@anything4him
I switched to Nubeqa (Darolutamide) After being on Zytiga (abiraterone) for 2 1/2 years. I didn’t fail Zytiga, It just caused too many problems with my heart. Switching to Nubeqa At that point is the optimal time to do it because when zytiga fails to work for you, you are a little less likely to have the lutamide be successful in keeping your PSA down. Switching to Nubeqa In that situation is successful for about 60% of people In keeping their PSA undetectable.

So the thing to do is not stay on Zytiga Too long, Switched over to the lutamides while it is still keeping your PSA suppressed.

It did give me 2 1/2 years more time with an aggressive cancer case.

Here is an article about optical sequencing of the drugs
https://www.thelancet.com/journals/lanonc/article/PIIS1470-2045(19)30688-6/abstract
cid=c2dca8aa74&mc_eid=99575fc699

@anything4him If it's working well, don't switch, obviously, unless the side-effects become unbearable.

The old thinking was to start on Abiraterone and the switch to a -lutamide when Abiraterone stopped working. That's been shifting recently, based on various big trials, to starting on the most-effective drug (the -lutamide) right from the beginning, since that's when it will give you the biggest benefit.

As Jeff mentioned, IF you're going to sequence, a -lutamide may work after Abiraterone, but less likely the other way around. The article he cited doesn't suggest that sequencing is better (or worse); it just deals with the order if you decide to do it.

Unfortunately, you might not get the full benefit of the -lutamide if you already became castrate-resistant on Abiraterone, but this is still very much under study and in flux.