CVS Caremark moved my $480 medication to "non-formulary" mid-year - is there anything I can do?

I take a brand name biologic injection for psoriatic arthritis that has been on my plan's formulary since i started it in 2022. Got a letter last week saying as of July 1 its being moved to non-formulary and my copay is going from $50 to $480 per month. There is no generic. The biosimilar they want me to switch to is one my rheumatologist already tried and it didnt control my symptoms.

I called Caremark and they said i can request a formulary exception with a letter of medical necessity from my doctor. Has anyone actually gotten one of these approved mid-year? My HR person told me the plan year doesnt reset til january so any appeal needs to be done through the PBM not my employer.

What kind of documentation should the doctor include to give this the best shot? Im worried about going back to the biosimilar because last time i had a flare so bad i couldn't pick up my kid. Any tips would help.