The FDA approved abemaciclib (Verzenio, Lilly) with endocrine therapy (tamoxifen or an aromatase inhibitor) for adjuvant treatment of adults who have hormone receptor (HR)-positive, HER2-negative, node-positive, early breast cancer at high risk for recurrence and a Ki-67 score of 20% or higher, as determined by an FDA-approved test. 

The agency also approved the Ki-67 IHC MIB-1 pharmDx (Dako Omnis, Agilent) assay as a companion diagnostic for selecting patients for this indication. 

Abemaciclib in combination with endocrine therapy has the potential to become a new standard of care in the early breast cancer setting, according to Sara M. Tolaney, MD, MPH, a medical oncologist at Dana-Farber Cancer Institute, in Boston, who was an investigator on the monarchE study on which the approval was based. “We are encouraged by the marked reduction in the risk of recurrence even beyond the two-year treatment period in these patients, and I'm grateful to be able to offer this as a treatment option to my patients," noted Dr. Tolaney.  

The multicenter, randomized, open-label, two-cohort monarchE trial  included adults with HR-positive, HER2-negative, node-positive, resected, early breast cancer with clinical and pathologic features consistent with a high risk for disease recurrence (ClinicalTrials.gov Identifier: NCT03155997). Patients were randomly assigned, in a 1:1 fashion, to receive either two years of abemaciclib (150 mg twice daily) plus their physician’s choice of standard endocrine therapy or standard endocrine therapy alone. Patients in both treatment arms were instructed to continue to receive adjuvant endocrine therapy for up to five to 10 years as recommended by their clinician. The major efficacy outcome measure was invasive disease?free survival (IDFS). 

Among patients with a high risk for recurrence and Ki-67 score of 20% or higher (N=2,003), the trial demonstrated a significant improvement in IDFS (hazard ratio, 0.626; 95% CI, 0.488-0.803; P=0.0042). The IDFS at 36 months was 86.1% (95% CI, 82.8%-88.8%) for patients receiving abemaciclib plus tamoxifen or an aromatase inhibitor and 79.0% (95% CI, 75.3%-82.3%) for those given just tamoxifen or an aromatase inhibitor. Overall survival data were not mature at the time of the IDFS analysis. 

The most common adverse events (incidence ≥20%) were diarrhea, infections, neutropenia, fatigue, leukopenia, nausea, anemia and headache.

For more information, see the complete prescribing information for abemaciclib.

—Clinical Oncology News Staff

Based on press releases from the FDA and Lilly.