A Study to Evaluate Safety and Efficacy of LX1606 in Subjects With Acute, Mild to Moderate Ulcerative Colitis

Inclusion Criteria:

- Diagnosis of ulcerative colitis of at least 6 months duration

- Disease extends at least 15 cm proximally from the anal verge, documented within the
past 3 years

- Flare occurs on 5-aminosalicylic acid (5-ASA)/mesalamine therapy and subject is
willing to remain on a stable dose for the duration of the study

- Age ≥18 and <70 years of age

- Able and willing to provide written informed consent

Exclusion Criteria:

- Prior terminal ileum or colonic surgery, except appendectomy or hemorrhoid surgery

- Presence of indeterminate colitis, microscopic colitis, ischemic colitis, infectious
colitis, or clinical findings suggestive of Crohn's disease

- Clinical signs of fulminant colitis or toxic megacolon

- History of dysplasia associated lesion or mass (DALM)

- Subjects who have had surgery for ulcerative colitis, or in the opinion of the
investigator, are likely to require surgery for ulcerative colitis during the study

- History of primary sclerosing cholangitis

- Any physical or laboratory abnormality deemed by the investigator as clinically
significant

- Major surgery within 60 days of Screening

- Use of any investigational agent within 30 days of Screening or any therapeutic
protein or antibody within 90 days of Screening