ABI-M201 in Adult Subjects With Mildly-to-Moderately Active Ulcerative Colitis

Inclusion Criteria: * Established diagnosis of UC for at least 3 months prior to screening, with minimum disease extent of 15 cm from the anal verge * Mildly to moderately active UC * Inadequate response to ongoing treatment with oral mesalamine ≥2.4 g/day for ≥4 weeks from screening visit Exclusion Criteria: * Possible or confirmed diagnosis of Crohn's Disease or other forms of inflammatory bowel disorders * Ongoing or failed prior treatment for UC with methotrexate, azathioprine, 6-mercaptopurine, cyclosporine, tofacitinib, mycophenolate mofetil, sirolimus (rapamycin), thalidomide, tacrolimus (FK-506), or biologics (e.g., TNF-alpha-antagonists, anti-integrin therapies, or agents targeting IL-12 or IL-23, etc.) * Any immunosuppressive condition or treatment with immunosuppressive medications * History of prior surgical intervention in any region of the gastrointestinal tract (excluding minor surgery) * Prior diagnosis of any cardiovascular, renal, hepatic, endocrine, infectious, hematological, oncologic, neuro-psychiatric or immune-mediated disorder, which in the opinion of the Principal Investigator might impact the subject's safety or compliance, or the interpretation of results * Treatment with any other investigational drugs ≤12 weeks prior to baseline visit * The participant has a condition or is in a situation which, in the Principal Investigator's opinion, may put the participant at significant risk, may confound the study results, or may interfere significantly with the participant's participation in the study