Phase III Trial of CDK 4/6 Inhibitor Abemaciclib in Early-Stage Breast Cancer Seeks Participants

Trial will study adding abemaciclib to hormonal therapy in hormone receptor-positive, early-stage breast cancer
Featured Clinical Trials
April 26, 2018
Eric Fitzsimmons, Copy Editor and Content Coordinator
Reviewed By: 
Christiana M. Brenin, MD

The monarchE trial is studying if adding abemaciclib (Verzenio) to hormonal therapyinfo-icon will help lower the risk of cancer returning for people with early-stageinfo-icon, hormone receptorinfo-icon-positive breast cancer.

Researchers are looking for men and women with hormone receptor-positive, HER2-negative breast cancer that have a high risk of recurrenceinfo-icon to participate.


Abemaciclib is a medicineinfo-icon that blocks two specific proteins, cyclin dependent kinases 4 and 6. Medicines that block these proteins are known as CDK 4/6 inhibitors. There are three CDK 4/6 inhibitors currently approved by the FDAinfo-icon to treat metastaticinfo-icon breast cancer. Palbociclib (Ibrance) was the first medicine of this type approved in 2015. It was followed by ribociclib (Kisqali) and abemaciclib in 2017.

Because these medicines improve outcomes for people with metastatic breast cancer, researchers want to know whether using abemaciclib with hormonal therapy for early-stage breast cancerinfo-icon will lower the risk of recurrence for certain people.


The monarchE trial is studying the possible benefits of giving abemaciclib to people with early-stage, hormone receptor-positive, HER2-negative breast cancer with a high risk of recurrence. Factors such as the size of the tumorinfo-icon, Ki-67 proliferation index and whether cancer cells were found in the lymphinfo-icon nodes are used in measuring the risk of breast cancer returning. This study will also be looking at the quality of lifeinfo-icon of participants taking abemaciclib with hormonal therapy compared with those taking hormonal therapy alone.


MonarchE is a phase III, open label trial. People in the trial will be randomly assigned to take hormonal therapy alone or take it with abemaciclib, the medicine being studied. Open label means participants will know which treatment they have been assigned. Researchers are hoping to recruit 3,580 people to participate.


The study is accepting women and men with early-stage, hormone receptor-positive, HER2-negative breast cancer. People eligible for this study have breast cancer with one of the following high-risk features

  • cancer cells found in 4 or more axillary lymph nodes
  • a tumor that is 5 centimeters or larger
  • a gradeinfo-icon 3 tumor, meaning the tumor cells are very active and do not look like normal cells under a microscope
  • a Ki-67 index of 20 percent or greater, measuring how quickly cancer cells are turning over

Abemaciclib comes in pill form so you must be able to take medicines by mouth to participate. You may not be able to participate if you have other serious health conditions. Your doctor or a guide from the trial will be able to tell if you have a conditioninfo-icon that would keep you from participating. You should not participate until you have recovered from the effects of surgeryinfo-icon, radiationinfo-icon or chemotherapyinfo-icon. Other reasons you would not be eligible to participate include

  • your breast surgery was more than 16 months ago
  • you have already been on hormonal therapy for your breast cancer for more than 12 weeks
  • you are pregnant or planning to become pregnant
  • you have been treated for breast cancer in the past (except for non-invasive breast cancerinfo-icon, such as Ductal Carcinoma in Situinfo-icon, or DCISinfo-icon)
  • you have been treated for another cancer in the last 5 years
  • you have already used a CDK 4/6 inhibitor for treatment
  • you are taking hormoneinfo-icon replacement medicines or hormonal birth control
  • You have previously had a blood clot

There are multiple study locations throughout the United States. Visit the trial listing on for more details and speak to your healthcare team about your interest in participating.

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Hormone Receptor-Positive