Docetaxel or Hormone Therapy as Second Line Treatment in Patients With Asymptomatic or Oligosymptomatic Metastatic Castration-resistent Prostate Cancer (mCRPC) Progressing After Abiraterone or Enzalutamide.

Inclusion Criteria:

* Histologically or cytologically confirmed adenocarcinoma of the prostate
* Distant metastatic disease
* Previous first line treatment with abiraterone or enzalutamide for 6 cycles interrupted at least 2 weeks before randomization
* Patients must be ≥ 18 years of age
* Patients must have castrate serum level of testosterone of \< 0.5 ng/mL ( 1.7 nmol/L)
* Asymptomatic or Oligosymptomatic disease
* Progressive disease according to Prostate Cancer Clinical Trials Working Group 3 (PCWG3) criteria
* ECOG performance status (PS) of 0-2
* Sexually active males must use an accepted and effective method birth control measure
* Written informed consent

Exclusion Criteria:

* Prior exposure to docetaxel or abiraterone for treatment of hormone-sensitive metastatic prostate cancer (mHSPC)
* History of adrenal insufficiency or hypoaldosteronism
* Any medical condition that would make prednisone use contraindicated
* Any medical condition that would make docetaxel use contraindicated
* Patients unable to swallow orally administered medication
* Immunocompromised patients, e.g., patients who are known to be serologically positive for human immunodeficiency virus (HIV) requiring antiretroviral therapy
* Other malignancy within the last 5 years, except for adequately treated non melanoma skin cancer, bladder cancer (pTis, pTa, pT1) or other solid tumours curatively treated with no evidence of disease for \> 5 years
* Participation in another clinical study with an investigational product within 30 days prior to randomization
* Persistent toxicities \[\>Common Terminology Criteria for Adverse Event (CTCAE) grade 1)\] caused by previous cancer therapy prior to randomization
* Uncontrolled medical conditions including diabetes mellitus. Clinically significant cardiovascular disease (e.g.: uncontrolled hypertension or arrhythmia, unstable angina pectoris, congestive heart failure (CHF), vascular disease (arterial thrombosis) and myocardial infarction within \< 6 months
* Left ventricular ejection fraction \< 50%
* Peripheral neuropathy \[\> CTCAE grade 2\]
* Inadequate bone marrow function defined as:

  * haemoglobin \< 9.0 g/dL
  * absolute neutrophils count (ANC) \<1.5 x 109/L (\> 1500 per mm3)
  * platelet count \<100 x 109/L (\>100,000 per mm3)
* Inadequate renal and hepatic function, defined as:

  * total serum bilirubin \> 1,0 x ULN
  * AST/SGOT o ALT/SGPT \> 1,5 x ULN
  * calculated creatinine clearance \< 40 mL/min
  * potassium level \< 3,5 mmol/L
  * Child-Pugh class C