For a friend, what next after Xtandi?

[This didn't get any responses as a follow up on the original thread, so posting it fresh to see if anyone has any thoughts about this.]

I have a friend who had metastatic recurrence in 2014, 4 years after his surgery (discovered when he broke his hip in a minor fall). He's been on Lupron with success the first 2 years, then added Zytiga for another 2 year reprieve. That failed in Dec 2016 and his PSA has been going up again. So he went on Xtandi (as part of the TRANSFORMER trial, but that doesn't really matter at this point). That never even slowed it down. His PSA is 67 now, up 20 points in a month and that happened while on Xtandi.

Bone pain issues will prevent trying BAT.

They originally skipped the usual 1st step of chemo because he was having trouble recovering from the hip replacement (necessitated by a bone metastasis induced weakening of the hip bone). With persistent infections, he couldn't take the risk of whacking his immune system with chemo at the time. So, they started on Zytiga. He hasn't had any chemo yet.

He's wondering what's next. They've already discussed chemo (docetaxel) as the next step. They haven't discussed Provenge, or much of anything else.

For those who've traveled this road, what does the map look like? What's the sequence? Where would Provenge fit in? Now, before chemo? He doesn't think U of M does the Provenge treatment, but plans to talk to his oncologist about it. Or, skip Provenge and just jump into chemo?

In summary, with mCRPC, failed Lupron, failed 2nd-line hormonals. So now what?:
1) Provenge
2) Docetaxel
3) Jevtana?
4) ?

Is there a known sequence somewhere? Any ideas on how long these things can help someone in his situation? He's rather distraught about it all right now, as you can imagine.

My opinion is the first line chemo, Docetaxel is the best next step if the patient can tolerate it. The second line chemo, Cabazitaxel can also be used, but from what I've read is better to save it for when resistance develops to Docetaxel or if Docetaxel doesn't work. Xofigo can be used later, but I think you would want to do the chemo first. Xofigo is equally effective if done before or after chemo. Good luck with your decision. Here's an article I just read on the subject:

http://www.hematologyandoncology.net/archives/may-2015/which-should-be-used-first-in-symptomatic-metastatic-castration-resistant-prostate-cancer-docetaxel-or-radium/

Docetaxel, definitely. In fact, can he get on this clinical trial at UMich?

/clinicaltrials.gov/ct2/show/NCT02494921