This clinical trial is for adults who have advanced and metastatic castrate resistant prostate cancer (mCRPC).
   
The purpose of this study is to test new compounds (64Cu-SAR-bisPSMA and 67Cu-SAR-bisPSMA) as possible treatment for metastatic castrate resistant prostate cancer (mCRPC), an advanced form of prostate cancer.
   
It is known that most prostate cancers, including mCRPC, express specific proteins on their surface, such as the Prostate Specific Membrane Antigen (PSMA) protein. The compounds used in this research study use a radioactive form of copper, and can specifically attach to the PSMA protein.

64Cu-SAR-bisPSMA is an imaging agent, which contains copper-64 (64Cu) and is used to visualize tumors that express the PSMA protein using a positron emission tomography (PET) scanner.

67Cu-SAR-bisPSMA is the study drug agent that contains copper-67 (67Cu) and is used to deliver radiation to tumors that express the PSMA protein. The effectiveness of this therapy depends on delivering the highest possible radiation dose to the tumor, while sparing normal organs and tissues from damage.
   
Both study drugs tested in this research study are investigational. An investigational drug is one that is not yet approved by the U.S. Food and Drug Administration (FDA). 
   
This study is being completed in three phases. The first phase, referred to as the Dosimetry Phase, looks at the distribution of the imaging agent 64Cu-SAR-bisPSMA in the body. The second phase of the study is the Dose Escalation Phase. This phase of the study will look at the safety of different dose levels of the study drug agent (67Cu-SAR-bisPSMA) to find the highest dose level that can be administered. The third phase of the study is the Cohort Expansion Phase, which will be assessing the safety and efficacy of multiple doses of 67Cu-SAR-bisPSMA.
   
Participants will receive an administration of 64Cu-SAR-bisPSMA via injection into a vein in their arm, followed by a PET/CT scan to see if their tumors express the PSMA protein. If so, participants will receive 1 or 2 administration cycles of 67Cu-SAR-bisPSMA via intravenous (IV) infusion into a vein in their arm depending on which phase of the study they enter.

During the study drug administration period, participants will be asked to attend study visits to the study center every 2 weeks between the therapy cycles and until the end of their participation. Each study drug administration cycle lasts for at least 6 weeks, but can be up to 16 weeks depending on how the participant’s body responds to 67Cu-SAR-bisPSMA.

Participation in the screening, study drug administration, and safety follow up period of this research will last about 14 to 23 months. There will also be a long-term follow-up period that will last up to 5 years from participant’s first 67Cu-SAR-bisPSMA dose.