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.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
DIAGNOSTIC
Masking
NONE
Enrollment
13
PSMA is highly expressed on prostate cancer and is associated with metastasis and resistance to anti-androgen therapies. Researchers have evaluated the expression of PSMA in the tumor and tumor-associated neovasculature in primary tumors and distant metastases in patients with breast cancer.
University of Wisconsin School of Medicine and Public Health
Madison, Wisconsin, United States
RECRUITINGPSMA Expression as measured by 18F-DCFPyL SUV
Quantitative analysis of 18F-DCFPyL PSMA PET uptake will be performed at the lesion-level. Standardized uptake values (SUV) will be measured by manually drawing a region of interest (ROI) to encompass the entire lesion guided by the lesion extent visualized on conventional imaging. PET SUV based quantitative tumor uptake parameters will be obtained.
Time frame: up to 3 days
Expression of PSMA in CTCs
Expression of PSMA in CTCs will be measured via immunofluorescence.
Time frame: up to 2 weeks
Expression of PSMA in diagnostic metastatic tissue
PSMA expression in tumors will be semi-quantitatively scored by a study pathologist using published methods including separate assessment of tumor-associated and non-tumor vasculature, with the endothelium highlighted by a CD31 immunostain to facilitate definitive recognition.
Time frame: up to 3 days
Change in PSMA Expression on CTCs after 2 weeks of bicalutamide
The change in PSMA expression on CTCs will be measured pre and post treatment via immunofluorescence.
Time frame: baseline and up to 2 weeks
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