TNF and spondylitis: The Assessment of SpondyloArthritis International Society (ASAS), the European League Against Rheumatism (EULAR), the American College of Rheumatology (ACR)/Spondylitis Association of America, and the Spondyloarthritis Research and Treatment Network (SPARTAN) treatment guidelines recommend non-steroidal anti-inflammatory drugs (NSAIDs) as the first-line treatment for active AS, followed by anti-tumor necrosis factor (TNF) agents or interleukin (IL)-17 inhibitors for patients who are nonresponsive to NSAIDs (2, 7).