Rob, fascinating to read of your trial and the very best of luck. I don't think apalutamide is yet approved for UK use in PCa, but even in the US it is for non metastatic PCa. Presumably it is a pretty powerful anti-androgen used instead of Zoladex or equivalent. The abiraterone/prednisolone combination, with the latter in a non-addictive small dose regime, is in use here as in the US and is effective against mets. It held my PCa at bay for three years nearly. I assume the theory is to get rid of mets then deal with the source of the problem with a RP. The RT is to make sure of dealing with any local spread, I guess. A very radical approach, unlikely to be available here for years, alas, as we always seem to follow where the larger market if the US leads.
You're in for a pretty tough time but I hope at the end of it you have a long and trouble free life. As a fellow Gleason 9 survivor, treated much more conservatively, I have managed 11 years plus post diagnosis, so you should certainly look to better that!
AC