Hemorrhagic Proctocolitis Clinical Trials

• Voluntarily participate in the study and sign the informed consent form (ICF);

• Males or females aged ≥18 and ≤75 years at the time of signing the ICF;

• Diagnosed with UC for ≥3 months at the time of signing the ICF, with the diagnosis of UC supported by clinical manifestations and colonoscopy evidence, and confirmed by a histopathology report (pre-randomization colonoscopy and histopathology examination are acceptable as supporting evidence);

• Active UC, defined as: a modified Mayo score (including hematochezia, stool frequency, and endoscopy findings) of 4-9, with an endoscopy subscore of ≥2 (confirmed by central reading) and a hematochezia subscore of ≥1 in the Mayo score;

• At pre-randomization colonoscopy, the extent of UC lesions extends beyond the rectum (active disease ≥15 cm from the anal verge on colonoscopy, confirmed by central reading);

• Participants must have had an inadequate response or intolerance to at least one of the following UC treatments (inadequate response is defined as that the participant has previously discontinued the corresponding drug due to lack of efficacy as judged by the investigator; intolerance is defined as that the participant has previously discontinued the drug due to adverse reactions as judged by the investigator): oral sulfasalazine (SASP) and/or 5- aminosalicylate (5-ASA); oral corticosteroids; azathioprine or 6- mercaptopurine; marketed anti-tumor necrosis factor-α (TNF-α) agents: infliximab or adalimumab, etc.; vedolizumab; marketed JAK inhibitors: tofacitinib, upadacitinib, etc.; marketed interleukin 12/23 (IL-12/23) inhibitors: ustekinumab, etc.; selective sphingosine-1-phosphate (S1P) receptor modulators: etrasimod, etc.; sulfasalazine (SASP) and/or 5- aminosalicylate (5-ASA); oral corticosteroids; azathioprine or 6- mercaptopurine; marketed anti-tumor necrosis factor-α (TNF-α) agents: infliximab or adalimumab, etc.; vedolizumab; marketed JAK inhibitors: tofacitinib, upadacitinib, etc.; marketed interleukin 12/23 (IL-12/23) inhibitors: ustekinumab, etc.; selective sphingosine-1-phosphate (S1P) receptor modulators: etrasimod, etc.;

• If participants are currently using the following drugs to treat UC, they must also meet the following requirements:

‣ Glucocorticoid therapy: oral prednisone ≤20 mg/d (or equivalent drug dose) or budesonide ≤9 mg/d or beclomethasone ≤5 mg/d, with a stable dose for at least 2 weeks before the screening colonoscopy;

⁃ Aminosalicylate preparations: oral sulfasalazine and/or 5- aminosalicylate must be stable for at least ≥2 weeks before the screening colonoscopy and must remain stable during the study;

• Throughout the entire study period from the signing of the ICF and for 3 months after the last dose, female participants of childbearing potential and male participants who have not undergone vasectomy must comply with the specified contraception requirements.