Orencia is a biologic used for the treatment of rheumatoid arthritis with the intention of slowing down the progression of joint damage. Rheumatoid arthritis is a disease of the immune system which consists of complex network cells, such as the T cell. If T cells are activated they cause the inflammation and swelling that is associated with rheumatoid arthritis. Orencia targets the T cells, reducing its activity, causing a chain reaction to other related cells.