Study of the Effect of Chemotherapy With Cabazitaxel on Prostate Cancer

This is an open-label, interventional study to explore the effect of Cabazitaxel on survival pathways and androgen signaling in the tumor microenvironment (bone marrow) of patients with castration resistant metastatic prostate cancer. A total of 30 evaluable patients are needed. An estimated 50% chance of failure to harvest evaluable bone marrow biopsy or aspirate is anticipated based on investigators prior experience. Thus a total of 60 patients will be accrued in the study. This will provide the investigators an 80% power to detect an effect size of at least 0.82, using a two-sided paired t-test and at a 0.05 significance level.The changes in androgen signaling (androgen receptor expression and other survival pathway markers, between baseline and 9 weeks will be assessed by paired t-test and Wilcoxon signed-rank test. The association between serum Prostate-Specific Androgen (PSA) and bone marrow androgen signaling level will be evaluated using scatter plot and spearman's correlation coefficient. Similar methods will be used to explore the association between circulating androgens and those in the bone marrow. Biomarker data will also be summarized and compared between baseline and after treatment using paired t-test or Wilcoxon signed-rank test. ECOG changes from baseline will be provided for each treatment period. All Adverse Events (AE) will be graded using the National Cancer Institute - Common Terminology Criteria for Adverse Events (NCI-CTCAE) classification, version 4.3. Summary tables of Adverse Events (AE)s, Treatment Emergent Adverse Event(TEAE), Serious Adverse Events (SAE)s and withdrawals for adverse events will be provided by treatment period. Adverse events will be summarized by worst severity grade AEs. All registered subjects who take at least 1 dose of agent will be included in the safety analyses. Adverse events will be summarized by worst severity grade. AEs, as well as treatment-emergent AEs, will be summarized by system organ class, and preferred term. Investigational Medicinal Products (IMP) -related adverse events, adverse events leading to death or to discontinuation from treatment, events classified as NCI-CTCAE v4 Grade 3 or Grade 4 (or moderate/severe if other rating scale is used), (IMP)-related events, and serious adverse events will be summarized separately.