Title
Evaluation of Prostate Specific Membrane Antigen (PSMA) in HER2-Negative, Androgen Receptor Positive (AR+) Metastatic Breast Cancer 18F-DCFPyL PSMA-based PET/CT

Description
Evaluation of Prostate Specific Membrane Antigen (PSMA) in HER2-negative, Androgen Receptor (AR)-Positive Metastatic Breast Cancer With 18F-DCFPyL PSMA-based PET/CT

Objective
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.

Treatment 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.

Key Eligibility 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

Applicable Disease Sites
Breast

Participating Institutions
UW Health University Hospital; Wisconsin Institute for Medical Research (WIMR)