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