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BELLE-2 Study Explores Use of PI3K Inhibitor

Seeks 1,060 women with hormone receptor-positive metastatic disease

Trial Starts: February 2012 Trial Ends: April 2017

Written By Nicole Katze, MA, Editor and Manager, Content Development
Reviewed By Saranya Chumsri, MD

Postmenopausal women with hormone receptor-positive, HER2-negative metastatic breast cancer that continued to grow during or after treatment with an aromatase inhibitor (anastrozole, letrozole, and exemestane) are needed for a clinical trial. Researchers conducting the trial are examining the safety and effectiveness of combining the PI3K inhibitor BMK120 with fulvestrant (Faslodex).


Researchers believe activation of the PI3K pathway plays an important role in the growth of cancer cells, because past studies have shown that when the PI3K pathway is overactive cancer cells are more resistant to cell death and are more likely to survive and grow. PI3K inhibitors, like BMK120, aim to interfere with overactive PI3K pathways to help control breast cancer.

Fulvestrant is a selective estrogen receptor downregulator, or SERD, that blocks the effect of the estrogen that drives cancer growth in estrogen receptor-positive breast cancer. It is a hormonal therapy given to women who have already been treated with aromatase inhibitors or tamoxifen. Fulvestrant is often given to women after the cancer progresses with treatment with these other hormonal therapies.

Trial investigators wish to explore whether adding BMK120 to fulvestrant is more beneficial than fulvestrant alone.


The primary endpoint, or goal, of this study is to measure progression-free survival (PFS), the time from assignment to a trial treatment until radiological (imaging) evidence that the disease has grown or until death from any cause. Secondary endpoints include overall survival (OS), the time from assignment until death from any cause, and clinical benefit rate, the proportion of participants with the best response being either complete response (disappearance of all signs of cancer); partial response (decrease in the size of the tumor or extent of the cancer); or stable disease (cancer that neither increases nor decreases) in response to treatment.


Participants will be assigned to one of two treatment arms (groups):

  • Arm I will take a daily 100 mg pill of BMK120, and receive 500 mg of fulvestrant as an injection into muscle on days 1 and 15 of the first treatment cycle, and on day 1 of all following cycles. Treatment will continue until the cancer grows or spreads.
  • Arm II will take a daily 100 mgs of a placebo, an inactive substance, in pill form and will receive fulvestrant as described above.

Participants will be followed throughout the study, with PFS measurement an average of every 8 weeks after assigned to a treatment arm. OS will be measured an average of every 3 months after treatment ends.

The phase III trial is double-blind, meaning neither the participant nor the trial doctors know to which treatment the participant is assigned.


You may be eligible to participate if you

  • are 18 years of age
  • are a postmenopausal woman with hormone-positive, HER2-negative metastatic breast cancer that progressed during or after treatment with an aromatase inhibitor
  • have a tumor sample that can be shipped to a designated laboratory to perform testing.
  • have good bone marrow and organ function

You may not be eligible if you

  • have been treated with PI3K, AKT or mTOR inhibitors in the past
  • have been treated with more than one chemotherapy line for metastatic breast cancer
  • have untreated or unstable brain metastases
  • are taking steroids or immune suppressing medicines
  • have heart disease
  • have a certain level of anxiety or depression asmeasured by questionnaire

For more information or to findout if you are eligible, talk with your doctor about trial NCT01610284 on

Study Locations

This trial is being held in nearly 300 locations nationally and internationally. For a full list of locations and contact information, visit