aromatase inhibitor had an IDFS of 79.0 percent (95 percent CI: 75.3, 82.3). At the time of the IDFS analysis, the overall survival data was not complete.
Diarrhea, infections, neutropenia, tiredness, leukopenia, nausea, anaemia, and headache were the most prevalent side effects (20%).
The recommended beginning dose of abemaciclib is 150 mg twice daily in combination with tamoxifen or an aromatase inhibitor for 2 years or until disease recurrence or intolerable toxicity, whichever comes first.