I did several months of Zytiga, which worked really well (got me done to about
1.5 from over 5), but it shut down my liver. I was off for several months (PSA went up), then went on Xtandi. Xtandi worked very little (when any) for 8 months, with tiny PSA drops, but last month I went from 1.5 > 1.1. Crossed fingers for 16 January test.
(keep in mind I am a G4+5, and never had the PSA to go with my extensive involvement)
I don't know that Xtandi after Zytiga is supposed to quit after a year. If it does, I had best get busy spending my retirement money
But remember, each one of us is different, or they would have cured this by now.