This study is looking for postmenopausal patients with advanced breast cancer with an ESR1 mutation to compare lasofoxifene (Fablyn) to fulvestrant (Faslodex). The main outcome measured in this trial will be the patient’s survival without tumor growth or spread. This trial is recruiting in multiple locations in the United States.
Breast cancer is caused by different mutations. Estrogen receptor (ER), human epidermal growth factor receptor 2 (HER2) are two such mutations. Different abnormal genes can cause ER-positive breast cancer, including ESR1. Different treatments target different breast cancer mutations which means that some treatments may not work for all types of breast cancer.
Lasofoxifene and fulvestrant are both drugs that attach to the ER and stop cancer cell growth. Currently, fulvestrant is used to treat patients with ER-positive breast cancer. Lasofoxifene is a drug that works similarly, but it's safety and effectiveness are still under investigation.
This study aims to compare the effectiveness of lasofoxifene versus fulvestrant in postmenopausal patients with advanced breast cancer and an ESR1 mutation. The main outcome to be measured is survival without tumor growth or spread.
Who are they looking for?
This study is recruiting 100 patients that are postmenopausal and have either locally advanced or metastatic breast cancer. Patients must be ER-positive with an ESR1 mutation but HER2-negative. Patients must have previously received an aromatase inhibitor (hormonal therapy) and a cyclin-dependent kinase 4/6 inhibitor drug. Patients must have previously received chemotherapy but be free from the side effects by the beginning of the trial. Patients should have normal blood cell levels, and good kidney and liver function.
Patients who previously received drugs targeting the ER and certain other drugs cannot participate. Patients with cancer in the brain or lungs cannot participate. Patients should not have received radiotherapy at least 30 days before beginning the study. Patients with certain heart and blood conditions cannot participate. Patients with certain infections, including HIV and Hepatitis B and C, cannot participate. Patients with other types of cancer in the last 5 years cannot participate. Patients with vaginal bleeding in the last year cannot participate. Patients who participated in another clinical trial within a month of the present study cannot participate.
How will it work
Patients will be divided into two groups. The first group will receive lasofoxifene and the second will receive fulvestrant.
Patient’s survival without tumor growth or spread will be measured for 1 year. The response of the tumor to the drugs will also be measured for 1 year. Side effects experienced by patients will be recorded for 1 year.