Evaluation of PSMA in HER2- AR+ Metastatic Breast Cancer
Evaluation of PSMA in HER2- AR+ Metastatic Breast Cancer
The purpose of this research is to determine the expression of prostate specific membrane
 antigen (PSMA) in human epidermal growth factor receptor 2 (HER2)-negative, androgen receptor
 (AR)-positive metastatic breast cancer, and to determine its role in resistance to the
 anti-androgen, bicalutamide. The investigators hypothesize that PSMA expression will
 correlate with resistance to anti-androgen therapies, as has been documented in prostate
 cancer, and this can be used to select patients most likely to benefit from these therapies
 in future clinical trials. 15 people with HER2-negative, AR-positive metastatic breast cancer
 will be enrolled and be on study for about 3 days.
Primary Objective:

 -  To evaluate the expression of PSMA via 18F-DCFPyL PSMA-based PET/CT in patients with
 metastatic HER2-negative, AR-positive breast cancer. Expression of PSMA will be
 quantified using PSMA-based PET imaging using a novel agent, 18F-DCFPyL, as a
 non-invasive imaging biomarker of tumor neovasculature in HER2-negative, AR-positive
 metastatic breast cancer.

 Secondary Objectives:

 -  PSMA PET will be compared with the expression of PSMA in CTCs and diagnostic metastatic
 tissue from patients with HER2-negative, AR-positive metastatic breast cancer.

 -  PSMA expression will be correlated with clinical benefit (objective response and
 progression-free survival) to bicalutamide and ribociclib for patients enrolled in
 NCT03090165.
Inclusion Criteria:

 -  Patients diagnosed with metastatic HER2-negative breast cancer AR expression of ≥ 10%

 Exclusion Criteria:

 -  Other (non-breast) known active malignancy. Participants with previously treated
 cancers which are in remission or have no evidence of disease are eligible.

 -  Unable to lie flat during or tolerate PET/CT

 -  Participants with any medical condition or other circumstances that, in the opinion of
 the investigator, compromise the safety or compliance of the subject to produce
 reliable data or completing the study

 -  Women of childbearing potential must not be pregnant or breast feeding (pregnancy test
 negative within 7 days prior to PET/CT