A Phase I Study of BYL719 with Letrozole or Exemestane for Treating Locally Advanced Inoperable or Metastatic Breast Cancer

Full Title

A Phase I Trial of BYL719 Plus Letrozole or Exemestane for Patients with Hormone-Receptor Positive Locally-Advanced Unresectable or Metastatic Breast Cancer


Letrozole and exemestane - drugs called “aromatase inhibitors” that block estrogen production - are used to treat metastatic breast cancer in postmenopausal women whose tumors contain hormone receptors. However, these drugs often stop working. The purpose of this study is to find the highest dose of an investigational drug called BYL719 that can be given safely in women with locally advanced inoperable or metastatic breast cancer who are already taking letrozole or exemestane.

BYL719 is an inhibitor of PI3 kinase, an enzyme which fuels the growth of several types of cancer, including many breast cancers. It is taken orally (by mouth). In this study, women who are taking either letrozole or exemestane will continue taking those drugs and will also receive BYL719.


To be eligible for this study, patients must meet several criteria, including but not limited to the following:

  • Patients must be postmenopausal women with hormone receptor-positive locally advanced inoperable or metastatic breast cancer and have already been receiving treatment with letrozole OR exemestane for 4 weeks or more.
  • Patients may not have previously been treated with a PI3 kinase inhibitor.
  • For patients who had radiation therapy or surgery, at least 2 weeks must have passed since completion of radiation therapy and 4 weeks since any major surgery and entry into the study.
  • Patients must be physically well enough that they are fully ambulatory, capable of all self care, and are capable of all but physically strenuous activities. As an example, patients must be well enough that they would be able to carry out office work or light housework.
  • This study is open to patients age 18 and older.

For more information about this study and to inquire about eligibility, please contact Dr. Maura Dickler at 646-888-5456.