The purpose of this study is to evaluate the clinical efficacy and safety of OD-07656 in participants with moderately to severely active ulcerative colitis (UC). In addition, the study will evaluate the potential of OD-07656 to enhance the therapeutic benefit of vedolizumab when given after OD-07656.

Inclusion Criteria:

The main inclusion criteria include but are not limited to the following:

• Has a confirmed diagnosis of ulcerative colitis (UC)
• Has moderate to severely active UC as defined by the 3-component Modified Mayo clinic score
• Has an inadequate response, loss of response, or intolerance/medical contraindication to at least one of the following therapies: oral aminosalicylates, corticosteroids, immunosuppressants, anti-tumor necrosis factor biologic, anti-interleukin 12/23 biologic, Janus kinase inhibitors, or sphingosine-1-phosphate (S1P) modulators

Exclusion Criteria:

The main exclusion criteria include but are not limited to the following:

• Has diagnosis of Crohn's disease or indeterminate colitis
• Has had extensive colonic resection
• Has colostomy or ileostomy
• Has uncontrolled primary sclerosing cholangitis