Up to 30 men with metastatic prostate cancer will undergo up to 2 FTT PET/CT scans to look at PARP activity in sites of known cancer. Subjects will undergo a baseline scan prior to starting new therapy and a second, optional, post-therapy scan 1-21 days after the start of treatment. Tissue from a clinical or research biopsy will be compared to imaging measures, if available.

Up to 30 evaluable patients with a histological diagnosis of prostate cancer with clinical evidence of metastatic disease who are being considered for new therapy or for a change in therapy with a PARP inhibitor, androgen deprivation therapy, and/or chemotherapy as part of their clinical care will be enrolled in this study. A pre-treatment 18F-FluorThanatrace ([18F]FTT) positron emission tomography/ computed tomography (PET/CT) scan will be done prior to the start of a new therapy regimen. PET/CT imaging will be used to evaluate PARP-1 expression in sites of prostate cancer using the investigational radiotracer [18F]FTT. This is an observational study in that [18F]FTT PET/CT will not be used to direct treatment decisions. While patients and referring physicians will not be blinded to the [18F]FTT PET/CT results, treatment decisions will be made by the treating physicians based upon clinical criteria. After injection of [18F]FTT patients will undergo a skull base to mid-thigh scan, starting at approximately 60 minutes post injection. PET/CT imaging sessions will include an injection of 12 mCi of [18F]FTT intravenously (approximate range for most studies is anticipated to be 8-12 mCi ). of [18F] FTT. Data will be collected to evaluate uptake of [18F]FTT in sites of prostate cancer, which will be compared with PARP-1 expression in tissue, when available. All evaluable patients may start new therapy following the [18F]FTT PET/CT scan. It is expected that due to patient preference and time considerations, approximately 80% will also undergo a second (optional) scan that will be performed approximately 1-21 days after new therapy has started. The second scan is obtained to evaluate whether the initiation of a PARP inhibitor and/or androgen deprivation therapy and/or chemotherapy alters [18F] FTT uptake.

Inclusion Criteria:

1. Participants will be ≥ 18 years of age
2. Histologically proven prostate carcinoma
3. Clinical evidence of metastatic disease with at least one lesion identified on standard of care imaging (CT, MRI, Bone Scan, FDG or other PET/CT, Ultrasound)
4. Considered a candidate for new therapy or change in therapy with PARP inhibitor therapy and/or androgen deprivation therapy (ADT) and/or chemotherapy with or without additional agents, either on a clinical trial or as part of clinical care.
5. Participants must be informed of the investigational nature of this study and be willing to provide written informed consent and participate in this study in accordance with institutional and federal guidelines prior to study-specific procedures.

Exclusion Criteria:

1. Inability to tolerate imaging procedures in the opinion of an investigator or treating physician
2. Any current medical condition, illness, or disorder as assessed by medical record review and/or self-reported that is considered by a physician investigator to be a condition that could compromise participant safety or successful participation in the study

Patients with a histological diagnosis of prostate cancer with clinical evidence of metastatic disease who are being considered for new therapy or for a change in therapy with a PARP inhibitor, androgen deprivation therapy, and/or chemotherapy as part of their clinical care.