Study of OSE-127 vs Placebo in Patients With Moderate to Severe Active Ulcerative Colitis

Inclusion Criteria:

1. Provision of signed and dated informed consent document indicating that the patienthas been informed of all the pertinent aspects of the trial prior to enrollment
2. Willingness and ability to comply with scheduled visits, treatment plans, laboratorytests, and other study procedures
3. Willingness to refrain from live or attenuated vaccines during the study and for 12weeks after last dose
4. Male or female 18 to 75 years of age, inclusive
5. Diagnosis of moderate to severe active UC made at least 3 months before the screeningvisit. The diagnosis of UC must have been confirmed by endoscopy, with a minimalextent of 15 cm from anal margin and histology (Moderate to severe active UC isdefined by a modified Mayo score between 4 and 9, inclusive. The modified Mayo scoreis defined by the addition of the rectal bleeding subscore, the stool frequencysub-score, and the endoscopic sub-score. Thus, to be included, a patient must have thefollowing:
6. a rectal bleeding score ≥ 1,
7. a stool frequency score ≥ 1 (sub-score calculated before bowel preparation), and
8. an endoscopic sub-score ≥ 2
9. No previous biologic therapy (i.e., TNF antagonists, vedolizumab or ustekinumab) andprior or current UC documented medication history that includes at least 1 of thefollowing:
10. Corticosteroids
11. Immunosuppressive agents OR Previous or current biologic therapy

Exclusion Criteria:

1. Stoma, proctocolectomy, or subtotal colectomy
2. Physician judgment that patient is likely to require any surgery for UC during thestudy duration, or double-blind phase duration at least
3. Evidence of fulminant colitis, toxic megacolon, or perforation
4. Current or recent (within 4 weeks prior to screening) hospitalization for UC careand/or treatment with IV steroids
5. The following laboratory results at screening:
6. Elevation at screening of aminotransferase (AST), alanine aminotransferase (ALT) > 3 × the upper limit of normal (ULN) or total bilirubin > 2 × ULN (unless due toGilbert's disease) or evidence of chronic liver disease
7. Platelet count < 100,000/mm3
8. Hemoglobin (Hgb) < 8.5 g/dL
9. Neutrophils < 1500/mm3
10. Lymphocytes < 800/mm3
11. Absolute white blood cell (WBC) count < 3000/mm3
12. Crohn's disease or indeterminate colitis or any other diagnosis not consisting with UC
13. History or evidence of incompletely resected colonic dysplasia or unconventionallesion at risk of colonic adenocarcinoma
14. Stool culture or other examination positive for enteric pathogen, includingClostridium difficile (C. diff) toxin. If positive, the patient should be treated andrescreening is allowed.
15. Men or women with childbearing potential not willing to use adequate birth controlduring the study. Adequate birth control includes surgical sterilization, intrauterinedevice, oral contraceptive, contraceptive patch, long-acting injectable contraceptive,partner's vasectomy, double-barrier method (condom, diaphragm with spermicide), orabstinence during study and 30 days following the last follow-up visit. Women ofchildbearing potential will enter the study after a negative pregnancy test.
16. Breastfeeding
17. Chronic use of nonsteroidal anti-inflammatory drugs (NSAIDs) from screening throughthe end of the study
18. Use of topical steroids and/or topical 5-aminosalicylic acid preparations within 2weeks before the screening visit (all such medications should be withdrawn at least 2weeks prior to the screening visit)
19. Use of antidiarrheals within 2 weeks before the screening visit (all such medicationsshould be withdrawn at least 2 weeks prior to the screening visit)
20. Treatment with azathioprine, 6-MP, methotrexate (MTX), cyclosporin, tacrolimus,sirolimus, leflunomide and/or mycophenolate mofetil within 4 weeks before thescreening visit (all such medications should be withdrawn at least 4 weeks prior tothe screening visit)