You can google this information. There are different inflammatory substances that contribute to PMR and GCA. According to the Google search, "In Polymyalgia Rheumatica (PMR), key inflammatory substances include cytokines like IL-6, IL-1, and TNF-alpha. Elevated levels of inflammatory markers like erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are also common. Other substances like glutamate and prostaglandin E2 (PGE2) may also contribute to pain in PMR. "

People with GCA and PMR have different mixes of these substances. Actemra and Kevzara both limit the effect of IL-6. So if someone's inflammation is mostly caused by IL-6, Actemra and Kevzara will be effective. I have GCA and PMR, and I have been taking prednisone for 11 months and Actemra for 10. I just stepped down on the prednisone to 3 mg per day, after starting at 60 originally. I haven't had any pain from the GCA or PMR since starting treatment. So it seems like my inflammation is mostly caused by IL-6.

It could be that if your inflammation if caused more by the other substances than IL-6, then you will have to keep taking prednisone until a more effective medication is approved.