['ulcerative colitis']
['abx464', 'placebo oral capsule']

        Inclusion Criteria:

          -  Diagnosis of moderate to severe active UC confirmed by endoscopy and histology at
             least 12 weeks prior to screening visit. Moderate to severe active UC defined by Mayo
             Clinic Score (MCS) of 6 to 12 inclusive (on a scale of 0-12). Moderate to severe
             active UC should be confirmed at screening visit with a centrally read MCS endoscopy
             score of at least 2 (on a scale of 0-3);

          -  Subjects receiving oral corticosteroids must have been on a stable dose of prednisone
             or prednisone equivalent ≤20 mg/day) or on beclomethasone diproprionate (≤5mg/day) or
             on budesonide MMX (≤9mg/day), for ≥2 weeks before first dosing (i.e. baseline);

          -  Topical corticosteroids and topical 5-aminosalicylic acid preparations must have been
             withdrawn ≥2 weeks before first dosing (i.e. baseline);

          -  Subjects who are on oral 5-aminosalicylic acid must have been on a stable dose ≥4
             weeks before first dosing (i.e. baseline);

          -  Subjects who are receiving immunosuppressants in the form of azathioprine,
             6-mercaptopurine, or methotrexate needed to be on a stable dose for 4 weeks before
             first dosing (i.e. baseline). Subjects taking methotrexate also are advised to take
             folic acid 1 mg/day (or equivalent) supplementation if there is no contraindication;

          -  Subjects on probiotics (e.g., Culturelle® [Lactobacillus GG, i-Health, Inc.],
             Saccharomyces boulardii) must be on stable doses for 2 weeks before first dosing (i.e.
             baseline);

          -  Subjects on antidiarrheals (e.g., loperamide, diphenoxylate with atropine) must be on
             stable doses for 2 weeks before first dosing (i.e. baseline);

          -  Subjects who have previously received anti-tumor necrosis factor (TNF) therapy or
             vedolizumab must have discontinued therapy ≥8 weeks before first dosing (i.e.
             baseline);

          -  Subjects previously treated with cyclosporine or tacrolimus must have discontinued
             therapy ≥4 weeks before first dosing (i.e. baseline);

          -  Subjects previously treated with tube feeding, defined formula diets, or parenteral
             alimentation/nutrition must have discontinued treatment 3 weeks before first dosing
             (i.e. baseline).

        Exclusion Criteria:

          -  Subject with Crohn's Disease (CD), indeterminate colitis (IC) or presence or history
             of fistula with CD;

          -  History of toxic megacolon, abdominal abscess, symptomatic colonic stricture or stoma;
             history or is at imminent risk of colectomy;

          -  History or current evidence of colonic dysplasia or adenomatous colonic polyps.
             Subject with severe gastrointestinal complications; e.g., short bowel syndromes,
             obstructing strictures, recent or planned bowel surgery, Ileostomy and/or colostomy,
             recent bowel perforation;

          -  Subject with significant and known active infections at screening such as Infected
             abscess, positive for Clostridium difficile (stool antigen and toxin), CMV, TB and
             recent infectious hospitalization;
      