A Phase 3 Study to Investigate the Efficacy and Safety of SHR0302 With Moderately to Severely Active Ulcerative Colitis

Inclusion Criteria: Inclusion Criteria for Part 1

1. Male or female subjects must be at least at ≥18 and ≤75 years of age
2. Subject has at least a three-month history of Ulcerative Colitis diagnosis atbaseline.
3. Subject has active Ulcerative Colitis with a 9-point modified Mayo score of ≥ 5 atbaseline, with an endoscopic subscore of ≥ 2
4. Subject is deemed by the physician as having inadequate response, loss of response orintolerance to at least one conventional treatment (oral 5-ASA, immunosuppressants orcorticosteroids), or was previously exposed to anti-TNF therapy (e.g., infliximab,adalimumab) or other biological treatment (e.g., vedolizumab) having Discontinued the treatment for:

• Infliximab: a minimum of 8 weeks prior to baseline.
• Adalimumab: a minimum of 10 weeks prior to baseline.
• Ustekinumab: a minimum of 14 weeks prior to baseline.
• Vedolizumab: a minimum of 17 weeks prior to baseline. Inclusion Criteria for Part 2 1. Subject has completed Part 1 and achieved clinicalresponse at week 8 Inclusion Criteria for Part 3

1. Subject has completed the 8-week Part 1 and was classified as not meeting clinicalresponse criteria. OR Subject has discontinued treatment early in the Maintenance phase dueto disease worsening OR Subject has completed the Maintenance phase. Study Exclusion Criteria for Part 1

Exclusion Criteria:

1. Subject has a diagnosis of indeterminate colitis, or clinical findings suggestive ofCrohn'sDisease.
2. Subject with Ulcerative Colitis, which is confined to a proctitis (distal 15 cm orless).
3. Treatment naïve subject diagnosed with Ulcerative Colitis (without previous exposureto any of the following therapies for UC treatment: oral 5-ASA, corticosteroids,immunosuppressants, or biological treatments).
4. Subject is displaying clinical signs of ischemic colitis, fulminant colitis or toxicmegacolon.
5. Subject had previous surgery as a treatment for Ulcerative Colitis or likely torequire surgery during the study period.
6. Subject has evidence of pathogenic bowel infection. Subjects had Clostridium difficileor other intestinal infection within 30 days of screening endoscopy or test positiveat screening for C.difficile toxin or other intestinal pathogens.
7. Subject currently has or has a history of active tuberculosis (TB) or latent TBinfection.
8. Subject is receiving any of the following therapies:

• Azathioprine/6-mercaptopurine, methotrexate, thalidomide within 7 days prior tobaseline.
• Cyclosporine, mycophenolate, tacrolimus within 4 weeks prior to baseline.
• Interferon therapy within 8 weeks prior to baseline.
• Intravenous corticosteroids or rectally administered formulation ofcorticosteroids or 5- ASA within 2 weeks prior to baseline.

9. Subject had any prior treatment with lymphocyte-depleting agents/therapies (such asCamPath® [alemtuzumab], alkylating agents [e.g., cyclophosphamide or chlorambucil],total lymphoid irradiation, etc.). Subjects who have received rituximab or otherselective B lymphocyte depleting agents are eligible if they have not received suchtherapy for at least 1 year prior to baseline.
10. Subject has previously received JAK inhibitors, such as tofacitinib, baricitinib,upadacitinib, filgotinib.
11. Subject with evidence of clinically relevant laboratory abnormalities which may affectsubject safety or interpretation of study results at screening
12. Subject has a screening 12-lead ECG that demonstrates clinically relevantabnormalities
13. Subject currently has or had:

• A clinically significant infection within 1 month of baseline (e.g., thoserequiring hospitalization or parenteral antimicrobial therapy or haveopportunistic infections).
• A history of more than one episode of herpes zoster, or disseminated zoster (single episode).
• Any infection otherwise judged by the investigator to have the potential forexacerbation by participation in the study.
• Any infection requiring antimicrobial therapy within 2 weeks of screening.

14. Subject has current immunization with any live virus vaccine or history ofimmunization with any live virus vaccine within 8 weeks of baseline.
15. Subject with a first-degree relative with a hereditary immunodeficiency.
16. Subject with a history of any lymphoproliferative disorder (such as EBV-relatedlymphoproliferative disorder, as reported in some subjects on other immunosuppressivedrugs), history of lymphoma, leukemia, multiple myeloma, or signs and symptoms thatare suggestive of current lymphatic disease.
17. Subject has any condition possibly affecting oral drug absorption e.g., gastrectomy,or clinically significant diabetic gastroenteropathy, or certain types of bariatricsurgery such as gastric bypass. (Procedures such as gastric banding, gastric balloonthat simply divide stomach into separate chambers, are NOT exclusionary.) Subject hasundergone significant trauma or major surgery within 4 weeks of baseline.
18. Women who are pregnant or lactating, or planning pregnancy while enrolled in thestudy. Male who plan to donate sperm during the study and within 30 days after thelast dose of study drug.
19. Subject who has a history of alcohol or drug abuse with less than 6 months ofabstinence prior to baseline that in the opinion of the investigator will precludeparticipation in the study.
20. Subject with malignancies or with a history of malignancies with exception ofadequately treated or excised non-metastatic basal cell or squamous cell cancer of theskin.
21. Subject infected with human immunodeficiency virus (HIV) or hepatitis B or C viruses.
22. Subject has received any investigational drug or device within 3 months, or 5half-lives (if known) prior to baseline.
23. Subject is receiving or expected to receive prohibited concomitant medication(s) inthe 4 weeks prior to the first dose of study drug and through follow-up visit.
24. Any other condition which in the opinion of the investigator would make the subjectunsuitable for inclusion in the study.
25. Subject with historical or current evidence of clinically significant cardiovascular,neurological, psychiatric, renal, hepatic, immunological, gastrointestinal,urogenital, nervous system, musculoskeletal, skin, sensory, endocrine (includinguncontrolled diabetes or thyroid disease), or hematological abnormalities that areuncontrolled. Significant is defined as any disease that, in the opinion of theInvestigator, would put the safety of the subject at risk through participation, orwhich would affect the efficacy or safety analysis if the disease/conditionexacerbated during the study.
26. Subject with a history of thromboembolic events, including deep vein thromboses (DVT),pulmonary embolism (PE), and those with known inherited conditions that predispose tohypercoagulability. Study Exclusion Criteria for Parts 2 and 3
27. Subject with any clinically significant condition at the end of 8-week Inductiontreatment from Part 1 Induction phase, and Part 2 Maintenance Phase that in theopinion of investigator, would put the safety of the subject at risk throughparticipation, or which would affect the efficacy or safety analysis.
28. Subject who, in the opinion of the investigator or sponsor, is unlikely to becooperative or able to comply with study procedures, or any other condition which inthe opinion of the investigator would make the subject unsuitable for inclusion.