The purpose of the trial is to investigate new clinical tests that could predict what treatments work best for certain patients with advanced prostate cancer by identifying markers and indicators present in blood and tissue which correlate with treatment response.

Prostate Cancer (PCa) is a complex disease and not all patients respond to every treatment available.

This study aims to investigate new clinical tests based on simple and routine blood tests to allow men with PCa and their doctors to choose the correct treatment for their metastatic PCa.

In this way, only men likely to respond to the specific treatment will be chosen, sparing unnecessary or prolonged treatment for those who will not respond and allowing them to avail of alternative therapies likely to have more benefit. This is termed personalised therapy.

The study will perform research on biological elements present in the blood including deoxyribonucleic acids (DNA), ribonucleic acid (RNA), protein and circulating tumour cells (CTCs) which are cancer cells that have spread beyond the prostate gland and can be found floating in the blood. Clinical data will be correlated to research findings to form conclusions on personalised therapy.

Additional optional sub studies include; magnetic resonance imaging (MRI) with a biopsy of another tumour in a different site of their body such as bone, lung or liver (metastatic biopsy), metastatic biopsy only and biopsies of the fluid of solid part of the bone. These optional components provide more detailed information on prostate cancer and how men are responding to treatment. The research results from these optional sub studies will be correlated with the research analysis from the blood samples and clinical data and will help to make treatment decisions.

Inclusion Criteria:

1. Stage 4 mPCa as confirmed by CT/MRI or by bone scan
2. Patient with visceral disease and/or bone lesions (excluding patients who only have nodal disease), who have commenced or are about to commence ADT and whose disease has not shown any evidence of castration resistance (cohort 1) Or Patient with castrate-resistant disease at time of treatment change (cohort 2)
3. Stable medical condition, including the absence of acute exacerbations of chronic illnesses, serious infections, or major surgery within 28 days prior to recruitment
4. Life expectancy of at least 6 months
5. Ability to give written informed consent obtained before any study-related procedures
6. Age ≥ 18 years and male

Exclusion Criteria:

1. Diagnosis of or treatment for another systemic malignancy within 2 years before study entry.*
2. Any evidence of residual disease from a previously diagnosed malignancy. *Patients with non-melanoma skin cancer or carcinoma in situ of any type are not excluded if they have undergone complete resection

Men with castrate sensitive (cohort 1) or castrate resistant (cohort 2) metastatic prostate cancer.