• Adult participants 18 to 75 years old, inclusive, at Screening.

• Willing to provide informed consent and to be compliant with the schedule of study visits and protocol assessments.

• Diagnosis of UC established at least 12 weeks prior to Screening by standard clinical and endoscopic evidence and corroborated by a histopathology report.

• Moderately to severely active UC, at the time of Screening, defined as a modified Mayo Score (mMS) of 5-9, inclusive, with an endoscopic subscore of ≥ 2 (from central reading), and a rectal bleeding (RB) subscore of ≥ 1.

• Evidence of active UC, extending proximal to the rectum with ≥ 15 cm of involved colon.

• Stable doses of concomitant medications:

∙ Subjects receiving oral corticosteroids for the treatment of UC must be on a stable dose of ≤ 20 mg/day (prednisone or equivalent), or ≤ 9 mg/day budesonide. This dose must be stable from the initial Screening visit until the end of the Induction Phase.

‣ Subjects receiving oral 5-aminosalicylic acid (5-ASA) must be on a stable dose from the initial Screening visit until the end of study.

‣ Subjects receiving immunosuppressants (azathioprine, 6-mercaptopurine \[6-MP\] or methotrexate) must be on a stable dose for 4 weeks prior to Screening until the end of study treatment. Subjects taking methotrexate are also advised to take folic acid 5 mg/week (or equivalent) if there is no contraindication.

‣ Subjects receiving probiotics must be on a stable dose from the initial Screening visit until the end of study.

‣ Subjects receiving an anti-diarrhetic must be on a stable dose for ≥ 2 weeks prior to Screening until the end of study.

• Previous treatment with one or two advanced therapy that demonstrated an inadequate response and/or loss of response.

• Negative pregnancy test during Screening and Day 1 (V0) in females of childbearing potential.

• Females with reproductive potential must be sexually abstinent or be willing to use a highly effective method of contraception from study start to ≥ 3 months after the final dose of the study drug. Highly effective methods of contraception include:

∙ Hormonal contraceptives (e.g., combined oral contraceptives, patch, vaginal ring, injectables, and implants); male partner should use a condom;

‣ Intrauterine device or system; or

‣ Surgical sterilization or partner sterile (must have documented proof).

⁃ Male subjects must be either surgically sterile (must have documented proof), agree to be sexually abstinent, or use a double-barrier method of birth control (e.g., condom and diaphragm with spermicide, condom with cervical cap and spermicide) from first study drug administration to ≥ 3 months after the final dose administration.

⁃ Male subjects must agree to refrain from donating sperm from first study drug administration to ≥ 3 months after final dose administration.