IL1R1 and rheumatoid arthritis: Moreover, MEDI8968 exposure was higher than in subjects with rheumatoid arthritis receiving 250 mg SC Q4W, in whom a statistically significant improvement was seen [16], and more than 10 times higher than the MEDI8968 concentration of 2.03 ng/μL that resulted in a 90% inhibition of IL-1R1 signalling in vitro.