TNF and ankylosing spondylitis: Autoimmune diseases such as inflammatory bowel disease (eg, Crohn disease, ulcerative colitis) and autoimmune rheumatic diseases such as rheumatoid arthritis, ankylosing spondylitis, psoriasis, and psoriatic arthritis are commonly treated with highly effective immunotherapies such as tumor necrosis factor (TNF) inhibitors.1,2,3 Five TNF inhibitors (etanercept, infliximab, adalimumab, golimumab, and certolizumab pegol) have been approved by the US Food and Drug Administration (FDA) for these diseases.