Study to Determine the Feasibility, Evaluability and Variability in Markers of Drug Action in Castration Resistant Prostate Cancer

Inclusion Criteria:

* Patients with metastatic prostate cancer post maximal androgen blockade (MAB) with primary or metastatic cancer deposits amenable to biopsy
* Patients aged 18 years and older
* Histologically or cytologically confirmed adenocarcinoma of the prostate
* World Health Organisation (WHO) performance status 0 to 2 with no deterioration over the previous 2 weeks and minimum life expectancy of 12 weeks
* Provision of archival tumour sample for PTEN status determination as directs group assignment
* Provision of written informed consent
* Provision of cancer tissue samples, willing to undergo 1-3 biopsies on 2 separate occasions
* No change of cancer treatment anticipated until final biopsy/ blood samples have been taken
* Serum testosterone level \<50 ng/dL sustained by medical or surgical castration

Exclusion Criteria:

* Involvement in the planning and/or conduct of the study (applies to both AstraZeneca staff and/or staff at the study site)
* Previous enrolment in the present study
* As judged by the investigator, any evidence of severe or uncontrolled systemic disease (e.g. unstable or uncompensated respiratory, cardiac, hepatic or renal disease)
* Evidence of any other significant clinical disorder or laboratory finding that made it undesirable for the patient to participate in the study
* Any investigational agents or study drugs from a previous clinical study within 30 days of the first tissue collection
* Radiotherapy to lesion to be biopsied within 4 weeks of biopsy
* Spinal cord compression or brain metastases unless asymptomatic, treated and stable and not requiring steroids for at least 4 weeks prior to start of study treatment
* Judgment by the investigator that the patient should not participate in the study if the patient is unlikely to comply with study procedures, restrictions and requirements
* Patients at increased risk of bleeding as a result of biopsy
* History of bleeding disorders or thrombocytopenia (platelets \<100)
* Concomitant treatment with anticoagulant therapy such as warfarin/low molecular weight heparin (Aspirin not contra-indicated but consider temporary cessation if biopsy site has higher risk of bleeding e.g. liver)
* Current urinary tract infection (UTI) or prostatitis
* Known infection with HIV, Hepatitis B or Hepatitis C