Comparison of steroid levels in A. serum and B. metastatic tissue biopsies, based on achieving a 30% percent PSA decline at 12 weeks. C. Distribution of pre-treatment PSA levels and waterfall plot showing percent change in PSA at 12-weeks by quartile (Q1-Q4) of pre-treatment serum DHEAS levels. P values for the indicated comparison calculated via non-parametric Wilcoxon rank sum test (Mann Whitney test). D. Radiographic progression free survival (rPFS) as a function of baseline serum androgen levels comparing subjects in the lowest vs highest three quartiles (Q4 vs Q1–3). E. rPFS as a function of on-treatment serum DHEAS levels at week 4 (wk4) and week 8 (wk8) comparing subjects in the lowest vs highest three quartiles (Q4 vs Q1–3). F. rPFS as a function of pre-treatment tissue DHEAS and AED levels comparing subjects in the lowest vs highest three quartiles (Q4 vs Q1–3). In each case, the cut-off value reflects the highest number of the bottom 1/4th of the values. The quartiles were separately assessed in the pre and on-treatment populations. G. rPFS comparing subjects with detectable vs undetectable levels of DHEAS in tissue biopsies taken at 4 and 12 weeks of therapy. H. rPFS as a function of serum 3-keto-5a-abiraterone levels (keto-Abi) at week 4 (wk4) and week 8 (wk8) comparing subjects above vs below the median. Progression-free survival was estimated using Kaplan-Meier methods and compared using the Gehan-Wilcoxan test. Dehydroepi-androsterone sulfate (DHEAS), dehydroepiandrosterone (DHEA), androstenedione (AED), testosterone (test), dihydrotestosterone (DHT), androsterone (androst), quartile (Q).