This study will examine the safety and efficacy in subjects with mild to moderate ulcerative colitis, as measured by Modified Mayo Score, Modified Baron Score, IBDQ, calprotectin and other assessments.

Inclusion Criteria:

• Male or female, ≥18 years of age, who has a diagnosis of active UC for at least 6 months prior to screening
• A rectal/colonic biopsy obtained previously and consistent with a diagnosis of UC
• Endoscopy (flexible sigmoidoscopy unless surveillance colonoscopy is clinically indicated) confirming diagnosis of UC within 2 weeks prior to randomization
• Endoscopy (flexible sigmoidoscopy unless surveillance colonoscopy is clinically indicated) confirming diagnosis of UC within 2 weeks prior to randomization
• Active UC despite previous treatment with at least one 5-ASA compound at a dose of ≥2000 mg/day for at least 4 weeks or documented intolerance to such therapy

Exclusion Criteria:

• Diagnosis of indeterminate colitis, Crohn's disease, or clinical findings suggestive of Crohn's disease (fistula or granulomas on biopsy) or microscopic colitis (collagenous colitis or lymphocytic colitis)
• Subject whose symptoms are likely caused by factors other than inflammatory UC, including infection or irritable bowel syndrome (IBS)
• History of dysplasia on colonic biopsy
• Subject with ≥ 8 year history of pancolitis or ≥ 15 year history of left sided colitis unless a colonoscopy with surveillance biopsies to screen for colon cancer has been performed within the past year
• Subject ≥ 50 years of age who has not had a colonoscopy to screen for colorectal polyps and colon cancer within the past 5 years
• Subject who has had any prior surgical resection of any part of the colon excluding the appendix
• Previous treatment with any biologic product including investigational biologic products within 1 year prior to baseline visit
• The subject is taking Systemic corticosteroids, Azathioprine/6-mercaptopurine/methotrexate, immunosuppressants, Oral 5-ASA compounds unless they have been on a stable dose of sufficient duration prior to Baseline. If recently discontinued the subject must have had a wash-out periods of sufficient duration prior to Baseline
• Rectally administered corticosteroids or 5-ASA, antibiotics for the treatment of UC and probiotics within 14 days of the Baseline Visit and throughout the study
• The subject has with a stool culture positive for pathogenic ova or parasites, enteric pathogens or Clostridium difficile toxin at the Screening Visit
• Presence of, or history of cancer, with the exception of skin cancer