A Study of AC-101 Tablets in Patients With Ulcerative Colitis

Inclusion criteria

• Male or female participants aged ≥ 18 and ≤ 75 years；
• Must sign the Informed Consent Form and be willing to participate in the study.
• Diagnosis of UC confirmed at least 3 months prior to screening, supported by both endoscopic and histological evidence.
• Evidence of UC extending ≥ 15 cm from the anal verge as assessed by colonoscopy. Moderately to severely active UC, defined as a modified Mayo Score of 5 to 9, with an Endoscopic Subscore ≥ 2.
• Documented failure to prior advanced therapies or prior conventional therapies
• Female participants must meet either criterion a) or b), and male participants must meet criterion c) to be eligible for enrollment:

• Female participants of non-childbearing potential;
• Female participants of childbearing potential who are not pregnant must agree to use highly effective contraception during the treatment period and for at least 1 month after the last dose of study treatment;
• Male participants with a pregnant or non-pregnant female partner of childbearing potential must agree to use contraception during the treatment period and for at least 1 month after the last dose of study treatment.

Exclusion criteria

• Severe extensive colitis.
• Hospitalization for exacerbation of UC within 12 weeks prior to screening.
• History of gastrointestinal dysplasia, or presence of dysplasia detected in any biopsy performed during the screening colonoscopy.
• Adenomatous colonic polyps that have not been removed prior to study enrollment.
• Diagnosis of indeterminate colitis, microscopic colitis, ischemic colitis, or Crohn's disease, or clinical findings suggestive of Crohn's disease.
• Positive stool pathogen test or positive test for Clostridioides difficile toxin at screening.
• Presence of an ostomy or fistula.
• Risk of tuberculosis .
• History of current or prior serious opportunistic infection.
• Presence of active or chronic recurrent infection.
• Patients with any of the following hepatitis B screening results:

Acute or chronic hepatitis B infection; or Positive hepatitis B virus (HBV) test at screening (HBsAg positive); or HBsAg negative, hepatitis B core antibody (HBcAb) positive, with detectable HBV-DNA.

• Current hepatitis C infection, or positive hepatitis C virus (HCV) test at screening.
• Human immunodeficiency virus (HIV) infection/acquired immunodeficiency syndrome , or positive HIV antibody test at screening.
• Syphilis, or positive syphilis-specific antibody test at screening.
• Treatment with advanced therapies for UC within 8 weeks or 5 half-lives prior to randomization.
• Treatment with intravenous corticosteroids within 2 weeks prior to randomization.
• Treatment with leukocyte apheresis within 12 weeks prior to randomization.
• Treatment with intravenous immunoglobulins or plasmapheresis within 12 weeks prior to randomization.
• Treatment with lymphocyte-depleting therapy.
• History of fecal microbiota transplantation.
• Vaccination with live attenuated vaccines within 4 weeks prior to randomization, or a plan to receive such vaccines during the study period.
• Requirement for parenteral nutrition.
• History of myocardial infarction, acute stroke, transient ischemic attack, thromboembolic events, clinically significant arrhythmia, unstable angina, coronary artery bypass grafting, or severe pulmonary heart disease/pulmonary hypertension within 3 months prior to randomization, which, in the investigator's judgment, may affect the evaluation of study results.
• Presence of any other unstable or uncontrolled cardiovascular, pulmonary, hepatic, renal, gastrointestinal, genitourinary, hematological, coagulation, immunological, endocrine/metabolic, neurological/psychiatric, or other medical condition that, in the investigator's judgment, may interfere with the study results.
• Known history of immunodeficiency; other acquired or congenital immunodeficiency disorders; or history of organ transplantation.
• History of malignancy within 5 years prior to screening, with the exception of adequately treated carcinoma in situ of the cervix, or basal cell or squamous cell carcinoma of the skin.
• Female patients who are pregnant, lactating, or have a positive serum pregnancy test at screening.
• Any other condition that, in the investigator's opinion, may affect the patient's safety or compliance, or preclude the patient from completing the study.