A Phase II Study Evaluating the Efficacy of Enzalutamide and the Role of ARv7 in Metastatic Castration Resistant Prostate Cancer (mCRPC) Patients With Visceral Disease.

1. Age \> 18

2. ECOG PS 0-1-2

3. Biopsy (primary tumour or metastases) confirming the diagnosis of prostate adenocarcinoma

4. Documented measurable metastatic visceral disease (according to RECIST 1.1 criteria) considering metastases in lung or liver or extraregional lymphnodes

5. Written informed consent

6. Platelets \> or = 100 x109/L; haemoglobin \> or = 9 g/dl; neutrophils \> or 1.5 x 109/L

7. Bilirubin \< or = 2 mg/dl, AST and ALT \< or = 2.5 times the UNL or \< or = 5 times UNL for pts with liver metastases; serum albumin \> or = the LNL

8. Patients of childbearing age should use contraceptive methods

9. Life expectancy \> 3 months

10. Able to swallow the study drug and comply with study requirements;

11. Willing and able to give informed consent.

12. Ongoing androgen deprivation therapy with a GnRH analogue or orchiectomy (i.e., surgical or medical castration);

13. Patients may have received previous therapy including chemotherapy (docetaxel) last cycle must be received 3 weeks before start of experimental treatment. Hormonal treatment containing bicalutamide must be interrupted 2 weeks before start of study therapy

14. Previous radiotherapy (prostate and/or bone) is accepted but must be interrupted 3 weeks before start of experimental treatment.

15. Serum testosterone level \< 1.7 nmol/L (50 ng/dL) at the Screening visit

16. Progressive disease by PSA or imaging in the setting of medical or surgical castration. Disease progression for study entry is defined as one or more of the following three criteria (according with PCWG2):

* PSA progression defined by a minimum of three rising PSA levels with an interval of ≥ 1 week between each determination. The PSA value at the Screening visit should be ≥ 2 g/L (2 ng/ml); if the third PSA value is less than second PSA, a fourth PSA must be repeated and if it the value is higher than second must be considered as disease

* Soft tissue/visceral disease progression defined by RECIST 1.1;

* Bone disease progression defined by two or more new lesions on bone scan.

What this study is about