Participants Wanted for Trial Studying CDK 4/6 Inhibitor in Early-Stage Breast Cancer

PALLAS study will test palbociclib added to hormonal therapy in HR-positive breast cancer
Featured Clinical Trials
January 26, 2017
Eric Fitzsimmons, Copy Editor and Content Coordinator
Reviewed By: 
Sarah Mougalian, MD

A new clinical trialinfo-icon is looking for people being treated for stageinfo-icon II or III hormone receptorinfo-icon-positive breast cancer to test if adding a new medicineinfo-icon to hormonal therapyinfo-icon will lower the risk of cancer returning.


The FDAinfo-icon granted accelerated approval to the targeted therapyinfo-icon palbociclib (Ibrance) in 2015 for use in women with metastaticinfo-icon hormone receptor-positive breast cancer. The approval was the first for a type of medicines called cyclin-dependent kinase (CDK) inhibitors. CDK inhibitors work by blocking two enzymes, CDK4 and CDK6, from giving a signal to cancer cells that causes them to reproduce and tumors to grow.

Palbociclib’s approval was based on results from the PALOMA-1 trial. This trial paired it with the aromatase inhibitorinfo-icon letrozoleinfo-icon (Femarainfo-icon) and involved women with hormone receptor-positive, HER2-negative metastatic breast cancer who had been through menopauseinfo-icon.  In 2016, the FDA approved palbociclib for use with another hormonal therapy called fulvestrantinfo-icon (Faslodexinfo-icon), based on results from the PALOMA-3 trial.

Researchers are interested in learning if palbociclib can prevent recurrenceinfo-icon in early-stage breast cancerinfo-icon.


The PALLAS study is a phase III trialinfo-icon designed to see if adding palbociclib to standard hormonal therapy will lower the chance of breast cancer returning for people with early-stage breast cancer. It will recruit more and different people than the PALOMA trials, including women who have not reached menopause and men, and it will look at how palbociclib works with different hormonal therapies like tamoxifeninfo-icon and aromatase inhibitors.

The main interest will be invasive disease-free survival, the amount of time from the start of the trial until doctors find new signs of breast cancer that is invasive, meaning it’s stage I or higher, or that person dies. Researchers will also look at

  • overall survival
  • how long it takes until cancer travels to other parts of the body
  • side effects


Researchers aim to include 4,600 people in the study. Participants will be randomly assigned to one of two groups. One group will take palbociclib alongside a standard hormonal therapy, like tamoxifen or an aromatase inhibitor, for 2 years. This group will then continue taking hormonal therapy alone for at least 3 years, totaling at least 5 years of hormonal therapy. The other group will take at least 5 years of hormonal therapy but will not receive palbociclib. The PALLAS trial is open label, meaning you and your doctor will know if you are taking the palbociclib or not.


This study is accepting women, both those who have been through menopause and those who haven’t, and men. To participate you must have breast cancer that is

  • Stage II or III
  • Hormone receptor-positive
  • HER2-negative

You must have completed any necessary breast surgeryinfo-icon and completed any radiation therapyinfo-icon or chemotherapyinfo-icon before enrolling. You also must be receiving hormonal therapy, or getting ready to start hormonal therapy.

Pregnant women and anyone who has been treated with a CDK inhibitor in the past are not eligible for the study.

Your doctor may be able to tell you if you are eligible for the study. If you think you may be eligible, you can find more information, including where to find participating health centers and a guide to speaking with your doctor at You can also read all the requirements to participate in the trial’s listing on

You must have Javascript enabled to use this form.
Additional Related Topics 
Hormone Receptor-Positive
Hormonal Therapy