Objective and design: To evaluate the potency of RORγt blockade for treatment of Inflammatory Bowel Disease (IBD), the efficacy of TAK-828F, a novel RORγt inverse agonist, in anti-TNF-α mAb non-responsive mouse colitis model and effect of TAK-828F on IL-17 production in peripheral mononuclear blood cells (PBMCs) of anti-TNF-α naive and treatment-failure patients of IBD was investigated. Methods and results: The colitis model showed Th17-dependent pathogenicity and response to anti-IL-12/23p40 monoclonal antibody (mAb), but no response to anti-TNF-α mAb. In the model, TAK-828F, at oral dosages of 1 and 3 mg/kg, inhibited progression of colitis and reduced the immune reaction that characterize Th17 cells. Anti-IL-17A mAb showed neither efficacy nor change in the T cell population and colonic gene expression in the model. In the normal mouse, a 4-week treatment of TAK-828F at 30 mg/kg did not severely reduce lymphocyte cell counts in peripheral and intestinal mucosa, which was observed in RORγ−/− mice. TAK-828F strongly inhibited IL-17 gene expression with IC50 values from 21.4 to 34.4 nmol/L in PBMCs from anti-TNF mAb naive and treatment-failure patients of IBD. Conclusions: These results indicate that RORγt blockade would provide an effective approach for treating refractory patients with IBD by blocking IL-23/Th17 pathway.
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