Rituximab (anti-CD 20) is currently undergoing trials for AS. My sparse googling just now shows that rituximab probably only has a moderate effect, so probably second-line to anti-TNFa therapy. Probably.
Safe to say for boards that AS: TNFa > CD20
Monoclonal Antibodies are always last resort! I just use this as a general rule
Many autoimmune/autoinflammatory conditions, including ankylosing spondylitis, are treated with DMARDs like anti-TNF-alpha medications when milder stuff doesn’t do the trick. Common examples are infliximab (Remicade) and adalimumab (Humira).