Study of Cabozantinib (XL184) Versus Mitoxantrone Plus Prednisone in Men With Previously Treated Symptomatic Castration-resistant Prostate Cancer

Inclusion Criteria:

   - Histological or cytological diagnosis of castration resistant prostate cancer (serum
   testosterone less than 50 ng/dL).

   - Evidence of bone metastasis related to prostate cancer on bone scans.

   - Documented pain from bone metastases that requires opioid narcotic intervention.

   - Adopted a narcotic regimen that consists of one sustained release opioid agent taken
   daily for chronic pain and one immediate release opioid agent for breakthrough pain.

   - Received prior docetaxel and either abiraterone or MDV3100 treatment and has evidence
   of investigator assessed prostate cancer progression on each agent independently.

   - Maintenance of LHRH agonist or antagonist unless treated with orchiectomy.

   - Recovered from toxicities related to any prior treatments, unless the toxicities are
   clinically non significant or easily manageable.

   - Adequate organ and marrow function.

   - A left-ventricular ejection fraction (LVEF) of >/= 50% assessed by echocardiogram or
   MUGA (multigated acquisition scan).

   - Capable of understanding and complying with the protocol requirements (including
   having the ability to access an interactive voice recognition system and self-report
   pain and narcotic use) and signed the informed consent form.

   - Sexually active fertile patients and their partners must agree to use medically
   accepted methods of contraception (eg, barrier methods, including male condom, female
   condom, or diaphragm with spermicidal gel) during the course of the study and for 3
   months after the last dose of study treatment.

Exclusion Criteria:

   - Prior treatment with cabozantinib or mitoxantrone.

   - Treatment with docetaxel, abiraterone, or MDV3100 in the last 2 weeks; or with any
   other type of cytotoxic or investigational anticancer agent in the last 2 weeks.

   - Radiation therapy in the last 4 weeks (includes radiation targeting bone metastases),
   radionuclide treatment in the last 6 weeks, or radiation therapy to the thoracic
   cavity (unless radiation targets bone metastases) in the past 3 months.

   - Treatment with serotonergic psychiatric medication(s) in the last 2 weeks (5 weeks for
   fluoxetine).

   - Known brain metastases or uncontrolled epidural disease.

   - Requires concomitant treatment, in therapeutic doses, with anticoagulants such as
   warfarin or warfarin-related agents, heparin, thrombin or FXa (coagulation factor X)
   inhibitors, or antiplatelet agents (eg, clopidogrel). Low dose aspirin (above low dose
   levels for cardioprotection per local applicable guidelines), low-dose warfarin (≤ 1
   mg/day), and prophylactic low molecular weight heparin are permitted.

   - Uncontrolled, significant intercurrent illness including, but not limited to,
   cardiovascular disorders, gastrointestinal disorders, active infections, non-healing
   wounds, recent surgery.

   - Clinically significant hematemesis or hemoptysis of > 0.5 teaspoon of red blood, or
   other signs indicative of pulmonary hemorrhage in the last 3 months, or history of
   other significant bleeding in the past 6 months.

   - Cavitating pulmonary lesion(s) or a lesion invading or encasing a major blood vessel.

   - Corrected QT interval (QTc) > 500 ms in the last 4 weeks.

   - Unable to swallow capsules or tablets or tolerate infusions.

   - Previously-identified allergy or hypersensitivity to components of the study treatment
   formulations investigator or designee.

   - History of another malignancy (except non-melanoma skin cancer, adequately treated
   stage I colon cancer, superficial transitional carcinoma of the bladder) in the past 2
   years.