This is a Phase 2, multicenter, randomized, double-blind, placebo-controlled study to evaluate the efficacy, safety, and pharmacokinetics of IPG11406, an investigational oral drug, in adult patients with moderately to severely active ulcerative colitis (UC).

UC is a chronic inflammatory bowel disease that causes long-term inflammation and ulcers in the colon, leading to symptoms like frequent diarrhea, rectal bleeding, abdominal pain, and urgent bowel movements. IPG11406 works by targeting the GPR183 receptor, which helps reduce immune cell migration to the inflamed colon, potentially easing UC symptoms and promoting mucosal healing.

In this study, 144 eligible adult patients will be randomly assigned (1:1:1:1) to receive one of three doses of IPG11406 (10 mg, 20 mg, or 40 mg, taken twice daily by mouth) or a matching placebo for 12 weeks. Neither the patients nor their study doctors will know who is receiving the active drug or placebo to ensure unbiased results.

The main goal of the study is to see how well IPG11406 works to achieve clinical remission (reduced or no UC symptoms) at 12 weeks, measured by the modified Mayo Score. Additional goals include evaluating other efficacy measures (such as clinical response, endoscopic remission, and histological improvement), long-term safety, how the drug is absorbed and processed in the body (pharmacokinetics), and changes in inflammatory biomarkers like fecal calprotectin and hsCRP.

All participants will undergo regular study visits for safety assessments, including physical exams, laboratory tests, colonoscopies, and monitoring for any side effects throughout the 12-week treatment period and a 2-week follow-up. This study will help determine the optimal dose of IPG11406 for future larger clinical trials in UC patients.

Inclusion Criteria:1.Males and females aged ≥18 and ≤70 years at randomization 2.Diagnosis of moderately to severely active UC with mMS 5-9, mMES 2-3, SF ≥1, RB ≥1 3.Documented UC diagnosis for ≥3 months prior to screening 4.Inadequate response, loss of response, or intolerance to conventional or advanced therapies 5.Stable background UC therapy for specified intervals before baseline 6.Willingness to use effective contraception throughout the study and for 1 month after last dose 7.Ability to comply with study visits and procedures 8.Signed informed consent

Exclusion Criteria:

1. Diagnosis of indeterminate colitis or Crohn's disease
2. History of bowel surgery for UC or likely requiring surgery during study
3. Ulcerative proctitis only (distal ≤15 cm)
4. History of colonic dysplasia or adenomatous polyps not completely removed
5. Active intestinal infection (including C. difficile) within 30 days
6. HBV, HCV, HIV, or untreated latent/active TB
7. Significant cardiovascular disease or uncontrolled hypertension
8. Clinically significant abnormal ECG or QTcF prolongation
9. Treatment with prohibited medications within specified windows
10. Abnormal laboratory values at screening
11. History of malignancy (except non-melanoma skin cancer or in situ cervical cancer)
12. Pregnancy, breastfeeding, or plan to become pregnant
13. Alcohol or drug abuse within 6 months
14. Prior participation in an IPG11406 study
15. Other conditions deemed inappropriate by the investigator