CABAzitaxel With or Without Prednisone in Patients With Metastatic CAstration REsistant Prostate Cancer Progressed During or After a Previous Docetaxel-based Chemotherapy

Inclusion Criteria:

1. Signed informed consent.
2. Histological diagnosis of prostate adenocarcinoma;
3. Metastatic castration-resistant disease with documented radiographic progression (osseous or measurable lesions) during or after a docetaxel-based chemotherapy;
4. Testosterone level in the castration range (levels \<50 ng/dl) because of a previous, and ongoing, androgen deprivation with LH-RH agonists or antagonists or bilateral orchiectomy;
5. Prior surgery and/or radiation therapy (to less or equal than 30% of the bone marrow) are allowed. However, at least 4 weeks must have been elapsed since surgery or completion of radiation therapy and the patient must has recovered from side effects;
6. Life expectancy ≥ 3 months;
7. Age \> 18 years;
8. ECOG performance status 0-2;
9. ANC ≥ 1.5 x 109/L;
10. PLT ≥ 100 x 109/L;
11. Hb ≥ 10 g/dl;
12. Serum total bilirubin ≤ UNL;
13. AST/SGOT and/or ALT/SGPT ≤1,5 x ULN;
14. Serum Creatinine ≤1,5 times UNL (in case of limit values of serum creatinine, creatinine clearance calculated by CKD-EPI formula should be ≥60 ml/min);
15. PT or INR and PTT \<1,5 times UNL (Note: patients who receive anti-coagulation treatment will be allowed to participate provided that any abnormality in these parameters exists);
16. Patients must be accessible for treatment and follow up;

Exclusion Criteria:

1. Participation in clinical trials with other investigational drug within 28 days of study entry;
2. Symptomatic or uncontrolled brain metastases. Patients with neurological symptoms must undergo a computed tomography (CT) scan/magnetic resonance imaging (MRI) of the brain to exclude brain metastasis; previously treated brain metastases will be allowed as long as the patient is neurologically stable and does not require steroids and anticonvulsants;
3. Less than 4 weeks elapsed from prior anticancer-therapy or surgery to the time of randomization. Prior treatment with abiraterone or enzalutamide is allowed and is used as a stratification factor at randomization. Patient may be on biphosphonates prior to study entry;
4. Less than 4 weeks from palliative Radiotherapy to time of randomization;
5. Any of the following within 6 months prior to study enrollment: myocardial infarction, severe/unstable angina pectoris, coronary/peripheral artery bypass graft, NYHA class III or IV congestive heart failure, stroke or transient ischemic attack, pulmonary embolism or other uncontrolled thromboembolic event;
6. Any severe acute or chronic medical condition which could impair the ability of the patient to participate to the study or interfere with interpretation of study results, or patient unable to comply with the study procedures;
7. Unstable diabetes mellitus, resistant peptic ulcer disease, erosive esophagitis or gastritis, infectious or inflammatory bowel disease, acute diverticulitis or other contraindications to use of corticosteroid treatment;
8. Peripheral neuropathy Grade \> 2 (National Cancer Institute Common Terminology Criteria (NCI CTCAE v.4.03);
9. Previous beta or gamma Isotope treatment (e.g. strontium or samarium), alpha emitters are allowed;
10. History of severe hypersensitivity reaction (\> grade 2) to polysorbate 80 containing drugs;
11. Concurrent or planned treatment with strong inhibitors or strong inducers of cytochrome P450 3A4/5 (a 2-week washout period is necessary for patients who are already on these treatments);
12. Previous malignancy except for basal cell or squamous cell skin cancer adequately treated, or any other cancer from which the patient has been disease-free for ≥ 5 years;
13. Patients with reproductive potential who do not agree to use accepted and effective method of contraception, based on the investigator's judgment, during the study treatment period.