A Study to Assess Efficacy and Safety of SER-287 in Adults With Active Mild-to-Moderate Ulcerative Colitis

Exclusion Criteria

• •Known history of Crohn's disease
• •No previous history of treatment for UC (treatment-naïve)
• •Subjects on steroid medication who are unable to have steroids tapered and be completely off steroids at least two weeks prior to screening
• •Unable to stop steroid enemas or suppositories, or 5-ASA enemas or suppositories, at least two weeks prior to screening
• •Subjects who have received any investigational or approved biologic therapy within eight weeks or five half-lives prior to screening (whichever is longer)
• •Subjects who have received any investigational or approved non-biologic therapy, except for those specifically listed in the Permitted Concomitant Medications, for the treatment of underlying disease, within 30 days or five half-lives prior to screening (whichever is longer)
• •Major gastrointestinal surgery (not including appendectomy or cholecystectomy) within two months before screening, or any history of total colectomy