On October 12, 2021, the FDA approved a new indication for the cyclin-dependent kinase 4/6 inhibitor abemaciclib (Verzenio; Eli Lilly), in combination with tamoxifen or an aromatase inhibitor as initial endocrine-based therapy, for the treatment of adult patients with hormone receptor-positive, HER2-negative, node-positive, early breast cancer at high risk for recurrence, and a Ki-67 score ≥20%, as determined by an FDA-approved test.
This new indication is based on results of the monarchE trial, a randomized, open-label, multicenter study of adult women and men with hormone receptor-positive, HER2-negative, node-positive, resected early breast cancer with clinical and pathologic features consistent with a high risk for disease recurrence. Patients were randomized in a 1:1 ratio to receive 2 years of abemaciclib 150 mg twice daily plus physician’s choice of standard endocrine therapy, or standard endocrine therapy alone.
The main efficacy end point measure in the trial was invasive DFS (iDFS). In patients with risk for recurrence and Ki-67 score ≥20%, results showed a statistically significant improvement in iDFS (hazard ratio, 0.62; 95% CI, 0.49-0.8; P = .0042). The iDFS at 36 months was 86.1% (95% CI, 82-88.8) for patients treated with abemaciclib plus endocrine therapy and 79% (95% CI, 75.3-82.3) for those treated with endocrine therapy alone. Overall survival data were not mature at the time of the iDFS analysis.
The most common (≥20%) AEs were diarrhea, infections, neutropenia, fatigue, leukopenia, nausea, anemia, and headache.
