I agree with your oncologist that what is really of interest to you is what they are trying in some of the more interesting clinical trials. I think your best bet for second opinions would come from the leaders in initiating clinical trials for men with mCRPC. The short-list would be:
• Emmanuel Antonarakis at Johns Hopkins
• Howard Scher at MSK
• Celestia Higano at UW Seattle
• Christopher Logothetis at MD Anderson
They are the heads of large departments heavily into research of urological oncology, and are the lead investigators on many of the major clinical trials for mCRPC. These are most likely to have trials that have not yet been announced.
The only approved therapies you haven't tried yet are Xofigo and Zytiga. I think you got an excellent response from Xtandi, and wouldn't be so quick to give up on it just yet -- PSA of 1.6 is excellent considering that your PSA had been 200 - and what did it do for your bone mets?
In fact, if you received the Jevtana treatment while you were still hormone sensitive, you may be eligible for the clinical trial at Vanderbilt that combines Xofigo with an immune checkpoint inhibitor:
/clinicaltrials.gov/ct2/show/NCT02814669 Some of the interesting clinical trials for men in your situation are the Lu-177-trial in Houston and soon at UCLA, and the 131I-MIP-1095 trial at MSKCC.
/clinicaltrials.gov/ct2/show/NCT03030885/clinicaltrials.gov/ct2/show/NCT03042312If you have a mutation that affects DNA repair, one of the PARP-inhibitor trials may be a good choice:
/clinicaltrials.gov/ct2/show/NCT02484404 note: an NIH trial - they pay for travel and accomodations
/clinicaltrials.gov/ct2/show/NCT02975934 note: in Nashville
/clinicaltrials.gov/ct2/show/study/NCT02854436You can also consider de-bulking the prostate.