Abatacept, a modulator of T-cell co-stimulation, has demonstrated efficacy and an acceptable safety profile in patients with RA and an inadequate response to methotrexate7 and in the challenging group of patients resistant to TNF blockade.8 Little information is available on the changes that occur with abatacept on the synovium, the primary site of disease. The gene discussed is TNF; the disease is rheumatoid arthritis.