Crohn’s disease [CD] and ulcerative colitis [UC] are chronic relapsing–remitting forms of inflammatory bowel disease [IBD].1 Since the 1990s anti-tumour necrosis factor [anti-TNF] agents have dramatically improved outcomes, particularly in moderate/severe IBD.2,3 Nonetheless, many patients do not respond, or lose response to anti-TNFs, while others are intolerant or experience side effects. Here, TNF is linked to inflammatory bowel disease.