Orencia (Abatacept) isn't FDA approved for the treatment of PMR so I doubt any insurance will cover it. That doesn't mean it won't work for you. Is PMR your only diagnosis?
https://www.drugs.com/history/orencia.html
There is a study called the ALORS study that is investigating Abatacept for PMR.

"Due to its good safety profile in rheumatoid arthritis and its potential to modulate T cell activation and derived cytokines, abatacept is an attractive agent to investigate in patients with PMR."
https://clinicaltrials.gov/ct2/show/NCT03632187