Study to Evaluate the Clinical Activity and Safety of Oral NX-13 in Moderate to Severe Ulcerative Colitis

Inclusion Criteria:

• Adult subjects aged 18 to 75 years (inclusive)

• Diagnosis of UC ≥ 90 days before screening confirmed by histologic evidence

• Active UC defined as a total Mayo Score (MMS) of ≥ 5 (inclusive) at baseline

• ES ≥ 2 within 14 days prior to randomization

• RBS ≥ 1.

Exclusion Criteria:

• Severe extensive colitis as evidenced by physician judgment that the participant islikely to require hospitalization for medical care or surgical intervention of anykind for UC (e.g., colectomy) within the 12 weeks after randomization;

• Current evidence of fulminant colitis, toxic megacolon or recent history (within 6months prior to screening) of toxic megacolon, or bowel perforation

• Diagnosis of Crohn's disease (CD) or indeterminate colitis, or the presence orhistory of a fistula consistent with CD

• Diagnosis of microscopic colitis, ischemic colitis, or radiation colitis

• Bacterial or parasitic pathogenic enteric infection;