@stonewheel

I don't know how the molecular structure compares. I only know that Actemra and Kevzara are in the same classification of medications. They are both IL-6 antagonists or IL-6 inhibitors.

Actemra was developed first and FDA approved for RA in 2009. Actemra was the first interleukin-6 (IL-6) receptor antagonist. It was derived from mouse proteins which didn't sound too good to me when I first heard that.

Kevzara was developed later and was the second IL-6 inhibitor. It was FDA approved for RA in 2017. I think Kevzara is made from human proteins.

Both Actemra and Kevzara have difficulty competing in the RA market because there are other biologics--especially TNF-inhibitors. Timing is everything when medications are developed. "The market" is also an important consideration. The RA market gets a lot of attention. The PMR/GCA market almost no attention until now. TNF-inhibitors don't seem to work well for PMR so the door was open for IL-6 inhibitors.

This is why Rinvog and Cosentyx will be interesting for people with PMR/GCA. We need more alternatives to prednisone. I'm happy prednisone isn't the "only option" anymore.