The purpose of this study is to collect prostate cancer tissue from males with metastatic prostate cancers in order to study the tumor microenvironment (TME), which is the area surrounding the tumor including cells, blood vessels, etc., in men with metastatic prostate cancer. The type of research performed on these tissue samples include genetic & molecular analyses.

The overall aim of this protocol is to collect prostate cancer tissue from males with metastatic prostate cancers in order to perform comprehensive profiling of the tumor microenvironment (TME) across sites of metastasis in males with metastatic prostate cancer. The TME is comprised of proliferating tumor cells, the tumor stroma, blood vessels, infiltrating inflammatory cells and a variety of associated tissue cells. This study will enable analysis of the prostate TME in the context of different sites of metastasis as well as a variety of clinical states of disease (i.e no prior androgen deprivation therapy, progression on abiraterone, progression on an androgen receptor (AR) antagonist, or progression on chemotherapy etc). Furthermore, the expression and receptor density of prostate lineage antigens that can be targeted for development of novel therapeutics for prostate cancer will be evaluated in parallel.

Inclusion Criteria:

• Be willing and able to provide written informed consent for the trial.
• Age ≥18 years of age on day of signing informed consent.
• Eastern Cooperative Oncology Group (ECOG) performance status: 0,1 or 2
• Histologically proven adenocarcinoma of the prostate. (Rarely pathology is not available but if clinical situation confirms prostate cancer - such as prior response to androgen ablation and/or metastatic disease typical of prostate cancer, i.e. involving bone or pelvic/extra pelvic lymph nodes or para-aortic lymph nodes, AND an elevated serum concentration of prostate-specific antigen (PSA) typical of prostate cancer) pathology is not required and patient can be enrolled after discussed with study PI.
• Clinical stage N1 or M1
• Evidence of nodal or distant metastasis by MRI/CT scan, bone scan or positron emission tomography (PET) scan
• Planned specimen from subjects that undergo core needle biopsy must allow for cores of at least 21 gauge with depth of 5 mm. A goal of 3-8 core specimens (3 to 8 passages of the needle into the lesion) will be sought during the procedure, if felt to be safe by the performing physician.
• Laboratory tests meet minimum safety requirements:
• Hemoglobin >7mg/dL
• Platelet count ≥75,000/mm3
• Coagulation: prothrombin time (PT)/international normalized ratio (INR), Partial thromboplastin time (PTT) ≤ 1.5 upper limit of normal (ULN) (except if on therapeutic anticoagulation in which case the patient can be enrolled if stable and anticoagulation levels are appropriate for their condition per good clinical practice).

Exclusion Criteria:

• A psychiatric disorder, medical condition, or other life circumstance, which in the opinion of the investigators, would make it difficult for a patient to successfully complete the informed consent process.
• Acute illness or any medical condition in the judgment of the study physician making specimen collection inadvisable

Male adults age 18 or older diagnosed with metastatic castration-resistant prostate cancer (mCRPC).