['ulcerative colitis']
['ser-287', 'placebo', 'placebo pre-treat', 'vancomycin pre-treat']

        Inclusion Criteria:

          -  Ulcerative colitis diagnosed by routine clinical, radiographic, endoscopic and
             pathologic criteria (preferably confirmed by colonoscopy and pathology records within
             last 2 years or if unavailable, will need approval by medical monitor) Active
             mild-moderate UC as determined by sigmoidoscopy within approximately 3 days of
             randomization to study

        Exclusion Criteria:

          1. Fever > 38.3°C

          2. Known or suspected toxic megacolon and/or known small bowel ileus

          3. Known history of Crohn's disease

          4. Subjects with serum albumin <2.5 g/dL at baseline

          5. CMV polymerase chain reaction (PCR) positive from blood plasma at screening

          6. Known stool studies positive for ova and/or parasites or stool culture within the 30
             days before enrollment

          7. Subjects on cyclosporine or triple immunosuppression, Triple immunosuppression will
             include any three of the following classes of drugs taken in combination: steroids
             (i.e., prednisone/budesonide/budesonide MMX), immunosuppressant (i.e.,
             methotrexate/azathioprine/6-mercaptopurine), and/or other immunosuppressant (i.e.,
             tacrolimus, cellcept).

          8. Biologic medication (infliximab/ adalimumab/ golimumab/
             certolizumab/vedolizumab/ustekinumab/natalizumab) use within 3 months prior to
             screening

          9. Known active malignancy except for basal cell skin cancer, squamous cell skin cancer

         10. Subjects with previous colectomy, ostomy, J-pouch, or previous intestinal surgery
             (excluding cholecystectomy, appendectomy)

         11. Subjects with known history of celiac disease or gluten enteropathy

         12. Subjects with Clostridium difficile positive stool at Screening Visit

         13. Antibiotic use within the prior 1 month before randomization

         14. Expected to receive antibiotics within 8 weeks of signing the Informed Consent Form
             (ICF) (i.e., for planned/anticipated procedure)

         15. Received an investigational drug within 1 month before study entry

         16. Received an investigational antibody or vaccine within 3 months before study entry

         17. Previously enrolled in a SER-109/SER-287 study

         18. Received an FMT within the last 6 months

         19. Subjects with anatomic or medical contraindications to flexible sigmoidoscopy,
             including but not necessarily limited to toxic megacolon, gastrointestinal (GI)
             fistulas, immediate post-operative status from abdominal surgery, severe coagulopathy,
             large or symptomatic abdominal aortic aneurysm, or any subject where study physician
             deems subject at significant risk of complications of flexible sigmoidoscopy

         20. Unable to stop steroid enemas or suppositories or mesalamine enemas or suppositories
             before screening visit

         21. Unable to stop opiate treatment unless on a stable dose and no increase in dose
             planned for the duration of the study

         22. Unable to stop probiotics before screening visit

         23. Concurrent intensive induction chemotherapy, radiotherapy, or biologic treatment for
             active malignancy (subjects on maintenance chemotherapy may only be enrolled after
             consultation with medical monitor)

         24. Known allergy or intolerance to oral vancomycin

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