Overview
There are several approved and guideline-recommended treatments for metastatic, estrogen receptor-positive breast cancer that has progressed on an aromatase inhibitor and a CDK4/6 inhibitor. Right now, doctors do not have a good way of choosing between these treatments. Scientists we work with have come up with ways to use the biology of the tumor to try to predict which treatment is best. This study is being done to test if those predictions are right and to learn more about these tumors to design better treatments in the future.
Eligibility
Inclusion Criteria:
- Histologic diagnosis of breast cancer
- Metastatic or incurable
- Prior treatment with an anastrozole or letrozole and a CDK4/6 inhibitor
- Progression while on or within 6 months of stopping the CDK4/6 inhibitor
- At least one lesion amenable to percutaneous biopsy that is not a purely sclerotic bone lesion
- ECOG 0-2
- Age 18 or greater
- Able to provide informed consent and willing to sign an approved consent form that conforms to federal and institutional guidelines.
Exclusion Criteria:
- Prior treatment within 2 years with fulvestrant, alpelisib, everolimus, or capecitabine
- Comorbid disease other than breast cancer with a life expectancy of less than 2 years
- Cancer other than breast cancer that is expected to need treatment within 2 years
- Platelets < 100,000/microliter
- INR > 1.5