FDA Approves Adjuvant Abemaciclib Plus Endocrine Therapy for Select HR+ Early Breast Cancer

The FDA has approved abemaciclib (Verzenio) in combination with endocrine therapy for the adjuvant treatment of adult patients with hormone receptor–positive, HER2-negative, node-positive, early breast cancer at high risk of recurrence and a Ki-67 score of 20% or higher, as determined by an FDA-approved test.

The regulatory agency also greenlit the Ki-67 IHC MIB-1 pharmDx (Dako Omnis) assay for use as a companion diagnostic for selecting eligible patients for this indication.

"FDA approves abemaciclib in the adjuvant setting for hormone receptor–positive breast cancer! Incredible for our high-risk patients with hormone receptor–positive disease!" Sara M. Tolaney, MD, MPH, associate director, Susan F. Smith Center for Women's Cancers, director, Clinical Trials, Breast Oncology, director, Breast Immunotherapy Clinical Research, senior physician, Dana-Farber Cancer Institute; and associate professor of medicine, Harvard Medical School, wrote in a tweet. "Interesting that the approval includes Ki-67 of 20% or higher given benefits seen in patients with both low and high Ki-67."

Abemaciclib was examined in the phase 3 monarchE (NCT03155997), which enrolled adult women and men with hormone receptor–positive, HER2-negative, node-positive, resected, early breast cancer with clinical and pathological features consistent with a high risk of disease recurrence.

Study participants were randomized 1:1 to receive 2 years of either abemaciclib plus physician’s choice of standard endocrine therapy or standard endocrine therapy alone. The major efficacy outcome measure was invasive disease-free survival (iDFS).

In a total of 2003 patients with a high risk of recurrence and a Ki-67 score of 20% or higher, a statistically significant improvement in iDFS was observed with the addition of abemaciclib (HR, 0.626; 95% CI, 0.488-0.803; P = .0042). The 36-month iDFS rate was 86.1% (95% CI, 82.8-88.8) in those who received abemaciclib plus tamoxifen or an aromatase inhibitor (AI) and 79.0% (95% CI, 75.3-82.3) in those given tamoxifen or an AI. Notably, overall survival data were not mature at the time of the iDFS analysis.

The most common adverse effects reported with the approach in 20% or more of patients included diarrhea, infections, neutropenia, fatigue, leukopenia, nausea, anemia, and headache.

The recommended starting dose for abemaciclib is 150 mg to be administered twice daily in combination with tamoxifen or an aromatase inhibitor until completion of 2 years of treatment or until disease recurrence or intolerable toxicity.

Reference

1. Abemaciclib. Prescribing information. Eli Lilly and Company; 2021. Accessed October 12, 2021. https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/208716s006s007s008lbl.pdf