A Phase 1b Trial to Evaluate the Safety of MB310 in Patients With Active, Mild-to-Moderate Ulcerative Colitis

Inclusion Criteria: The main inclusion criteria include but are not limited to the following: * Must be aged 18 to 70 years, inclusive, at the time of signing informed consent; * Must have newly diagnosed or a history of recurrent UC based on clinical, endoscopic, and histological assessments; * Must have active, mild-to-moderate UC as defined by the Modified Mayo Score (MMS) of ≥4 and ≤7, and an Endoscopic Subscore of ≤2 in the most affected area proximally ≥15 cm from anal verge; * Male patients, and female patients of childbearing potential who are at risk of pregnancy, must agree to use a highly effective method of birth control * Female patients must not be pregnant or breastfeeding; * Male patients must agree to abstain from sperm donation; * Must be able to understand and comply with the Protocol requirements; and * Must be willing and able to provide written informed consent at Screening (Visit 1). Exclusion Criteria: The main exclusion criteria include but are not limited to the following: * Disease limited to proctitis \<15 cm from anal verge; * Short bowel or malabsorption syndromes; * Prior intestinal or colon resection surgery (with exception of cholecystectomy or appendectomy); * Severe/fulminant UC; * Other forms of inflammatory bowel disease including diagnostic uncertainty by the Investigator, or functional gastrointestinal disorders; * Positive stool test for parasites, bacterial pathogens, or Clostridium difficile; * Use of any of the following treatme…