A 28-year-old with newly diagnosed moderate-to-severe Crohn's disease (CDAI 280) involving the ileocolon has failed mesalazine. Biologic therapy is initiated. The mechanism of action of vedolizumab differs from anti-TNF agents in that it:

• A Blocks IL-12/23 signalling via the p40 subunit to inhibit Th1/Th17 differentiation
• B Neutralises soluble and membrane-bound TNF-alpha to reduce mucosal inflammation
• C Inhibits JAK1/2 kinases to block cytokine receptor signalling
• D Inhibits lymphocyte trafficking specifically to the gut by blocking α4β7 integrin, with gut-selective immunosuppression ✓

Explanation

Vedolizumab is a gut-selective anti-α4β7 integrin monoclonal antibody that prevents lymphocyte homing to the intestinal mucosa by blocking MAdCAM-1 interaction, without systemic immunosuppression. This gives it a favourable safety profile compared to anti-TNF agents. Ustekinumab targets the p40 subunit of IL-12/23. Infliximab and adalimumab neutralise TNF-alpha. Tofacitinib and upadacitinib are JAK inhibitors approved for IBD.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.