64Cu-SAR-BBN and 67CU SAR-BBN for Identification and Treatment of Gastrin Releasing Peptide Receptor (GRPR)-Expressing Metastatic Castrate Resistant Prostate Cancer in Patients Who Are Ineligible for Therapy With 177Lu-PSMA-617 (COMBAT)

Inclusion Criteria: * Signed informed consent; * ≥18 years of age; * Eastern Cooperative Oncology Group performance status of 0 to 2; * Life expectancy \>6 months; * Histological, pathological, and/or cytological confirmation of prostate cancer (PCa); * ≥1 metastatic lesion that is present at screening computed tomography (CT), magnetic resonance imaging (MRI), or bone scan imaging obtained ≤28 days prior to enrollment into the study; * Positive 64Cu-SAR-BBN PET/CT scan, where 64Cu-SAR-BBN uptake (standardized uptake value \[SUV\] max) of at least 1 known lesion is positive (higher than that of the liver). Any lesions on anatomical imaging larger in short axis than size as follows: organs ≥ 1 cm, lymph nodes ≥ 2.5 cm, bones (soft tissue component) ≥ 1 cm on the 1 hour positron emission tomography (PET)/ CT scan must also be positive for 64Cu-SAR-BBN uptake. NOTE: ALL OTHER ELIGIBILITY CRITERIA MUST BE FULFILLED BEFORE THE 64Cu-SAR-BBN ADMINISTRATION IS PERMITTED; * Castrate level of serum/plasma testosterone (\<50 ng/dL or \<1.7 nmol/L); * Have progressive mCRPC despite prior androgen deprivation therapy and at least either enzalutamide and/or abiraterone (or other such androgen receptor pathway inhibitors). Documented progressive mCRPC will be based on at least 1 of the following criteria: * Serum/plasma prostate specific antigen (PSA) progression defined as 2 consecutive increases in PSA over a previous reference value measured at least 1 week prior. The minimal value for …