Mitoxantrone, Prednisone Plus Sorafenib in Taxane-Refractory Metastatic Hormone Refractory Prostate Cancer (HRPC)

The primary objective of this study is to test the hypothesis that the combination of Mitoxantrone, Prednisone and Sorafenib in taxane-refractory patients with metastatic hormone refractory prostate cancer (mHRPC) will result in an improvement of the median time to progression (TTP). Since the median (i.e 50% of patients) TTP for Mitoxantrone/Prednisone is 3 months, our hypothesis is that 70% will have not progressed at 3 months with this investigational combination. Progression will be assessed by radiologic imaging criteria. The early stopping point is 21 subjects. If 10 or fewer subjects with tumor favorable response are observed when 21 subjects are accrued then the null hypothesis is accepted and the trial is terminated. If 16 or more subjects with tumor favorable response are observed when 21 subjects are accrued then the alternative hypothesis is accepted and the trial is terminated. The probability of early stopping under the null is 0.51, and under the alternative is 0.39. If the trial progresses until 42 subjects are evaluated and 24 or more subjects with favorable response are observed then the null hypothesis is rejected. This design minimizes the average sample number under the null, which is 31.2.