Phase II Trial to Evaluate Benefit of Early Switch From First-Line Docetaxel/Prednisone to Cabazitaxel/Prednisone and the Opposite Sequence, Exploring Molecular Markers and Mechanisms of Taxane Resistance in Men With Metastatic Castration-Resistant Prostate Cancer (mCRPC) Who Have Not Received Prior Chemotherapy

Inclusion Criteria

Inclusion criteria :

- Histologically- or cytologically-confirmed prostate adenocarcinoma with documented
distant metastases (M1 disease)

- Progressive disease while receiving hormonal therapy or after surgical castration

- Effective castration (serum testosterone levels ≤50 ng/dL) by orchiectomy and/or
luteinizing hormone releasing hormone agonists or antagonist with or without
anti-androgens.

Exclusion criteria:

- Prior chemotherapy for prostate cancer, except estramustine and adjuvant/neoadjuvant
treatment completed >3 years ago. Prior treatment with sipuleucel-T immunotherapy is
allowed at the condition patient did not received prior chemotherapy.

- Less than 28 days elapsed from prior treatment with estramustine, radiotherapy or
surgery to the time of random allocation.

- Prior beta isotope therapy, whole pelvic radiotherapy, or radiotherapy to >30% of
bone marrow.

- Adverse events (excluding alopecia and those listed in the specific exclusion
criteria) from any prior anticancer therapy of grade >1(National Cancer Institute
Common Terminology Criteria for Adverse Events [NCI CTCAE] v4.03) at the time of
random allocation.

- Less than 18 years of age

- Eastern Cooperative Oncology Group (ECOG) performance status >2.

- History of brain metastases, uncontrolled spinal cord compression, or carcinomatous
meningitis or new evidence of brain or leptomeningeal disease.

- Prior malignancy. Adequately treated basal cell or squamous cell skin or superficial
(pTis, pTa and pT1) bladder cancer are allowed, as well as any other cancer for which
chemotherapy has been completed ≥3 years ago and from which the patient has been
disease-free for ≥3 years.

- Participation in another clinical trial and any concurrent treatment with any
investigational drug within 30 days prior to random allocation.

- Any of the following within 6 months prior to study enrollment: myocardial
infarction, severe/unstable angina pectoris, coronary/peripheral artery bypass graft,
New York Heart Association (NYHA) class III or IV congestive heart failure, stroke or
transient ischemic attack.

- Any of the following within 3 months prior to random allocation: treatment resistant
peptic ulcer disease, erosive esophagitis or gastritis, infectious or inflammatory
bowel disease, diverticulitis, pulmonary embolism, or other uncontrolled
thromboembolic event.

- Acquired immunodeficiency syndrome (AIDS)-related illnesses or known HIV disease
requiring antiretroviral treatment.

- Any severe acute or chronic medical condition which could impair the ability of the
patient to participate in to the study or interfere with interpretation of study
results, or patient unable to comply with the study procedures.

- Concomitant treatment with biphosphonates or denosumab except if the dose has been
stable for 12 weeks prior to enrollment

- Absence of signed and dated Institutional Review Board (IRB)-approved patient
informed consent prior to enrollment into the study.

- Patients with reproductive potential who do not agree to use an accepted and
effective method of contraception during the study treatment period. The definition
of "effective method of contraception" will be based on the investigator's judgment.

- History of hypersensitivity to docetaxel or polysorbate 80.

- Inadequate organ and bone marrow function

- Contraindications to the use of corticosteroid treatment

- Symptomatic peripheral neuropathy grade >2 (NCI CTCAE v.4.03).

- Treatment with strong inhibitors or strong inducers of cytochrome P450 3A4/5 (a
two-week wash-out period is necessary for patients who are already on these
treatments)

The above information is not intended to contain all considerations relevant to a
patient's potential participation in a clinical trial.