I loved Cosentyx-almost forgot I had PSA/AS. Humira, Cimzia, Cosentyx were the best biologics for me (had days where I felt normal again), but I build up resistance (probably anti-bodies) to all biologics after about 12 months.
There isn't overwhelming evidence to support being on MTX will stop antibody formation...it may just be how some of us are wired. Some can be on one biologic for years with great results. For me, it just stops working. Upping the dose can help, but it usually only gets me a few more months.
I took and liked Remicade, stopped because of the infusion services cost. I went back on it and had a terrible reaction-whole body reaction that put me in the hospital for a week. So if you build up antibodies to these things, once you are done with them, don't go back.
Check the pipeline of PSA/Psoriasis and other suppressants to pace yourself-for me they are not making them fast enough for me to go through them. :-/