Inclusion Criteria:

1. Moderately to severely active Ulcerative Colitis (UC) diagnosed prior to the Screening Visit
2. Evidence of UC extending beyond the rectum, as determined by baseline endoscopy
3. Has had an inadequate response, loss of response to, or is intolerant to at least 1 of the following treatments for UC: oral aminosalicylates, systemic corticosteroids, immunomodulators, biologic therapy

Exclusion Criteria:

1. Diagnosis of Crohn's disease or indeterminate colitis
2. Has documentation of positive test for toxin producing Clostridium difficile, or polymerase chain reaction examination of the stool
3. Apheresis within 2 weeks of randomization
4. History of or currently active primary or secondary immunodeficiency, or participants with known genetic disorders as a cause for colitis

Other protocol-defined inclusion/exclusion criteria apply