Age of monarchE.

Top Line: Do CDK 4/6 inhibitors reduce the risk of recurrence in women with early stage, hormone receptor positive breast cancer?

The Study: While there’s been a dramatic shift in adjuvant therapy for hormone receptor positive breast cancer with the use of genetic recurrence scores, there hasn’t been much change in the actual agents used in treatment. At the same time, CDK 4/6 inhibitors have changed the landscape of advanced HR+ disease. The monarchE trial sought to determine if the addition of abemaciclib to endocrine therapy (ET) could reduce the risk of early recurrence in women at particularly high risk. A whopping 5600+ women with early stage HR+, HER2- breast cancer and certain high risk features (4+ nodes or 1-3+ nodes plus another high risk feature) were randomized to standard adjuvant ET with or without 2 years of abemaciclib. Prior to enrollment, they completed standard therapy with surgery, radiation, and chemo as indicated. Over 95% of patients received radiation and chemotherapy as part of initial treatment, and just over ⅔ of patients received aromatase inhibitors as their ET. At 2 years, the rate of invasive disease-free survival was 3.5% higher with the addition of abemaciclib (88.7→ 92.2%). 

TBL: Two years of adjuvant abemaciclib improves disease-free survival by 3.5% among women with node-positive, hormone receptor-positive breast cancer. | Johnston, J Clin Oncol 2020