Differential effects of ontamalimab versus vedolizumab on immune cell trafficking in intestinal inflammation and IBD

The anti-MAdCAM-1 antibody ontamalimab demonstrated efficacy in a phase II trial in UC and results of early terminated phase III trials are pending, but its precise mechanisms of action are still unclear. Thus, we explored the mechanisms of ontamalimab and compared it to the anti-α4β7 antibody vedolizumab. C57/BL6J mice were treated with 1.5% DSS in their drinking water for 7 days, followed by 3 days of normal drinking water. Mice were treated with 250µg of vedolizumab surrogate MECA-367, ontamalimab surrogate DATK32 or rat IgG isotype control antibody intraperitoneally (i.p.) three times a week. Mini-endoscopy and LPMC isolation were performed as described above.