Sorry you did not get in the treatment arm. At the link to clinicaltrials.gov you provided it says: "Best supportive/best standard of care will be determined by the treating physician/investigator but will exclude investigational agents, cytotoxic chemotherapy, other systemic radioisotopes, and hemi-body radiotherapy. Novel androgen axis drugs [NAADs] (such as abiraterone or enzalutamide) are allowed."
So you could do a rechallenge with Zytiga or Xtandi, but not use Cabazitaxel or Radium 223. However, you could get a gene test for BRCA2 and take Olaparib if you have a BRCA2 mutation.
As long as you do not want to have Cabazitaxel I would stay in the trial. Maybe they allow the control-group to cross-over at some point next year. The current endpoint they agreed on with the FDA is radiographic progression free survival (rPFS) i.e. new mets. See page 62 in this presentation: https://www.novartis.com/sites/www.novartis.com/files/2018-11-r-d-day-investor-presentation.pdf
If they can show rPFS, they will get the approval and usually allow the control group to cross-over.