Inclusion Criteria:  Confirmed diagnosis of ulcerative colitis (UC) Moderately to severely active UC as defined by 3-component Modified Mayo score Must have corticosteroid dependence or have had no response, insufficient response, loss of response, and/or intolerance to at least one of the following therapies: corticosteroid, immunosuppressants, or an approved anti-TNF, anti-integrin, anti-IL12/23, JAK inhibitor, S1PR modulator. Able to provide written informed consent and understand and comply with the requirements of the study.  Exclusion Criteria:  WOCBP and men with female partners of childbearing potential who are unwilling or unable to use two highly effective methods of contraception to avoid pregnancy for the entire study period and for up to 12 weeks after the last dose of study drug Diagnosis of Crohn's disease or indeterminate colitis Current evidence of fulminant colitis, toxic megacolon, bowel perforation, total proctocoloectomy or partial colectomy Current or impending need for colostomy or ileostomy Surgical bowel resection within 3 months before screening Past or current evidence of definite low-grade or high-grade colonic dysplasia not completely removed Subjects in the opinion of the investigator are at an unacceptable risk for participation in the study Subjects who meet the protocol criteria for important laboratory exclusion criteria