Cabazitaxel in Men 75 Years of Age or Older With Castration-Resistant Prostate Cancer

This is a single arm, open label, phase II trial of cabazitaxel every 3 weeks in patients who are ≥ 75 years of age with castration-resistant, metastatic prostate cancer who have progressed during or after docetaxel. Primary objective: -The primary objective is to determine the efficacy of cabazitaxel in men 75 years of age or older with castration-resistant, metastatic prostate cancer who have progressed during of following treatment with docetaxel. Secondary objectives: * To characterize the safety and tolerability of cabazitaxel in patients ≥ 75 years of age * To determine the PSA response * To determine the effect of cabazitaxel on functional status using geriatric assessments Exploratory objectives: * Determine the effect of therapy with cabazitaxel on the number of circulating tumor cells (CTC) * To measure the effects of cabazitaxel on apoptosis in CTCs from patients ≥ 75 years of age using H2AX and M30 as biomarkers. * To determine the relationship between geriatric-focused assessment of comorbidity and functional ability and toxicity and response. Patients will receive cabazitaxel 25 mg/m2 every 3 weeks with 10 mg prednisone daily until progression, intolerance of therapy, or withdrawal of consent. Patients will receive granulocyte colony stimulating factor (Neulasta 6 mg sc) with each cycle, starting with the first cycle, to minimize the risk of complications from neutropenia. Patients will be followed for 28 days after discontinuation of therapy or death, whichever occurs first. Patients with serious adverse events at the time of removal from the trial will be followed until the toxicities resolve or are deemed irreversible by the treating physician.