Study of Weekly Cabazitaxel for Advanced Prostate Cancer

Inclusion Criteria: 1. Patients who have given written informed consent. 2. Age ≥ 18 years. 3. ECOG 0-2. 4. Patients with a histologic or cytologic diagnosis of advanced prostate cancer (any Gleason grade). 5. Previous and ongoing castration by orchiectomy or LHRH agonists. Antiandrogen must be discontinued prior to study start. 6. Disease progression, clinically or radiologically documented, during or after treatment with docetaxel, with a minimum cumulative dose of 225 mg/m2. 7. "Unfit" patients defined as patients who satisfy at least one of the following criteria: * ECOG 2 * Dose reduction due to febrile neutropenia during the previous treatment with docetaxel * Radiation therapy affecting more than 25% of bone marrow reserve 8. Documented metastatic disease and progressing after docetaxel treatment. Progression criteria is considered any of the following three or more than one at once: * Progressive elevation of PSA measured in three successive determinations one week difference between them at least; * Should be considered progression of measurable disease by RECIST criteria; * Bone progression as evidenced by the appearance of two or more new lesions on bone scan. 9. Patients who have received a maximum of one prior chemotherapy for metastatic disease. 10. Prior anticancer therapy should have been interrupted 28 days before the start of study treatment (the patient may have continued treatment with prednisone 5 mg bid. 11. Adequate blood, liver and kidney function: * Hemoglobin \> 9.0 g/dl * ANC \> 1.5 x 10\*9/L * Platelets \> 100 x 10\*9/L * AST/SGOT and ALT/SGPT \< 2.5 x ULN * Bilirubin \< 1.0 x ULN * Creatinine \<1.5 mg/dL x ULN. If creatinine 1.0 - 1.5 x ULN, creatinine clearance will be calculated according to CKD-EPI formula and patients with creatinine clearance \<60 mL/min should be excluded (see Annex 7 for formula) 12. Adequate baseline cardiac function (LVEF ≥ 50%). 13. Life expectancy ≥ 12 weeks. 14. Patients must agree to use an effective contraceptive method during treatment with the study drug and up to 1 month after ending the treatment. Exclusion Criteria: 1. Patients who received radiation therapy that exceeded 40% of the bone marrow reserve or that ended within the last 3 weeks prior to inclusion. 2. If being treated with radiation therapy, should be completed before the three weeks prior to initiation of treatment research. 3. Previous treatment with two or more chemotherapy regimens for metastatic disease. A new line of treatment is also when a patient receives again docetaxel after clinical, radiological or PSA progression to a prior regimen with docetaxel. 4. Previous treatment with chemotherapy or surgery in the last 4 weeks. 5. Peripheral neuropathy or stomatitis ≥ 2 (National Cancer Institute Common Terminology Criteria - NCI CTCAE vs. 4.03). 6. Any other type of cancer in the last 5 years, except for basal cell skin carcinoma. 7. Cerebral or leptomeningeal metastasis. 8. Myocardial infarction, severe/unstable angina pectoris, coronary/peripheral artery bypass, congestive heart failure (NYHA class III or IV), stroke or transitory ischemic episodes. 9. Patients who present any severe or uncontrolled medical condition (including uncontrolled diabetes mellitus) or any other condition that may affect the patient's participation and study compliance. 10. Previous treatment with cabazitaxel. 11. Known hypersensitivity (≥ grade 3)to cabazitaxel, polysorbate 80, prednisone or prednisolone, or docetaxel or paclitaxel. 12. Known history of active infection that requires systemic antibiotic or antifungal treatment. 13. Patients who are receiving or expect to receive treatment with strong inhibitors or strong inducers of cytochrome CYP450 3A4/5 (a one week wash-out period is necessary for patients who are already on these treatments) (see Annexes 5 and 6). 14. Patients being treated with any investigational product.