Posted: Tuesday, March 7, 2023
On March 3, the U.S. Food and Drug Administration (FDA) expanded the indication for the CDK4/6 inhibitor abemaciclib (Verzenio) plus endocrine therapy (tamoxifen or an aromatase inhibitor) to include adults with early-stage, hormone receptor (HR)-positive, HER2-negative, node-positive, high-risk breast cancer. Patients defined as high risk include those having either four or more pathologic axillary lymph nodes or one to three pathologic axillary lymph nodes and either a grade 3 tumor or a tumor ≥ 50 mm.
The expanded label is based on 4-year follow-up findings from the phase III monarchE trial (ClinicalTrials.gov identifier NCT03155997), a randomized (1:1), open-label, two-cohort multicenter trial including adult women and men with HR-positive, HER2-negative, node-positive, resected breast cancer with clinical and pathologic features consistent with a high risk of recurrence. Patients were randomly assigned to receive either 2 years of abemaciclib plus physician’s choice of standard endocrine therapy or standard endocrine therapy alone.
Study investigators reported that the invasive disease–free survival rate (the major efficacy outcome measure) was 85.5% at 4 years with abemaciclib plus standard endocrine therapy, compared with 78.6% with standard endocrine therapy alone. The risk of recurrence decreased by 35% with the abemaciclib combination versus endocrine therapy alone.
The recommended abemaciclib starting dose is 150 mg taken twice daily with tamoxifen or an aromatase inhibitor until completion of 2 years of treatment or until disease recurrence or unacceptable toxicity.
“The magnitude of benefit seen in the 4-year data from the monarchE study reinforces my confidence in adjuvant [abemaciclib] as the standard of care for high-risk patients in this setting,” stated Erika P. Hamilton, MD, of Sarah Cannon Research Institute, in a press release.